Comparison of the electronic properties of diarylamido-based PNZ pincer ligands: Redox activity at the ligand and donor ability toward the metal

Article

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Comparison of the Electronic Properties of Diarylamido-Based PNZ

Pincer Ligands: Redox Activity at the Ligand and Donor Ability

Toward the Metal

Jillian J. Davidson,^†Jessica C. DeMott,^†Christos Douvris,^∥,‡Claudia M. Fafard,^§,‡Nattamai Bhuvanesh,^†

Chun-Hsing Chen,^⊥,‡David E. Herbert,^#,†Chun-I Lee,^†Billy J. McCulloch,^†Bruce M. Foxman,^‡

and Oleg V. Ozerov*^,†

^†Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77842, United States

^‡Department of Chemistry, Brandeis University, MS 015, 415 South Street, Waltham, Massachusetts 02454, United States

S

* Supporting Information

ABSTRACT: This paper presents the synthesis and characterization of

a series of pincer ligands and their Ni, Pd, Pt, and Rh complexes. The

ligands under examination are based on a diarylamine which is modiﬁed

either by two phosphino (-PR₂) substituents in the ortho-positions (PNP

ligands) or by a combination of a phosphino and an iminyl (−CHNX)

substituent (PNN ligands). The ligands can be broken down into three

groups: (a) C_2v-symmetric PNP ligands with identical side −PR₂donors,

(b) C_s-symmetric PNP′ ligands with diﬀerent −PR₂side donors, and (c)

PNN ligands containing a −PⁱPr₂side donor. All of the ligands under

study readily formed square-planar complexes of the types (PNZ)PdCl,

(PNZ)Pd(OAc), and (PNZ)RhCO, where PNZ is the corresponding

anionic tridentate pincer ligand. For select PNP ligands, (PNP)NiCl and

(PNP)PtCl were also studied. The (PNZ)MCl complexes (M = Ni, Pd, Pt) underwent quasireversible oxidation in cyclic

voltammetry experiments. Based on the close similarity of formal potentials for Ni, Pd, and Pt analogs, and based on the previous

literature evidence, these oxidation events are ascribed primarily to the PNZ ligand, and the E_1/2values can be used to compare

the ease of oxidation of diﬀerent ligands. A (PNP)PdCl complex containing methoxy substituents para- to the central nitrogen

underwent two quasireversible oxidations. Two mono-oxidized complexes were isolated and structurally characterized in

comparison to their neutral analog, revealing minimal changes in the bond distances and angles. Several other neutral complexes

were also structurally characterized. The carbonyl stretching frequency in (PNZ)RhCO complexes was used to gauge the

donating ability of the various pincer ligands toward the metal. Comparison of E_1/2values for (PNZ)PdCl and ν_COvalues for

(PNZ)RhCO revealed that the two are not consistently correlated across all the studied ligands and can be tuned to diﬀerent

degrees through judicious ligand alteration.

center. Common redox noninnocent ligand scaﬀolds include

dithiolenes,⁴semiquinones,⁵diimines,⁶⁻⁹amido pheno-

lates,¹⁰⁻¹²and terpyridines.¹³Redox noninnocent ligands are

seen as a promising tool in enabling two-electron reactivity in

the 3d metal series, a process necessary for organometallic

catalysis.¹⁴Arguably the most prominent example of this

approach is the use of Fe complexes of 2,6-bis(imino)pyridine

ligands (A, Figure 1), which catalyze ethylene polymer-

ization,^15,16[2 + 2] cycloadditions;¹⁷enyne cyclizations;¹⁸

hydrogenation of oleﬁns, alkynes, and aryl azides;¹⁹and

hydrosilylation.²⁰Ligand A is an example of a noninnocent

ligand capable of undergoing reduction vs its closed-shell

(neutral) form. As a tridentate, meridionally chelating ligand, it

can also be characterized as a pincer ligand.²¹Pincer ligands

that are oxidizable have largely been based on the diarylamido

INTRODUCTION

■

The reactivity of a metal complex as a whole is derived from the

interactions between the metal center and its surrounding

ligands. In the traditional approach, the steric and electronic

nature of the ancillary ligands is taken advantage of to modulate

the reactivity at the metal center, but the ancillary ligands

themselves remain “spectators”¹and preserve their connectiv-

ity, composition, and charge. Recently, another approach to the

utilization of supporting ligands has emerged in which they are

designed to remain bound to the metal center but undergo

chemical changes over the course of reactions. These ligands

are often referred to as noninnocent and assist the metal center

in carrying out desired transformations, most commonly by

accepting or losing protons²or electrons. Redox-active

noninnocent ligands have attracted signiﬁcant attention.³

These ligands provide a site other than the metal center for

redox events to occur, serve as electron or hole reservoirs, and

can be used to modify the electronic properties of the metal

Received: December 22, 2014

A

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Figure 1. Redox active pincer ligands denoted by their three donor atoms and showing the charge of the closed-shell form.

Figure 2. Generic representation of complexes of pincer ligands under study in this work.

backbone. Heyduk has reported the NNN^22,23(B) and ONO²⁴

(C) redox noninnocent trianionic ligands (Figure 1), the

former of which promotes catalytic nitrene transfer by

complexes of a redox-inactive d⁰metal.²²Our own group, in

collaboration with Nocera et al.,²⁵as well as Mindiola et al.

investigated the redox noninnocence of the PNP (D) ligand,²⁶

while Vicic et al. reported on the noninnocence of [NNN]⁻

pincer ligands such as E.^27,28

Owing to the convenient modularity of the diarylamido

scaﬀold, a large number of derived pincer ligands have been

reported, including various PNP,²⁹⁻³¹SNS,³²NNN,³³and

PNN ligands.³⁴In this report, we aimed to analyze an array of

diarylamido-based pincer complexes in order to systematically

examine the eﬀects of various substituents on the redox

properties and on the overall donating ability of the pincer

ligand toward the metal in group 10 and rhodium complexes.

Analysis of three classes of ligands (Figure 2) is presented: C_2v

symmetric PNP pincer ligands (contain two identical

phosphine arms), C_ssymmetric PNN ligands, and C_s

symmetric PNP′ ligands (contain two diﬀerent phosphine

arms). The PNP′ ligands containing phosphines substituted

with ﬂuorinated alkoxy groups were inspired by the reports of

Milstein et al.,³⁵Roddick et al.,³⁶and van Koten et al.³⁷

describing aryl(bisphosphine) PCP pincer ligands with

electron-withdrawing substituents on the phosphorus atoms.

RESULTS AND DISCUSSION

■

Synthesis of C_2vSymmetric PNP Ligands. PNP ligands

can be prepared in their NH form (i.e., 1-H, 2-H,³⁸3-H^29a) or

the NMe form (i.e., 4-Me, 5-Me^29c). We have previously

reported that N-methylated PNP ligands with two PⁱPr₂arms

can give rise to group 9 and 10 PNP complexes via N−Me

cleavage at the metal center.^29dThe synthesis of the new ligand

1-H closely followed our previous syntheses of 2-H and 3-H.

Trilithiation of a common precursor A with three equivalents of

n-butyllithium followed by reaction with three equivalents

ClPEt₂yielded 1-H as a yellow oil upon hydrolytic workup

1

(Scheme 1). Analysis of the oil by H NMR spectroscopy

revealed that it was a mixture that contained an 87%

composition of 1-H; however, the crude ligand was adequate

for the synthesis of 1-PdCl (vide infra) without further

puriﬁcation.

The preparation of 4-Me was carried out analogously to the

synthesis of 5-Me. Buchwald-Hartwig coupling of p-anisidine

B

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Scheme 1. Synthetic Routes to C_2vSymmetric Ligands

Scheme 2. Synthetic Routes to C_sSymmetric Pincer Ligands

and p-bromoanisole produced bis(p-methoxyphenyl)amine

(B). Ortho-bromination of B with two equivalents of N-

bromosuccinimide followed by N-methylation gave the key

precursor D. The addition of two equivalents of n-butyllithium

and subsequent quenching with ClPⁱPr₂gave 4-Me in a 93%

yield.

Synthesis of C_sSymmetric PNP and PNN Ligands. Our

syntheses of the C_s-symmetric PNP and PNN ligands (Scheme

2) rely on the conveniently accessible common precursor F. Its

C

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preparation by selective lithiation/phosphination of A was

previously reported by our group in 2011 when we used it for

the synthesis of binucleating PNN ligands via G.³⁴The new

monomeric PNN ligands 7-H and 8-H were synthesized

analogously, via Schiﬀ-base condensation between G and a

primary amine (2,4,6-trimethylaniline or tert-butylamine) in the

presence of an acid catalyst (Scheme 1). 7-H and 8-H were

isolated as yellow solids in 71% and 87% yields, respectively.

6-H was produced by dilithiation of F with two equivalents

of n-butyllithium, followed by the addition of one equivalent of

ClPPh₂. Aqueous workup and recrystallization in a pentane/

toluene mixture yielded 6-H as a colorless solid with a

moderate yield of 62%. Our synthesis of 6-H closely follows the

synthesis of a related C_s-symmetric PNP′ ligand diﬀering from

6-H only in the absence of the Me groups para to the nitrogen

on the diarylamine backbone by Liang et al.³⁹6-H itself was

previously reported by Goldberg et al., but via a diﬀerent

synthetic approach.⁴⁰

The synthesis of 10-H and 11-H was envisaged to proceed

via alcoholysis of 9-H (Scheme 2). 9-H could not be

synthesized from F in the exact manner used for 6-H, where

dilithiation of F was followed by selective C-phosphination.

Instead, the synthesis of 9-H was carried out in a stepwise

manner. Deprotonation of F with one equivalent of n-

butyllithium, followed by N-phosphination with one equivalent

of ClP(NMe₂)₂, produced H. The net migration of the

P(NMe₂)₂group to the ortho-carbon of the aryl ring to give

9-Li was then observed upon the addition of a second

equivalent of n-butyllithium. Controlled protolysis of 9-Li with

triﬂuoroethanol occurs readily and can be monitored via the

disappearance of the yellow color of the reaction mixture. It is

imperative that only one equivalent of triﬂuoroethanol be

added to the reaction, because 9-H is susceptible to reaction

with excess triﬂuoroethanol. 9-H was isolated as a white

powder in a 78% yield. 10-H and 11-H were then formed by

treatment of 9-H with an excess of triﬂuoroethanol or

hexaﬂuoroisopropanol, respectively. 10-H was obtained in

greater than 98% yields as a colorless oil (>95% purity) upon

removal of the volatiles in vacuo. Isolation of 11-H by simple

exposure to a vacuum was not possible as the formation of side

products was evident by NMR spectroscopy. This was

circumvented by producing the ligand in situ in the presence

of excess hexaﬂuoroisopropanol and then reacting it directly

with a metal precursor (vide infra).

NMR Characterization of the Pincer Ligands. All of the

ligands synthesized above were characterized in solution by

multinuclear NMR spectroscopy. Table 1 reports the

corresponding chemical shifts of their ³¹P NMR and ¹H

NMR (N−H or N−Me) resonances, as well as the symmetry

observed by NMR spectroscopy at ambient temperature.

Ligands with two diﬀerent PR₂groups displayed no discernible

spin−spin coupling between the two inequivalent ³¹P nuclei.

The N−H hydrogens of PNP and PNN ligands resonate at

chemical shifts similar to those previously reported for similar

pincer ligands.^29c,34Other spectroscopic details for the

individual ligands can be found in the Supporting Information

of this report.

Synthesis of Group 10 Pincer Complexes. The PNP and

PNN ligands discussed in this publication are ideally suited to

support a variety of square-planar pincer complexes of the

general formula (PNZ)MX (M = Ni, Pd, Pt; Z = P, N; X =

OAc, Cl). Two forms of the ligand precursor (N−H or N−Me)

were used to introduce the amidoPNX ligand into the

Table 1. Select NMR Data for PNP and PNN Pincer Ligands

in C₆D₆Solution

symmetry in

1

pincer

δ, ³¹P NMR

−13.9 PⁱPr₂

δ, H NMR, NH

solution

F

7.69 (d, 10 Hz)

C_s

6-H

−16.1 PPh₂

−14.2 PⁱPr₂

−8.0 PⁱPr₂

Overlapping with Ar

signals

G

10.69 (s)

C_s

7-H

8-H

9-H

−5.8 PⁱPr₂

11.33 (s)

−7.3 PⁱPr₂

11.80 (s)

98.2 P(NMe₂)₂

−13.1 PⁱPr₂

8.55 (d, 8 Hz)

10-H

166.3

7.43 (d, 5 Hz)

NA

C_s

P(OCH₂CF₃)₂

−15.0 PⁱPr₂

215.2

P(OCH(CF₃)₂)₂

a

11-H

35.9 (PⁱPr₂)

−36.5 PEt₂

−18.9 PPh₂

−12.9 PⁱPr₂

1-H

2-H

3-H

7.87 (t, 8 Hz)

7.08 (t, 6 Hz)

8.23 (t, 8 Hz)

3.48 (s)

C_2v

4-Me −6.3 PⁱPr₂

5-Me −6.2 PⁱPr₂

3.27 (s)

a

11-H was not isolated; the spectra were collected in the reaction

mixture in hexaﬂuoroisopropanol.

coordination sphere of a group 10 metal. In the case of the

(PNZ)H form of the ligand, the direct reaction of the neutral

pincer with a group 10 metal chloride (Pd(COD)Cl₂, NiCl₂or

Pt(COD)Cl₂) or acetate (Pd(OAc)₂) precursor generated

(PNZ)MX. When a group 10 metal chloride was the reagent,

the addition of a base such as 2,6-lutidine was necessary to

remove the net HCl byproduct observed during the formation

of (PNZ)MCl. In the case of Pd(OAc)₂, the addition of a base

was not necessary, and the reaction produced (PNZ)PdOAc in

conjunction with an equivalent of acetic acid as a byproduct.

Compounds 1-PdCl, 3-PdCl,^29d6-PdCl,⁴⁰7-PdCl, 8-PdCl,

and 10-PdCl were prepared by stirring one equivalent of the

corresponding free ligand, with one equivalent of both 2,6-

lutidine and Pd(COD)Cl₂in diethyl ether. The colorless

solution immediately became red, demonstrating conversion to

the desired complexes with concomitant formation of a

lutidinium chloride salt and free 1,5-cyclooctadiene. 6-PtCl

and 3-PtCl^29dwere prepared in an analogous manner by

treatment of one equivalent of the corresponding free ligand

with one equivalent of both Pt(COD)Cl₂and 2,6-lutidine.

Compound 3-NiCl was synthesized by heating a benzene

solution of 3-H with one equivalent of anhydrous NiCl₂and

one equivalent of 2,6-lutidine for 18 h.^29dCompounds 2-

PdOAc,^29c6-PdOAc, 7-PdOAc, 8-PdOAc, 10-PdOAc, and 11-

PdOAc were all synthesized by stirring the corresponding free

ligand and Pd(OAc)₂in diethyl ether for 1 h. Each complex was

then isolated upon workup as a red solid. These reactions are

demonstrated graphically in Scheme 3.

In the case of (PNP)Me precursors 4-Me and 5-Me, the free

ligand was reacted with a group 10 metal chloride precursor

(Pd(COD)Cl₂, NiCl₂, or Pt(COD)Cl₂) to produce (PNP)MCl

and an equivalent of MeCl by N−C cleavage (Scheme 4).^29c4-

PdCl was prepared from the reaction of 4-Me and Pd(COD)-

Cl₂in toluene. The reaction mixture was heated in an 80 °C oil

bath for 3 days. Upon workup, 4-PdCl was isolated as a green

powder in a 41% yield. 4-PdOAc was synthesized from the

reaction of 4-Me and Pd(OAc)₂. 5-PdCl, 5-PtCl, and 5-NiCl

D

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Scheme 3. N−H Cleavage

This synthetic route was used to prepare compounds 2-PdCl,

8-PdCl, and 11-PdCl.

Scheme 4. N−Me Cleavage

Synthesis of (pincer)RhCO Complexes. (pincer)RhCO

complexes were all synthesized through the reaction of a pincer

ligand with 0.5 equiv of [Rh(COD)Cl]₂in the presence of one

equivalent of 2,6-lutidine under 1 atm of carbon monoxide

(Scheme 5). The (pincer)Rh-CO complexes 1-RhCO, 2-

RhCO, 3-RhCO,⁴¹4-RhCO, 5-RhCO,⁴¹6-RhCO, 7-RhCO, 8-

RhCO, 9-RhCO, 10-RhCO, and 11-RhCO were all synthe-

sized by the given route. These complexes were all isolated as

brown, yellow, or orange powders and have been fully

characterized by infrared and multinuclear NMR spectroscopy.

Characterization of Rh and Pd Complexes. Spectro-

scopic and experimental data associated with the pincer

complexes prepared in this work can be found in Table 2

and the Supporting Information of this work. It can be

were prepared by heating a benzene solution of 5-Me with

Pd(COD)Cl₂, Pt(COD)Cl₂, or NiCl₂for 18 h.^29dThe acetate

ligand in (PNZ)PdOAc can be conveniently exchanged for

chloride by reaction with Me₃SiCl, resulting in the formation of

(PNZ)PdCl and expulsion of one equivalent of Me₃SiOAc.

Scheme 5. Synthetic Route to (pincer)RhCO Complexes

E

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lower symmetry of the PNN pincer complexes suggests that the

“ﬂipping” of the two aromatic rings of the diarylamido

backbone past each other is signiﬁcantly slower in the PNN

pincer complexes than in the PNP systems. The symmetry of

these complexes is reﬂective of the symmetry observed for the

binucleating PNN ligand complexes previously reported.³⁴

Structural Analysis of Neutral Pincer Complexes in

the Solid State. The solid-state structures of 8-PdOAc, 8-

PdCl, 7-PdCl, 11-RhCO, and 6-RhCO, as obtained by single-

crystal X-ray diﬀractometry, are depicted in Figure 3, and select

metric parameters are tabulated in Table 3. In each case, the

environment about the metal center was found to be

approximately square planar. One notable feature is that the

pincer bite angles of complexes of ligands 7 and 8 are relaxed

relative to those observed for the more traditional PNP ligands

and closely resemble the bite angles observed in the

binucleating PNN type pincer ligand complexes.³⁴This

expansion is related to incorporation of a six-membered ring

containing the metal center. The angle is, however, not as

expanded as that observed for the carbazole-based NNN

complex, 12-PdCl, whose pincer bite angle was observed to be

ca. 176.8°.^33aThe bond distances of the donor atoms to Pd

resemble those of previously reported similar com-

pounds.^29c,33a,44

Table 2. NMR Features of (pincer)RhCO and (pincer)PdX

Complexes

³¹P NMR (C₆D₆) δ

J_Rh−P

(Hz)

J_P−P

(Hz)

complex

ppm

color

symmetry

2-RhCO 41.3 (d)

3-RhCO 61.5 (d)

4-RhCO 62.0 (d)

5-RhCO 61.5 (d)

6-RhCO 64.7 (dd, PⁱPr₂)

39.2 (dd, PPh₂)

135

131

130

131

133

134

130

154

163

orange

yellow

brown

yellow

C_2v

C_s

270

7-RhCO 76.3 (d)

8-RhCO 78.7 (d)

9-RhCO 130.9

red

C₁

C_s

red

315

346

340

yellow

(dd, P(NMe₂)₂)

58.7 (dd, PⁱPr₂)

123

190

125

10-

RhCO

190.7

red

C_s

(dd, P (OCH₂CF₃)₂)

60.1 (dd, PⁱPr₂)

207.5

11-

RhCO

195

127

(dd, P(OCH(CF₃)₂))

59.3 (dd, PⁱPr₂)

30.2 (s)

2-PdCl

4-PdCl

6-PdCl

green

red

C_2v

C_s

47.9 (s)

54.0 (d, PⁱPr₂)

25.9 (d, PPh₂)

70.3 (s)

438

The structure of 11-RhCO contains an apparent close

contact between the hydrogen of the hexaﬂuoroisopropoxy

group and Rh (d_Rh−H= 2.8143(5) Å). Such contacts between

C−H hydrogens and square-planar d⁸metal centers along the

axis perpendicular to the main coordination plane have been

analyzed previously and can be viewed as a form of hydrogen

bonding.⁴⁵This is especially compelling here, given that the

carbon of the C−H bond in question possesses three electron-

withdrawing substituents.

7-PdCl

8-PdCl

red

C₁

C_s

70.4 (s)

red

10-PdCl 159.2 (d,

P(OCH₂CF₃)₂)

545

525

purple

53.5 (d, PⁱPr₂)

11-PdCl 172.3 (d,

purple

C_s

P(OCH(CF₃)₂)₂)

57.9 (d, PⁱPr₂)

28.9 (s)

2-

PdOAc

red

C_2v

C_s

Solid-State Structures of 5-NiCl, [5-NiCl][CHB₁₁Cl₁₁], 4-

PdCl, and [4-PdCl][CHB₁₁Cl₁₁]. Chemical oxidation of 5-

NiCl with [Ag][CHB₁₁Cl₁₁] resulted in isolation of [5-

NiCl][CHB₁₁Cl₁₁] as brown crystals. The chemical oxidation

of 4-PdCl with [tris(4-bromophenyl)aminium][CHB₁₁Cl₁₁]

resulted in a rapid color change from purple to brown. The

neutral amine was extracted from the reaction mixture with

pentane. Slow diﬀusion of pentane into a dichloromethane

solution of crude [4-PdCl][CHB₁₁Cl₁₁] resulted in precip-

itation of orange crystals of [4-PdCl][CHB₁₁Cl₁₁] with a 95%

yield. Single crystals of 5-NiCl, [5-NiCl][CHB₁₁Cl₁₁], 4-PdCl,

and [4-PdCl][CHB₁₁Cl₁₁] were subjected to an X-ray

diﬀraction study (Figure 4) which allowed for the determi-

nation of the solid-state structures. In all four structures, the

geometry about the metal center is approximately square

planar. The carborane anion in [5-NiCl][CHB₁₁Cl₁₁] and [4-

PdCl][CHB₁₁Cl₁₁] is well separated from the cation and can

be considered noncoordinating. Close inspection of the metric

parameters of 5-NiCl and [5-NiCl][CHB₁₁Cl₁₁] (Table 4)

revealed little diﬀerence between the corresponding bond

angles and distances, apart from modest shortening of the Ni−

N and Ni−Cl bonds upon oxidation. Similarly, only minor

changes in the metric parameters were revealed upon close

inspection of the molecular structures of 4-PdCl and [4-

PdCl][CHB₁₁Cl₁₁] (Table 5). Szilagyi, Meyer, and Mindiola

undertook a thorough study of the analogous 3-NiCl and [3-

NiCl][OTf] employing NMR, EPR, UV−vis, and multiedge

XAS spectroscopy in addition to structural and theoretical

studies.²⁶They also found a similar close correspondence

between the structures of the neutral and cationic complexes

4-

PdOAc

48.1 (s)

6-

PdOAc

25.8 (d, PⁱPr₂)

55.8 (d, PPh₂)

65.6 (s)

412

517

7-

PdOAc

red

C₁

C_s

8-

PdOAc

66.3 (s)

red

11-

PdOAc

176.2 (d,

purple

P(OCH(CF₃)₂)₂)

58.6 (d, PⁱPr₂)

generally noted that metalation was accompanied by a

downﬁeld shift of the ³¹P{¹H} NMR signal. In the case of

2

the C_ssymmetric (PNP′)M complexes, large J_PPvalues were

observed, characteristic for spin−spin coupling between two

inequivalent trans-phosphines. These ²J_PPvalues were generally

greater for PdCl complexes (>400 Hz) than for RhCO

complexes (<350 Hz) and were largest for complexes of

ligands 10 and 11. The ﬂuoroalkoxy-substituted phosphorus

1

atoms also displayed the largest J_Rh−Pvalues.

The NMR spectra of 1-PdCl, 1-PdOAc, 2-PdCl, 2-RhCO,

3-PdCl, 3-PdOAc, 3-RhCO, 4-PdCl, 4-PdOAc, 4-PdOAc, and

4-RhCO were consistent with C_2vsymmetry on the NMR time

scale. 6-PdCl, 6-RhCO, 6-PdOAc, 9-RhCO, 10-PdCl, 10-

PdOAc, 10-RhCO, 11-PdCl, 11-PdOAc, and 11-RhCO exist

as C_ssymmetric complexes in solution. On the other hand, 7-

PdCl, 7-PdOAc, 7-RhCO, 8-PdCl, 8-PdOAc, and 8-RhCO are

consistent with C₁symmetry on the NMR time scale. The

F

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Figure 3. POV-Ray renditions⁴²of the ORTEP drawings⁴³(50% probability ellipsoids) of 8-PdOAc, 8-PdCl, 7-PdCl, 11-RhCO, and 6-RhCO

showing selected labeling. Hydrogen atoms are omitted for clarity. Top left: 8-PdOAc. Top center: 8-PdCl; dichloromethane of cocrystallization not

shown. Top right: 7-PdCl. Bottom left: 11-RhCO. Bottom right: 6-RhCO.

Table 3. Comparison of the Metric Parameters Associated with Group 10 Pincer Complexes

a

complex

d(M−X) (Å)

d(M−amido) (Å)

d(M−P₁) (Å)

d(M−P₂/N (imine)) (Å)

pincer bite angle (deg)

8-PdOAc

2.0554(3)

2.3157(7)

2.314(4)

2.002(3)

2.0258(19)

2.028(1)

2.018(2)

2.0201(18)

2.039(2)

1.989(5)

2.2348(13)

2.2914(4)

2.300(4)

2.138(3)

2.2914(4)

168.21(7)

b

3-PdCl

163.54(3)

6-PdCl

8-PdCl

7-PdCl

4-PdCl

2.278(4)

163.72(1)

2.3433(7)

2.3224(9)

2.3320(9)

2.3081(15)

2.2180(6)

2.2311(10)

2.2894(15)

2.1543(17)

170.99 (3)

171.24(5)

2.1022(18)

2.2840(15)

169.28(3)

c

12-PdCl

2.060(5)/2.065(5)

176.77(17)

bite angle (deg)

complex

d(M−CO) /d(C−O) (Å)

d(M−amido) (Å)

d(M−P₁) (Å)

d(M−P₂) (Å)

11-RhCO

6-RhCO

1.829(4)/1.148(5)

2.070(3)

2.3122(10)

2.2861(4)

2.2184(10)

2.2777(4)

160.00(3)

1.8180(16)/1.149(2)

2.0643(12)

162.045(14)

a

The term pincer bite angle refers to the angle formed by the two trans donor atoms of the pincer ligand and the metal center (e.g., P−M−P).

b

c

Taken from ref 29a. Taken from ref 33a.

and concluded that oxidation takes place at the ligand, with no

change in the oxidation state of Ni.

complexes can be varied within a range of about 0.6 V within

the framework of diarylamido-based PNZ ligands; this range

expands to almost 1 V (−0.27 to 0.69 V) if the carbazole-based

ligand (12) is included. The cyclic voltammograms of 1-PdCl,

2-PdCl, 3-PdCl 3-PtCl, 3-NiCl, 5-PdCl, 5-PtCl, 5-NiCl, 6-

PdCl, 6-PtCl, 7-PdCl, 8-PdCl, 10-PdCl, 11-PdCl, and 12-

PdCl exhibit quasi-reversible one-electron redox events. The

notable exception to this observation is the cyclic voltammo-

gram obtained for 4-PdCl, which is characterized as having two

quasi-reversible one-electron redox events. Further studies on

the noninnocent character of this ligand are in progress.

The data reported in Table 5 are consistent with the notion

of ligand-based redox events in (pincer)MCl complexes. This is

supported by three major observations. (1) The redox potential

appears to be aﬀected to a great degree by substituents

conjugated with the diarylamido π-system but are remote from

the metal center (vide infra). (2) Only small changes in the E_1/2

values are observed upon varying the identity of the metal (e.g.,

3-PdCl, 3-PtCl, and 3-NiCl).⁴⁷(3) Exchange of the diary-

lamido backbone for a carbazole unit has the largest eﬀect on

the redox potential. The ionization potential of carbazole is

considerably higher than that of diphenylamine, so the greater

diﬃculty in oxidizing 12-PdCl is to be expected.⁴⁸This is

Analysis of the Electronic Properties. Our investigation

of the electronic properties of the pincer ligands discussed

within this report was a two part endeavor where we (a)

obtained cyclic voltammograms for (pincer)MCl compounds of

group 10 metals and (b) measured the IR stretching

frequencies of (pincer)RhCO compounds. Our underlying

assumptions are that the redox potentials obtained from CV

studies report on the ease of oxidation of the pincer ligand

(reﬂects the “electron-richness” of the π-system of the ligand)

and that the ν(CO) IR stretching frequencies give insight into

the “electron-richness” of the metal center. The “electron-

richness” of the metal center is a direct reﬂection of the

donating ability of the pincer ligand toward the metal center.

The redox properties of 1-PdCl, 2-PdCl, 3-PdCl, 3-PtCl, 3-

NiCl, 4-PdCl, 5-PdCl, 5-PtCl, 5-NiCl, 6-PdCl, 6-PtCl, 7-

PdCl, 8-PdCl, 10-PdCl, 11-PdCl, and 12-PdCl were

investigated by cyclic voltammetry using 0.3 M [Bu₄N][PF₆]

as the electrolyte in dichloromethane. Ferrocene was used as an

internal standard, and the potentials reported in Table 6 are

referenced vs the ferrocene/ferrocenium redox couple.⁴⁶It is

noteworthy that the redox potentials of the (pincer)PdCl

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Article

Figure 4. POV-Ray renditions of ORTEP⁴³drawings (50% probability ellipsoids) of 5-NiCl (top left), [5-NiCl][CHB₁₁Cl₁₁] (top right), 4-PdCl

(bottom left), and [4-PdCl][CHB₁₁Cl₁₁] (bottom right). Selected bond distances (Å) and angles (deg) are reported in Tables 4 and 5. Hydrogen

atoms in all structures and cocrystallized toluene in the structure of 4-PdCl are omitted for clarity. For the structure of [4-PdCl][CHB₁₁Cl₁₁], only

one of the two crystallographically independent cation/anion pairs is shown.

Table 4. Metric Parameters Associated with 5-NiCl and [5-

NiCl][CHB₁₁Cl₁₁]

Table 6. E_1/2(V) for (pincer)MCl Complexes

Pd−Cl E/V vs Fc/

Pt−Cl E/V vs Fc/

Ni−Cl E/V vs Fc/

ligand

Fc⁺

metric (Å or deg)

5-NiCl

[5-NiCl][CHB₁₁Cl₁₁]

4

−0.27 (4-PdCl)

0.94

Ni−Cl (Å)

Ni−N (Å)

Ni−P(1) (Å)

Ni−P(2) (Å)

Cl−Ni−N (deg)

Cl−Ni−P(1) (deg)

N−Ni−P(1) (deg)

P(1)−Ni-P(2) (deg)

2.1841(7)

1.8947(19)

2.1746(7)

2.1998(7)

175.45(7)

92.62(3)

2.1520(7)

1.859(2)

3

−0.08 (3-PdCl)

−0.05 (1-PdCl)

−0.02 (6-PdCl)

0.04 (7-PdCl)

0.04 (2-PdCl)

0.06 (8-PdCl)

0.11 (5-PdCl)

0.15 (10-PdCl)

0.32 (11-PdCl)

0.69 (12-PdCl)

−0.11 (3-PtCl)

−0.05 (6-PtCl)

−0.19 (3-NiCl)

−0.01 (5-PdCl)

2.1910(7)

2.2158(7)

170.08(6)

91.66(3)

1

6

7

2

85.33(6)

87.13(6)

8

170.18(2)

168.48(3)

5

0.06 (5-PdCl)

10

11

12

Table 5. Selected Bond Distances (Å) and Angles (deg) from

the Solid-State X-ray Studies of 4-PdCl and [4-

PdCl][CHB₁₁Cl₁₁]

a

metric (Å or deg)

4-PdCl

[4-PdCl][CHB₁₁Cl₁₁]

dramatically diﬀerent from the PNP analogs. In addition, the

reported E_1/2value for the (NNN*)NiCl complex by Vicic et

al. (−0.12 V vs Fc/Fc⁺, NNN* = (2-Me₂NC₆H₄)₂N) is quite

close to that of 3-NiCl, reﬂecting the similarity of the

diarylamido backbones.²⁷

Pd1−N(1) (Å)

Pd1−P(1) (Å)

Pd1−P(2) (Å)

O−C_Ar

2.039(2)

2.2923(9)

2.2998(9)

1.393(3)

1.384(3)

2.3320(9)

84.78(7)

84.71(7)

169.28(3)

178.09(7)

94.00(4)

96.45(4)

2.013(6)

2.300(2)

2.2845(19)

1.354(8)

O−C_Ar

1.356(9)

A comparison of the ν(CO) frequencies of 2-RhCO, 3-

RhCO,⁴¹4-RhCO, 5-RhCO, 6-RhCO, 7-RhCO, 8-RhCO, 9-

RhCO, 10-RhCO, 11-RhCO, 13-RhCO,⁴⁹14-RhCO,⁵⁰15-

RhCO,⁵¹16-RhCO,⁵²17-RhCO,⁵³18-RhCO,^30aand 19-

RhCO³⁵allowed for an assessment of the donor strength of

the corresponding pincer ligands toward Rh via the extent of

backbonding to CO (see Table 7).⁵⁴It is important to note that

the magnitude of ν(CO) may be inﬂuenced by factors other

than the “electron-richness” of the metal center; such inﬂuences

have been discussed in the literature.^55,54dHowever, we expect

that within the conﬁnes of our study, various other inﬂuences

on the diﬀerences in ν(CO) are minimal because of the

similarity among the analyzed complexes. A survey of the

Pd1−Cl(1) (Å)

N1−Pd−P(1) (deg)

N1−Pd−P(2) (deg)

P1−Pd1−P(2) (deg)

N1−Pd1−Cl(2) (deg)

P1−Pd1−Cl(1) (deg)

P2−Pd1−Cl(1) (deg)

2.299(2)

83.11(17)

84.59(17)

166.39(8)

172.01(18)

97.99(7)

95.00(7)

a

For [4-PdCl][CHB₁₁Cl₁₁], metric parameters for only one of the

two crystallographically independent cations are given.

clearly not just a consequence of the nitrogenous side donors in

12: the redox potentials for 7-PdCl and 8-PdCl are not so

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Article

recognized as resulting in some of the most strongly π-

accepting PX₃ligands.⁵⁷Rh complexes of ﬂuoroalkoxy-

substituted phosphines have recently been used in the direct

coupling of arenes with aryl iodides⁵⁸and in designs relevant to

water and HX photosplitting catalysis.⁵⁹

Table 7

ligand

Pd−Cl E/V vs Fc/Fc⁺

ν(CO) (cm⁻¹

)

4

−0.27 (4-PdCl)

0.94

1933 (4-RhCO)

3

−0.08 (3-PdCl)

−0.05 (1-PdCl)

−0.02 (6-PdCl)

0.04 (7-PdCl)

0.04 (2-PdCl)

0.06 (8-PdCl)

0.11 (5-PdCl)

0.15 (10-PdCl)

0.32 (11-PdCl)

1938 (3-RhCO)

It is instructive to examine the relationship between ν(CO)

values for (pincer)RhCO complexes and E_1/2values for

(pincer)PdCl complexes as a function of the nature of the

pincer ligand. The numerical values are collected in Table 6,

and Figure 6 shows these values plotted in a graphical form.

There does not appear to be a smooth relationship between

ν(CO) and E_1/2that encompasses the whole set of ligands. For

example, it is quite obvious that the ligand responsible for the

lowest ν(CO) (8-RhCO) does not give rise to the easiest

oxidation. On the other hand, there are trends that can be

identiﬁed within smaller subsets of ligands wherein only

substituents at speciﬁc sites are varied. The red trendline

(ligands shown explicitly in Figure 7) in Figure 6 connects

ligands 3, 6, 2, 10, and 11. These are all PNP ligands with a

constant diarylamido backbone (Me groups para to N) with

varying substituents on the phosphorus atoms (R in Scheme 3).

This subset shows a smooth, approximately linear relationship,

with the increase in ν(CO) corresponding to an increase in

E_1/2. The blue trendline (ligands shown explicitly in Figure 7)

connects ligands 4, 3, and 5. This subset of PNP ligands shares

the same two PⁱPr₂side donors with varying substituents para

to N in the diarylamine (Y in Scheme 4). Here, an increase in

ν(CO) also corresponds to an increase in E_1/2, but it is clear

that the slope of this trendline is very diﬀerent: the rather large

changes in E_1/2correspond to relatively small changes in

ν(CO). The (PNP)M complexes can be viewed as a system

composed of four fused rings: the two aromatic rings of the

1

6

1941 (10-RhCO)

1942 (6-RhCO)

1952 (2-RhCO)

1930 (8-RhCO)

1944 (5-RhCO)

1960 (17-RhCO)

1980 (11-RhCO)

7

2

8

5

10

11

ν(CO) values for a series of (pincer)RhCO complexes is

summarized in Figure 5. The IR spectra of 2-RhCO, 4-RhCO,

5-RhCO, 6-RhCO, 7-RhCO, 8-RhCO, 9-RhCO, 10-RhCO,

and 11-RhCO were collected in this work under the same

conditions and on the same instrument. The ν(CO) values for

3-RhCO,⁴¹13-RhCO,⁴⁹14-RhCO,⁵⁰15-RhCO,⁵¹16-

RhCO,⁵²17-RhCO,⁵³18-RhCO,^30aand 19-RhCO³⁵come

from literature sources and have been obtained on diﬀerent

instruments and in diﬀerent media, which may cause deviations

on the order of a few wavenumbers.⁵⁶The ν(CO) frequencies

of these (pincer)RhCO compounds range from 1900 to 1980

cm⁻¹, a span of 80 cm⁻¹. The lowest stretching frequency, and

thus the most donating pincer ligand in this series, is observed

for 14-RhCO where the pincer combines trialkylphosphine side

arms with the central alkyl donor. The new complex with a

bis(hexaﬂuoroisopropoxy)phosphino arm (11-RhCO) is the

least donating pincer in this series, with the highest ν(CO)

value. Fluoroalkoxy substituents on phosphorus have been

Figure 5. ν(CO) values (cm⁻¹) for a series of (pincer)RhCO complexes.

I

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Article

Figure 6. A plot of ν(CO) values (cm⁻¹) in (pincer)RhCO vs E_1/2values (V) for (pincer)PdCl complexes.

Figure 7. Top: the ligand series comprising the blue trendline in Figure 6. Bottom: the ligand series comprising the red trendline in Figure 6.

diarylamino backbone and the two ﬁve-membered metalla-

cycles about the metal center. This four-ring system is constant

for (PNP)M complexes with the same M, and the blue and the

red trendlines in Figure 6 explore the inﬂuence of the

substituents on this system. The red trendline explores

substituents on P, close to the metal, and so for changes

across the set there is a more pronounced eﬀect on ν(CO) than

in the blue trendline, where the substituents changing are

conjugated with the diarylamido π-system and are relatively

remote from the metal. It understandable that the two PNN

ligands (7 and 8) do not fall onto either the blue or the red

trendline, as the change to PNN involves a change to the four-

ring core. While an imine as an N-donor toward Rh is

apparently more donating than a phosphine, the iminyl

(−HC=NX) as a substituent on the diarylamine backbone is

probably somewhat π-electron-withdrawing.⁶⁰

especially interested in exploring the relationship between the

redox activity of the metal-bound pincer ligand and the

electronic eﬀect of the pincer on the metal center. The

electronic properties of a series of pincer ligands were analyzed

on the basis of redox potentials observed for group 10 metal

complexes (PNZ)MCl (P = phosphine, Z = phosphine or

imine) and ν(CO) values in the corresponding (PNZ)RhCO

complexes. Overall, this analysis is consistent with the oxidation

of (PNZ)MCl being ligand-based as it is more aﬀected by

substituents on the diarylamine backbone, whereas the ν(CO)

in (PNZ)RhCO and thus the donor ability of the pincer ligand

toward the metal is more strongly aﬀected by the nature of the

donors directly attached to the metal. As a ﬁnal note, the metal

and the oxidizable pincer ligand are directly connected, and

their electronic properties cannot be modiﬁed completely

independently. However, judicious choice of the donor atoms

and the nature of their substituents as well as modiﬁcations to

the diarylamido framework allows for some control of the

degree to which the redox activity of the ligand and the

electronic eﬀect of the ligand on a metal center are inﬂuenced.

CONCLUSION

■

In summary, a series of new pincer ligands based on the

diarylamido backbone have been prepared which incorporate a

variety of substituents that change the stereo and electronic

properties of the ligand. In the context of this work, we were

J

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Article

vacuo to yield B as a colorless solid (25.3 g, 110 mmol, 69%). ¹H NMR

(C₆D₆): δ 6.81 (d, J = 7 Hz, 4H, Ar H), 6.76 (d, J = 7 Hz, 4H, Ar H),

4.77 (s, 1H, NH), 3.35 (s, 6H, CH₃). ¹³C{¹H} NMR (C₆D₆): δ 154.8

(s, 3° Ar C), 138.4 (s, 3° Ar C), 119.9 (s, Ar CH), 115.0 (s, Ar CH),

55.2 (s, OCH₃).

EXPERIMENTAL SECTION

■

General Considerations. Unless otherwise speciﬁed, all manip-

ulations were performed under an atmosphere of argon using a

standard Schlenk line or a glovebox. Toluene, diethyl ether, hexanes,

tetrahydrofuran, dichloromethane, trimethylsilyl chloride, C₆D₆, 2,6-

lutidine, and toluene-d₈were all dried over CaH₂; distilled or vacuum

transferred; and then stored over molecular sieves in an argon ﬁlled

glovebox. Pd(COD)Cl₂,⁶¹A,⁶²3-H,^29a5-Me,^29c3-PdCl,^29d3-

PdOAc,^29d3-PtCl, 3-NiCl,^29d5-PdCl,^29c5-PdOAc,^29c5-PtCl,^29d5-

NiCl,^29d2-PdCl,^29c5-Me,^29cF,³⁴and G³⁴were prepared according to

the published procedures. 2,6-Lutidine and DMF were dried over

CaH₂and distilled prior to use. All other chemicals used were received

from commercial venders. NMR spectra were recorded on an Inova

300 (¹H, ¹³C, ³¹P), Inova 500 (¹H, ¹³C, ³¹P, ¹⁹F), or a Varian 500 (¹H,

¹³C, ³¹P, ¹⁹F) spectrometer. ³¹P and ¹⁹F NMR spectra were referenced

externally using H₃PO₄(85%, 0 ppm) and CF₃COOH (−78.5 ppm),

respectively. Electrochemical studies were carried out using a CH

Instruments Model 700 D Series Electrochemical Analyzer and

Workstation in conjunction with a three electrode cell. The working

electrode was a CHI 104 glassy carbon disk with a 3.0 mm diameter,

and the auxiliary electrode was composed of platinum wire. The third

electrode, the reference electrode, was a Ag/AgNO₃electrode. This

was separated from solution by a ﬁne porosity frit. CVs were

conducted in dichloromethane with 0.3 M [Bu₄N][PF₆] as the

supporting electrolyte at scan rate of 100 mV/s. The concentrations of

the analyte solutions were approximately 1.00 × 10⁻³M. CVs were

C. A Schlenk ﬂask was charged with B (5.05 g, 22.1 mmol), a stir

bar, and dichloromethane (250 mL). N-bromosuccinimide (7.85 g,

44.1 mmol) was then added to the reaction vessel in small portions

over the course of 10 min. The reaction mixture was stirred for 24 h

under a steady ﬂow of argon, and then a small aliquot was removed

1

and dried in vacuo. H NMR analysis revealed 99% conversion to C.

The volatiles were removed, and the resulting solid was dissolved in

tetrahydrofuran, ﬁltered through a pad of Celite, and dried. The

solution was then concentrated, layered with pentane, and stored at

−35 °C to yield purple crystals. Removal of the volatiles a second time

resulted in isolation of C (7.73 g, 20.1 mmol, 91%) as a purple solid.

¹H NMR (C₆D₆): δ 7.09 (d, 2H, J_HH= 3 Hz, Ar H), 6.82 (d, 2H, J_HH

=

9 Hz, Ar H), 6.56 (dd, 2H, J_HH= 3 Hz, J_HH= 9 Hz, Ar H), 6.00 (s, 1H,

NH), 3.13 (s, 6H, CH₃). ¹³C{¹H} NMR (C₆D₆): δ 155.4 (Ar CN),

135.4 (Ar CP), 120.4 (Ar C), 118.3 (Ar C), 115.7 (Ar CCH₃), 115.0

(Ar C), 55.3 (CH₃).

D. A Schlenk ﬂask was charged with hexamethyldisilazane (1.0 mL,

5.0 mmol), n-butyllithium (2.0 mL of a 2.5 M solution in hexanes, 5.0

mmol), and tetrahydrofuran (5 mL). The reaction mixture was stirred

for 20 min, and then C (1.7 g, 4.5 mmol) was added. After 5 min of

continued stirring, CH₃I (0.42 mL, 6.7 mmol) was added to the

solution. The reaction mixture was stirred overnight, and then the

volatiles were removed in vacuo. The resulting colorless solid was taken

up in diethyl ether and ﬁltered through a bed of silica gel. The addition

of pentane to the ethereal solution resulted in copious precipitation.

The precipitation was collected to yield D as a colorless powder (0.78

+

referenced to the Fe(Cp)₂/ Fe(Cp)₂redox couple. Low-temperature

X-ray data were obtained on a Bruker APEXII CCD based

diﬀractometer (Mo sealed X-ray tube, K_α= 0.71073 Å). All

diﬀractometer manipulations, including data collection, integration,

and scaling, were carried out using the Bruker APEXII software.

Elemental analyses were performed by CALI Laboratories, Parsippany,

New Jersey. FT-IR spectra were collected using a Bruker ALPHA-P

FT-IR Spectrometer with a diamond ATR. The samples were analyzed

in the solid state.

1

g, 2.0 mmol, 44%). H NMR (C₆D₆): δ 7.16 (d, J_HH= 3 Hz, 2H, Ar

H), 6.70 (d, J_HH= 9 Hz, 2H, Ar H), 6.62 (dd, J_HH= 9 Hz, J_HH= 3 Hz,

2H, Ar H), 3.13 (s, 6H, OCH₃), 2.93 (s, 3H, NCH₃). ¹³C{¹H} NMR

(C₆D₆): δ 156.6 (s), 142.9 (s), 124.6 (s), 121.5 (s), 119.5 (s), 114.5

(s).

A. A 3000 mL three-necked ﬂask was charged with ditolylamine

(142 g, 0.400 mol), a stir bar, and CH₂Cl₂(1.50 L). N-

bromosuccinimide (142 g, 0.800 mol) was subsequently added to

the reaction mixture in 10 portions over the course of 2.5 h. The

reaction was vigorously stirred at ambient temperature for 48 h. To

ensure quantitative conversion to the desired product, a 1 mL aliquot

F. A (13 g, 36 mmol) was dissolved in anhydrous diethyl ether (100

mL) and cooled with a dry ice/acetone bath. The amine solution was

then treated with n-butyllithium (29 mL, 2.5 M in hexanes) in a

dropwise fashion via an addition funnel. The reaction was then stirred

for 30 min before being warmed to room temperature to yield a yellow

solution. The reaction was again cooled with a dry ice/acetone bath,

and ClPⁱPr₂(12 mL, 73 mmol) was added in a dropwise fashion via

syringe, resulting in an immediate color change from yellow to orange.

The reaction was stirred for 12 h before being hydrolyzed with an

ethanol/H₂O solution (2.5 mL, 1:1). Stirring was commenced for an

additional 1 h before removing the volatiles in vacuo. The resulting

colorless solid was then extracted in a pentane/diethyl ether solution

(10:1) and stirred vigorously over silica gel for 30 min before being

ﬁltered through a pad of Celite. The volatiles were removed, and the

resulting white solid was washed with 3 × 5 mL portions of pentane to

1

was removed and dried in vacuo in a J. Young tube. A H NMR

experiment was conducted in CDCl₃concluding that 99% conversion

to the desired product had occurred. The volatiles were then removed

in vacuo, and the resulting black solid was dissolved in pentane (1.20

L), stirred vigorously over silica gel for 30 min, and then ﬁltered

through a pad of Celite. Removal of the volatiles in vacuo and

recrystallization in cold pentane at −35 °C resulted in pure product as

a white solid. An additional fraction was obtained by again washing the

black residue with pentane (4 × 200 mL). The pentane solution was

then concentrated under a vacuum, and the resulting solution was

recrystallized at −35 °C to obtain a second crop of A (181.6 g, 0.510

1

yield pure product as a white solid (12 g, 87%). H NMR (C₆D₆): δ

7.69 (d, 1H, J = 10 Hz, NH), 7.23 (m, 3H, Ar H), 7.17 (m

(overlapping with solvent), 1H, Ar H). 6.90 (d, 1H, J = 8 Hz, Ar H),

6.71 (d, 1H, J = 9 Hz, Ar H), 2.18 (s, 3H, Ar CH₃), 1.96 (m, 2H,

CH(CH₃)₂), 1.93 (s, 3H, Ar CH₃), 1.06 (dd, 6H, J_PH= 16 Hz, J_HH= 7

Hz, CH(CH₃)₂), 0.92 (dd, 6H, J_PH= 11 Hz, J_HH= 7 Hz, CH(CH₃)₂).

¹³C{¹H} NMR (C₆D₆): δ 146.1 (d, J_CP= 19 Hz, CN), 139.7 (Ar C),

133.9 (Ar C), 133.9 (d, J_CP= 2 Hz, Ar CH), 131.0 (Ar C), 130.7 (Ar

C), 130.0 (Ar C). 128.9 (Ar C), 128.3 (Ar C), 118.5 (d, J_CP= 3 Hz, Ar

CH), 116.5 (Ar C), 114.1 (Ar C), 23.2 (d, J_CP= 11 Hz, CH(CH₃)₂),

20.9 (Ar CH₃), 20.4 (Ar CH₃), 20.2 (d, J_CP= 10 Hz, CH(CH₃)₂), 18.9

(d, J_CP= 8 Hz, CH(CH₃)₂). ³¹P{¹H} NMR (C₆D₆): δ −13.9.

Note: Often times, a small amount of 3-H is formed. This can be

readily removed by washing the solid with a small amount of pentane.

¹H NMR (C₆D₆): δ 8.28 (t, 1H, J_PH= 8 Hz, N H), 7.38 (d, 2H, J = 6

Hz, Ar H), 7.19 (s, 2H, Ar H), 6.91 (d, 2H, J = 8 Hz, Ar H), 2.18 (s,

6H, Ar CH₃), 2.01 (m, 4H, CH(CH₃)₂), 1.12 (dd, 12H, J_PH= 15 Hz,

J_HH= 7 Hz, CH(CH₃)₂), 0.97 (dd, J_PH= 12 Hz, J_HH= 7 Hz, 12H,

CH(CH₃)₂). ³¹P{¹H} NMR (C₆D₆): δ −12.9.

1

mmol, 71%). H NMR (CDCl₃): δ 7.38 (s, 2H, Ar H), 7.09 (d, 2H,

J_HH= 8 Hz, Ar H), 6.98 (d, 2H, J_HH= 8 Hz, Ar H), 6.16 (s, 1H, NH),

2.26 (s, 6H, Ar CH₃).

B. In the glovebox, a Schlenk ﬂask was charged with p-anisidine

(20.0 g, 162 mmol), Pd(OAc)₂(200 mg, 0.892 mmol), DPPF (640

mg, 1.16 mmol), and toluene (250 mL). Degassed 4-bromoanisole

(20.4 mL, 162 mmol) and sodium tert-pentoxide (20.6 g, 187 mmol)

were quickly added to the reaction mixture under an atmosphere of

argon. The reaction was reﬂuxed for 36 h and then cooled to ambient

temperature. A 1 mL aliquot was removed from the reaction mixture

and dried in a J. Young tube. ¹H NMR analysis revealed conversion to

the coupled product. The reaction was quenched with 3.3 mL of

degassed H₂O and stirred for an additional 40 min prior to removing

the volatiles in vacuo. The resulting solid was then dissolved in

dichloromethane, stirred over silica gel, and then ﬁltered through a pad

of Celite. The solution was then concentrated and stored at −35 °C

for 12 h. The resulting precipitate was then collected and dried in

K

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1

G. A Schlenk ﬂask was charged with F (1.2 g, 3.1 mmol), a stir bar,

and diethyl ether (25 mL). n-Butyllithium (2.5 mL, 6.1 mmol, 2.5 M in

hexanes) was then added dropwise via addition funnel. The mixture

was stirred for 1 h, and then DMF (0.50 mL, 6.2 mmol) was added to

the reaction vessel. The mixture was stirred for 20 h and then

quenched with a degassed solution of ethanol/water (3:1, 1.0 mL).

The volatiles were removed in vacuo, and the resulting yellow solid was

dissolved in diethyl ether and stirred vigorously over silica gel before

being passed through a pad of Celite. The ethereal solution was then

concentrated in vacuo and stored at −35 °C. The resulting yellow

precipitate was dried to yield G as a yellow solid (0.74 g, 2.2 mmol,

71%). If F is still present in the solid, it can be removed via column

chromatography (with silica gel) using ﬁrst pentane to remove F and

isolated yield). H NMR (C₆D₆): δ 7.72 (dvt, J_HH= 8 Hz, J_PH= 3 Hz,

2H, Ar H), 6.77 (d, J_HH= 8.5 Hz, 2H, Ar H), 6.73 (vt, J_PH= 6 Hz, 2H,

Ar H), 2.10 (s, 6H, Ar CH₃), 1.86 (m, 4H, CH₂CH₃), 1.49 (m, 4H,

CH₂CH₃), 1.25 (m, 12H, CH₂CH₃). ¹³C{¹H} NMR (C₆D₆): δ 161.6

(vt, J_PC= 11.5 Hz), 132.7, 131.5, 126.3 (vt, J_PC= 4 Hz), 120.9 (vt, J_PC

= 20 Hz), 116.2 (vt, J_PC= 7 Hz), 20.2, 19.1 (vt, J_PC= 14 Hz), 8.9.

³¹P{¹H} NMR (C₆D₆): δ 33.5. Elemental analysis, calculated for

C₂₂H₃₂ClNP₂Pd: C, 51.38; H, 6.27%. Found: C, 51.68; H, 6.52%.

2-PdOAc. A Schlenk ﬂask was charged with 2-H (1.00 g, 1.76

mmol), Pd(OAc)₂(396 mg, 1.76 mmol) and toluene (5 mL). The

reaction mixture was stirred for 18 h, and then the resulting solid was

taken up in additional toluene and recrystallized at −35 °C to yield 2-

PdOAc as a red solid (0.906 g, 1.24 mmol 69%). ¹H NMR (C₆D₆): δ

8.01 (m, 8H, Ar H), 7.65 (d, 2H, J = 11 Hz, Ar H), 7.05−6.97 (m,

14H, 8 Hz), 6.67 (d, 2H, J_HH= 8 Hz, Ar H), 1.93 (s, 3H, CH₃), 1.89

1

then ethyl acetate to wash G completely oﬀ the column. H NMR

(C₆D₆): δ 10.69 (s, 1H, NH), 9.71 (s, 1H, (O)CH), 7.30 (dd, 1H, J_PH

= 4 Hz, J_HH= 8 Hz, Ar H), 7.25 (s, 1H, Ar H), 7.05 (d, 1H, J_HH= 8

Hz, Ar H), 6.90 (d, 1H, J_HH= 8 Hz, Ar H), 6.846.80 (m, 2H, Ar H),

2.16 (s, 3H, CH₃), 1.98 (m, 2H, CH(CH₃)₂), 1.97 (s, 3H, CH₃), 1.07

(dd, 6H, J_HH= 7 Hz, J_PH= 15 Hz, CH(CH₃)₂), 0.92 (dd, 6H, J_HH= 7

Hz, J_PH= 12 Hz, CH(CH₃)₂). ¹H{³¹P} NMR (C₆D₆): δ 10.69 (s, 1H,

NH), 9.71 (s, 1H, imine CH), 7.30 (d, 1H, J_HH= 8 Hz, Ar H), 7.25 (s,

1H, Ar H), 7.05 (d, 1H, J_HH= 8 Hz, Ar H), 6.90 (d, 1H, J_HH= 8 Hz,

Ar H), 6.84 (s, 1H, Ar H), 2.16 (s, 3H, CH₃), 1.98 (m, 2H,

CH(CH₃)₂), 1.97 (s, 3H, CH₃), 1.07 (d, 6H, J_HH= 7 Hz, CH(CH₃)₂),

0.92 (d, 6H, J_HH= 7 Hz, CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): δ 193.5

((O)CH), 146.3 (CC(O)H), 143.7 (d, J_CP= 23 Hz, Ar CN), 136.5

(Ar CH), 136.2 (Ar CH), 134.5 (Ar CH), 133.1 (Ar C), 130.4 (Ar

CH), 129.8 (d, J_CP= 23 Hz, Ar C), 125.8 (Ar C), 124.1 (Ar CH),

120.5 (Ar C), 113.4 (Ar CH), 23.5 (d, J_CP= 14 Hz, CH(CH₃)₂), 21.1

(Ar CH₃), 20.3 (d, J_CP= 20 Hz, CH(CH₃)₂), 20.0 (Ar CH₃), 19.2 (d,

J_CP= 10 Hz, CH(CH₃)₂). ³¹P{¹H} NMR (C₆D₆): δ −8.0 (s).

[Tris(4-bromophenyl)aminium][CHB₁₁Cl₁₁]. A Schlenk ﬂask

was charged with Na[CHB₁₁Cl₁₁] (628 mg, 1.15 mmol), tris(4-

bromophenyl)amine (555 mg, 1.15 mmol), PhI(OAc)₂(185 mg,

0.575 mmol), and dichloromethane (10 mL). Trimethylsilyl chloride

(209 μL, 1.15 mmol) was then added to the colorless solution,

resulting in a color change to royal blue. Stirring was continued for 30

min, and then the volatiles were removed extensively under a vacuum.

The resulting blue powder was dissolved in dichloromethane and

ﬁltered through a pad of Celite. The dichloromethane solution was

then layered with pentane, and slow diﬀusion at −35 °C resulted in

isolation of [tris(4-bromophenyl)aminium][CHB₁₁Cl₁₁] (457 mg,

40%) as a paramagnetic blue powder. Elemental analysis, calculated:

C, 22.73; H, 1.31. Found C, 22.87; H, 1.17.

(s, 6H, CH₃). ³¹P{¹H} NMR (C₆D₆): δ 29.6. H NMR (CDCl₃): δ

1

7.82−7.78 (m, 8H, Ar H), 7,47−7.42 (m, 14H, Ar H), 6.86 (d, 2H, J =

8 Hz, Ar H), 6.83 (m, 2H, Ar H), 2.13 (s, 6H, Ar CH₃), 1.68 (s, 3H,

CH₃). ¹³C{¹H} NMR (CDCl₃): δ 176.0 (OAc), 160.2 (d, J_CP= 27 Hz,

Ar CN), 133.9 (Ar CH), 133.8 (Ar CH), 132.7 (Ar CH), 131.1 (Ar C),

130.9 (Ar CH), 130.7 (Ar CH), 129.2 (Ar C), 128.8 (Ar CH), 127.0

(Ar C), 121.8 (Ar C), 116.8 (Ar CH), 23.6 (OAc), 20.3 (Ar CH₃).

³¹P{¹H} NMR (CDCl₃): δ 28.9.

2-PdCl. A Schlenk ﬂask was charged with 2-PdOAc (117 mg, 0.160

mmol), a stir bar, diethyl ether (5 mL), and Me₃SiCl (100 μL, 0.801

mmol) and stirred for 12 h at room temperature. The volatiles were

then removed in vacuo while being warmed in a 100 °C oil bath,

resulting in a green powder. The solid was then recrystallized in

pentane to yield 2-PdCl as a green powder (83.0 mg, 0.127 mmol,

80%).

2-RhCO. A Schlenk ﬂask was charged with 2-H (302 mg, 0.534

mmol), [Rh(COD)Cl]₂(132 mg, 0.267 mmol), 2,6-lutidine (61.0 μL,

0.534 mmol), diethyl ether (10 mL) and a stir bar. Exposure to CO (1

atm) resulted in formation of an orange solution. The reaction mixture

was stirred for 12 h, and then the volatiles were removed in vacuo. The

resulting solid was taken up in dichloromethane and passed through a

pad of Celite. The solution was then concentrated and layered with

diethyl ether. Recrystallization at −35 °C resulted in the isolation of 2-

1

RhCO as an orange solid (165 mg, 0.246 mmol, 46%). H NMR

(CDCl₃): δ 8.12 (m, 10H, Ar H), 7.44 (s, 2H, Ar H), 7.34 (t, J_PH= 3

Hz, 2H, Ar H), 7.26 (m, 10H, Ar H), 7.06 (d, J_HH= 9 Hz, 2H, Ar H),

2.24 (s, 6H, CH₃). H{³¹P} NMR (CDCl₃): δ 8.12 (m, 10H, Ar H),

1

7.44 (s, 2H, Ar H), 7.34 (s, 2H, Ar H), 7.26 (m, 10H, Ar H), 7.06 (d,

J_HH= 9 Hz, 2H, Ar H), 2.24 (s, 6H, CH₃). ¹³C{¹H} NMR (CDCl₃): δ

196.3 (d, J = 13 Hz, CO), 161.2 (t, J_CP= 14 Hz, Ar C), 135.2 (Ar C),

135.0 (Ar C), 134.8 (Ar C), 134.7 (Ar C), 134.6 (Ar C), 134.6 (Ar C),

133.3 (Ar C), 131.2 (Ar C), 129.7 (t, J_CP= 5 Hz, Ar C), 128.9 (Ar C),

126.9 (Ar C), 123.7 (t, J_CP= 23 Hz, Ar C), 116.7 (d, J_CP= 21 Hz, Ar

C), 21.4 (CH₃). ³¹P{¹H} NMR (CDCl₃): δ 41.1 (d, J_RhP= 136 Hz).

¹H NMR (C₆D₆): δ 7.82 (m, 9H, Ar H), 7.04 (m, 3H, Ar H), 6.97 (m,

12H, Ar H), 6.77 (d, J_HH= 9 Hz, 2H, Ar H), 1.95 (s, 6H, CH₃).

³¹P{¹H} NMR (C₆D₆): δ 41.3 (d, J_RhP= 135 Hz). IR ν(CO) = 1952

cm⁻¹.

3-NiCl. A C₆D₆solution of 3-NiOAc (55 mg, 0.10 mmol) was

charged with Me₃SiCl (4.0 μL, 0.30 mmol). The reaction’s progress

was monitored by ³¹P NMR spectroscopy. After 18 h, only one signal

was observed at 34.2 ppm. The volatiles were then removed in vacuo to

yield a green powder (43 mg, 0.082 mmol, 81%).

4-Me. A Schlenk ﬂask was charged with D (0.68 g, 1.7 mmol), a stir

bar, diethyl ether (10 mL), and n-butyllithium (1.4 mL, 3.4 mmol).

After 1 h, ClPⁱPr₂(0.54 mL, 3.4 mmol) was added to the ethereal

solution via syringe. The reaction was stirred for 2 h and then ﬁltered

through a pad of silica gel. Removal of the volatiles under a vacuum

and recrystallization in pentane gave 4-Me as a colorless powder (0.75

g, 1.6 mmol, 93%). ¹H NMR (C₆D₆): δ 7.17 (dd, J_HH= 3 Hz, J_PH= 2

Hz, 2H, Ar H), 6.90 (dd, J_HH= 9 Hz, J_PH= 3 Hz, 2H, Ar H), 6.68 (dd,

J_HH= 9 Hz, J_HH= 3 Hz, 2H, Ar H), 3.48 (s, 3H, NCH₃), 3.38 (s, 6H,

1-H. In a 25 mL Schlenk ﬂask under Ar, A (0.42 g, 1.2 mmol) was

dissolved in diethyl ether. The solution was placed in a freezer for 1 h

at −35 °C. n-Butyllithium (1.6 mL of 2.5 M solution in hexanes, 3.9

mmol) was then added, and the solution was stirred overnight. The

solution was cooled to −35 °C in a freezer for 1 h; then ClPEt₂(0.53

mL, 4.4 mmol) was added. The mixture immediately became bright

yellow-orange. After 3 h, the reaction was quenched with 30 μL of

degassed H₂O/MeOH solution. The solution was stirred for 20 min,

and then the volatiles were removed. The product was extracted with

pentane and toluene, then ﬁltered over Celite and silica gel, yielding a

pale yellow solution. The volatiles were reduced, leaving a yellow oil.

The oil was found to be a mixture containing approximately 87%

desired ligand by ³¹P NMR. This mixture was used without further

1

puriﬁcation for the synthesis of 1-PdCl. H NMR (C₆D₆): δ 7.87 (t,

J_PH= 8 Hz, 1H, NH), 7.28 (dd, J = 4 Hz, J = 8 Hz, 2H, Ar H), 7.19 (br

s, 2H, Ar H), 6.93 (dd, J = 2 Hz, J = 8 Hz, 2H, Ar H), 2.21 (s, 6H, Ar

CH₃), 1.60 (m, 8H, CH₂CH₃), 1.02 (m, 12H, CH₂CH₃). ¹³C{¹H}

NMR (C₆D₆): δ 146.3 (m), 131.4, 130.5, 129.9, 126.8 (m), 117.4,

20.9, 19.7 (d, J_PC= 8 Hz), 10.3 (m). ³¹P{¹H} NMR (C₆D₆): δ −36.5.

1-PdCl. In a 25 mL Schlenk ﬂask, under Ar, Pd(COD)Cl₂(86 mg,

0.33 mmol) was added to a toluene solution of 1-H (0.12 g, 0.33

mmol). The solution became a dark red and was stirred overnight at

RT. After 12 h, solution was ﬁltered through Celite and silica gel. The

volatiles were removed, and a red oily solid was dissolved in toluene.

The product was recrystallized from a toluene solution layered with

pentane to yield red crystals of 1-PdCl (0.11 g, 0.22 mmol, 73%

OCH₃), 2.13−1.97 (m, 4H, CH(CH₃)₂), 1.18 (dd, J_PH= 13 Hz, J_HH

8 Hz, 12H, CH(CH₃)₂), 1.01 (dd, J_PH= 12 Hz, J_HH= 7 Hz, 12H,

=

L

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CH(CH₃)₂). H{³¹P} NMR (C₆D₆): δ 7.17 (dd, J_HH= 3 Hz, 2H, Ar

1.15 (dvt, J_PH= 15 Hz, J_HH= 7 Hz, 12H, CHCH₃)₂), 0.98 (dvt, J_PH=

H), 6.90 (dd, J_HH= 9 Hz, 2H, Ar H), 6.68 (dd, J_HH= 9 Hz, J_HH= 3 Hz,

2H, Ar H), 3.48 (s, 3H, NCH₃), 3.38 (s, 6H, OCH₃), 2.13−1.97 (m,

4H, CH(CH₃)₂), 1.18 (dd, J_HH= 8 Hz, 12H, CH(CH₃)₂), 1.01 (dd,

J_HH= 7 Hz, 12H, CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): δ 155.7 (s, 3°

C, Ar CN), 152.4 (d, J_CP= 5 Hz, 3° C, Ar C), 134.3 (d, J_CP= 10 Hz, 3°

C, Ar C), 124.8 (s, Ar C), 120.0 (s, Ar C), 114.2 (s, Ar C), 55.0 (s,

OCH₃), 25.0 (d, J_CP= 1 Hz, CH(CH₃)₂), 21.1 (s, CH₃), 20.3 (s, CH₃).

³¹P{¹H} NMR (C₆D₆): δ −6.2 (s).

15 Hz, J_HH= 7 Hz, 6H, CHCH₃)₂). ¹H{³¹P} NMR (C₆D₆): δ 7.76 (d,

J_HH= 9 Hz 2H, Ar H), 6.82 (d, J_HH= 4 Hz, 2H, Ar H), 6.64 (dd, J_HH

=

9 Hz, J_HH= 3 Hz, 2H, Ar H), 3.43 (s, 6H, OCH₃), 2.61 (m, J = 7 Hz,

2H, CH(CH₃)₂), 2.38−2.34 (m, 2H, CH(CH₃)₂), 2.33 (d, J_RhH= 3

Hz, 3H, Rh CH₃), 1.49 (d, J_HH= 7 Hz, 6H, CHCH₃)₂), 1.15 (d, J_HH

=

7 Hz, 12H, CHCH₃)₂), 0.98 (d, J_HH= 7 Hz, 6H, CHCH₃)₂). ¹³C{¹H}

NMR (C₆D₆): δ 158.1 (s, 3° Ar C), 151.2 (s, 3° Ar C), 121.0 (s, 3° Ar

C), 118.0 (s, Ar CH), 117.8 (s, Ar CH), 117.1 (s, Ar CH), 55.7 (s,

OCH₃), 27.0 (d, J_CP= 11 Hz, CH(CH₃)₂), 24.2 (d, J_CP= 12 Hz,

CH(CH₃)₂), 19.4 (d, J_CP= 33 Hz, CH(CH₃)₂), 18.1 (d, J_CP= 17 Hz,

CH(CH₃)₂), 2.0 (d, J_RhC= 33 Hz, Rh CH₃). ³¹P{¹H} NMR (C₆D₆): δ

36.5 (d, J_RhP= 109 Hz).

4-PdCl. A Teﬂon stoppered Schlenk ﬂask was charged with toluene

(10 mL), a stir bar, 4-Me (541 mg, 1.14 mmol), and Pd(COD)Cl₂

(324 mg, 1.14 mmol). The reaction vessel was then placed in an 80 °C

oil bath for 3 days. After warming the reaction vessel to room

temperature, the toluene solution was passed through a pad of silica

gel and washed with diethyl ether. Removal of the volatiles and

recrystallization at −35 °C in toluene gave 4-PdCl as a green powder

4-RhCO. A J. Young tube was charged with 4-Rh(CH₃)Cl (44 mg,

72 μmol), CO (1 atm), and C₆D₆(1 mL). The J. Young tube was

placed in a 70 °C oil bath for 18 h. Crystals were then obtained by

layering the benzene solution with diethyl ether. The brown crystals

were collected by decanting the solvent layer and drying the resulting

orange blocks under a vacuum. 4-RhCO was isolated as an orange

powder (10 mg, 17 μmol, 24%). ¹H NMR (C₆D₆): δ 7.64 (d, J_HH= 9

Hz, 2H, Ar H), 6.80 (q, J_PH= 4 Hz, 2H, Ar H), 6.64 (dd, J_HH= 9 Hz,

J_HH= 3 Hz, 2H, Ar H), 3.44 (s, 6H, OCH₃), 2.14−2.06 (m, 4H,

CH(CH₃)₂), 1.24 (dvt, J_PH= 15 Hz, J_HH= 7 Hz, 12H, CH(CH)₃)₂),

1.03 (dvt, J_PH= 15 Hz, J_HH= 7 Hz, 12H, CH(CH)₃)₂). ¹H{³¹P} NMR

(C₆D₆): δ 7.64 (d, J_HH= 9 Hz, 2H, Ar H), 6.80 (s, 2H, Ar H), 6.64

(dd, J_HH= 9 Hz, J_HH= 3 Hz, 2H, Ar H), 3.44 (s, 6H, OCH₃), 2.10

(hept, J_HH= 7 Hz, 4H, CH(CH₃)₂), 1.24 (d, J_HH= 7 Hz, 12H,

CH(CH)₃)₂), 1.03 (d, J_HH= 7 Hz, 12H, CH(CH)₃)₂). ¹³C{¹H} NMR

(C₆D₆): δ 198.2 (d, J_RhC= 65 Hz, CO), 159.1 (d, J_CP= 15 Hz, 3° Ar

C), 150.9 (s, 3° Ar C), 122.2 (t, J_CP= 17 Hz, 3° Ar C), 118.1 (s, Ar

CH), 116.9 (s, Ar CH), 115.1 (s, Ar CH), 55.8 (s, OCH₃), 25.8 (s,

CH(CH₃)₂), 19.5 (s, CH₃), 18.5 (s, CH₃). ³¹P{¹H} NMR (C₆D₆): δ

62.0 (d, J_RhP= 135 Hz). IR ν(CO): 1933 cm⁻¹.

1

(281 mg, 467 mmol, 41%). H NMR (C₆D₆): δ 7.61 (d, 2H, J_HH= 9

Hz, Ar H), 6.71 (s, 2H, Ar H), 6.62 (d, 2H, J_HH= 9 Hz, Ar H), 3.38 (s,

6H, MeO), 2.27−2.24 (m, 4H, CH(CH₃)₂), 1.42 (dvt, 12H, J_PH= 16

Hz, J_HH= 7 Hz, CH(CH₃)₂), 1.11 (dvt, 12H, J_PH= 15 Hz, J_HH= 7 Hz,

CH(CH₃)₂). ¹H{³¹P} NMR (C₆D₆): δ 7.61 (d, 2H, J_HH= 9 Hz, Ar H),

6.71 (s, 2H, Ar H), 6.62 (d, 2H, J_HH= 9 Hz, Ar H), 3.38 (s, 6H,

CH₃O), 2.27−2.24 (m, 4H, CH(CH₃)₂), 1.42 (d, 12H, J_HH= 7 Hz,

CH(CH₃)₂), 1.11 (d, 12H, J_HH= 7 Hz, CH(CH₃)₂). ¹³C{¹H} NMR

(C₆D₆): δ 159.0 (Ar CN), 151.4 (Ar C), 119.2 (Ar C), 117.7 (Ar CH,

appears to be two overlapping peaks), 116.0 (Ar CH), 55.7 (OCH₃),

25.1 (t, J_CP= 12 Hz, CH(CH₃)₂), 18.69 (CH₃), 18.0 (CH₃). ³¹P{¹H}

NMR (C₆D₆): δ 47.9. Elemental analysis, calculated: C, 51.84; H, 6.69.

Found: C, 51.76; H, 6.74.

[4-PdCl][CHB₁₁Cl₁₁]. A Schlenk ﬂask was charged with 4-PdCl (85

mg, 0.14 mmol), [tris(4-bromophenyl)aminium][CHB₁₁Cl₁₁] (0.14 g,

0.14 mmol), a stir bar, and dichloromethane (5 mL). An immediate

color change to brown is observed, and a brown precipitate forms.

After 30 min, the volatiles were removed under a vacuum, and the

resulting brown precipitate was washed with diethyl ether. The solid

was then dissolved in a minimal amount of dichloromethane and

stored at −35 °C for 36 h. The resulting brown crystals were then

5-NiCl. A Schlenk ﬂask was charged with 5-Me (3.00 g, 6.65

mmol), NiCl₂·(H₂O)₆(1.90 g, 7.98 mmol), toluene (25 mL), and a

stir bar. The reaction mixture was then reﬂuxed under a ﬂow of argon

for 6 h. The solution was then passed through a pad of Celite. The

volatiles were then removed in vacuo, and the resulting green solid was

washed with pentane to yield 5-NiCl (2.58 g, 73%). ¹H NMR (C₆D₆):

δ7.13 (ddt, J_HH= 9 Hz, J_HH= 4 Hz, J_PH= 2 Hz, 2H, Ar H), 6.75 (dq,

J_HH= 7 Hz, J_HH= 4 Hz, 2H, Ar H), 6.57 (td, J_RhC= 8 Hz, J_HH= 3 Hz,

2H, Ar H), 2.03 (m, 4H, CH(CH₃)₂), 1.41 (dvt, J_PH= 15 Hz, J_HH= 7

Hz, 12H, CH(CH₃)₂), 1.10 (dvt, J_PH= 15 Hz, J_HH= 7 Hz, 12H,

1

collected by decanting oﬀ the solvent. H NMR analysis revealed that

the amine has been completely removed, and no signals corresponding

to a diamagnetic complex were observed. Elemental analysis,

calculated: C, 28.82; H3.76. Found: C, 28.76; H 3.62.

4-PdOAc. A J. Young tube was charged with 4-Me (40 mg, 0.11

mmol), Pd(OAc)₂(25 mg, 0.11 mmol), and C₆D₆(1 mL). The

reaction mixture immediately turned a deep red color. The volatiles

were removed in vacuo, and the resulting red solid was taken up in

diethyl ether and ﬁltered through a pad of silica gel. The volatiles were

again removed while heating at 100 °C to yield 4-PdOAc as a red

powder (20 mg, 32 μmol, 30%). ¹H NMR (C₆D₆): δ 7.57 (d, 2H, J = 9

Hz, Ar H), 6.68 (s, 2H, Ar H), 6.61 (d, J = 3 Hz, Ar H), 3.39 (s, 6H, Ar

CH₃), 2.26−2.24 (m, 4H, CH(CH₃)₂), 2.23 (s, 3H, OAc), 1.36 (dvt,

12H, J_PH= 17 Hz, J_HH= 8 Hz, CH(CH₃)₂), 1.09 (dvt, 12H, J_PH= 15

Hz, J_HH= 8 Hz, CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): δ 175.8 (C

1

CH(CH₃)₂). H{³¹P} NMR (C₆D₆): δ7.13 (dd, J = 9 Hz, J = 4 Hz,

2H), 6.75 (dd, J = 7 Hz, J = 4 Hz, 2H), 6.57 (td, J = 8 Hz, J = 3 Hz,

1H), 2.03 (hept, J = 7 Hz, 4H), 1.41 (d, J = 7 Hz, 12H), 1.10 (d, J = 7

Hz, 12H). ¹³C{¹H} NMR (C₆D₆): δ160.5 (t, J_CP= 13 Hz, Ar C), 155.4

(s, Ar C), 153.5 (s, Ar C), 121.8 (t, J_CP= 18 Hz, Ar C), 117.9 (dd, J_CF

= 101 Hz, J_CP= 22 Hz, Ar C), 116.4 (d, J_CP= 9 Hz, Ar C), 24.0 (t, J_CP

= 12 Hz, P(CH(CH₃)₂)₂), 18.4 (s, P(CH(CH₃)₂)₂), 17.5 (s,

P(CH(CH₃)₂)₂). ¹⁹F NMR (C₆D₆): δ −128.6 (q, J_RhC= 8 Hz).

³¹P{¹H} NMR (C₆D₆): δ32.7 (s). Elemental analysis, calculated: C,

60.11; H, 6.39. Found: C, 60.06; H, 6.42.

6-H. A Schlenk ﬂask was charged with F (0.98 g, 2.5 mmol) and a

stir bar. The solid was then dissolved in diethyl ether (30 mL), and the

resulting solution was cooled to −35 °C in the glovebox freezer. n-

Butyllithium (2.0 mL, 0.80 mmol, 2.5 M in hexanes) was then added

slowly to the reaction ﬂask via syringe, resulting in a bright yellow

solution. The reaction mixture was then stirred for 2 h at ambient

temperature. ClPPh₂(0.50 mL, 2.5 mmol) was added slowly via

syringe, resulting in a red solution. The reaction mixture was stirred

overnight and then quenched with degassed H₂O (0.20 mL). Stirring

was commenced for an additional hour, resulting in a colorless

solution. The volatiles were then removed in vacuo, and the ﬂask was

brought into the glovebox where it was dissolved in diethyl ether and

stirred vigorously over silica gel. The resultant mixture was then

ﬁltered through a pad of Celite, and the diethyl ether was removed in

vacuo. The resulting colorless solid was then dissolved in a 1:1 mixture

of pentane and toluene and recrystallized at −35 °C to yield 6-H as a

colorless solid (0.78 g, 1.6 mmol, 62%). ¹H NMR (C₆D₆): δ 7.65 (dd,

O), 159.0 (t, J_CP= 11 Hz, CN), 151.2 (t, J_CP= 4 Hz), 119.6 (t, J_CP

19 Hz), 117.8, 117.6, 116.3 (t, J_CP= 8 Hz), 55.7 (MeO), 24.7 (t, J_CP

=

11 Hz, CH(CH₃)₂), 23.3 (OAc), 18.4 (CH(CH₃)₂)), 17.7 (CH-

(CH₃)₂)). ³¹P{¹H} NMR (C₆D₆): δ 48.1.

4-Rh(CH₃)(Cl). A J. Young tube was charged with 4-Me (0.18 g,

0.38 mmol), [Rh(COD)Cl]₂(93 mg, 0.19 mmol), and C₆D₆(1.5 mL).

After the reaction mixture at 90 °C for 18 h, a color change from red

to green was observed. The solution was then passed through a pad of

silica gel, using diethyl ether to ensure quantitative transfer. The

volatiles were removed in vacuo, and the resulting solid was washed

three times with toluene. The volatiles were again removed, and the oil

was taken up in a 1:1 mixture of pentane to diethyl ether and

recrystallized at 35 °C to yield 4-Rh(CH₃)(Cl) as a green powder (66

mg, 0.11 μmol, 29%). ¹H NMR (C₆D₆): δ 7.76 (dt, J_HH= 9 Hz, J_PH

=

2 Hz, 2H, Ar H), 6.82 (dvt, J_PH= 8 Hz, J_HH= 4 Hz, 2H, Ar H), 6.64

(dd, J_HH= 9 Hz, J_HH= 3 Hz, 2H, Ar H), 3.43 (s, 6H, OCH₃), 2.61 (m,

J = 7 Hz, 2H, CH(CH₃)₂), 2.38−2.34 (m, 2H, CH(CH₃)₂), 2.33 (m,

3H, Rh CH₃), 1.49 (dvt, J_PH= 15 Hz, J_HH= 7 Hz, 6H, CHCH₃)₂),

M

DOI: 10.1021/ic503062w

Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry

Article

1H, J_PH= 11 Hz, J_HH= 3 Hz), 7.49−7.46 (m, 4H), 7.39 (dd, 1H, J = 5

Hz, J = 9 Hz), 7.23 (dd, 1H, J = 5 Hz, J = 9 Hz), 7.11 (s, 1H), 7.08−

J

_CP= 13 Hz, Ar C), 116.0 (d, J_CP= 13 Hz, Ar C), 24.5 (d, J_CP= 4 Hz,

CH(CH₃)₃), 24.4 (d, J_CP= 4 Hz, CH(CH₃)₃), 23.0 (CH₃), 20.4 (Ar

CH₃), 20.3 (Ar CH₃), 18.4 (d, J_CP= 6 Hz, CH(CH₃)₃), 17.7 (d, J_CP= 3

Hz, CH(CH₃)₃). ³¹P{¹H} NMR (CDCl₃): δ 55.8 (d, J_PP= 412 Hz),

25.8 (d, J_PP= 412 Hz).

6.99 (m, 6H), 6.95 (d, 1H, J = 4 Hz), 6.88 (dd, 2H, J_HH= 8 Hz, J_PH

=

20 Hz), 2.15 (s, 3H, Ar CH₃), 1.95 (s, 3H, Ar CH₃), 1.87 (m, 2H,

CH(CH₃)₂), 1.01 (dd, 6H, J_HH= 7 Hz, J_PH= 15 Hz, CH(CH₃)₂), 0.87

(dd, 6H, J_HH= 7 Hz, J_PH=12 Hz, CH(CH₃)₂). ¹³C{¹H} NMR

(CDCl₃): δ 147.2 (d, J_CP= 19 Hz, quaternary CN), 144.4 (d, J_CP= 20

Hz, quaternary CN), 136.4 (d, J_CP= 10 Hz, Ar C), 134.3 (Ar C), 134.2

(Ar C), 134.1 (Ar C), 133.6 (Ar C), 131.2 (Ar C), 130.4 (Ar C), 130.2

(Ar C), 128.8 (Ar C), 128.7 (Ar C), 128.6 (Ar C), 128.5 (Ar C), 128.4

(Ar C), 121.8 (d, J_CP= 16 Hz, Ar C), 119.2 (Ar C), 116.5 (Ar C), 23.1

(d, J_C−P= 11 Hz, CH(CH₃)₂), 20.9 (Ar-CH₃), 20.8, (Ar-CH₃), 20.1 (d,

J_CP= 19 Hz, CH(CH₃)₂), 19.0 (d, J_CP= 9 Hz, CH(CH₃)₂). ³¹P{¹H}

NMR (C₆D₆): δ −16.1 (s), −14.2 (br s).

6-RhCO. A J. Young tube was charged with 6-H (24 mg, 47 μmol),

[Rh(COD)Cl]₂(24 mg, 48 μmol), 2,6-lutidine (5.5 μL, 48 μmol), and

C₆D₆(1 mL). The mixture was then degassed, and then CO (1 atm)

was added, resulting in a red color change. The volatiles were then

removed, and the resulting solid was ﬁltered through a pad of silica gel

with ﬂuorobenzene. Removal of the ﬂuorobenzene in vacuo resulted in

pure 6-RhCO, which was isolated as a yellow solid after washing with

3 mL portions of toluene (25 mg, 40 μmol, 60%). ¹H NMR (C₆D₆): δ

7.92−7.85 (m, 4H, Ar H), 7.80 (dd, 1H, J_PH= 9 Hz, J_HH= 5 Hz, Ar

H), 7.74 (dd, 1H, J_PH= 8 Hz, J_HH= 4 Hz, Ar H), 7.07 (d, 1H, J_PH= 10

Hz, Ar H), 7.00−6.97 (m, 6H, Ar H), 6.89 (d, 1H, J_PH= 8 Hz, Ar H),

6.82−6.78 (m, 3H, Ar H), 2.20−2.13 (m, 2H, CH(CH₃)₂), 2.17 (s,

3H, Ar CH₃), 1.95 (s, 3H, Ar CH₃), 1.27 (dd, 6H, J_PH= 17 Hz, J_HH= 7

Hz, CH(CH₃)₂), 0.98 (dd, 6H, J_PH= 15 Hz, J_HH= 7 Hz, CH(CH₃)₂).

¹³C{¹H} NMR (C₆D₆): δ 197.2 (CO), 162.6 (t, J_CP= 22 Hz, CN),

135.3 (Ar C), 135.0 (Ar C), 134.9 (Ar C), 134.1 (d, J_CP= 13 Hz, Ar

C), 133.2 (Ar C), 132.6 (d, J_CP= 13 Hz, Ar C), 130.4 (Ar C), 129.2 (d,

J_CP= 11 Hz, Ar C), 126.2 (d, J_CP= 7 Hz, Ar C), 125.8 (d, J_CP= 7 Hz,

Ar C), 123.6 (d, J_CP= 44 Hz, Ar C), 121.8 (d, J_CP= 37 Hz, Ar C),

116.8 (d, J_CP= 12 Hz, Ar C), 115.9 (d, J_CP= 13 Hz, Ar C), 25.9 (d, J_CP

= 23 Hz, CH(CH₃)₂), 20.9 (Ar CH₃), 20.6 (Ar CH₃), 20.0 (d, J_CP= 6

Hz, CH(CH₃)₂), 18.9 (CH(CH₃)₂). ³¹P{¹H} NMR (C₆D₆): δ 64.7

(dd, J_PP= 270 Hz, J_RhP= 133 Hz), 39.2 (dd, J_PP= 270 Hz, J_RhP= 134

Hz). IR: 1941 cm⁻¹.

6-PtCl. A vial was charged with 6-H (52 mg, 0.10 mmol),

Pt(COD)Cl₂(39 mg, 0.10 mmol), and toluene (3 mL). 2,6-Lutidine

(12 μL, 0.10 mmol) was added to the solution via microsyringe. The

reaction was allowed to react for 30 min, and then the volatiles were

removed in vacuo. The resulting yellow solid was ﬁltered through a pad

of silica gel with toluene and a small amount of diethyl ether. NMR

analysis after removal of the volatiles revealed a slight impurity. The

solid was again ﬁltered through silica gel using CH₂Cl₂, and the

volatiles were again removed under a vacuum to yield pure product as

a yellow solid (56 mg, 77 μmol, 71%). Crystals were obtained by

dissolving the solid in dichloromethane and storing the solution at

6-PdCl. A Schlenk ﬂask was charged with a stir bar, 6-H (0.27 g,

0.54 mmol), and Pd(COD)Cl₂(0.15 g, 0.54 mmol). The solids were

dissolved in toluene (10 mL), resulting in a dark red solution. 2,6-

Lutidine (63 μL, 0.54 mmol) was added to the mixture via syringe.

The resulting solution was stirred for 12 h and then ﬁltered through a

pad of silica gel. The volatiles were removed in vacuo, and the resulting

red oil was dissolved in a 1:1 mixture of pentane to toluene and then

stored at −35 °C. The resulting precipitate was dried in vacuo and

recrystallized in benzene to yield 6-PdCl as a red powder (0.23 g,

62%). ¹H NMR (C₆D₆): δ 8.00−7.95 (m, 4H, Ar H), 7.77 (dd, 1H, J =

8 Hz, J = 5 Hz, Ar H), 7.67 (dd, 1H, J = 9 Hz, J = 4 Hz, Ar H) 7.03−

6.98 (m, 7H, Ar H), 6.80 (d, 1H, J = 9 Hz, Ar H), 6.76−6.73 (m, 2H,

Ar H), 2.31−2.23 (m, 2H, CH(CH₃)₂), 2.10 (s, 3H, Ar CH₃), 1.90 (s,

3H, Ar CH₃), 1.42 (dd, 6H, J_PH= 17 Hz, J_HH= 7 Hz, CH(CH₃)₂),

1.06 (dd, 6H, J_PH= 16 Hz, J_HH= 7 Hz, CH(CH₃)₂). ³¹P{¹H} NMR

1

(C₆D₆): δ 54.0 (d, J_PP= 438 Hz), 25.9 (d, J_PP= 438 Hz). H NMR

(CDCl₃): δ 7.77−7.73 (m, 4H, Ar H), 7.49 (dd, 1H, J = 9 Hz, J = 5

Hz, Ar H), 7.45−7.40 (m, 7H, Ar H), 6.92 (d, 1H, J = 9 Hz, Ar H),

6.88 (t, 2H, J = 7 Hz, Ar H), 6.82 (d, 1H, J = 10 Hz, Ar H), 2.60 (m,

2H, CH(CH₃)₂), 2.22 (s, 3H, Ar CH₃), 2.14 (s, 3H, Ar CH₃), 1.48

(dd, 6H, J_PH= 17 Hz, J_HH= 7 Hz, CH(CH₃)₂), 1.31 (dd, 6H, J_PH= 16

Hz, J_HH= 7 Hz, CH(CH₃)₂). ¹³C{¹H} NMR (CDCl₃): δ 161.2 (d, J_CP

= 21 Hz, Ar CN), 160.8 (d, J_CP= 26 Hz, Ar CN), 137.8 (Ar C), 133.7

(d, J_CP= 2 Hz, Ar CH), 133.6 (d, J_CP= 2 Hz, Ar CH), 132.8 (d, J_CP= 2

Hz, Ar CH), 132.4 (Ar C), 132.3 (d, J_CP= 2 Hz, Ar CH), 130.8 (d, J_CP

= 4 Hz, Ar CH), 130.7, (d, J_CP= 2 Hz, Ar CH), 130.5 (d, J_CP= 3 Hz,

Ar CH), 129.2 (Ar C), 128.8 (d, J_CP= 11 Hz, Ar CH), 128.3 (Ar C),

126.7 (d, J_CP= 7 Hz, Ar CH), 126.5 (d, J_CP= 7 Hz, Ar CH), 125.4 (s,

Ar C), 120.9, (d, J_CP= 3 Hz, Ar C), 120.5 (d, J_CP= 3 Hz, Ar C), 118.7

(d, J_CP= 3 Hz, Ar C), 118.4 (d, J_CP= 3 Hz Ar C), 116.4 (d, J_CP= 13

Hz, Ar CH), 116.1 (d, J_CP= 14 Hz, Ar CH), 25.1 (d, J_CP= 4 Hz,

CH(CH₃)₃), 24.9 (d, J_CP= 4 Hz, CH(CH₃)₃), 20.4 (Ar CH₃), 20.3 (Ar

CH₃), 18.7 (d, J_CP= 5 Hz, CH(CH₃)₃), 18.1 (d, J_CP= 2 Hz,

CH(CH₃)₃)). ³¹P{¹H} NMR (CDCl₃): δ 55.6 (d, J_PP= 433 Hz), 27.2

(d, J_PP= 433 Hz). Elemental analysis, calculated: C, 60.20; H, 5.68; N,

2.19. Found: C, 60.13; H, 5.63; N, 2.04.

1

−35 °C. H NMR (CDCl₃): δ 7.79−7.75 (m, 4H, Ar H), 7.56 (dd,

1H, J = 6 Hz, J = 9 Hz, Ar H), 7.49 (dd, J = 5 Hz, J = 9 Hz, 1H, Ar H),

7.45−7.41 (m, 6H, Ar H), 6.98 (d, 1H, J = 9 Hz, Ar H), 6.90−6.86 (m,

3H, Ar H), 2.80−2.77 (m, 2H, CH(CH₃)₂), 2.25 (s, 3H, Ar CH₃), 2.17

(s, 3H, Ar CH₃), 1.46 (dd, 6H, J_HH7 Hz, J_PH17 Hz, CH(CH₃)₂), 1.29

(dd, 6H, J_HH7 Hz, J_PH16 Hz, CH(CH₃)₂). ¹³C{¹H} NMR (CDCl₃): δ

134.7, 133.8, 133.7, 132.6, 132.4, 132.1, 131.2, 130.7, 128.8, 128.7,

127.1, 126.9, 116.4, 116.0, 31.0, 28.2, 25.2, 20.3, 18.4, 18.1. ³¹P{¹H}

NMR (CDCl₃): δ 43.7 (d, J_PtP= 2751 Hz, J_PP398 Hz), 24.4 (d, J_PtP

=

1

2668 Hz, J_PP= 398 Hz). H NMR (C₆D₆): δ 8.02−7.98 (m, 4H, Ar

H), 7.84 (dd, 1H, J = 6 Hz, J = 9 Hz, Ar H), 7.74 (dd, 1H, J = 4 Hz, J =

9 Hz, Ar H), 7.09 (d, 1H, J = 11 Hz, Ar H), 7.02−6.97 (m, 7H, Ar H),

6.68 (d, 1H, J = 9 Hz, Ar H), 6.72 (t, 2H, Ar H), 2.52−2.46 (m, 2H,

CH(CH₃)₂), 2.13 (s, 3H, Ar CH₃), 1.93 (s, 3H, Ar CH₃), 1.42 (dd,

6H, J_PH= 17 Hz, J_HH= 7 Hz, CH(CH₃)₂), 1.08 (dd, 6H, J_PH= 16 Hz,

J_HH= 7 Hz, CH(CH₃)₂). ³¹P{¹H} NMR (C₆D₆): δ 43.3 (d, J_PtP= 2760

Hz, J_PP= 402 Hz), 24.6 (d, J_PtP= 2685 Hz, J_PP= 402 Hz).

6-PdOAc. A Schlenk ﬂask was charged with a stir bar, 6-H (0.31 g,

0.62 mmol), and Pd(OAc)₂(0.14 g, 0.62 mmol). The solids were

dissolved in toluene (10 mL), resulting in a dark red solution. The

resulting solution was stirred for 4 h and then ﬁltered through a pad of

silica gel. The volatiles were removed in vacuo, and the resulting red

solid was washed with 3 × 5 mL portions of toluene to yield 6-

1

Pd(OAc) as a red powder (0.37 mg, 69%). H NMR (CDCl₃): δ

7.79−7.74 (m, 4H, Ar H), 7.46−7.40 (m, 7H, Ar H), 7.37 (dd, 1H, J =

9 Hz, J = 4 Hz, Ar H), 6.89−6.80 (m, 4H, Ar H), 2.60 (m, 2H,

CH(CH₃)₂), 2.22 (s, 3H, Ar CH₃), 2.12 (s, 3H, Ar CH₃), 1.78 (s, 3H,

CH₃), 1.41 (dd, 6H, J_PH= 18 Hz, J_HH= 7 Hz, CH(CH₃)₂), 1.23 (dd,

6H, J_PH= 15 Hz, J_HH= 7 Hz, CH(CH₃)₂). ¹³C{¹H} NMR (CDCl₃): δ

176.5(CO), 161.1 (d, J_CP= 21 Hz, Ar CN), 160.8 (d, J_CP= 26 Hz,

7-H. A Teﬂon screw cap Schlenk ﬂask was charged with G (0.16 g,

0.48 mmol), toluene (15 mL), 2,4,6-trimethylaniline (0.14 mL, 0.96

mmol), acetic acid (6.0 μL, 20 mol %), molecular sieves, and a stir bar.

The ﬂask was then placed in a 110 °C oil bath for 72 h and then

cooled to ambient temperature, and the volatiles were removed in

vacuo. The remaining yellow solid was extracted in pentane and stirred

vigorously over silica gel for 1 h before being ﬁltered through a pad of

Celite. The ﬁltrate was evaporated to dryness, and the resulting oil was

recrystallized in pentane at −35 °C to give 7-H as a yellow powder

Ar CN), 134.2 (Ar CH), 133.6 (d, J_CP= 2 Hz, Ar CH), 133.5 (d, J_CP

=

2 Hz, Ar CH), 132.7 (d, J_CP= 3 Hz, Ar CH), 132.4 (Ar CH), 132.1 (d,

J_CP= 2 Hz, Ar CH), 131.1 (d, J_CP= 3 Hz, Ar CH), 130.7 (d, J_CP= 3

Hz, Ar CH), 129.2 (Ar CH), 128.8 (d, J_CP= 10 Hz, Ar CH), 128.3 (Ar

CH), 126.7 (Ar CH), 126.4 (Ar CH), 126.3 (Ar CH), 126.3 (Ar CH),

125.4 (Ar CH), 121.2 (d, J_CP= 3 Hz, Ar C), 120.8 (d, J_CP= 3 Hz, Ar

C), 118.8 (d, J_CP= 3 Hz, Ar C), 118.5 (d, J_CP= 3 Hz, Ar C), 116.9 (d,

1

(0.17 g, 0.36 mmol, 71%). H NMR (C₆D₆): δ 11.33 (s, 1H, NH),

8.08 (s, 1H, imine CH), 7.49 (dd, 1H, J_PH= 4 Hz, J_HH= 8 Hz, Ar H),

7.33 (d, 1H, J_HH= 9 Hz, Ar H), 7.28 (s, 1H, Ar H), 6.92−6.89 (m, 2H,

Ar H), 6.86 (d, 3H, J_PH= 4 Hz, Ar H), 2.28 (s, 6H, ortho-CH₃), 2.19

N

DOI: 10.1021/ic503062w

Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry

Article

(s, 3H, CH₃), 2.16 (s, 3H, CH₃), 2.10 (s, 3H, CH₃), 1.99 (m, 2H,

CH(CH₃)₂), 1.04 (dd, 6H, J_PH= 15 Hz, J_HH= 7 Hz, CH(CH₃)₂), 0.88

(dd, 6H, J_PH= 12 Hz, J_HH= 7 Hz, CH(CH₃)₂). ¹H{³¹P} NMR

(C₆D₆): δ 11.33 (s, 1H, NH), 8.08 (s, 1H, imine CH), 7.49 (d, 1H,

J_HH= 8 Hz, Ar H), 7.33 (d, 1H, J_HH= 9 Hz, Ar H), 7.28 (s, 1H, Ar H),

6.92 (m, 2H, Ar H), 6.86 (d, 3H, J_PH= 4 Hz, Ar H), 2.28 (s, 6H, ortho-

CH₃), 2.19 (s, 3H, CH₃), 2.16 (s, 3H, CH₃), 2.10 (s, 3H, CH₃), 1.99

(m, 2H, CH(CH₃)₂), 1.04 (dd, 6H, J_HH= 7 Hz, J_PH= 15 Hz,

CH(CH₃)₂), 0.88 (dd, 6H, J_HH= 7 Hz, J_PH= 12 Hz, CH(CH₃)₂).

(d, 3H, J_PH= 14 Hz, CH(CH₃)₂), 1.16 (d, 3H, J_PH= 10 Hz,

1

CH(CH₃)₂), 0.93 (d, 3H, J_PH= 9 Hz, CH(CH₃)₂). H{³¹P} NMR

(C₆D₆): δ 7.59 (d, 1H, J_HH= 9 Hz, Ar H), 7.38 (d, 1H, J_HH= 9 Hz, Ar

H), 7.21 (s, 1H, Ar H), 6.87−6.75 (m, 3H, Ar H), 6.70 (s, 1H, Ar H),

6.12 (s, 1H, Ar H), 2.58 (s, 3H, CH₃), 2.46 (m, 2H, CH(CH₃)₂), 2.36

(s, 3H, CH₃), 2.14 (s, 3H, CH₃), 2.07 (s, 3H, CH₃), 2.03 (s, 3H, CH₃),

1.40 (s, 3H, CH(CH₃)₂), 1.29 (s, 3H, CH(CH₃)₂), 1.16 (s, 3H,

CH(CH₃)₂), 0.93 (s, 3H, CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): δ 163.4

(Ar C), 163.1 (d, J_CP= 19 Hz, Ar CN), 150.7 (Ar C), 147.9 (Ar C),

135.1 (Ar C), 134.8 (Ar C), 134.7 (Ar C), 132.9 (Ar C), 132.3 (Ar C),

131.3 (Ar C), 129.3 (Ar C), 128.8(Ar C), 125.9 (Ar C), 125.5 (Ar C),

1

³¹P{¹H} NMR (C₆D₆): δ −5.8. H NMR (CDCl₃): δ 10.63 (s, 1H,

NH), 8.25 (s, 1H, imine CH), 7.35 (dd, 1H, J_PH= 4 Hz, J_HH= 8 Hz,

Ar H), 7.24 (m, 1H, Ar H), 7.11 (m, 2H, Ar H), 7.02 (s, 1H, Ar H),

6.88 (s, 1H, J_PH= 4 Hz, Ar H), 2.28 (s, 6H, ortho-CH₃), 2.19 (s, 3H,

CH₃), 2.16 (s, 3H, CH₃), 2.10 (s, 3H, CH₃), 1.99 (m, 2H,

CH(CH₃)₂), 1.04 (dd, 6H, J_PH= 15 Hz, J_HH= 7 Hz, CH(CH₃)₂),

0.88 (dd, 6H, J_PH= 12 Hz, J_HH= 7 Hz, CH(CH₃)₂). ¹³C{¹H} NMR

(CDCl₃): δ 165.5(s, imine CH), 148.8 (s, Ar C), 145.0 (s, Ar C), 144.1

(d, J_CP= 18 Hz, Ar CN), 140.3 (s, Ar C), 135.0 (s, Ar C), 134.6 (s, Ar

C), 132.9 (s, Ar C), 132.5 (d, J_CP= 11 Hz, Ar C), 130.1 (s, Ar C),

129.0 (s, Ar C), 128.7 (s, Ar C), 127.8 (s, Ar C), 127.3 (s, Ar C), 125.6

(s, Ar C), 123.7 (s, Ar C), 122.0 (s, Ar C), 118.7 (s, Ar C), 113.9 (s, Ar

C), 23.6 (d, J_CP= 14 Hz, CH(CH₃)₂), 21.2 (s CH₃), 20.5 (s, CH₃),

20.4 (d, J_CP= 5 Hz, CH(CH₃)₂), 19.6 (d, J_CP= 10 Hz, CH(CH₃)₂),

18.77 (s, CH₃), 17.72 (s, CH₃). ³¹P{¹H} NMR (CDCl₃): δ −3.3 (s).

7-PdOAc. A 25 mL Schlenk ﬂask was charged with 7-H (0.15 g,

0.33 mmol) and dissolved in toluene (3 mL) under ambient

temperature. Pd(OAc)₂(76 mg, 0.33 mmol) was then added to the

reaction mixture, resulting in an immediate color change from yellow

to purple. The reaction mixture was stirred for 12 h and then the

volatiles were removed in vacuo. The resulting red solid was then

washed two times with cold pentane and dried to yield pure product

121.1 (Ar C), 121.0 (Ar C), 120.9 (Ar C), 119.0 (Ar C), 26.9 (d, J_CP

=

23 Hz, CH(CH₃)₂), 24.0 (d, J_CP= 29 Hz, CH(CH₃)₂), 21.0 (CH₃),

20.5 (CH₃), 20.0 (CH₃), 19.6, (d, J_CP= 14 Hz, CH(CH₃)₂), 19.0

1

(CH₃), 17.9 (CH₃), 17.5 (CH₃). ³¹P{¹H} NMR (C₆D₆): δ 70.3. H

NMR (CDCl₃): δ 7.79 (s, 1H, Ar CH), 7.55 (s, 1H, Ar CH), 7.17 (s,

1H, Ar CH), 7.08 (s, 1H, Ar CH), 7.00 (s, 1H, Ar CH), 6.88 (s, 2H, Ar

CH), 2.64 (d, J = 26 Hz, 4H, CH(CH₃)₂overlapping with CH₃), 2.47

(s, 1H, CH(CH₃), 2.36 (s, 3H, CH₃), 2.27 (s, 6H, CH₃), 2.19 (s, 3H,

CH₃), 1.48−1.18 (m, 12H, CH(CH)₃)₂). Elemental analysis,

calculated for 7-PdCl: C, 60.11; H, 6.39; N. Found: C, 60.06; H, 6.42.

7-RhCO. A J. Young tube was charged with 7-H (41 mg, 90 μmol),

[Rh(COD)Cl]₂(46 mg, 93 μmol of Rh), 2,6-lutidine (11 μL, 90

μmol), and C₆D₆(1 mL). The solution was then degassed and

exposed to CO (1 atm). A red color change was observed, and ³¹P

NMR analysis revealed conversion to 7-RhCO. The reaction mixture

was then ﬁltered through a pad of silica gel and washed with diethyl

ether. 7-RhCO was obtained as a red solid after removal of the

volatiles in vacuo and recrystallization by slow diﬀusion of pentane into

dichloromethane (26 mg, 44 μmol, 50%). ¹H NMR (C₆D₆): δ 7.78 (d,

1H, J = 9 Hz, Ar H), 7.47 (d, 1H, J = 9 Hz, Ar H), 6.94 (d, 1H, J = 7

Hz, Ar H), 6.85 (s, 1H, imine CH), 6.80 (d, 1H, J = 7 Hz, Ar H),

6.75−6.72 (m, 2H, Ar H), 2.51 (s, 3H, CH₃), 2.41 (m, 1H,

CH(CH₃)₂), 2.37 (s, 3H, CH₃), 2.15 (s, 3H, CH₃), 2.13 (s, 3H, CH₃),

2.09 (s, 3H, CH₃), 1.90 (m, 1H, CH(CH₃)₂), 1.31−1.29 (m, 6H,

1

(0.15 g, 76%). H NMR (C₆D₆): δ 7.63 (d, 1H, J_HH= 9 Hz, imine

CH), 7.38 (dd, 1H, J_PH= 4 Hz, J_HH= 9 Hz, Ar H), 7.13 (d, 1H, J_PH

=

13 Hz, Ar H), 6.82 (s, 1H, Ar H), 6.80 (d, 1H, J_PH= 8 Hz, Ar H), 6.75

(d, 2H, J_PH= 9 Hz, Ar H), 6.67 (d, 1H, J_HH= 9 Hz, Ar H), 6.62 (s, 1H,

Ar H), 2.74 (m, 1H, CH(CH₃)₂), 2.60 (s, 3H, CH₃), 2.29 (s, 3H,

CH₃), 2.15 (s, 3H, CH₃), 2.10 (s, 3H, CH₃), 2.05 (s, 3H, CH₃), 2.03

(s, 3H, CH₃), 1.94 (septet, 1H, CH(CH₃)₂), 1.51 (dd, 3H, J_PH= 19

Hz, J_HH= 6 Hz, CH(CH₃)₂), 1.24 (dd, 3H, J_PH= 19 Hz, J_HH= 6 Hz,

CH(CH₃)₂), 1.14 (dd, 3H, J_PH= 15 Hz, J_HH= 6 Hz, CH(CH₃)₂), 0.87

(dd, 3H, J_PH= 11 Hz, J_HH= 6 Hz, CH(CH₃)₂). ¹H{³¹P} NMR

(C₆D₆): δ 7.60 (d, 1H, J_HH= 9 Hz, Ar H), 7.35 (d, 1H, J_HH= 9 Hz, Ar

H), 7.16 (s, 1H, Ar H), 7.08 (s, 1H, Ar H), 6.80 (s, 1H, Ar H), 6.77 (s,

1H, Ar H), 6.73 (s, 1H, Ar H), 6.64 (d, 1H, J_HH= 9 Hz, Ar H), 6.60 (s,

1H, Ar H), 2.80 (m, 1H, CH(CH₃)₂), 2.55 (s, 3H, CH₃), 2.24 (s, 3H,

CH₃), 2.13 (s, 3H, CH₃), 2.06 (s, 3H, CH₃), 2.04 (s, 3H, CH₃), 1.90

(m, 1H, CH(CH₃)₂), 1.50 (d, 3H, J_HH= 6 Hz, CH(CH₃)₂), 1.20 (d,

3H, J_HH= 6 Hz, CH(CH₃)₂), 1.11 (d, 3H, J_HH= 6 Hz, CH(CH₃)₂),

0.91 (d, 3H, J_HH= 6 Hz, CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): δ 176.3

(OAc), 163.5 (Ar CN), 163.3 (Ar CH), 150.6 (Ar C), 146.8 (Ar C),

135.3 (Ar CH), 134.8 (Ar CH), 132.7 (Ar CH), 132.7 (Ar C), 131.5

(Ar CH), 130.1 (Ar C), 128.8 (Ar CH), 127.5 (Ar C), 125.7 (Ar C),

125.4 (Ar CH), 120.8 (Ar C), 120.7 (Ar C), 120.6 (Ar C), 120.1 (Ar

1

CH(CH₃)₂), 1.11−1.04 (m, 6H, CH(CH₃)₂). H NMR (CDCl₃): δ

7.74 (dd, J = 9.2 Hz, J = 2.3 Hz, 1H, Ar H), 7.56 (d, J = 8.9 Hz, 1H, Ar

H), 7.28 (dd, J = 8.6 Hz, J = 3.9 Hz, 1H, Ar H), 7.03 (dd, J = 7.9 Hz, J

= 2.2 Hz, 1H, Ar H), 6.96 (s, 1H, Ar H), 6.94−6.86 (m, 3H, Ar H),

2.45 (m, 2H, CH(CH₃)₂), 2.38 (s, 3H, CH₃), 2.31 (s, 3H, CH₃),

2.30−2.27 (s, 3H, CH₃), 2.25 (s, 3H, CH₃), 2.21 (s, 3H, CH₃), 1.37−

1.00 (m, 12H, CH(CH₃)₂). ¹H{³¹P} NMR (CDCl₃): δ 7.74 (d, J = 2.3

Hz, 1H, Ar H), 7.56 (d, J = 8.9 Hz, 1H, Ar H), 7.28 (d, J = 8.6 Hz, 1H,

Ar H), 7.03 (d, J = 2.2 Hz, 1H, Ar H), 6.96 (s, 1H, Ar H), 6.94−6.86

(m, 3H, Ar H), 2.45 (m, 2H, CH(CH₃)₂), 2.38 (s, 3H, CH₃), 2.31 (s,

3H, CH₃), 2.30−2.27 (s, 3H, CH₃), 2.25 (s, 3H, CH₃), 2.21 (s, 3H,

CH₃), 1.37−1.00 (m, 12H, CH(CH₃)₂). ¹³C{¹H} NMR (CDCl₃): δ

192.95−191.29 (m, CO), 162.5 (s, Ar C), 162.3 (s, Ar C), 162.2 (s, Ar

C), 153.60 (s, Ar C), 150.51 (s, Ar C), 134.61 (s, Ar C), 134.08 (s, Ar

C), 133.39 (s, Ar C), 131.65 (s, Ar C), 131.15 (s, Ar C), 130.50 (s, Ar

C), 128.59 (s, Ar C), 127.74 (s, Ar C), 124.03 (s, Ar C), 123.59 (s, Ar

C), 122.91 (s, Ar C), 122.59 (s, Ar C), 119.20 (d, J_CP= 12.1 Hz, Ar C),

118.88 (s, Ar C), 27.43 (d, J_CP= 27 Hz, CH(CH₃)₂), 23.64 (d, J_CP

=

32 Hz, CH(CH₃)₂), 21.04 (s, CH₃), 20.69 (s, CH₃), 20.19 (s, CH₃),

19.59 (s, CH₃), 18.89 (s, CH₃), 18.73 (s, CH₃), 17.95 (s, CH₃).

³¹P{¹H} NMR (CDCl₃): δ 76.3 (d, J_RhP= 130 Hz). IR ν(CO) = 1942

cm⁻¹. Elemental analysis, calculated for C₃₁H₃₈N₂OPRh: C, 63.27; H,

6.51%. Found: C, 63.09; H, 6.38%.

C), 119.7 (Ar CH), 26.8 (d, J_CP= 24 Hz, CH(CH₃)₂), 21.8 (d, J_CP

=

24 Hz, CH(CH₃)₂), 20.9 (CH₃), 20.5 (CH₃), 20.1 (CH₃), 19.5

(broad, CH₃), 18.9 (broad, CH₃), 18.2 (broad, CH₃), 16.3 (CH₃), 16.2

(broad, CH₃). ³¹P{¹H} NMR (C₆D₆): δ 65.6.

7-PdCl. A Schlenk ﬂask was charged with 7-H (0.12 mg, 0.27

mmol), Pd(COD)Cl₂(78 mg, 0.27 mmol), 2,6-lutidine (31 μL, 0.27

mmol), toluene (3 mL), and a stir bar. The reaction mixture was

stirred for 5 h to yield a red solution. The toluene solution was ﬁltered

through a pad of silica gel. To ensure quantitative transfer, the silica gel

was washed with diethyl ether. The volatiles were then removed in

vacuo. The resulting red solid was washed with toluene to yield 7-PdCl

8-H. G (0.40 g, 1.2 mmol) was dissolved in toluene (15 mL) and

treated with tert-butylamine (0.40 mL, 2.3 mmol) and tosylic acid (12

mg, 0.070 mmol, 10 mol %) in a Teﬂon screw-capped Schlenk ﬂask.

The reaction mixture was then heated in a 110 °C oil bath for 10 days

while stirring over molecular sieves. The reaction was then cooled to

ambient temperature, the solution decanted, and the volatiles were

removed in vacuo. The remaining yellow oil was dissolved in pentane

and stirred vigorously over silica gel for 5 min before being passed

through a pad of Celite. The volatiles were removed, and the resulting

yellow oil was recrystallized from ﬂuorobenzene at −35 °C to yield 15-

1

as a red solid (62 mg, 0.10 mmol, 39%). H NMR (C₆D₆): δ 7.59 (d,

1H, J_HH= 9 Hz, Ar H), 7.38 (dd, 1H, J_HH= 9 Hz, J_PH= 4 Hz, Ar H),

7.21 (d, 1H, J_PH= 13 Hz, Ar H), 6.87−6.75 (m, 3H, Ar H), 6.70 (d,

1H, J_PH= 9 Hz, Ar H), 6.12 (s, 1H, Ar H), 2.58 (s, 3H, CH₃), 2.46 (m,

2H, CH(CH₃)₂), 2.36 (s, 3H, CH₃), 2.14 (s, 3H, CH₃), 2.07 (s, 3H,

CH₃), 2.03(s, 3H, CH₃), 1.40 (d, 3H, J_PH= 14 Hz, CH(CH₃)₂), 1.29

1

H as a yellow solid (0.40 mg, 1.0 mmol, 87%). H NMR (C₆D₆): δ

11.80 (s, 1H, NH), 8.26 (s, 1H, imine CH), 7.48 (dd, 1H, J_PH= 4 Hz,

O

DOI: 10.1021/ic503062w

Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry

Article

J_HH=8 Hz, Ar H), 7.34 (d, 1H, J_HH= 9 Hz, Ar H), 7.24 (s, 1H, Ar H),

6.94 (s, 1H, Ar H), 6.89 (d, 2H, J_HH= 8 Hz, Ar H), 2.18 (s, 3H, CH₃),

2.16 (s, 3H, CH₃), 1.99 (m, 2H, CH(CH₃)₂), 1.34 (s, 9H, CH₃), 1.11

(dd, 6H, J_PH= 15 Hz, J_HH= 7 Hz, CH(CH₃)₂), 0.99 (dd, 6H, J_PH= 11

(C₆D₆): δ 70.4. Elemental analysis, calculated for 8-PdCl: C, 55.87;

H, 6.60; N, 5.21. Found: C, 55.72; H, 6.88; N, 5.09.

8-PdCl. A J. Young tube was charged with 8-PdOAc (77 mg, 14

μmol) and C₆D₆(1 mL). Me₃SiCl (18 μL, 14 μmol) was added to the

reaction mixture via syringe. After 72 h, the volatiles were removed in

vacuo, and the resulting solid was washed three times with toluene (1

mL). After the ﬁnal wash, the volatiles were removed in vacuo to yield

8-PdCl as a purple solid (63 mg, 12 μmol, 85%).

1

Hz, J_HH= 7 Hz, CH(CH₃)₂). H{³¹P} NMR (C₆D₆) δ 11.80 (s, 1H,

NH), 8.26 (s, 1H, imine CH), 7.48 (dd, 1H, J_HH= 8 Hz, Ar H), 7.34

(1H, d, J_HH= 9 Hz, Ar H), 7.24 (s, 1H, Ar H), 6.94 (s, 1H, Ar H), 6.89

(d, 2H, J_HH= 8 Hz, Ar H), 2.18 (s, 3H, CH₃), 2.16 (s, 3H, CH₃), 1.99

(m, 2H, CH(CH₃)₂), 1.34 (s, 9H, CH₃), 1.11 (dd, 6H, J_HH= 7 Hz,

CH(CH₃)₂), 0.99 (dd, 6H, J_HH= 7 Hz, CH(CH₃)₂). ¹³C{¹H} NMR

(C₆D₆): δ 158.2 (imine C), 145.8 (d, J_CP= 20 Hz, Ar CN), 145.6 (Ar

C), 134.6 (Ar C), 134.0 (Ar C), 131.5 (Ar C), 131.4 (Ar C), 130.3 (Ar

C), 128.6 (Ar C), 25.4 (Ar C), 122.7 (Ar C), 120.3 (Ar C), 113.5 (Ar C

H), 57.4 (C(CH₃)₃), 29.9 (C(CH₃)₃), 23.4 (d, J_CP= 13 Hz,

CH(CH₃)₂), 21.0 (Ar CH₃), 20.5 (d, J_CP= 20 Hz, CH(CH₃)₂), 20.4

(Ar CH₃), 19.5 (d, J_CP= 10 Hz, CH(CH₃)₂). ³¹P{¹H} NMR (C₆D₆): δ

−7.3.

8-PdOAc. A Schlenk ﬂask was charged with 8-H (0.10 g, 0.26

mmol), Pd(OAc)₂(58 mg, 0.26 μmol), toluene (5 mL), and a stir bar.

An immediate color change to a purple solution is observed. The

solution was stirred for 1 h and then passed through a pad of Celite.

Removal of the volatiles and washing with 3 × 5 mL of toluene yielded

8-PdOAc as a red powder (0.11 g, 0.20 mmol, 78%). ¹H NMR

(C₆D₆): δ 7.41 (d, 1H, J_HH= 5 Hz, imine CH), 7.39 (s, 1H, Ar H),

7.20 (dd, 1H, J_PH= 9 Hz, J_HH= 4 Hz, Ar H), 6.84 (d, 1H, J = 8 Hz, Ar

H), 6.73 (d, 1H, J_PH= 9 Hz, J_HH= 2 Hz, Ar H), 6.67 (d, 1H, J = 9 Hz,

Ar H), 6.62 (s, 1H, Ar H), 2.90 (m, 1H, CH(CH₃)₂), 2.19 (s, 3H,

CH₃), 2.07 (s, 3H, CH₃), 2.06 (s, 3H, CH₃), 2.00 (m, 1H,

CH(CH₃)₂), 1.47 (dd, 3H, J_PH= 20 Hz, J_HH= 7 Hz, CH(CH₃)₂),

1.44 (s, 9H, C(CH₃)₃), 1.40 (dd, 3H, J_PH= 8 Hz, J_HH= 7 Hz,

CH(CH₃)₂), 1.25 (dd, 3H, J_PH= 16 Hz, J_HH= 7 Hz, CH(CH₃)₂), 0.85

(dd, 3H, J_PH= 13 Hz, J_HH= 7 Hz, CH(CH₃)₂). ¹³C{¹H} NMR

(C₆D₆): δ 175.9 (CO), 162.6 (d, J_CP= 21 Hz, N C of pincer

backbone), 157.7 (Ar C), 150.3 (Ar C), 134.7 (Ar C), 133.9 (Ar C),

132.9 (Ar C), 131.2 (Ar C), 129.3 (Ar C), 125.5 (Ar C), 122.0 (Ar C),

121.9 (Ar C), 121.4 (Ar C), 118.7 (Ar C), 62.7 (C(CH₃)₃), 30.6

(C(CH₃)₃), 27.4 (d, J_CP= 22 Hz, CH(CH₃)₂), 24.1 (CH₃), 22.0

(CH₃), 21.8 (CH₃), 20.2 (CH₃), 19.6 (d, J_CP= 5 Hz, CH(CH₃)₂), 18.7

(d, J_CP= 4 Hz, CH(CH₃)₂), 16.3 (CH₃), 15.9 (d, J_CP= 5 Hz,

CH(CH₃)₂). ³¹P{¹H} NMR (C₆D₆): δ 66.3.

8-RhCO. A J. Young tube was charged with 8-H (42 mg, 0.11

mmol), [Rh(COD)Cl]₂(52 mg, 0.11 mmol of Rh), 2,6-lutidine (13

μL, 0.11 mmol), and C₆D₆(1 mL). Upon the addition of CO (1 atm),

the solution immediately turns red. The solution was allowed to react

overnight and was then passed through a pad of silica gel. The frit was

washed with diethyl ether, and the volatiles were removed in vacuo to

yield a red solid. This was then taken up in dichloromethane and

stored at −35 °C to yield red crystals of 8-RhCO (47 mg, 0.089 mmol,

1

84%). H NMR (C₆D₆): δ 7.81 (d, 1H, J_PH= 9 Hz, imine CH), 7.53

(d, 1H, J_HH= 8 Hz, Ar H), 7.30 (dd, 1H, J_PH= 8 Hz, J_HH= 4 Hz, Ar

H), 7.01 (d, 1H, J_HH= 7 Hz, Ar H), 6.80 (d, 1H, J_HH= 9 Hz, Ar H),

6.76 (s, 1H, Ar H), 6.75 (m, 1H, Ar H), 2.30 (m, 1H, CH(CH₃)₂),

2.14 (s, 3H, CH₃), 2.12 (s, 3H, CH₃), 1.46 (s, 9H, C(CH₃)₃), 1.32−

1.19 (m, 9H, CH(CH₃)₂), 0.98 (dd, 3H, J_PH= 13 Hz, J_HH= 7 Hz,

1

CH(CH₃)₂). H NMR (CDCl₃): δ 8.25 (dd, J = 9 Hz, J = 3 Hz, 1H,

imine CH), 7.50 (d, J = 3 Hz, 1H, Ar H), 7.47 (dd, J = 9 Hz, J = 3 Hz,

1H, Ar H), 7.38−7.30 (m, 2H Ar H), 7.17 (s, 1H, Ar H), 7.01 (d, J = 9

Hz, 1H, Ar H), 2.81 (m, 1H, CH(CH₃)₂), 2.50 (s, 3H, Ar CH₃), 2.48

(m, 1H, CH(CH₃)₂), 2.41 (s, 3H, Ar CH₃), 1.86 (s, 9H, C(CH₃)₃),

1.57 (dd, J = 16 Hz, J = 7 Hz, 3H, CH(CH₃)₂), 1.49 (dd, J = 15 Hz, J

= 7 Hz, 6H, CH(CH₃)₃), 1.42 (dd, J = 14 Hz, J= 7 Hz, 3H,

CH(CH₃)₃). ¹³C{¹H} NMR (CDCl₃): δ 194.7 (CO), 161.6 (d, J =

21.7 Hz, Ar C), 158.2 (s), 150.1 (s), 134.2 (s), 133.1 (s), 132.0 (s),

130.8 (s), 128.6−127.3 (m), 124.6 (s), 123.5 (s), 120.50 (d, J = 13

Hz), 117.19 (d, J = 43 Hz), 63.71 (s (C(CH₃)₃), 31.95 (s, (C(CH₃)₃),

27.46 (d, J = 26 Hz, CH(CH₃)₂), 23.99 (d, J = 34 Hz, CH(CH₃)₂),

20.79 (s, CH₃), 20.15 (s, CH₃), 19.82 (s, CH₃), 19.13 (s, CH₃), 18.20

(s, CH₃), 17.68 (s, CH₃). ³¹P{¹H} NMR (C₆D₆): δ 78.7 (d, J_RhP= 154

Hz). IR ν(CO) =1930 cm⁻¹.

H. A Schlenk ﬂask was charged with F (0.30 g, 0.77 mmol), a stir

bar, and diethyl ether. n-Butyllithium (0.31 mL, 0.77 mmol) was then

added in a dropwise fashion. After 30 min, ClP(NMe₂)₂(0.11 mL,

0.77 mmol) was added, and stirring was commenced for an additional

1.5 h. The ethereal solution was then ﬁltered through a pad of Celite.

Removal of the volatiles in vacuo and recrystallization in pentane at

−35 °C resulted in isolation of H as colorless crystals (0.30 g, 0.59

mmol, 77%). ¹H NMR (C₆D₆): δ 7.93 (dd, J_HH= 5 Hz, J_P1H= 10 Hz,

1H, Ar H), 7.56 (dd, J_HH= 5 Hz, J_P1H= 10 Hz, 1H, Ar H), 7.31 (m,

1H, Ar H), 7.21 (d, J_HH= 5 Hz, 1H, Ar H), 6.99 (d, J_HH= 5 Hz, 1H,

Ar H), 6.89 (d, J_HH= 5 Hz, 1H, Ar H), 2.48 (d, J_P2H= 10 Hz, 12H,

P(N(CH₃)₂)₂), 2.15 (s, 3H, Ar CH₃), 1.93 (s, 3H, Ar CH₃), 1.90 (m,

2H, CH(CH₃)₂), 1.15 (dd, J_HH= 7 Hz, J_P1H= 15 Hz, 6H, CH(CH₃)₂),

0.95 (dd, J_HH= 7 Hz, J_P1H= 15 Hz, 6H, CH(CH₃)₂). ¹H{³¹P₁} NMR

(C₆D₆): δ 7.93 (d, J_HH= 5 Hz, 1H, Ar H), 7.56 (d, J_HH= 5 Hz, 1H, Ar

8-PdCl. A Schlenk ﬂash was charged with 15-H (51 mg, 0.13

mmol), 2,6-lutidine (15 μL, 0.13 mmol), Pd(COD)Cl₂(38 mg, 0.13

mmol), toluene (5 mL) and a stir bar. The resulting red solution was

then stirred overnight and then ﬁltered through a pad of Celite. The

volatiles were then removed in vacuo, and the solid was recrystallized

in toluene to yield 15-PdCl as a deep red powder (32 mg, 60 μmol,

50%). ¹H NMR (C₆D₆): δ 7.48 (d, 1H, J_PH= 13 Hz, imine CH), 7.32

(d, 1H, J_HH= 9 Hz, Ar H), 7.22 (dd, 1H, J_PH= 5 Hz, J_HH= 9 Hz, Ar

H), 6.89 (d, 1H, J_PH= 8 Hz, Ar H), 6.76 (d, 1H, J_HH= 9 Hz, Ar H),

6.69 (d, 1H J_HH= 9 Hz, Ar H), 6.61 (s, 1H, Ar H), 2.52 (m, 1H,

CH(CH₃)₂), 2.13 (m, 1H, CH(CH₃)₂), 2.10 (s, 3H, Ar CH₃), 2.05 (s,

3H, Ar CH₃), 1.64 (s, 9H, C(CH₃)₃), 1.58 (dd, 3H, J_PH= 17 Hz, J_HH

=

H), 7.31 (m, 1H, Ar H), 7.21 (d, J_HH= 5 Hz, 1H, Ar H), 6.99 (d, J_HH

=

9 Hz, CH(CH₃)₂), 1.32 (dd, 3H, J_PH= 17 Hz, J_HH= 9 Hz,

CH(CH₃)₂), 1.26 (dd, 3H, J_PH= 18 Hz, J_HH= 11 Hz, CH(CH₃)₂),0.87

(dd, 3H, J_PH= 15 Hz, J_HH= 8 Hz, CH(CH₃)₂). ¹H{³¹P} NMR

(C₆D₆): δ 7.49 (s, 1H, imine CH), 7.32 (d, 1H, J_HH= 9 Hz, Ar H),

7.22 (dd, 1H, J_HH= 9 Hz, Ar H), 6.89 (s, 1H, Ar H), 6.76 (d, 1H, J_HH

= 9 Hz, Ar H), 6.69 (d, 1H, J_HH9 Hz, Ar H), 6.61 (s, 1H. Ar H), 2.52

(m, 1H, CH(CH₃)₂), 2.13 (m, 1H, CH(CH₃)₂), 2.10 (s, 3H, Ar CH₃),

2.05 (s, 3H, Ar CH₃), 1.64 (s, 9H, C(CH₃)₃), 1.57 (d, 3H, J_HH= 7 Hz,

5 Hz, 1H, Ar H), 6.89 (d, J_HH= 5 Hz, 1H, Ar H), 2.48 (d, J_P2H= 10

Hz, 12H, P(N(CH₃)₂)₂), 2.15 (s, 3H, Ar CH₃), 1.93 (s, 3H, Ar CH₃),

1.90 (m, 2H, CH(CH₃)₂), 1.15 (d, J_HH= 7 Hz, 6H, CH(CH₃)₂), 0.95

(d, J_HH= 7 Hz, 6H, CH(CH₃)₂). ¹H{³¹P₂} NMR (C₆D₆): δ 7.93 (dd,

J_HH= 5 Hz, J_P1H= 10 Hz, 1H, Ar H), 7.56 (dd, J_HH= 5 Hz, J_P1H= 10

Hz, 1H, Ar H), 7.31 (m, 1H, Ar H), 7.21 (d, J_HH= 5 Hz, 1H, Ar H),

6.99 (d, J_HH= 5 Hz, 1H, Ar H), 6.89 (d, J_HH= 5 Hz, 1H, Ar H), 2.48

(s, 12H, P(N(CH₃)₂)₂), 2.15 (s, 3H, Ar CH₃), 1.93 (s, 3H, Ar CH₃),

1.90 (m, 2H, CH(CH₃)₂), 1.15 (dd, J_HH= 7 Hz, J_P1H= 15 Hz, 6H,

CH(CH₃)₂), 0.95 (dd, J_HH= 7 Hz, J_P1H= 15 Hz, 6H, CH(CH₃)₂).

¹³C{¹H} NMR (C₆D₆): δ 151.4 (dd, J = 17 Hz, J = 21 Hz, 3° Ar CN),

143.5 (s, 3° Ar C), 136.4 (s, Ar CH), 135.6 (dd, J = 4 Hz, J = 9 Hz, 3°

Ar C), 134.5 (s, Ar CH), 134.3 (s, Ar CH), 133.8 (d, J = 22 Hz, 3° Ar

C), 132.4 (s, Ar CH), 130.1 (dd, J = 6 Hz, J = 10 Hz, 3° Ar C), 129.6

(s, Ar CH), 127.4 (s, Ar CH), 124.6 (s, 3° Ar C), 38.8 (d, J = 2 Hz,

N(CH₃)₂), 38.6 (d, J = 2 Hz, N(CH₃)₂), 26.8 (d, J = 5 Hz,

CH(CH₃)₂), 26.7 (d, J = 5 Hz, CH(CH₃)₂), 21.9 (s, CH₃), 21.8 (s,

CH(CH₃)₂), 1.32 (d, 3H, J_HH= 7 Hz, CH(CH₃)₂), 1.26 (d, 3H, J_HH

=

7 Hz, CH(CH₃)₂), 0.88 (d, 3H, J_HH= 7 Hz, CH(CH₃)₂). ¹³C{¹H}

NMR (C₆D₆): δ 162.7 (d, J_CP= 21 Hz, CN), 158.0 (Ar C), 150.7 (Ar

C), 134.4 (Ar C), 133.8 (Ar C), 133.2 (Ar C), 131.2 (Ar C), 129.0 (d,

J_CP= 7 Hz, Ar C), 125.6 (Ar C), 122.5 (d, J_CP= 16 Hz, Ar C), 122.2

(Ar C), 121.9 (Ar C), 118.1 (Ar C), 63.6 (C(CH₃)₃), 31.5 (C(CH₃)₃),

26.6 (d, J_CP= 24 Hz, CH(CH₃)₂), 24.4 (d, J_CP= 30 Hz, CH(CH₃)₂),

20.5 (Ar CH₃), 2.02 (Ar CH₃), 18.9 (d, J_CP= 4 Hz, CH(CH₃)₂), 18.3

(CH(CH₃)₂), 18.1(CH(CH₃)₂), 17.1(CH(CH₃)₂). ³¹P{¹H} NMR

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CH₃), 20.9 (s, CH₃), 20.6, 20.4 (s, CH₃), 20.4(s, CH₃). ³¹P{¹H} NMR

(C₆D₆): δ 124.5 (s, P₂, P(NCH₃)₂), −9.1 (s, P₁, P(ⁱPr)₂).

analysis, calculated for C₂₅H₃₈N₃OP₂Rh: C, 53.48; H, 6.82%. Found:

C, 53.19; H, 6.68%.

10-H. A Teﬂon stoppered Schlenk ﬂask was charged with 9-H (2.00

g, 4.64 mmol), CF₃CH₂OH (1.70 mL, 23.2 mmol), toluene (15 mL),

and a stir bar. The reaction mixture was then reﬂuxed at 100 °C for 3

days. Cooling the reaction mixture to room temperature and removal

of the volatiles in vacuo resulted in yellow oil. Recrystallization in

diethyl ether yielded 10-H as a colorless oil (2.47 g, 4.57 mmol, 98%).

¹H NMR (CDCl₃): δ 7.43 (d, J_PH= 5 Hz, 1H, NH), 7.19−7.17 (m,

4H, Ar H), 7.01 (d, J_HH= 10 Hz, 1H, Ar H), 6.89 (dd, J_HH= 10 Hz,

J_P1H= 5 Hz, 1H, Ar H), 4.30−4.24 (m, 2H, OCH₂CF₃), 4.19−4.13 (m,

2H, OCH₂CF₃), 2.35 (s, 3H, Ar CH₃), 2.29 (s, 3H, Ar CH₃), 2.17−

2.11 (m, 2H, CH(CH₃)₂), 1.13 (dd, J_P1H= 15 Hz, J_HH= 5 Hz, 6H,

CH(CH₃)₂), 0.96 (dd, J_P1H15 Hz, J_HH= 5 Hz, 6H, CH(CH₃)₂).

¹H{³¹P₁} NMR (CDCl₃): δ 7.43 (d, J_PH= 5 Hz, 1H, NH), 7.19−7.17

(m, 4H, Ar H), 7.01 (d, J_HH= 10 Hz, 1H, Ar H), 6.89 (d, J_HH= 10 Hz,

J_PH= 5 Hz, 1H, Ar H), 4.30−4.24 (m, 2H, OCH₂CF₃), 4.19−4.13 (m,

2H, OCH₂CF₃), 2.35 (s, 3H, Ar CH₃), 2.29 (s, 3H, Ar CH₃), 2.17−

2.11 (m, 2H, CH(CH₃)₂), 1.13 (d, J_HH= 5 Hz, 6H, CH(CH₃)₂), 0.96

(d, J_HH= 5 Hz, 6H, CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): δ 147.7 (d,

J_CP= 20 Hz, CN), 144.7 (d, J_CP= 19 Hz, CN), 133.7 (d, J_CP= 5 Hz, Ar

C), 133.4 (s, Ar C), 132.1 (d, J_CP= 3 Hz, Ar C), 131.5 (d, J_CP= 13 Hz,

Ar C), 131.0 (s), 129.6 (s, Ar C), 129.5 (s, Ar C), 129.4 (s, Ar C),

9-H. A Schlenk ﬂask was charged with F (2.7 g, 6.8 mmol), a stir

bar, and diethyl ether (100 mL). n-Butyllithium (2.7 mL, 6.8 mmol)

was then added to the reaction via syringe and allowed to react for 20

min. ClP(NMe₂)₂(1.0 mL, 6.8 mmol) was then added to the solution.

Stirring was continued for 30 min, and then a second equivalent of n-

butyllithium (2.7 mL, 6.8 mmol) was added to the reaction mixture.

Removal of a small aliquot and analysis via ³¹P NMR reveal conversion

to 9-Li as observed by the formation of two singlets at δ109.5 and

−3.4 ppm in diethyl ether. The addition of CF₃CH₂OH (0.49 mL, 6.8

mmol) results in immediate precipitation of LiOCH₂CF₃and

formation of a colorless solution. The diethyl ethereal solution was

then ﬁltered through a pad of Celite, concentrated, and stored at −35

°C. The resulting precipitate was collected and dried in vacuo to yield

9-H as a colorless solid (2.4 g, 82%). ¹H NMR (C₆D₆): δ 8.55 (d, J_P1H

= 8 Hz, 1H, NH), 7.43−7.33 (m, 3H, Ar H), 7.13 (s, 1H, Ar H), 6.93

(d, J_HH= 9 Hz, 1H, Ar H), 6.84 (d, J_HH= 8 Hz, 1H, Ar H), 2.80 (d,

J_P2H= 9 Hz, 12H, P(NCH₃)₂), 2.26 (s, 3H, Ar CH₃), 2.18 (s, 3H, Ar

CH₃), 1.98−1.87 (m, 2H, CH(CH₃) ₂), 1.09 (dd, J_P1H= 15 Hz, J_HH

=

7 Hz, 6H, CH(CH₃)₂), 0.94 (dd, J_P1H= 12 Hz, J_HH= 7 Hz, 6H,

1

CH(CH₃)₂). H{³¹P₁} NMR (C₆D₆): δ 8.54 (s, 1H), 7.44−7.32 (m,

3H), 7.13 (s, 1H), 6.93 (d, J = 9 Hz, 1H), 6.84 (d, J = 8 Hz, 1H), 2.80

(d, J = 9 Hz, 12H), 2.26 (s, 3H), 2.18 (s, 3H), 1.95 (m 2H), 1.09 (d, J

121.0 (s, Ar C), 117.5 (d, J= 3 Hz, Ar C), 64.1 (m, CH₂), 23.7 (d, J_CP

=

1

= 7 Hz, 6H), 0.94 (d, 6H). H{³¹P₂} NMR (C₆D₆): δ 8.55 (d, J = 8

10 Hz, CH(CH₃)₂), 20.8 (d, J_CP= 8 Hz, CH(CH₃)₂), 20.4 (s, Ar

CH₃), 20.3 (s, Ar CH₃), 19.2 (d, J_CP= 9 Hz, CH(CH₃)₂). ³¹P{¹H}

NMR (C₆D₆): δ 166.3 (s, POCH₂CF₃), −15.0 (s, PⁱPr₂). ³¹P{¹H}

NMR (CDCl₃): δ 167.5 (s, POCH₂CF₃), −14.7 (s, PⁱPr₂). ¹⁹F NMR

(C₆D₆): δ 75.6.

Hz, 1H), 7.45−7.32 (m, 3H), 7.13 (s, 1H), 6.93 (d, J = 8 Hz, 1H),

6.84 (d, J = 8 Hz, 1H), 2.80 (d, J = 1 Hz, 12H), 2.26 (s, 3H), 2.18 (s,

3H), 1.95 (m, 2H), 1.09 (dd, J = 15 Hz, J = 7, 6H), 0.94 (dd, J = 12

Hz, J = 7 Hz, 6H). ¹³C{¹H} NMR (C₆D₆): δ 147.8 (d, J_CP= 20, Ar

CN), 143.5 (d, J_CP= 18 Hz, Ar CN)), 133.6 (d, J_CP= 3 Hz, Ar C),

132.8 (d, J = 8 Hz, Ar C), 130.7 (s, Ar C), 130.0 (s, Ar C), 128.8 (s, Ar

10-RhCO. A J. Young tube was charged with 10-H (0.15 g, 0.28

mmol), (Rh(COD)Cl)₂(65 mg, 0.13 mmol), 2,6-lutidine (32 μL, 0.28

mmol), and C₆D₆. The mixture was degassed by freeze pump thaw

techniques and then exposed to 1 atm of CO. The volatiles were then

removed in vacuo, and the resulting red oil was taken up in pentane

and ﬁltered through a pad of Celite. Removal of the volatiles yielded

10-RhCO as a red solid. No additional workup was conducted (0.12

mg, 0.18 mmol, 65%). ¹H NMR (C₆D₆): δ 7.60 (dd, J_HH= 8 Hz, J_P1H

= 4 Hz, 1H, Ar H), 7.53 (t, J_HH= 8 Hz, 1H, Ar H), 7.24 (d, J_P2H= 11

Hz, 1H, Ar H), 6.83 (d, J_P1H= 8 Hz, 1H, Ar H), 6.78 (d, J_HH= 9 Hz,

1H, Ar H), 6.75 (d, J_HH= 9 Hz, 1H, Ar H), 4.57−4.20 (m, 2H,

OCH₂CF₃), 3.93 (m, 2H, OCH₂CF₃), 2.14 (s, 3H, Ar CH₃), 2.09−

1.99 (m, 2H, CH(CH₃)₂), 1.98 (s, 3H, Ar CH₃), 1.13 (dd, J_P1H= 17

Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂), 0.92 (dd, J_P1H= 15 Hz, J_HH= 7 Hz,

6H, CH(CH₃)₂). ¹H{³¹P₁} NMR (C₆D₆): δ 7.60 (d, J = 9 Hz, 1H, Ar

H), 7.53 (t, J = 8 Hz, 1H, Ar H), 7.24 (d, J = 11 Hz, 1H, Ar H), 6.83

(s, 1H, Ar H), 6.78 (d, J_HH= 9 Hz, 1H, Ar H), 6.75 (d, J_HH= 9 Hz,

1H, Ar H), 4.43−4.24 (m, 2H, OCH₂CF₃), 4.05−3.82 (m, 2H,

OCH₂CF₃), 2.14 (s, 3H, Ar CH₃), 2.12−1.96 (m, 2H, CH(CH₃)₂),

1.98 (s, 3H, Ar CH₃), 1.13 (d, J_HH= 6.9 Hz, 6H, CH(CH₃)₂), 0.92 (d,

J_HH= 6.8 Hz, 6H, CH(CH₃)₂). ¹H{³¹P₂} NMR (C₆D₆): δ 7.60 (dd, J =

8 Hz, J = 4 Hz, 1H, Ar H), 7.53 (d, J = 9 Hz, 1H, Ar H), 7.24 (s, 1H,

Ar H), 6.83 (d, J = 8 Hz, 1H, Ar H), 6.78 (d, J_HH= 9 Hz, 1H, Ar H),

6.75 (d, J_HH= 9 Hz, 1H, Ar H), 4.36 (m 1H, OCH₂CF₃), 3.92 (m, 1H,

OCH₂CF₃), 2.14 (s, 2H, Ar CH₃), 2.09−2.01 (m, 1H, CH(CH₃)₂),

1.98 (s, 1H, CH(CH₃)₂), 1.13 (dd, J_PH= 17 Hz, J_HH= 7 Hz, 3H,

CH(CH₃)), 0.92 (dd, J_PH= 15 Hz, J_HH= 7 Hz, 3H, CH(CH₃)).

¹³C{¹H} NMR (C₆D₆): δ 189.3 (d, J = 71 Hz, CO), 158.8 (d, J = 19

Hz, Ar CN), 157.9 (d, J = 34 Hz, Ar CN), 135.1 (s, Ar C), 132.3 (s, Ar

C), 132.1 (s, Ar C), 129.6 (s, Ar C), 126.7 (s, Ar C), 125.1 (br, CF₃),

123.0 (br, CF₃), 120.7 (s, Ar C), 120.5 (s, Ar C), 117.4 (s, Ar C), 116.5

(d, J = 14 Hz, Ar C), 70.9−68.0 (m, CH₂), 34.0 (d, J = 21 Hz,

CH(CH₃)₂), 29.5 (s, CH₃), 29.0 (s, CH₃), 28.6 (s, CH₃), 27.6 (s,

CH₃). ³¹P{¹H} NMR (C₆D₆): δ 190.7 (dd, J_PP= 346 Hz, J_RhP= 190

C), 128.5 (s, Ar C), 127.6 (s, Ar C), 122.80 (s, Ar C), 118.00 (d, J_CP

=

3 Hz, Ar C), 117.09 (s, Ar C), 41.95 (dd, J_CP= 15 Hz, J_CP= 3 Hz,

P(NCH₃)₂), 23.53 (d, J_CP= 11 Hz, CH(CH₃)₂), 21.23 (s, Ar CH₃),

20.94 (s, Ar CH₃), 20.48 (d, J = 19 Hz, CH(CH₃)₂), 19.28 (d, J = 9

Hz, CH(CH₃)₂). ³¹P{¹H} NMR (C₆D₆): δ 98.2 (s, P, P(NMe₂)₂),

−13.1 (s, P, P(ⁱPr₂)₂).

9-RhCO. A J. Young tube was charged with 9-H (89 mg, 0.21

mmol), [Rh(COD)Cl]₂(51 mg, 0.21 mmol), 2,6-lutidine (24 μL, 0.21

mmol), and C₆D₆(1 mL). The reaction mixture was degassed and

then exposed to CO (1 atm). After 30 min, the reaction was ﬁltered

through a pad of silica gel. The silica gel was washed with diethyl ether,

and then the volatiles were removed in vacuo. Recrystallization of the

product in pentane at −35 °C resulted in isolation of 9-RhCO as a

1

yellow powder (76 mg, 0.14 mmol, 77%). H NMR (C₆D₆): δ 7.75−

7.67 (m, 2H, Ar H), 7.23 (d, J_P2H= 9 Hz, 1H, Ar H), 6.90 (d, J_P1H= 8

Hz, 1H, Ar H), 6.83 (d, J_HH= 9 Hz, 1H, Ar H), 6.79 (d, J_HH= 9 Hz,

1H, Ar H), 2.56 (d, J_P2H= 12 Hz, 12H, N(CH₃)₂), 2.18 (s, 3H, Ar

CH₃), 2.16 (s, 3H, Ar CH₃), 2.14 (m, 2H, CH(CH₃)₂), 1.28 (dd, J_P1H

= 17 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂), 1.05 (dd, J_P1H= 15 Hz, J_HH= 7

Hz, 6H, CH(CH₃)₂). ¹H{³¹P₁} NMR (C₆D₆): δ 7.75−7.67 (m, 2H, Ar

H), 7.23 (d, J = 9 Hz, 1H, Ar H), 6.90 (s, 1H, Ar H), 6.83 (d, J = 9

Hz,1H, Ar H), 6.79 (d, J = 9 Hz, 1H, Ar H), 2.56 (d, J = 12 Hz, 12H,

N(CH₃)₂), 2.18 (s, 3H, Ar CH₃), 2.16 (s, 3H, Ar CH₃), 2.14 (m, 2H,

CH(CH₃)₂), 1.28 (dd, J_PH= 17 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂), 1.05

(dd, J_PH= 15 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂). ¹H{³¹P₂} NMR

(C₆D₆): δ 7.75−7.67 (m, 2H, Ar H), 7.23 (s, 1H, Ar H), 6.90 (d, J = 8

Hz, 1H), 6.83 (d, J = 9 Hz, 1H, Ar H), 6.79 (d, J = 9 Hz, 1H, Ar H),

2.56 (s, 12H, N(CH₃)₂), 2.18 (s, 3H, Ar CH₃), 2.16 (s, 3H, Ar CH₃),

2.14 (m, 2H, CH(CH₃)₂), 1.28 (dd, J_PH= 17 Hz, J_HH= 7 Hz, 6H),

1.05 (dd, J_PH= 15 Hz, J_HH= 7 Hz, 6H). ¹³C{¹H} NMR (C₆D₆): δ

140.41−139.41 (m), 135.21 (s), 134.11 (s), 134.01 (s), 133.18 (s),

132.72−132.59 (m), 132.59−132.43 (m), 131.63−131.48 (m),

131.25−131.14 (m), 130.64 (s), 128.93 (d, J = 11 Hz), 117.32−

116.76 (m), 116.81−116.10 (m), 25.31−25.25 (m, CH(CH₃)₂), 25.07

(s, CH(CH₃)₂), 20.39 (s, CH₃), 20.13 (s, CH₃), 18.75 (d, J = 6 Hz,

CH(CH₃)₂), 17.98 (d, J_CP= 5 Hz, CH(CH₃)₂). ³¹P{¹H} NMR

(C₆D₆): δ 130.9 (dd, J_PP= 315 Hz, J_RhP= 163 Hz, P₂, P^NMe2), 58.7 (dd,

J_PP= 315 Hz, J_RhP123 Hz, P₁, P^iPr). IR: υ_CO= 1943 cm⁻¹. Elemental

Hz, P₂, P^OCH2CF3), 60.1 (dd, J_PP= 346 Hz, J_RhP= 125 Hz, P₁, P^iPr). ¹⁹

F

NMR (C₆D₆): δ −75.3 (t, J_RhC= 8 Hz, CF₃). IR ν(CO) = 1960 cm⁻¹.

10-PdCl. A Schlenk ﬂask was charged with 10-H (0.12 g, 0.22

mmol), Pd(COD)Cl₂(62 mg, 0.22 mmol), 2,6-lutidine (25 μL, 0.22

mmol), and diethyl ether. The reaction mixture was stirred for 12 h,

and then the solution was ﬁltered through a pad of silica gel with

additional diethyl ether. The ethereal solution was then concentrated

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and stored at −35 °C. The resulting precipitate was collected, and the

volatiles were removed in vacuo to yield 10-PdCl as a purple solid (88

mg, 013 mmol, 60%). H NMR (C₆D₆): δ 7.56−7.49 (m, 2H, Ar H),

J_P1H= 18 Hz, J_HH= 7 Hz, 5H), 0.88 (dd, J_P1H= 17 Hz, J_HH= 7 Hz,

6H). ¹³C{¹H} NMR (C₆D₆) δ 178.7 (OAc), 161.6 (Ar CN), 158.9 (d,

J_CP= 40 Hz, Ar CN), 137.1 (Ar C), 133.8 (Ar C), 134.1 (Ar C), 132.8

(d, J_CP= 38 Hz, Ar C), 131.4 (Ar C), 130.4 (Ar C). 126.8, 126.3, 122.8,

120.3(d, J_CP= 30 Hz, Ar C), 118.1, 117.3 (d, J_CP= 17 Hz, Ar C),

116.9, 116.6, 116.2, 116.1, 73.82 (OCH(CF₃)₂), 69.53 (HOCH-

(CF₃)₂), 24.82 (d, J = 22 Hz, CH(CH₃)₂), 21.88 (CH₃), 20.27 (CH₃),

19.81 (CH₃), 17.87 (CH₃), 17.36 (CH₃).³¹P{¹H} NMR (C₆D₆): δ

176.2 (d, J_P1P2= 517 Hz, P(OCH(CF₃)₂), 58.6 (d, J_P1P2= 517 Hz,

P(CH(CH₃)₂). ¹⁹F NMR (C₆D₆): δ −74.2 (s, CF₃), −74.5 (s, CF₃),

−76.5 (m, HOCH(CF₃)₂).

11-PdCl. A J. Young tube was charged with 11-PdOAc·HOCH-

(CF₃)₂(0.150 g, 0.18 mmol), C₆D₆(1 mL), and Me₃SiCl (46 μL, 0.26

mmol). After 72 h, ³¹P NMR analysis reveals complete conversion to

the desired product. The solution was then ﬁltered through a pad of

silica gel with diethyl ether. The volatiles were removed in vacuo, and

the product was dissolved in pentane and stored at −35 °C. After 18 h,

purple needles were collected by decantation and dried to yield 11-

PdCl (0.12 g, 87 μmol, 85%). ¹H NMR (C₆D₆): δ 7.50−7.35 (m, 2H,

Ar CH), 7.24 (d, J_P2H= 12 Hz, 1H, Ar H), 6.68 (d, J_HH= 9 Hz, 2H, Ar

H), 6.60 (d, J_P1H= 9 Hz, 1H, Ar H), 6.58−6.46 (m, 2H, CH(CF₃)₂),

2.19−2.08 (m, 2H, CH(CH₃)₂), 2.07 (s, 3H, CH₃), 1.80 (s, 3H, CH₃),

1

7.22 (d, J_P2= 12 Hz, 2H, Ar H), 6.78−6.68 (m, 2H, Ar H), 6.66 (d,

J_HH= 9 Hz, 1H, Ar H), 4.67 (m, 2H, CH₂CF₃), 4.59−4.45 (m, 2H,

CH₂CF₃), 2.26−2.12 (m, 2H, CH(CH₃)₂), 2.08 (s, 3H, CH₃), 1.88 (s,

3H, CH₃), 1.30 (dd, J_P1H= 18 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂), 1.02

(dd, J_P1H= 16 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂). ¹H{³¹P δ159.2} NMR

(C₆D₆): δ 7.56−7.49 (m, 2H, Ar H), 7.22 (s, 2H), 6.78−6.68 (m, 2H),

6.66 (d, J = 9 Hz, 1H, Ar H), 4.67 (m, 2H, CH₂CF₃), 4.59−4.45 (m,

2H, CH₂CF₃), 2.26−2.12 (m, 2H, CH(CH₃)₂), 2.08 (s, 3H, CH₃),

1.88 (s, 3H, CH₃), 1.30 (dd, J = 18 Hz, J = 7 Hz, 6H, CH(CH₃)₂),

1

1.02 (dd, J = 16 Hz, J = 7 Hz, 6H, CH(CH₃)₂). H{³¹P δ53.5} NMR

(C₆D₆): δ 7.56−7.49 (m, 2H, Ar H), 7.22 (s, 2H), 6.78−6.68 (m, 2H),

6.66 (d, J = 9 Hz, 1H, Ar H), 4.67 (m, 2H, CH₂CF₃), 4.59−4.45 (m,

2H, CH₂CF₃), 2.26−2.12 (m, 2H, CH(CH₃)₂), 2.08 (s, 3H, CH₃),

1.88 (s, 3H, CH₃), 1.30 (d, J_HH= 7 Hz, 6H, CH(CH₃)₂), 1.02 (d, J_HH

= 7 Hz, 6H, CH(CH₃)₂). ¹³C{¹H} NMR (C₆D₆): δ 161.3 (d, J_CP= 20

Hz, 3° Ar CN), 159.6 (d, J_CP= 38 Hz, 3° Ar CN), 137.9 (s, Ar CH),

136.1 (s, Ar CH), 133.1 (s, Ar CH), 132.5 (s, Ar CH), 130.2 (s, Ar

CH), 127.7 (s, Ar CH), 125.8 (d, J_CP= 60 Hz, CF₃), 124.7 (d, J_CP= 9

Hz, 3° Ar C), 122.4 (d, J_CP= 10 Hz, 3° Ar C), 118.1 (d, J_CP= 42 Hz,

3° Ar C), 117.0 (d, J_CP= 12 H, Ar CH), 116.4 (d, 12 Hz, Ar CH), 62.5

(m, CH₂CF₃), 25.1 (d, J_CP= 22 Hz, CH(CH₃)₂), 20.3 (s, CH₃), 19.8

(s, CH₃), 18.5 (s, CH₃), 17.9 (s, CH₃). ¹⁹F NMR (C₆D₆): δ 75.6 (d,

J_FH= 8 Hz, CH₂CF₃). ³¹P{¹H} NMR (C₆D₆): δ 159.2 (dd, J_PP= 545

Hz, P₂, P(OCH₂CF₃)), 53.5 (dd, J_PP= 545 Hz, P₁, P(CH(CH₃)₃).

Elemental analysis, calculated for 10-PdCl: C, 42.25; H, 4.43; N, 2.05.

Found: C, 42.32; H, 4.53; N, 1.98.

1.23 (dd, J_P1H= 18 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂), 0.96 (dd, J_P1H

=

16 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂). ¹H{³¹P₁} NMR (C₆D₆): δ 7.50−

7.35 (m, 2H, Ar H), 7.24 (d, J = 12 Hz, 1H, Ar H), 6.68 (d, J = 9 Hz,

2H, Ar H), 6.60 (s, 1H, Ar H), 6.58−6.46 (m, 2H, CH(CF₃)₂), 2.19−

2.08 (m, 2H, CH(CH₃)₂), 2.05 (s, 3H, CH₃), 1.79 (s, 3H, CH₃), 1.22

(d, J_HH= 7 Hz, 6H, CH(CH₃)₂), 0.95 (dd, J_HH= 7 Hz, 6H,

1

CH(CH₃)₂). H{³¹P₂} NMR (C₆D₆): δ 7.44 (d, J_HH= 9 Hz, 1H, Ar

11-H. A Teﬂon stoppered Schlenk ﬂask was charged with 9-H (82

mg, 0.19 mmol) and (CF₃)₂CHOH (1 mL). The ﬂask was placed in a

100 °C oil bath for 18 h at which point ³¹P NMR spectroscopy

demonstrated conversion to 11-H. The following NMR data were

H), 7.42 (m, 1H, Ar H), 7.24 (s, 1H, Ar H), 6.68 (d, J = 9 Hz, J_P1H= 4

Hz, 2H, Ar H), 6.60 (d, J_P1H= 9 Hz, 1H, Ar H), 6.58−6.46 (m, 2H,

CH(CF₃)₂), 2.19−2.08 (m, 2H, CH(CH₃)₂), 2.07 (s, 3H, CH₃), 1.80

(s, 3H, CH₃), 1.23 (dd, J_P1H= 18 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂),

0.96 (dd, J_P1H= 16 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂). ³¹P{¹H} NMR

1

obtained by ﬁrst referencing a spectrum of pure C₆D₆. Selected H

NMR ((CF₃)₂CHOH): δ 7.79 (d, J = 8 Hz, 1H), 7.60 (s, 1H), 7.58−

7.46 (m, 2H), 7.33 (d, J = 8 Hz, 1H), 6.81 (s, 1H), 6.48 (d, J = 8 Hz,

1H), 2.64 (s, 3H, CH₃), 2.46 (s, 3H, CH₃), 1.56 (dd, J_PH= 20 Hz, J_HH

= 7 Hz, 6H, CH(CH₃)₂), 1.43 (dd, J_PH= 14 Hz, J_HH= 7 Hz, 6H,

CH(CH₃)₂). ¹H{³¹P 35.9} NMR ((CF₃)₂CHOH): δ 7.79 (d, J = 8 Hz,

1H), 7.60 (s, 1H), 7.58−7.46 (m, 2H), 7.33 (d, J = 8 Hz, 1H), 6.81 (s,

(C₆D₆): δ 172.3 (d, J_PP= 525 Hz, P₂, P(OCH(CF₃)₂)₂), 57.9 (d, J_PP

=

525 Hz, P₁, P(iPr)₂). ¹³C{¹H} NMR (C₆D₆): δ 161.2 (d, J_CP= 20 Hz,

Ar CN), 160.0 (d, J_CP= 40 Hz, Ar CN), 137.0 (s, Ar C), 133.4 (s, Ar

C),132.3 (s, Ar C), 129.8 (s, Ar C), 124.2 (m, CH(CF₃)₂), 123.7 (m,

CH(CF₃)₂), 117.9 (d, J_CP= 3 Hz, Ar C), 117.6 (d, J_CP= 3 Hz, Ar C),

117.2 (d, J_CP= 3 Hz, Ar C), 116.9 (s, Ar C), 116.8 (s, Ar C), 116.7 (s,

Ar C), 74.0 (m, CH(CF₃)₂), 25.4 (d, J_CP= 4 Hz, CH(CH₃)₂), 25.2 (d,

J_CP= 4 Hz, CH(CH₃)₂), 20.3 (s, CH₃), 19.7 (s, CH₃), 18.2 (d, J_CP= 4

Hz, CH(CH₃)₂), 17.7(d, J_CP= 4 Hz, CH(CH₃)₂). ¹⁹F NMR (C₆D₆): δ

−74.0 (s), −74.5 (s). Elemental analysis, calculated for

C₂₆H₂₈ClF₁₂NO₂P₂Pd: C, 38.16; H, 3.45%. Found: C, 38.16; H,

3.38%.

1H), 6.48 (d, J = 8 Hz, 1H), 2.64 (s, 3H), 2.46 (s, 3H), 1.56 (d, J_HH

=

7 Hz, 6H), 1.43 (d, J_HH= 7 Hz, 6H). ³¹P{¹H} NMR ((CF₃)₂CHOH):

δ 215.2 (s, P(OCH(CH₃)₂), 35.9 (s, P(iPr)₂).

11-PdOAc·HOCH(CF₃)₂. A Teﬂon stoppered round-bottom ﬂask

was charged with 9-H (0.20 mg, 0.46 mmol), a stir bar, and

(CF₃)₂CHOH (5 mL). The reaction mixture was then stirred for 24 h

in a 100 °C oil bath. Pd(OAc)₂(0.11 g, 0.46 mmol) was then added to

the reaction vessel. Stirring was commenced for 3 days at room

temperature. The volatiles were then removed in vacuo, and the

resulting purple solid was ﬁltered through a pad of silica gel with

diethyl ether. The volatiles were again removed, and the resulting solid

was taken up in a minimal amount of pentane and recrystallized at −35

°C to yield 11-PdOAc·HOCH(CF₃)₂as dark purple crystals (0.25 g,

0.32 mmol, 64%). ¹H NMR (C₆D₆): δ 7.40−7.34 (m, 2H, Ar H), 7.32

(d, J_P2H= 12 Hz, 1H, Ar H), 6.65 (d, J_HH= 9 Hz. 1H, Ar H), 6.63 (d,

J_P1H= 11 Hz, 1H, Ar H), 6.59 (d, J_HH= 9 Hz, 1H, Ar H) 6.42 (m, 2H,

POCH(CF₃)₂), 4.73 (s, 1H, OH), 3.77 (m, 1H, HOCH(CF₃)₂), 2.06

(s, 3H, CH₃), 2.02 (s, 3H, CH₃), 2.00−1.89 (m, 2H, CH(CH₃)₂), 1.84

11-RhCO. A Schlenk ﬂask was charged with 9-H (304 mg, 0.705

mmol), a stir bar, and (CF₃)₂CHOH (4 mL). The ﬂask was heated at

100 °C for 18 h and then cooled to ambient temperature.

[Rh(COD)Cl]₂(174 mg, 0.353 mmol), 2,6-lutidine (812 μL, 0.705

mmol), and CO (1 atm) were then added to the ﬂask. The reaction

mixture was stirred for 2 h and then dried under vacuo. The resulting

red solid was taken up in diethyl ether and ﬁltered through a pad of

Celite. The volatiles were again removed. 11-RhCO was isolated as red

crystals after recrystallization at −35 °C in pentane (452 mg, 0.559

1

mmol, 79%). H NMR (C₆D₆): δ 7.54 (dd, J_HH= 9 Hz, J_P1H= 4 Hz,

1H, Ar H), 7.43 (t, J_HH= 8 Hz, 1H, Ar H), 7.35 (d, J_HH= 2 Hz, 1H, Ar

H), 6.74 (d, J_HH= 10 Hz, 1H, Ar H), 6.74 (d, J_P1H= 10 Hz, 1H, Ar H),

6.68 (dd, J_HH= 9 Hz, J_HH= 2 Hz, 1H, Ar H), 5.75 (m, 2H,

CH(CF₃)₂), 2.11 (s, 3H, CH₃), 1.98−1.91 (m, 2H, CH(CH₃)₂), 1.88

(s, 3H, CH₃), 1.05 (dd, J_P1H= 18 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂),

(s, 3H, OAc), 1.10 (dd, J_P1H= 18 Hz, J_HH=7 Hz, 5H), 0.88 (dd, J_P1H

=

17 Hz, J_HH=7 Hz, 6H). ¹H{³¹P₁} NMR (C₆D₆): δ 7.40−7.34 (m, 2H,

Ar H), 7.32 (d, J = 12 Hz, 1H, Ar H), 6.65 (d, J_HH= 9 Hz. 1H, Ar H),

6.63 (s, 1H, Ar H), 6.59 (d, J_HH= 9 Hz, 1H, Ar H), 6.42 (m, 2H,

CH(CF₃)₂), 4.73 (s, 1H, OH), 3.77 (m, 1H, HOCH(CF₃)₂), 2.06 (s,

3H, CH₃), 2.02 (s, 3H, CH₃), 2.00−1.89 (m, 2H, CH(CH₃)₂), 1.84 (s,

3H, OAc), 1.10 (dd, J_HH=7 Hz, 5H), 0.88 (dd, J_HH= 7 Hz, 6H).

¹H{³¹P₂} NMR (C₆D₆): δ 7.40−7.34 (m, 2H, Ar H), 7.32 (s, 1H, Ar

H), 6.65 (d, J_HH= 9 Hz. 1H, Ar H), 6.63 (d, J_P1H= 11 Hz, 1H, Ar H),

6.59 (d, J_HH=9 Hz, 1H, Ar H), 6.42 (m, 2H, CH(CF₃)₂), 4.73 (s, 1H,

OH), 3.77 (m, 1H, HOCH(CF₃)₂), 2.06 (s, 3H, CH₃), 2.02 (s, 3H,

CH₃), 2.00−1.89 (m, 2H, CH(CH₃)₂), 1.84 (s, 3H, OAc), 1.10 (dd,

1

0.83 (dd, J_P1H= 16 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂). H{³¹P, P₂}

NMR (C₆D₆): δ 7.54 (dd, J_HH= 9 Hz, J_P1H= 4 Hz, 1H, Ar H), 7.43 (t,

J_HH= 8 Hz, 1H, Ar H), 7.35 (d, J_HH= 2 Hz, 1H, Ar H), 6.74 (d, J_HH

=

10 Hz, 1H, Ar H), 6.74 (d, J_P1H= 10 Hz, 1H, Ar H), 6.68 (dd, J_HH= 9

Hz, J_HH= 2 Hz, 1H, Ar H), 5.75 (hept, J_HH= 6 Hz, 2H, CH(CF₃)₂),

2.11 (s, 3H, CH₃), 1.98−1.91 (m, 2H, CH(CH₃)₂), 1.88 (s, 3H, CH₃),

1.05 (dd, J_P1H= 18 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂), 0.83 (dd, J_P1H

=

16 Hz, J_HH= 7 Hz, 6H, CH(CH₃)₂). ¹H{³¹P, P₁} NMR (C₆D₆): δ 7.54

(d, J_HH= 9 Hz, 1H, Ar H), 7.43 (t, J_HH= 8 Hz, 1H, Ar H), 7.35 (d, J_HH

R

DOI: 10.1021/ic503062w

Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry

Article

= 2 Hz, 1H, Ar H), 6.74 (d, J_HH= 10 Hz, 1H, Ar H), 6.74 (s, 1H, Ar

H), 6.68 (dd, J_HH= 9 Hz, J_HH= 2 Hz, 1H, Ar H), 5.75 (dp, J_P2H= 17

Hz, J_HH= 6 Hz, 2H, CH(CF₃)₂), 2.11 (s, 3H, CH₃), 1.98−1.91 (m,

2H, CH(CH₃)₂), 1.88 (s, 3H, CH₃), 1.05 (d, J_HH= 7 Hz, 6H,

CH(CH₃)₂), 0.83 (d, J_HH= 7 Hz, 6H, CH(CH₃)₂). ¹³C{¹H} NMR

(C₆D₆): δ 193.8 (m, CO), 161.2 (d, J = 21 Hz, 3° Ar C), 160.3 (d, J =

40 Hz, 3° Ar C), 136.2 (d, J = 2 Hz, Ar C), 132.8 (d, J = 2 Hz, Ar C),

132.0 (s, Ar C), 129.2 (s, Ar C), 127.1 (d, J = 8 Hz, Ar C), 126.8 (d, J =

7 Hz, Ar C), 124.4 (m, CF₃), 122.2 (m, CF₃), 119.9 (m, CF₃), 118.8

(d, J = 2 Hz, Ar C), 118.4 (s, Ar C), 117.6 (m, CF₃), 116.0 (d, J = 12

Hz, Ar C), 115.4 (d, J = 18 Hz, Ar C), 74.6−72.8 (m, CH(CF₃)₂), 25.1

(d, J = 25 Hz, CH(CH₃)₂), 20.1 (s, CH₃), 19.6 (s, CH₃), 18.9 (d, J = 6

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Hz, CH₃), 17.90 (s, CH₃). ³¹P{¹H} NMR (C₆D₆): δ 207.4 (dd, J_P1P2

=

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340 Hz, J_P2Rh= 195 Hz, P₂, P(OCH(CF₃)₂), 59.3 (dd, J_P1P2= 340 Hz,

J_P1Rh= 127 Hz, P₁, P(ⁱPr)₂). ¹⁹F NMR (C₆D₆): δ −75.0 (s), −74.4 (s).

IR ν(CO) = 1980 cm⁻¹. Elemental analysis, calculated for

C₂₇H₂₈F₁₂NO₃P₂Rh: C, 40.17; H, 3.50%. Found: C, 40.28; H, 3.66%.

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ASSOCIATED CONTENT

* Supporting Information

■

S

Graphical depictions of the NMR spectra and details of the X-

ray data acquisition, solution, and reﬁnement, as well as

structural information in the form of CIF ﬁles. This material is

available free of charge via the Internet at http://pubs.acs.org.

AUTHOR INFORMATION

■

Corresponding Author

*E-mail: ozerov@chem.tamu.edu.

Present Addresses

^∥Department of Chemistry, McNeese State University, Lake

Charles, LA 70609, United States.

(20) Tondreau, A. M.; Atienza, C. C. H.; Weller, K. J.; Nye, S. A.;

Lewis, K. M.; Delis, J.; Chirik, P. J. Science 2012, 335, 567−570.

(21) The Chemistry of Pincer Compounds; Morales-Morales, D.,

Jensen, C., Eds.; Elsevier: Amsterdam, 2007.

^§Air Liquide, Delaware Research and Technology Center, 200

GBC Drive, Newark, Delaware 19702, United States.

^⊥Department of Chemistry, Indiana University, 800 E.

Kirkwood Ave., Bloomington, IN 47405, United States.

^#Department of Chemistry, University of Manitoba, Winnipeg,

MB R3T 2N2, Canada.

(22) Nguyen, A. I.; Zarkesh, R. A.; Lacy, D. C.; Thorson, M. K.;

Heyduk, A. F. Chem. Sci. 2011, 2, 166−169.

(23) Heyduk, A. F.; Zarkesh, R. A.; Nguyen, A. I. Inorg. Chem. 2011,

50, 9849−9863.

Notes

(24) Zarkesh, R. A.; Ziller, J. W.; Heyduk, A. F. Angew. Chem., Int. Ed.

2008, 47, 4715−4718.

The authors declare no competing ﬁnancial interest.

(25) Radosevich, A. T.; Melnick, J. G.; Stoian, S. A.; Bacciu, D.;

Chen, C.-H.; Foxman, B. M.; Ozerov, O. V.; Nocera, D. G. Inorg.

Chem. 2009, 48, 9214−9221.

ACKNOWLEDGMENTS

■

We are thankful for the support of this work by the U.S.

National Science Foundation through the “Powering the

Planet” Center for Chemical Innovation grant (CHE-

0802907), the Department of EnergyOﬃce of Basic Energy

Sciences (DE-FG02-06ER15815), the Welch Foundation

(grant A-1717), and the Dreyfus Foundation (Camille Dreyfus

Teacher-Scholar Award to O.V.O). We thank Linda Redd for

assistance with preparation of the manuscript.

(26) Adhikari, D.; Mossin, S.; Basuli, F.; Huffman, J. C.; Szilagyi, R.

K.; Meyer, K.; Mindiola, D. J. J. Am. Chem. Soc. 2008, 130, 3676−3682.

(27) Madhira, V. N.; Ren, P.; Vechorkin, O.; Hu, Z.; Vicic, D. A.

Dalton Trans. 2012, 41, 7915−7919.

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Nieto, J.; Hutchinson, J. M.; Klein, A.; Budnikova, Y.; Vicic, D. A.

Organometallics 2010, 29, 1451−1456.

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23, 326−328. (b) Ozerov, O. V.; Guo, C.; Papkov, V. A.; Foxman, B.

M. J. Am. Chem. Soc. 2004, 126, 4792−4793. (c) Fan, L.; Yang, L.;

Guo, C.; Foxman, B. M.; Ozerov, O. V. Organometallics 2004, 23,

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DOI: 10.1021/ic503062w

Inorg. Chem. XXXX, XXX, XXX−XXX

Article Doi

Comparison of the electronic properties of diarylamido-based PNZ pincer ligands: Redox activity at the ligand and donor ability toward the metal

DOI: 10.1021/ic503062w

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Full text of DOI:10.1021/ic503062w

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