Diimine supported group 10 hydroxo, oxo, amido, and imido complexes

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Diimine supported group 10 hydroxo, oxo, amido, and imido complexes†

Anupam Singh,^aU. Anandhi,^aMaria Agostina Cinellu^band Paul R. Sharp*^a

Received 11th October 2007, Accepted 29th January 2008

First published as an Advance Article on the web 4th March 2008

DOI: 10.1039/b715663d

A series of L₂= diimine (Bian = bis(3,5-diisopropylphenylimino)acenapthene, Bu^t₂bpy =

4,4^ꢀ-di-tert-butyl-2,2^ꢀ-bipyridine) supported aqua, hydroxo, oxo, amido, imido, and mixed complexes

2+

have been prepared. Deprotonation of [L₂Pt(l-OH)]₂with 1,8-bis(dimethylamino)naphthalene, NaH,

or KOH yields [(L₂Pt)₂(l-OH)(l-O)]⁺as purple (Bian) or red (Bu^t₂bpy) solids. Excess KOH gives dark

blue [(Bian)Pt(l-O)]₂. MeOTf addition to [(Bu^t₂bpy)₂Pt₂(l-OH)(l-O)]⁺gives

[(Bu^t₂bpy)₂Pt₂(l-OH)(l-OMe)]²⁺while [(Bian)Pt(l-O)]₂yields [(Bian)₂Pt₂(l-OMe)(l-O)]⁺. Treatment of

[(Bian)Pt(l-O)]₂with “(Ph₃P)Au⁺” gives deep purple [(Bian)₂Pt₂(l-O)(l-OAuPPh₃)]⁺while

(COD)Pt(OTf)₂gives a low yield of [(Bian)Pt₃(l-OH)₃(COD)₂](OTf)₃. Ni(Bu^t₂bpy)Cl₂and

[(Ph₃PAu)₃(l-O)]⁺in a 3 : 2 ratio yield red [Ni₃(Bu^t₂bpy)₃(l-O)₂]²⁺. M(Bu^t₂bpy)Cl₂(M = Pd, Pt) and

[(Ph₃PAu)₃(l-O)]⁺give [M(Bu^t₂bpy)(l-OAuPPh₃)]₂and [Pd₄(Bu^t₂bpy)₄(l-OAuPPh₃)]³⁺. Addition of

2+

ArNH₂to [M(Bu^t₂bpy)(l-OH)]₂(M = Pd, Pt) gives [Pt₂(Bu^t₂bpy)₂(l-NHAr)(l-OH)]²⁺(Ar = Ph,

4-tol, 4-C₆H₄NO₂) and [M(Bu^t₂bpy)(l-NHAr)]₂(Ar = Ph, tol). Deprotonation of

2+

[Pt₂(Bu^t₂bpy)₂(l-NH-tol)(l-OH)]²⁺with 1,8-bis(dimethylamino)naphthalene or NaH gives

[Pt₂(Bu^t₂bpy)₂(l-NH-tol)(l-O)]⁺. Deprotonation of [Pt(Bu^t₂bpy)(l-NH-tol)]₂with KOBu^tgives deep

2+

green [Pt(Bu^t₂bpy)(l-N-tol)]₂. The triﬂate complexes M(Bu^t₂bpy)(OTf)₂(M = Pd, Pt) are obtained

from M(Bu^t₂bpy)Cl₂and AgOTf. Treatment of Pt(Bu^t₂bpy)(OTf)₂with water gives the aqua complex

[Pt(Bu^t₂bpy)(H₂O)₂](OTf)₂.

by deprotonation of hydroxo and amido complexes and by oxo–

chloro exchange using the gold oxo complex [(Ph₃PAu)₃(l-O)]⁺.

Introduction

Complexes with late transition metals bonded to hydroxo,

amido, oxo and imido ligands^1–5have attracted wide atten-

tion for their conﬂicting soft acid–hard base interactions and

Results and discussion

their relevance in several areas including chemotherapy drugs,^6,7

enzyme modeling,^8–15and various catalytic and stoichiometric

processes.^1,16–27Our efforts have been primarily focused on the

synthesis of oxo and imido complexes of the heavier late transition

metals Rh, Ir, Pd, Pt, and Au.⁵Our simplest approach to these

oxo and imido complexes is deprotonation of the conjugate-acid

hydroxo and amido complexes. This has required the simultaneous

development of the hydroxo and amido chemistry. The majority of

these hydroxo and amido complexes bear supporting phosphine

ligands and our initial attempts to expand to N-donor ligand

systems such as pyridine and bipyridine met with limited success

due to the poor solubility of the complexes. Solubility problems

were overcome with substituted cyclic and acyclic diimine ligands

and we reported the synthesis and characterization of hydroxo

and amido complexes of Pt(II) and Pd(II) bearing various diimine

ligands.²⁸However, efforts to deprotonate the hydroxo and amido

complexes to give oxo and imido complexes were mostly unsuc-

cessful. We now report the synthesis of Ni(II), Pd(II), and Pt(II)

diimine supported complexes with oxo or imido ligands both

Oxo complexes by deprotonation

The dihydroxo complexes [(Bian)Pt(l-OH)]₂(BF₄)₂(Bian =

bis(3,5-diisopropylphenylimino)acenapthene) and [(Bu^t₂bpy)-

Pt(l-OH)]₂(BF₄)₂(Bu^t₂bpy = 4,4^ꢀ-di-tert-butyl-2,2^ꢀ-bipyridine)

undergo facile single deprotonation with stoichiometric or excess

1,8-bis(dimethylamino)naphthalene (Scheme 1). The resulting

hydroxo-oxo complexes are isolated as purple (1) or red (2)

salts. (Complex 2 was previously incorrectly reported as a dioxo

complex.²⁹) The same products are obtained when NaH (2)

or KOH (1) are used as the base and these are preferred for

clean isolation of the complexes. Treatment of [(Bu^t₂bpy)Pd(l-

OH)]₂(BF₄)₂with NaH gives a yellow complex that is believed to

be [(Bu^t₂bpy)₂Pd₂(l-OH)(l-O)]BF₄, the Pd analog of 2. However,

characterization is limited to ¹H NMR spectroscopy and elemental

analysis and this assignment must be considered tentative espe-

cially considering the rarity of Pd oxo complexes.^30–34

It should be noted that previous attempts to deprotonate

[(Bian)Pt(l-OH)]₂(BF₄)₂with LiN(SiMe₃)₂and KOBu^tgave com-

plex mixtures²⁸and that deprotonation of phosphine analogs,

2+

[L₂Pt(l-OH)]₂(L = a phosphine or L₂= a diphosphine)

^a125 Chemistry, University of Missouri, Columbia, Missouri, 65211, USA.

E-mail: sharpp@missouri.edu

require much stronger bases. While pK_a1in DMSO for these

phosphine complexes is only known to be less than 18, a value

^bDipartimento di Chimica, Universita` di Sassari, Via Vienna 2, I-07100,

Sassari, Italy

of 11.9

0.1 for related [(L₂Pt)₂(l-OH)(l-NMePh)]²⁺(L₂

=

dppe) has been measured.³⁵The pK_afor singly protonated 1,8-

† CCDC reference numbers 663517–663527. For crystallographic data in

CIF or other electronic format see DOI: 10.1039/b715663d

bis(dimethylamino)naphthalene in DMSO is reported as 7.5.^36,37

2314 | Dalton Trans., 2008, 2314–2327

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H-6 proton at 8.68 ppm. This strong shift to higher frequency

for one of the Bu^t₂bpy H-6 protons is attributed to weak hydrogen

interactions with the oxo ligand (Fig. 1). A similar shift is observed

in the analogous amido oxo complex 14 (see below).

Fig. 1 Drawing of the cationic portion of 2 showing proposed hydrogen

interactions.

Conﬁrmation of the hydroxo-oxo formulation for 2 is obtained

from the reaction of 2 with MeOTf which yields yellow hydroxo-

methoxo complex [(Bu^t₂bpy)₂Pt₂(l-OH)(l-OCH₃)](BF₄)(OTf) (3,

eqn (1)). ¹H NMR spectra for 3 show the OMe peak at 3.12 ppm

and the OH peak at 4.21 ppm. The two Bu^t₂bpy H-6 proton signals

appear at similar positions (8.72 and 8.68 ppm) consistent with loss

of the hydrogen interaction on methylation of the oxo ligand.

Scheme 1

(1)

Assuming that there is no large change in the relative ba-

sicities in CH₂Cl₂then pK_a1for [(Bian)Pt(l-OH)]₂(BF₄)₂and

[(Bu^t₂bpy)Pt(l-OH)]₂(BF₄)₂must be less than 7.5 in DMSO,

many units lower than the analogous phosphine complexes. This is

consistent with the weaker donor properties of the diimine ligands

as compared to the phosphine ligands. We also note that the

UV-Vis absorption spectrum of [(Bu^t₂bpy)₂Pt₂(l-OH)(l-O)]BF₄

(2) is essentially identical to that of the complex formulated as

[(bpy)₂Pt₂(l-OH)₃]⁺, produced by increasing the pH of an aqueous

solution of [(bpy)₂Pt₂(l-OH)₂]²⁺to above 8.³⁸We therefore propose

that [(bpy)₂Pt₂(l-OH)₃]⁺be reformulated as [(bpy)₂Pt₂(l-OH)(l-

O)]⁺, the water soluble bpy analog of 2.

Deprotonation of the remaining OH group in 1 is possible.

If the reaction mixture containing 1 and excess KOH is stirred

for prolonged periods (ca. 2 h) the mixture becomes deep blue

and dark blue dioxo complex [(Bian)Pt(l-O)]₂(4) is isolated

1

(Scheme 1). H NMR spectra for 4 show a single peak for each

type of Bian ligand proton indicative of a planar mmm-symmetric

structure. Again, peaks are often broadened from protic impurities

but sharpen when solid KOH is added to the solution. Attempts

to further characterize 4 by X-ray diffraction were thwarted by an

inability to isolate suitable crystals. The preparation of derivatives

of 4 was therefore undertaken.

¹H NMR spectra of isolated 1 often show broad peaks,

which sharpen on addition of 1,8-bis(dimethylamino)naphthalene

suggesting that the broadening is associated with proton exchange

with trace acidic impurities. The spectra show the expected

asymmetry in the Bian ligand with peaks observed for half the Bian

ligand on the hydroxo side and peaks for the other half on the oxo

side of the complex. Only two peaks are observed for the isopropyl

methyl groups indicating that the structure is either planar with

the OH group in the plane or if non-planar inverting rapidly on the

NMR time scale. An X-ray crystal structure determination on a

crystal of 1 grown from CD₂Cl₂–Et₂O was conducted. The crystals

contain two crystallographically independent cations each located

on an inversion center requiring disorder of the oxo and hydroxo

ligands and averaging of the Pt–O bond distances. This and poor

quality eliminate much of the signiﬁcance of the structure other

than to conﬁrm the connectivit_◦y.

“Ph₃PAuBF₄” (prepared from Ph₃PAuCl and AgBF₄) addition

to a stirred blue solution of 4 results in a dark purple solution

of [(Bian)₂Pt₂(l-O)(l-OAuPPh₃)](BF₄) (5) (Scheme 2). A crystal

of 5 was subjected to a single crystal X-ray structure analysis.

Crystal data and data parameters are listed in Table 1. Selected

distances and angles are listed in Table 2. A drawing of the

solid-state structure of the cationic portion is given in Fig. 2.

The Ph₃PAu⁺fragment is bonded to one of the oxo ligands

approximately perpendicular to the Pt₂O₂diamond core reducing

the mmm symmetry of 4 to m symmetry for 5. Relatively short Au–

Pt distances suggest closed-shell interactions between the metal

centers.^39,40

The ³¹P NMR spectrum for 5 shows the expected singlet

1

(23 ppm) but the H NMR spectrum displays only one peak (as

opposed to the two predicted from the X-ray structure) for each

type of proton in the acenaphthylene portion of the Bian ligand.

Similarly, while the X-ray structure predicts 8 signals for the Bian

isopropyl methyl groups and 4 signals for the isopropyl CHs only

half this number is observed. These data indicate effective mm

symmetry. This could come about if, in solution, the Ph₃PAu⁺

fragment is either bridging between the two oxo ligands or rapidly

exchanging (on the NMR time scale) between the two oxo sites.

1

The H NMR spectra at 25 C for 2 are broad and show only

one signal for each type of Bu^t₂bpy protons suggesting rapid

proton exchange between the hydroxo and oxo ligands. At −70 ^◦C

(M = Pt) the spectrum is also broad but is resolved into a pattern

expected for non-exchanging 2 with two signals for each type of

Bu^t₂bpy proton. The resonance for one of the Bu^t₂bpy H-6 protons

at 10.00 ppm is at signiﬁcantly higher frequency than for the other

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Table 2 Selected distances and angles for [(Bian)₂Pt₂(l-O)(l-

OAuPPh₃)]BF₄(5)

Au1–O1

Au1–P1

Pt1–O1

Pt1–O2

Pt1–N1

Pt1–N2

2.054(5)

2.218(2)

2.021(5)

1.961(5)

2.018(6)

1.993(7)

Au1–Pt1

Au1–Pt2

Pt2–O1

Pt2–O2

Pt2–N3

Pt2–N4

3.0494(5)

3.1949(5)

2.023(5)

1.972(5)

2.009(6)

2.007(6)

O1–Au1–P1

O2–Pt1–N2

O2–Pt1–N1

N1–Pt1–N2

O2–Pt1–O1

N1–Pt1–O1

N2–Pt1–O1

Pt1–O1–Au1

Pt2–O1–Au1

176.24(15)

97.8(3)

174.4(2)

79.3(3)

Pt1–Au1–Pt2

O2–Pt2–N4

O2–Pt2–N3

N4–Pt2–N3

O2–Pt2–O1

N3–Pt2–O1

N4–Pt2–O1

Pt1–O1–Pt2

Pt1–O2–Pt2

56.626(10)

101.4(2)

175.1(2)

80.1(3)

80.1(2)

99.1(2)

172.3(2)

94.3(2)

97.8(2)

80.4(2)

103.3(2)

170.6(2)

96.9(2)

103.2(2)

Fig. 2 Drawing (50% probability ellipsoids) of the cationic portion of the

solid-state structure of [(Bian)₂Pt₂(l-O)(l-OAuPPh₃)]BF₄(5).

Scheme 2

Interestingly, when the probe temperature is raised to 25 ^◦C

the ³¹P NMR peak broadens, as do the ¹H NMR signals for

1

the Bian isopropyl groups. The H NMR signals for the Bian

acenaphthylene unit remain sharp. This broadening is apparently

due to exchange of the Ph₃PAu⁺fragment with trace amounts of

Ph₃PAuCl that is visible in the low temperature ³¹P NMR spectra

(33 ppm) but not in the room temperature spectrum. Given the

crowded structure of 5 (see below) the exchange is attributed to

Ph₃PAu⁺dissociation from 5.

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Addition to the oxo ligand of 4 is also observed when MeOTf

is added to solutions of 4 and dark purple [(Bian)₂Pt₂(l-O)(l-

OMe)]OTf (6) is isolated. A crystal structure determination on a

crystal of 6 conﬁrms the connectivity but the structure is of poor

quality with badly disordered solvent molecules and triﬂate anion.

As in 5, ¹H NMR data for 6 are inconsistent with the m symme-

try of the solid-state structure. Two signals (overlapping) for each

type of proton in the acenaphthylene portion of the Bian ligand are

observed but only 4 signals for the Bian isopropyl methyl groups

and 2 signals for the isopropyl CHs are present. We attribute

this higher apparent symmetry to rapid inversion at the methoxo

ligand oxygen atom effectively producing mirror symmetry around

the Pt₂O₂plane. The methoxo methyl group signal is observed at

2.48 ppm. The reaction of 4 with excess MeOTf was investigated

and gave a red product that is likely (Bian)Pt(OTf)₂. However, this

product was not completely characterized (see Experimental).

Treatment of a blue solution of 4 with Pt(COD)(OTf)₂ﬁrst

gives a purple solution but this changes to yellow-brown. A

Fig. 3 Drawing (50% probability ellipsoids) of the cationic portion of the

solid-state structure of [(Bian)Pt₃(l-OH)₃(COD)₂] (OTf)₃(7).

Table 4 Selected distances and angles for [(Bu^t₂bpy)₃Ni₃(l-O)₂](BF₄)₂

(8)^a

1

brown solid is isolated that by H NMR spectroscopy shows a

symmetric environment for the Bian ligand and a Pt-bonded COD

ligand in about a 1 : 1 ratio. Recrystallization yielded a small

amount of orange-red crystals, which were identiﬁed by an X-ray

diffraction analysis as the hydroxo bridged complex [(Bian)Pt₃(l-

OH)₃(COD)₂] (OTf)₃(7) (Fig. 3, eqn (2)). Crystal data and data

parameters are listed in Table 1. Selected distances and angles are

given in Table 3. The H⁺source is unknown but is presumably

from trace water in the reaction system. Related complexes with a

Pt₃(l-OH)₃core have been reported.^41–45

Ni1–O1

Ni2–O1

Ni1–Ni2

1.852(4)

1.845(3)

2.4816(12)

Ni1–N1

Ni2–N2

Ni2–Ni2*

1.880(5)

1.874(4)

2.5488(15)

N1–Ni1–N1*

O1–Ni1–O1*

O1–Ni1–N1

O1–Ni2–N2

Ni2–O1–Ni2*

84.8(3)

76.7(3)

99.2(2)

99.27(15)

87.37(18)

N2–Ni2–N2

O1–Ni2–O1*

O1–Ni1–N1*

O1–Ni2–N2*

Ni2–O1–Ni1

84.3(2)

77.1(2)

176.0(2)

175.51(17)

84.33(15)

^aAtoms with an asterisk are related to unmarked atoms by inversion.

(2)

A drawing of the cationic portion of the solid-state structure of 8

is given in Fig. 4. Crystal data and data parameters are listed in

Table 1. Selected distances and angles are listed in Table 4. The

core structure consists of a triangle of Ni atoms bicapped by the

oxo ligands. H NMR data are in agreement with the solid-state

structure showing a single set of signals for a symmetric Bu^t₂bpy

ligand.

Oxo complexes by chloro–oxo exchange

1

We have previously reported the use of the Au oxo complex

[(Ph₃PAu)₃(l-O)]BF₄as an oxide ion source in exchange re-

actions with [M(diene)(l-Cl)]₂(M = Rh, Ir),⁴⁶(COD)PtCl₂,⁴⁷

(DBCOT)PtCl₂(DBCOT = dibenzo[a,e]cyclooctatetraene)⁴⁸and

(Bu^t₂bpy)PdCl₂and ﬁnd it effective here for Ni(II) and

30

(3)

Pt(II) chloro complexes. Thus, mixing Ni(Bu^t₂bpy)Cl₂with

[(Ph₃PAu)₃(l-O)]BF₄in a 3 : 2 ratio in CH₂Cl₂yields the red oxo

complex [Ni₃(Bu^t₂bpy)₃(l-O)₂](BF₄)₂(8) and Ph₃PAuCl (eqn (3)).

Treatment of Ni(Bu^t₂bpy)Cl₂with 1 equiv of [(Ph₃PAu)₃(l-

O)]BF₄gives a product different from 8 by ³¹P NMR spectroscopy.

Attempts to isolate this product yielded only 8. In analogy to the

Pd and Pt chemistry that follows this product is believed to be

[Ni(Bu^t₂bpy)(l-OAuPPh₃)]₂(BF₄)₂. Its instability relative to 8 and

the analogous Pt and Pd complexes is attributed to the greater

oxophilicity expected for the more electropositive Ni center.

In contrast to Ni, Pt(Bu^t₂bpy)Cl₂and [(Ph₃PAu)₃(l-O)]BF₄

gives only the mixed Pt–Au oxo complexes [M(Bu^t₂bpy)(l-

OAuPPh₃)]₂(BF₄)₂(9, M = Pt, Scheme 3). We previously reported

the analogous reaction with Pd(Bu^t₂bpy)Cl₂that gives the Pd

analog 9 (M = Pd).³⁰Both the Pd and Pt derivatives have now

been structurally characterized by X-ray diffraction. The crystals

are isomorphous and the complexes are isostructural. Crystal data

and data parameters are listed in Table 1. Selected distances and

angles for the Pt structure are listed in Table 5 and a drawing of

Table 3 Selected distances and angles for [(Bian)(COD)₂Pt₃(l-OH)₃)]

(OTf)₃(7)

Pt1–O1

Pt1–O2

Pt2–O2

Pt2–O3

Pt2–C41

Pt2–C42

Pt2–C38

Pt2–C37

2.001(6)

2.003(6)

2.047(6)

2.064(6)

2.123(9)

2.130(9)

2.156(9)

2.161(9)

Pt1–N1

Pt1–N2

Pt3–O1

Pt3–O3

Pt3–C50

Pt3–C46

Pt3–C49

Pt3–C45

2.004(7)

2.019(7)

2.040(6)

2.080(6)

2.136(10)

2.141(9)

2.152(9)

O1–Pt1–O2

O1–Pt1–N1

O2–Pt1–N1

O2–Pt2–O3

Pt1–O1–Pt3

Pt1–O2–Pt2

88.3(2)

94.8(3)

176.8(3)

92.4(2)

126.9(3)

123.1(3)

O1–Pt1–N2

O2–Pt1–N2

N1–Pt1–N2

O1–Pt3–O3

Pt2–O3–Pt3

175.3(3)

95.7(3)

81.2(3)

90.0(2)

131.1(3)

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Table 5 Selected Distances and Angles for [(Bu^t₂bpy)Pt(l-OAuPPh₃)]₂-

(BF₄)₂(9b)^a

Pt1–O1

Pt1–O1*

Pt1–N1

Pt1–N2

Pt1–Pt1*

2.034(3)

2.017(3)

1.996(4)

1.994(4)

3.0642(4)

Au1–O1

Au1–P1

Au1–Pt1

Au1–Pt1*

2.057(3)

2.2170(15)

2.9937(3)

3.2600(3)

Pt1–Au1–Pt1*

N1–Pt1–N2

N1–Pt1–O1*

N1–Pt1–O1

Pt1–O1–Au1

Pt1–O1–Au1*

58.493(8)

80.63(18)

177.60(15)

99.50(16)

94.06(14)

106.31(16)

O1–Au1–P1

N2–Pt1–O1*

N2–Pt1–O1

O1–Pt1–O1*

Pt1–O1–Pt1*

171.91(10)

98.06(16)

177.42(16)

81.71(15)

98.29(15)

^aAtoms with an asterisk are related to unmarked atoms by inversion.

Fig. 5 Drawing (50% probability ellipsoids) of the inversion-centered

cationic portion of the solid-state structure of [Pt(Bu^t₂bpy)(l-OAuPPh₃)]₂-

(BF₄)₂(9, M = Pt).

Altering the 1 : 1 reactant ratio in the reaction of M(Bu^t₂bpy)Cl₂

with [(Ph₃PAu)₃(l-O)]BF₄does not change the identity of the

reaction products when M = Pt. However, as previously re-

ported, with M = Pd the new oxo complex [Pd₄(Bu^t₂bpy)₄(l-

OAuPPh₃)](BF₄)₃(l-O)₂(10) is obtained (Scheme 3). Addition of

Pd(Bu^t₂bpy)Cl₂to 9 also yields 10. The lack of formation of a

similar complex for Pt is presumably kinetic.

Fig. 4 Drawing (50% probability ellipsoids) of the cationic portion of

the solid-state structure of [Ni₃(Bu^t₂bpy)₃(l-O)₂](BF₄)₂(8). Mirrors in the

Ni1, O1, N1 and the Ni atom plane relate labeled and unlabeled atoms.

Amido and imido complexes

A well-established method for the synthesis of late transition

metal amido complexes is by the reaction of amines, particularly

aryl amines, with hydroxo complexes (for recent examples, see

references 35,49–51). This is an effective method with the Bu^t₂bpy

complexes but the ﬁnal product depends on the metal and the

reaction conditions (Scheme 4). (Similar behavior is observed for

analogous phosphine complexes.⁵²) Treatment of the Pt dihydroxo

complex [Pt(Bu^t₂bpy)(l-OH)]₂(BF₄)₂with 4 equivalents of ArNH₂

yields the amido hydroxo complexes [Pt₂(Bu^t₂bpy)₂(l-NHAr)(l-

OH)](BF₄)₂(11, Ar = Ph, 4-tol, 4-C₆H₄NO₂). Under the same

conditions the Pd dihydroxo complex [Pd(Bu^t₂bpy)(l-OH)]₂(BF₄)₂

yields the diamido complexes [Pd(Bu^t₂bpy)(l-NHAr)]₂(BF₄)₂(12,

Ar = Ph, 4-tol, 4-C₆H₄NO₂). The analogous Pt diamido complex

[Pt(Bu^t₂bpy)(l-NH(4-tol))]₂(BF₄)₂(13) is obtained by further

treatment of 11 (Ar = 4-tol) with 4-toluidine. Complexes 11 and

12 are also formed from the dihydroxo complexes and LiNHAr.

The difference between the Pt and Pd chemistry is attributed to

the greater kinetic reactivity of a second row transition metal

as compared to a third row transition metal, a well-known

phenomenon.⁵³

Scheme 3

the cationic portion is given in Fig. 5. Data for the Pd complex

have been previously reported.³⁰

The cationic portion consists of an inversion symmetric dimer

containing a planar M₂O₂diamond core with a Ph₃PAu group

bonded to each oxo ligand. The Ph₃PAu groups are oriented

approximately perpendicular to the diamond plane in anti-

positions with respect to one another. NMR spectra for 9 suggest

the same structure in solution. A singlet for the AuPPh₃group

is observed at 25.5 (M = Pt) and 26.6 (M = Pd) ppm in the ³¹P

NMR spectra. ¹H NMR spectra show a symmetric pattern for the

Bu^t₂bpy ligand with a single Bu^tresonance.

Solid-state X-ray crystal structure determinations (Tables 1 and

6) on 12 (Ar = Ph, 4-tol) reveal retention of the diamond core with

slight deviations from planarity. A drawing of the structure of 12

(Ar = Ph) is given in Fig. 6. The aryl rings are found to be in an

2318 | Dalton Trans., 2008, 2314–2327

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Table 6 Selected distances and angles for [(Bu^t₂bpy)Pd(l-NHAr)]₂(BF₄)₂

(12, Ar = Ph, 4-tol)^a

Ar = Ph and 5.20 and 2.55 ppm for Ar = p-tol. The higher shift

resonance in each set is assigned to the NH group. Complexes

12 and 13 show only one resonance for each type of proton on

the Bu^t₂bpy ligand consistent with high symmetry of the dication.

The NH signals are observed at 2.83 (Ar = 4-tol), 2.89 (Ar = Ph),

and 3.54 (Ar = 4-NO₂C₆H₄) ppm for 12. A larger N–H shift of

4.97 ppm is observed for 13 and is similar to the N–H shifts in

11. Larger N–H and O–H shifts for Pt over the Pd complexes are

probably related to a greater acidity for the Pt complexes.

Ar = Ph

Ar = 4-tol

Pd1–N1

Pd1–N2

Pd1–N3

Pd1–N3*

Pd1–Pd1*

N3–C(ipso)

2.024(2)

2.045(2)

2.047(2)

2.053(2)

3.1099(4)

1.428(4)

2.034(3)

2.039(3)

2.055(2)

2.053(3)

3.1015(8)

1.434(4)

N1–Pd1–N2

N1–Pd1–N3

79.77(9)

176.29(11)

98.81(10)

100.45(10)

174.58(11)

81.31(11)

113.49(19)

113.3(2)

79.89(10)

175.83(10)

98.64(10)

99.85(10)

175.11(10)

81.96(10)

113.38(18)

111.70(18)

98.04(10)

Amido-oxo and diimido complexes

N1–Pd1–N3*

N2–Pd1–N3

N2–Pd1–N3*

N3–Pd1–N3*

C(ipso)–N3–Pd1

C(ipso)–N3–Pd1*

Pd1–N3–Pd1*

Deprotonation of amido hydroxo 11 (Ar = 4-tol) is accomplished

with either NaH or 1,8-bis(dimethylamino)naphthalene yielding

the orange amido oxo complex [Pt₂(Bu^t₂bpy)₂(l-NH-tol-4)(l-

O)]BF₄(14, Scheme 5). As with the dihydroxo complexes (see

above) deprotonation with 1,8-bis(dimethylamino)naphthalene

indicates a DMSO pK_afor 14 that is under 7.5, the pK_aof 1,8-

bis(dimethylamino)naphthalene in DMSO.^36,37This is consider-

ably less than the pK_a(11.9) for the diphosphine analog [(L₂Pt)₂(l-

OH)(l-NMePh)]²⁺(L₂= dppe).³⁵Complex 14 is also obtained

when [Pt(Bu^t₂bpy)(l-OH)]₂(BF₄)₂is reﬂuxed in THF with 4

equivalents of toluidine contrasting sharply to the formation of

amido-hydroxo 11 in CH₂Cl₂(see above). The ¹H NMR spectrum

for 14 is very similar to that of 11 (Ar = 4-tol) with two exceptions.

A signal for an OH group is absent and the resonance for one of the

Bu^t₂bpy H-6 protons is strongly shifted from 8.78 to 10.28 ppm.

The shift to higher frequency is attributed to interactions between

the Bu^t₂bpy H-6 protons and the new oxo ligand (see Scheme 5)

similar to what is observed for the analogous hydroxo-oxo complex

2 (see above). Unfortunately, crystals for an X-ray analysis, which

could possibly conﬁrm the interaction, could not be obtained.

98.69(11)

^aAtoms with an asterisk are related to unmarked atoms by inversion.

Scheme 4

Scheme 5

Treatment of diamido 13 with KOBu^tin CH₂Cl₂gives a deep

green complex, which we have assigned as the neutral diimido

complex [Pt(Bu^t₂bpy)(l-N-4-tol)]₂15 (eqn (4)). No ¹H NMR

signal for an N–H group could be detected and the signals for

the N–Ar ligand and the Bu^t₂bpy ligands indicate a symmetric

structure. While there is a slight shift of the Bu^t₂bpy H-6 protons

to higher frequency on deprotonation (from 8.47 ppm in 13 to

9.06 ppm in 15) there is not the dramatic shift indicative of the

hydrogen atom interactions observed for oxo complexes 2 and 14.

This is likely due to a blocking effect of the 4-tol group on the

imido nitrogen atom.

Fig. 6 Drawing (50% probability ellipsoids) of the solid-state structure

of [Pd(Bu^t₂bpy)(l-NHPh)]₂(BF₄)₂(12, Ar = Ph). Labeled and unlabeled

atoms are related by an inversion center.

anti-orientation across the diamond core in both structures with

the BF₄anions hydrogen bonded to the amido hydrogen atoms.

1

Solution H NMR data for 11, 12, and 13 are consistent with

the assigned structures. Two sets of resonances for each type of

proton on the Bu^t₂bpy ligand are observed for 11 and resonances

for the OH and NH groups are observed at 5.17 and 2.25 ppm for

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Table 7 Selected distances and angles for (Bu^t₂bpy)Pd(OTf)₂(16)

Pd1–N2

Pd1–N1

1.9715(17)

1.9815(16)

Pd1–O1

Pd1–O4

2.0503(15)

2.0589(14)

N2–Pd1–N1

N2–Pd1–O1

N1–Pd1–O1

81.31(7)

174.27(6)

92.99(6)

N2–Pd1–O4

N1–Pd1–O4

O1–Pd1–O4

95.00(6)

173.92(7)

90.72(6)

Table 8 Selected distances and dngles for [(Bu^t₂bpy)Pt(H₂O)₂](OTf)₂

(17), and [(Bu^t₂bpy)Pt(H₂O)₂](OTf)₂·Et₂O (17·Et₂O)

17

17·Et₂O

Pt1–N2

Pt1–N1

Pt1–O2

Pt1–O1

1.966(5)

1.974(5)

2.049(5)

2.052(5)

1.974(3)

1.982(2)

2.038(2)

2.043(2)

Fig. 7 Drawing (50% probability ellipsoids) of the solid-state structure

of Pd(Bu^t₂bpy)(OTf)₂(16, M = Pd). Rotational disorder observed in the

Bu^tgroups is illustrated.

N2–Pt1–N1

N2–Pt1–O2

N1–Pt1–O2

N2–Pt1–O1

N1–Pt1–O1

O2–Pt1–O1

81.1(2)

94.5(2)

175.1(2)

173.8(2)

94.9(2)

81.52(10)

93.37(10)

174.78(10)

175.87(9)

94.51(10)

90.61(10)

89.67(19)

(4)

Triﬂate and aqua⁵⁴complexes

During the course of this investigation the triﬂate complexes

(Bu^t₂bpy)M(OTf)₂(16, M = Pd, Pt) were prepared (Scheme 6).

The Pt complex has been previously prepared in an identical

manner,⁵⁵as have closely related triﬂate complexes.^56,57An X-ray

crystal structure determination of the Pd derivative (Tables 1 and

7) conﬁrmed the identity of the complex and shows bonding of

the triﬂate anions to the Pt center. A drawing of the molecule is

provided in Fig. 7. The triﬂate anions are readily displaced from

the Pt center of 16 (M = Pt) by water yielding the dicationic

aqua complex [Pt(Bu^t₂bpy)(H₂O)₂](OTf)₂(17) (for other diimine

Pt aqua complexes see: references 58,59). Unsolvated and ether

solvated crystals were isolated and both were subjected to X-ray

crystal structure determinations (Tables 1 and 8). A drawing of the

unsolvated structure is shown in Fig. 8. The ether solvate is similar

except that one of the triﬂate anions is only hydrogen bonded to

one of the water ligands allowing hydrogen bonding of the ether

molecule to the other water ligand (see supporting information).

Fig. 8 Drawing (50% probability ellipsoids) of the solid-state structure

of the unsolvated form of [Pt(Bu^t₂bpy)(H₂O)₂](OTf)₂(17).

planar, as found for the complexes here, or “bent” by folding along

the X–X axis.^60,61Planarity is promoted by high electronegativity

X groups and weak donor ligands on the metal center consistent

with the planarity of the structure reported here.

As a result of the similar sizes of Pt and Pd and O and

N the M₂X₂diamond core angles for our complexes are all

comparable with M–X–M angles close to 100^◦and the X–M–X

angles at about 80^◦. These angles fall within the range reported for

the many analogous Pt and Pd complexes with this core structure.⁶²

Three of the complexes reported here are exceptional. Complexes

1, 5, and 6 are the ﬁrst structurally characterized Pt complexes

containing truly l₂-oxo ligands bridging between two Pt centers.

Other reported Pt and Pd bridged oxo complexes are l₃,^{21,29,47,52,63–67}

or l₄,^33,68or if l₂are found to be associated with Li salts through

coordination of the oxo ligand to an alkali metal ion effectively

giving l₃-oxo complexes.^29,52,69,70While the disorder between the

oxo and hydroxo ligands in 1 and the poor structure quality of 6

do not allow an examination of the structural details of a l₂-oxo

ligand, complex 5 allows an internal comparative analysis of a

l₃-oxo and a l₂-oxo ligand and this structure will be examined in

more detail.

Scheme 6

Structures

˚

The Au–O distance of 2.054(5) A in 5 is in the range observed

All of the Pt and Pd structures, except that of triplatinum complex

7 and the mononuclear complexes 16 and 17, are based on an M₂X₂

diamond core (M = Pd, Pt; X = N, O). This core for d⁸metals with

a variety of X groups has attracted attention for its tendency to be

in other Au(I) l₃-oxo complexes^47,48,71including 9 (M = Pt). In

˚

addition, the Pt–Au distances (3.195 and 3.049 A) are consistent

with d⁸–d¹⁰closed-shell interactions between the Au and Pt centers.

˚

A difference of 0.056 A between the Pt–O distances for the

2320 | Dalton Trans., 2008, 2314–2327

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˚

to oxo and imido complexes. The diimine ligand supported

complexes described here show similar features but the facile

deprotonation of the hydroxo complexes and the amido complexes

indicate that the diimine ligands impart greater acidity to the

hydroxo and amido ligands. This apparent greater acidity may

be attributed to the reduced metal center electron donation of

diimine ligands as compared to phosphine ligands. The reduced

metal center electron density allows for a greater M–O interaction

and more electron density transfer from the hydroxo or amido

ligand to the metal center.

l₃-oxo ligand (average = 2.022 A) and the l₂-oxo ligand (average =

˚

1.967(8) A) suggests a lengthening of this distance on coordination

of the Ph₃PAu⁺fragment to the oxo ligand. This is consistent

with the well-known phenomenon of increasing bond lengths with

increasing atom coordination number.⁷²As discussed next, steric

interactions may also play a role in the lengthening of the Pt–O

distances.

The coordination environment of the Pt centers of 5 is strongly

distorted from planarity. This is primarily due to a displacement

of the Au bonded oxygen atom O1 out of the Pt coordination

˚

planes deﬁned by Pt1, N1, N2, O2 (deviation < 0.06 A) and Pt2,

˚

N3, N4, O2 (deviation < 0.05 A). The O1 displacement is 0.42 A

Experimental

˚

for the Pt1 plane and 0.93 A for the Pt2 plane. This displacement

appears to arise from steric interactions of the phenyl rings of the

Ph₃PAu⁺fragment with the Prⁱ₂C₆H₃groups of the Bian ligand and

probably accounts for the facile exchange of the Ph₃PAu⁺fragment

with Ph₃PAuCl in solution (see above).

Complex 9 (M = Pt) is related to 5 by replacement of the

Bian ligand with a Bu^t₂bpy ligand and by coordination of another

Ph₃PAu⁺fragment to the second oxo group. As might be expected,

Experiments were performed under a dinitrogen atmosphere in

a Vacuum Atmospheres Corporation dry box. Solvents were

dried by standard techniques and stored under dinitrogen over

˚

4 A molecular sieves or sodium metal unless otherwise indi-

cated. NMR spectra were recorded at ambient temperatures

unless otherwise indicated on a Bruker AMX-250, -300, or -500

spectrometer using external CFCl₃(¹⁹F), K₂PtCl₄(aq) (¹⁹⁵Pt), and

H₃PO₄(³¹P) as standards and are reported in ppm with negative

˚

the Pt–O (2.026(12) A) and Au–O (2.057(3) A) distances are

very similar to those of the l₃-oxo group in 5. Again, the steric

interactions causing the distortions in 5 are absent in 9 due now

to the replacement of the Bian ligand with the less sterically

demanding Bu^t₂bpy ligand and the coordination environment of

the Pt centers is now essentially planar.

1

shifts to lower frequency of the standard. For H NMR spectra

solvent impurities were used to reference back to SiMe₄. Labeling

of the Bian and Bu^t₂bpy ligands for the NMR assignments is

given in Scheme 1. Mass spectra were obtained on a Finnigan

TSQ7000 mass spectrometer. Desert Analytics performed the

microanalyses (inert atmosphere). The presence of solvent of

crystallization in the analyzed samples was conﬁrmed by NMR

Nickel complex 8 can also be considered to be based on a

diamond core where anyone of the three Ni(II) centers may be

taken to bridge across the two oxygen atoms of an Ni₂O₂diamond

core. With the smaller sized Ni center the core angles in 8 are

reduced to average values of 85.8^◦(Ni–O–Ni) and 76.9^◦(O–

Ni–O). A more accurate description of the core structure of 8

is that of a trigonal bipyramid or a dioxo bicapped triangle.

While this structural motif has been observed before for Ni(II)

complexes with an Ni₃O₂core these have been, with one exception,

RO ligand complexes and not oxo ligand complexes.^73–77The

exception is a Ni₆structure with a single l₆-oxo ligand bridging

two Ni₃OH units.⁷⁸The Ni–O bonds in these complexes range from

spectroscopy. Pd(Bu^t₂bpy)Cl₂,⁸⁸Pt(Bu^t₂bpy)Cl₂,²⁹[(Bu^t₂bpy)Pt(l-

OH)]₂(BF₄)₂,²⁹[(Ph₃PAu)₃(l₃-O)]BF₄,⁸⁹(COD)Pt(OTf)₂

and

90,91

92

(Bian)PtCl₂were prepared by literature procedures. Nickel(II)

chloride was dried overnight at 100 ^◦C. Other reagents were

purchased from commercial sources (Aldrich or Acros) and used

as received.

(Bu^t₂bpy)NiCl₂

A solution of NiCl₂(200 mg, 1.54 mmol) in absolute ethanol

(30.0 mL) was added to a stirred suspension of Bu^t₂bpy (413 mg,

1.54 mmol) in absolute ethanol (30.0 mL). The reaction mixture

was reﬂuxed with stirring. Over 5 h the yellow solution slowly

became green and a green solid deposited. The green solid product

was collected by ﬁltration, washed with hot ethanol and then

diethyl ether and then dried at 160 ^◦C for 3 h. Yield: 565.0 mg

(92%). The product was recrystallized for analysis from CH₂Cl₂–

ether. Anal. calcd (found) for C₁₈H₂₄N₂NiCl₂: C, 54.27 (54.15); H,

6.03 (6.13); N, 7.03 (6.87%). ¹H NMR (CD₂Cl₂): The paramagnetic

product shows only a broad peak at 1.69 ppm.

˚

1.906(8) to 2.516(5) A, generally longer than the average value of

˚

1.849 A in 8. Oxo ligands are encountered in diatomic Ni(III)

complexes with Ni₂O₂cores. Those that have been structurally

characterized show Ni–O bond distances similar to those in

8 (1.841(7), 1.870(8);¹⁵1.888(6), 1.854(7);⁷⁹1.843(5), 1.857(4),

1.76(3), 1.81(2) A ). A single Ni–O–Ni bridge exists in the Ni(III)

complex [Ni(salen)]₂O. Here the Ni–O distances are shorter than

in 8 at 1.790(2) A.⁸¹Mixed-metal Ni oxo complexes have also been

reported. In the Ni(II) complex [Ni(acac)₂(PhHgOHgPh)]₂the

structure consists of a Ni₂O₂diamond core with two PhHg units

coordinated to each oxo group. The Ni–O distance is 2.096(4) A.

80

˚

82

˚

[CrFeNiO(OCCH)(py)] metals are disordered.⁸³Finally, the Pd

and Pt sulﬁdo analogs of 8⁸⁴and sulﬁdo complexes with Ni₃S₂

trigonal bipyramidal cores with phosphine,⁸⁵allyl,⁸⁶and sulfur⁸⁷

ligands have been reported and structurally characterized.

[Pt(l-OH)(Bian)]₂(BF₄)₂

This complex was prepared by the following modiﬁed literature

procedure.²⁸(Bian)PtCl₂(50 mg, 0.065 mmol) was suspended in

2 mL of THF. AgBF₄(30 mg, 0.015 mmol), a small amount of

polyvinyl pyridine, and a drop of water were added. The mixture

was reﬂuxed overnight. The volatiles were then removed in vacuo

and the residue dissolved in 15 mL of CH₂Cl₂. The solution was

passed through a pad of diatomaceous earth, reduced in volume

Concluding remarks

Previous work in our group has focused on phosphine ligand

supported hydroxo and amido complexes and their deprotonation

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to ca. 3 mL, layered with diethyl ether, and cooled to 0^◦C to obtain

dark red needle shaped crystals of the product. Yield: 36 mg (70%).

0.800 mmol). The mixture became yellow within 20 min. The

mixture was further stirred for 20 h and then ﬁltered. The

ﬁltrate was concentrated in vacuo to ca. 10 mL. Ether (20 mL)

was added and the mixture was stored at −30 ^◦C for 3 h.

The resulting ﬁne microcrystalline yellow product was isolated

by ﬁltration. Yield: 113 mg (72%). Anal. calcd (found) for

C₃₆H₄₉BF₄N₄O₂Pd₂·0.5CH₂Cl₂: C, 48.02 (47.60); H. 5.48 (5.61);

N, 6.14 (6.01%). The product was recrystallized from CH₂Cl₂–

[(Bu^t₂bpy)Pd(l-OH)]₂(BF₄)₂

Solid AgBF₄(390 mg, 2.00 mmol) and 3–4 drops of water were

added to a solution of (Bu^t₂bpy)PdCl₂(445 mg, 1.00 mmol)

in CH₂Cl₂(60 mL). The reaction mixture was stirred for 6 h

and then ﬁltered. The ﬁltrate was concentrate in vacuo to ca.

10 mL. Ether (30 mL) was added and the mixture was cooled at

−30 ^◦C for 3 h. The resulting ﬁne microcrystalline pale yellow

product was isolated by ﬁltration. Yield: 365 mg (76%). The

product was recrystallized from CH₂Cl₂–ether. Anal. calcd (found)

for C₃₆H₅₀N₄B₂F₈O₂Pd₂: C, 45.17 (44.98); H. 5.26 (5.36); N, 5.85

1

ether. H NMR (250 MHz, CD₂Cl₂): 8.66 (d, J_HH= 5.9 Hz, 4H,

6,6^ꢀ-H-bpy), 7.95 (d, J_HH= 1.8 Hz, 4H, 3,3^ꢀ-H-bpy), 7.73 (dd,

J_HH= 5.9 and 1.8 Hz, 4H, 5,5^ꢀ-H-bpy), 1.42 (s, 36H, Bu^t).

M = Pt (2)

Method A.

A

solution of [{(Bu^t₂bpy)Pt(l-OH)]₂(BF₄)₂

1

(5.75%). H NMR (300 MHz, CD₂Cl₂): 8.31 (d, J_HH= 6.0 Hz,

4H, 6,6^ꢀ-H-bpy), 7.89 (d, J_HH= 1.6 Hz, 4H, 3,3^ꢀ-H-bpy), 7.65 (dd,

J_HH= 6.0 & 1.6 Hz, 4H, 5,5^ꢀ-H-bpy), 1.43 (s, 36H, Bu^t), 0.28 (s,

2H, OH).

(227 mg, 0.200 mmol) in CH₂Cl₂(20 mL) was vigorously stirred

with solid NaH (19.2 mg, 0.800 mmol). The mixture changed

from yellow to orange to red over a 30 min period. Stirring was

continued for 6 h and then the mixture was ﬁltered. The ﬁltrate

was concentrated in vacuo to ca. 10 mL. Ether (20 mL) was added

and the mixture was stored at −30 ^◦C for 24 h. The resulting brick

red microcrystalline solid was isolated by ﬁltration and dried in

vacuo. Yield: 187 mg (89%).

[Pt₂(l-OH)(l-O)(Bian)₂](BF₄) (1)

Method A. To a red solution of [Pt(l-OH)(Bian)]₂(BF₄)₂

(50 mg, 0.031 mmol) dissolved in 3 mL of reagent grade

CH₂Cl₂was added ∼10 equivalents of 1,8-bis(dimethylamino)-

naphthalene. The reaction mixture was stirred for 15 min during

which time it turned from red to purple. The mixture was stirred

for an additional 15 min, passed through a pad of diatomaceous

earth, and the volatiles removed in vacuo to give a purple solid. The

solid was dissolved in a minimum volume of CH₂Cl₂and ether was

added to give a purple precipitate of the product contaminated

with protonated 1,8-bis(dimethylamino)naphthalene salt which

could not be eliminated.

Method B. A THF solution (2 mL) of 1,8-bis(dimethyl-

amino)naphthalene (42.8 mg, 0.200 mmol) was added to a

suspension of [(Bu^t₂bpy)Pt(l-OH)]₂(BF₄)₂(113 mg, 0.100 mmol)

in THF (10 mL). The solution changed from yellow to orange

within 10 min then after 30 min it became red. The reaction

mixture was stirred for 16 h and then ﬁltered. The resulting product

was collected by ﬁltration. Yield: 90.0 mg (86%). The product

was recrystallized from CH₂Cl₂–ether. Anal. calcd (found) for

C₃₆H₄₉N₄BF₄O₂Pt₂·0.7CH₂Cl₂: C, 39.85 (38.82); H. 4.59 (4.61);

1

Method B. To a red solution of [Pt(l-OH)(Bian)]₂(BF₄)₂

(25 mg, 0.016 mmol) in 3 mL of reagent grade CH₂Cl₂was added

4 mg of a crushed KOH pellet. The reaction mixture slowly turns

purple after stirring for 15 min. At this point the stirring was

stopped and the volatiles removed in vacuo to obtain a purple

solid. The purple solid was dissolved in CH₂Cl₂, the solution

passed through a pad of diatomaceous earth and the solvent

N, 5.06 (4.96%). H NMR (250 MHz, CD₂Cl₂): 9.33 (br s, 4H,

6,6^ꢀ-H-bpy), 7.64 (d, J_HH= 2 Hz, 4H, 3,3^ꢀ-H-bpy), 7.49 (dd, 6 and

2 Hz, 4H, 5,5^ꢀ-H-bpy), 1.27 (s, 36H, Bu^t). The OH signal was not

observed. UV-Vis (k_max/nm, CH₂Cl₂): 380, 320, 305, 270, 250.

[(Bu^t₂bpy)₂Pt₂(l-OH)(l-OCH₃)](BF₄)(OTf) (3)

A solution of MeOTf (33.0 mg. 0.200 mmol) was added drop-wise

to a stirred solution of [(Bu^t₂bpy)₂Pt₂(l-OH)(l-O)](BF₄) (20 mg,

0.019 mmol) in CH₂Cl₂(10 mL). The mixture changed from red

to yellow within 10 min. Stirring was continued for 2 h then the

mixture was ﬁltered. The ﬁltrate was concentrate in vacuo to ca.

4 mL. Ether (12 mL) was added and mixture cooled at −30 ^◦C for

24 h. The resulting yellow solid was isolated by ﬁltration. Yield:

19.7 mg (90%). The product was recrystallized from CH₂Cl₂–ether.

Anal. calcd (found) for C₃₈H₅₂BF₇N₄O₅Pt₂S·0.5(CH₂Cl₂): C, 36.89

evaporated to dryness to give the purple product in quantitative

1

yield. H NMR (CD₂Cl₂): 8.31 and 8.23 (overlapping d’s, J_HH

=

ꢀ

7.8 Hz, 2H and 2H, H₅and H₅), 7.50 (br t, J_HH∼ 8 Hz, 4H,

ꢀ

H₄and H₄), 7.22–7.35 (m, 12H, H_{10,11,12,10 11 12}), 6.93 (br d, J_HH

ꢀ

∼ 7 Hz, 2H, H₃or H₃), 6.75 (br d, J_HH∼ 7 Hz, 2H, H₃or

ꢀ

H₃), 3.30 (br sept, J_HH∼ 7 Hz, 4H, CH(CH₃)₂), 3.17 (br sept,

J_HH∼ 7 Hz, 4H, CH(CH₃)₂), 1.33 (br d, J_HH∼ 7 Hz, 12H,

CH(CH₃)₂), 1.12 (br d, J_HH∼ 7 Hz, 12H, CH(CH₃)₂), 0.96

(br d, J_HH∼ 7 Hz, 12H, CH(CH₃)₂), 0.90 (br d, J_HH∼ 7 Hz,

12H, CH(CH₃)₂), −1.84 (br s, 1H, OH). The ¹H NMR spectrum

is often broadened due to trace protic impurities but sharpens

on addition of 1,8-bis(dimethylamino)naphthalene. Crystals were

grown at room temperature by layering a CD₂Cl₂solution with

1

(37.09); H, 4.26 (3.99); N, 4.47 (4.28%). H NMR (250 MHz,

CD₂Cl₂): 8.72 (d, J_HH= 6.1 Hz, 2H, 6-H-bpy), 8.68 (d, J_HH

=

5.6 Hz, 2H, 6^ꢀ-H-bpy), 7.93 (d, J_HH= 1.8 Hz, 2H, 3-H-bpy), 7.85

(d, J_HH= 1.8 Hz, 2H, 3^ꢀ-H-bpy), 7.69 (dd, J_HH= 6.1 and 1.8 Hz,

2H, 5-H-bpy), 7.62 (dd, J_HH= 6.1 and 1.8 Hz, 2H, 5^ꢀ-H-bpy), 4.21

(s, 1H, OH), 3.12 (s, 3H, Me), 1.44 (s, 18H, Bu^t), 1.42 (s, 18H, Bu^t).

˚

Et₂O. Crystal data: a = 18.4678(18) A, b = 15.3307(15) A, c =

◦

˚

24.099(2) A, b = 99.058(2) , monoclinic, P2₁/c.

[(Bu^t₂bpy)₂M₂(l-OH)(l-O)]BF₄. M = Pd

[Pt(l-O)(Bian)]₂(4)

A solution of [{(Bu^t₂bpy)Pd(l-OH)]₂(BF₄)₂(191 mg, 0.200 mmol)

To a red solution of [Pt(l-OH)(Bian)]₂(BF₄)₂(50 mg, 0.031 mmol)

dissolved in 3 mL of CH₂Cl₂was added a 10 mg portion of a

in CH₂Cl₂(20 mL) was vigorously stirred with solid NaH (19.2 mg,

2322 | Dalton Trans., 2008, 2314–2327

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crushed KOH pellet and one drop of water. The reaction mixture

turned purple after stirring for 15 min, and then ﬁnally became

the dark blue of the product after two hours of stirring. The

reaction mixture was then evaporated to dryness, the residue

dissolved in a minimum amount of CH₂Cl₂, passed through a

pad of diatomaceous earth, and the volatiles removed in vacuo.

The resulting blue solid product was washed with petroleum ether

and dried in vacuo. Yield (35 mg, 80%). ¹H NMR (CD₂Cl₂): 8.10

(d, J_HH= 8.2 Hz, 4H, H₅), 7.39 (t, J_HH= 7.7 Hz, 4H, H₁₁), 7.24 (d,

˚

with toluene. Crystal data: a = 16.346(3) A, b = 28.541(6) A, c =

◦

˚

15.987(3) A, b = 99.362(4) , monoclinic, P2₁/c.

Reaction of [Pt(l-O)(Bian)]₂(4) with excess MeOTf

To a solution of 4 (10 mg, 0.0070 mmol) dissolved in 4 mL of

CH₂Cl₂was added methyl triﬂate (6.0 mg, 0.036 mmol) in 2 mL of

CH₂Cl₂. As the mixture was stirred over an hour the color changed

from blue to purple and later to dark-red. The dark-red solution

was evaporated to dryness, washed with pentane and dried in vacuo

to give an incompletely characterized red compound that ma_◦y be

[(Bian)Pt(OTf)₂]. Yield (8.0 mg, 85%). ¹H NMR (CD₂Cl₂, 25 C):

8.29 (d, J_HH= 7.5 Hz, 4H, H₅), 7.33 (d, J_HH= 7.5 Hz, 8H, H₁₀),

7.60–7.51 (overlapping t, J_HH= 7.5 Hz, 8H, H₄and H₁₁) 6.78 (d,

J_HH= 7.5 Hz, 4H, H₃), 3.41 (septet, J_HH= 7.5 Hz, 8H, CH(CH₃)₂),

1.21 (d, J_HH= 7.5 Hz, 24H, CH(CH₃)₂), 0.82 (d, J_HH= 7.5 Hz,

24H, CH(CH₃)₂. ¹⁹F NMR (CD₂Cl₂, 25 ^◦C): −79.04.

J_HH= 7.7 Hz, H_10,12), 7.12 (t, J_HH= 7.7 Hz, 4H, H₄), 6.55 (d, J_HH

=

7.1 Hz, 4H, H₃), 3.38 (sept, J_HH= 6.9 Hz, 8H, CH(CH₃)₂), 1.22

(d, J_HH= 6.9 Hz, 24H, CH(CH₃)₂), 0.82 (d, J_HH= 6.9 Hz, 24H,

CH(CH₃)₂). Anal. calcd (Found) for C₇₂H₈₀N₄O₂Pt₂·0.5 CH₂Cl₂:

C, 59.44 (59.40); H, 5.58 (5.57); N, 3.73 (3.83%).

[(Bian)₂Pt₂(l₂-O)(l₃-OAuPPh₃)](BF₄) (5)

To a solution of 4 (15 mg, 0.011 mmol) dissolved in 2 mL of

CH₂Cl₂was added 10 mg of freshly prepared “Ph₃PAuBF₄” (from

Ph₃PAuCl and AgBF₄in THF)⁹³in CH₂Cl₂. The reaction mixture

changed from blue to dark purple. The reaction mixture was stirred

for 20 min and then the volatiles were removed in vacuo. The

residue was washed with petroleum ether and dried in vacuo to

give the bluish-purple solid product. Yield (25 mg, 91%). Crystals

suitable for X-ray diffraction and analysis were grown at room

temperature by layering a CH₂Cl₂solution with toluene. Anal.

calcd (Found) for C₉₀H₉₅AuBF₄N₄O₂PPt₂: C, 54.88 (55.14); H,

4.86 (4.73); N, 2.85 (2.76%). ¹H NMR (CD₂Cl₂, −20 ^◦C): 8.24 (d,

J_HH= 8.2 Hz, 4H, H₅), 7.50–7.18 (m, 31H, PPh₃and H_4,10,11,12),

6.76 (d, J_HH= 7.2 Hz, 4H, H₃), 3.55 (br sept, J_HH= 6.5 Hz, 4H,

CH(CH₃)₂), 3.10 (br sept, J_HH= 6.6 Hz, 4H, CH(CH₃)₂), 1.07

(d, J_HH= 6.6 Hz, 12H, CH(CH₃)₂), 0.98 (d, J_HH= 6.6 Hz, 12H,

CH(CH₃)₂), 0.72 and 0.70 (overlapping d’s, J_HH= 6.6 Hz, 12H and

12H, CH(CH₃)₂). ³¹P NMR (CH₂Cl₂, 101 MHz, −20 ^◦C): 22.9 (s).

Spectra (the 2,6-Prⁱ₂C₆H₃signals only) are broadened at 25 ^◦C due

to exchange with traces of Ph₃PAuCl, which is visible at 32 ppm

in the ³¹P NMR spectrum. Identical NMR spectra are observed

with mixtures of 4 and Ph₃PAuCl.

Reaction of [Pt(l-O)(Bian)]₂(4) with [Pt(COD)(OTf)₂]:

[(Bian)(COD)₂Pt₃(l-OH)₃](OTf)₃(7)

[Pt(COD)(OTf)₂] (9.0 mg, 0.015 mmol) in 1 mL of CH₂Cl₂was

added drop-wise to a blue solution of 4 (10 mg, 0.0070 mmol)

dissolved in 4 mL of CH₂Cl₂. The reaction slowly changed from

blue to purple and ﬁnally to yellow brown. The dark-yellow brown

solutionwas concentrated, layered withether, andstored at −30^◦C

to give a brown solid. ¹H NMR of the brown solid (CD₂Cl₂): 8.33

(d, J_HH= 7.5 Hz, H₅), 7.60–7.51 (overlapping t, J_HH= 7.5 Hz, H₄

and H₁₁), 7.33 (d, J_HH= 7.5 Hz, H₁₀), 6.79 (d, J_HH= 7.5 Hz, H₃),

5.67 (br s with satellites, J_Pt–H= 68 Hz, COD), 3.25 (sept, J_HH

=

6.7 Hz, CH(CH₃)₂), 2.76 (br m, COD), 2.23 (br d, J_Pt–H= 8 Hz,

COD), 1.37 (d, J_HH= 6.7 Hz, CH(CH₃)₂), 0.83 (d, J_HH= 6.7 Hz,

24H, CH(CH₃)₂). The Bian to COD ratio was ∼1 : 1 by integration.

A few orange-red crystals deposited from a CH₂Cl₂solution of

the brown solid over a 4-day period at room temperature. The

orange-red crystals were characterized by X-ray diffraction as the

trihydroxo complex [(Bian)(COD)₂Pt₃(l-OH)₃](OTf)₃(7).

[(Bu^t₂bpy)₃Ni₃(l₃-O)₂](BF₄)₂(8)

A solution of Ni(Bu^tbpy)Cl₂(30 mg, 0.075 mmol) in CH₂Cl₂

(3 mL) was added to a stirred solution of [(LAu)₃(l₃-O)]BF₄

(74 mg, 0.050 mmol) in CH₂Cl₂(3 mL). The mixture changed

from yellow to red within 5 min. The reaction was further stirred

for 25 min and then concentrated in vacuo to ca. 3 mL. THF

(6 mL) was added and the mixture was cooled at −30 ^◦C for 24 h.

The resulting ﬁne microcrystalline red product was isolated by

ﬁltration. Yield: 66 mg (74%). Crystals for the X-ray analysis were

obtained by slow recrystallization from CH₂Cl₂–THF. Anal. calcd

(found) for C₅₄H₇₂N₆Ni₃O₂B₂F₈: C, 54.65 (53.00); H. 6.11 (5.43);

[(Bian)₂Pt₂(l-O)(l-OMe)]OTf (6)

To a stirred solution of 4 (15 mg, 0.011 mmol) dissolved in 4 mL

of toluene was added methyl triﬂate (3 mg, 0.02 mmol) in 1 mL

of toluene. A purple solid precipitated from the mixture. The dark

purple solid was isolated by ﬁltration, washed with pentane and

dried in vacuo. Yield (11 mg, 75%). Crystals for the X-ray analysis

were obtained by layering a CH₂Cl₂solution with toluene. Anal.

calcd. (Found) for C₇₄H₈₃F₃N₄O₅Pt₂S: C, 55.97 (55.64); H, 5.27

(5.54); N, 3.53 (3.93%). ¹H NMR (CD₂Cl₂, 25 ^◦C): 8.29 and 8.26

ꢀ

(overlapping d’s, J_HH= 8 Hz, 2H and 2H, H_5,5), 7.52 (t, J_HH

=

1

N, 7.08 (6.37%). H NMR (250 MHz, CD₂Cl₂): 8.11 (d, J_HH

=

ꢀ

7.5 Hz, 4H, H_4,4) 7.40–7.28 (m, 8H, H_11,11and H_10,10or H_12,12),

5.9 Hz, 6H, 6,6^ꢀ-H-bpy), 7.84 (d, J_HH= 1.8 Hz, 6H, 3,3^ꢀ-H-bpy),

7.66 (dd, J_HH= 5.9 and 1.8 Hz, 6H, 5,5^ꢀ-H-bpy), 1.40 (s, 54H,

Bu^t).

ꢀ

7.22 (d, J_HH= 7.5 Hz, 4H, H_10,10or H_12,12), 6.70 (d, J_HH= 7.2 Hz,

ꢀ

4H, H₃or H₃) 6.59 (d, J_HH= 7.2 Hz, 4H, H₃or H₃), 3.38 (sept,

J_HH= 6.8 Hz, 4H, CH(CH₃)₂), 3.12 (septet, J_HH= 6.8 Hz, 4H,

CH(CH₃)₂), 2.48 (s with broad base, 3H, OMe), 1.40 (d, J_HH

=

[(Bu^t₂bpy)Pt(l₃-O)(AuPPh₃)]₂(BF₄)₂(9, M = Pt)

A solution of Pt(Bu^t₂bpy)Cl₂(106 mg, 0.200 mmol) in CH₂Cl₂

(3 mL) was added to a stirred solution of [(LAu)₃(l₃-O)]BF₄

(296 mg. 0.200 mmol) in CH₂Cl₂(3 mL). The mixture changed

6.8 Hz, 12H, CH(CH₃)₂), 1.13 (d, J_HH= 6.8 Hz, 12H, CH(CH₃)₂),

0.92 (d, J_HH= 6.8 Hz, 12H, CH(CH₃)₂), 0.85 (d, J_HH= 6.8 Hz,

12H, CH(CH₃)₂). ¹⁹F NMR (CD₂Cl₂, 25 ^◦C): −79.0. Crystals

were grown at room temperature by layering a CD₂Cl₂solution

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from yellow to golden-yellow within 15 min. The reaction was

further stirred for 25 min and then concentrated in vacuo to ca.

3 mL. Toluene (6 mL) was added and the mixture was stored at

−30 ^◦C for 24 h. The resulting ﬁne microcrystalline yellow-orange

product was isolated by ﬁltration. Yield: 150 mg (73%). Crystals

for X-ray analysis were obtained by recrystallization from CD₂Cl₂–

ether. Anal. calcd (found) for C₇₂H₇₈N₄Au₂B₂F₈O₂P₂Pt₂: C, 42.14

7.8 Hz, 2H, 2,2^ꢀ-H-aniline), 7.88 (d, J_HH= 1.5 Hz, 2H, 3-H-bpy),

7.82 (d, J_HH= 1.8 Hz, 2H, 3^ꢀ-H-bpy), 7.78 (dd, J_HH= 6.0 and

1.5 Hz, 2H, 5-H-bpy), 7.57 (dd, J_HH= 6.3 and 2.1 Hz, 2H, 5^ꢀ-H-

bpy), 7.39 (t, J_HH= 7.6 Hz, 1H, 3-H-aniline), 7.15 (t, J_HH= 6.6,

1H, 3^ꢀ-H-aniline), 5.20 (s, 1H, NH), 2.55 (br s, 1H, OH), 1.44 (s,

18H, Bu^t), 1.38 (s, 18H, Bu^t).

1

(42.13); H. 3.80 (3.87); N, 2.73 (2.80%). H NMR (300 MHz,

Ar = 4-C₆H₄NO₂

CD₂Cl₂): 9.00 (d, 4H, J_HH= 6.0 Hz, 6,6^ꢀ-H-bpy), 8.09 (d, 4H,

J_HH= 1.8 Hz, 3,3^ꢀ-H-bpy), 7.58 (dd, 4H, J_HH= 6.1 Hz, J_HH

=

A solution of 4-nitroaniline (97.0 mg, 0.704 mmol) was added

to a stirred solution of [(Bu^t₂bpy)Pt(l-OH)]₂(BF₄)₂(200 mg,

0.176 mmol) in CH₂Cl₂(50 mL). The solution turned from yellow

to orange within 20 min. The reaction was further stirred for

24 h and then ﬁltered. The resulting ﬁltrate was concentrated in

vacuo to ca. 15 mL. To this solution ether (30 mL) was added

and the product was isolated by ﬁltration. Yield: 326 mg (74%).

Crystals for an X-ray analysis were obtained by recrystallization

from CD₂Cl₂–ether at −30 ^◦C but these gave very poor results

and contained badly disordered solvent molecules. ¹H NMR

(300 MHz, CD₂Cl₂): 8.75 (d, 2H, J_HH= 5.8 Hz, 6-H-bpy), 8.46 (d,

2H, J_HH= 8.9 Hz, 2,2^ꢀ-H-p-nitroaniline), 8.41 (d, 2H, J_HH= 6.2 Hz,

6^ꢀ-H-bpy), 8.23 (d, 2H, J_HH= 8.9 Hz, 3,3^ꢀ-H-p-nitroaniline), 7.87

(d, 2H, 3-H-bpy), 7.83 (d, 2H, J_HH= 1.4 Hz, 3^ꢀ-H-bpy), 7.79 (d,

2H, J_HH= 6.0, 5-H-bpy), 7.60 (d, 2H, J_HH= 4.3, 5^ꢀ-H-bpy), 5.66

(s, 1H, NH), 2.83 (s, 1H, OH), 1.45 (s, 18H, Bu^t), 1.39 (s, 18H,

Bu^t).

1.9 Hz, 5,5^ꢀ-H-bpy), 7.44–7.24 (m, 30 H, Ph), 1.45 (s, 36H, Bu^t).

1

³¹P{ H} NMR (101 MHz, CD₂Cl₂): 23.1 (s). ¹⁹⁵Pt NMR (64 MHz,

CD₂Cl₂): −1255 (s).

[(Bu^t₂bpy)₂Pt₂(l-OH)(l-NHAr)](BF₄)₂(11). Ar = 4-tol

A CH₂Cl₂solution (5 mL) of p-toluidine (75.3 mg, 0.704 mmol)

was added to a stirred solution of [(Bu^t₂bpy)Pt(l-OH)]₂(BF₄)₂

(200 mg, 0.176 mmol) in CH₂Cl₂(50 mL). The mixture changed

from yellow to orange within 20 min. The reaction was further

stirred for 2 h and then ﬁltered. The ﬁltrate was concentrated in

vacuo (15 mL). To this solution ether (30 mL) was added and the

apricot colored product was isolated by ﬁltration. Yield: 200 mg

(93%). The product was recrystallized from CH₂Cl₂–ether. Anal.

calcd (found) for C₄₃H₅₇N₅B₂F₈OPt₂: C, 42.19 (42.27); H. 4.66

(4.79); N, 5.72 (5.58%).

MS (ESI/APC-direct infusion, CH₂Cl₂, m/z): 1136.4 (10%,

[{(C₁₈H₂₄N₂)₂Pt₂(l-OH)(l-NHC₆H₄CH₃-4)}]⁺), 1048.4 (13%,

[{(C₁₈H₂₄N₂)₂Pt₂(l-OH)(l-NHC₆H₄CH₃-4)}]²⁺), 525.1 (23%, [(C₁₈-

H₂₄N₂)Pt(C₇H₈N)(OH)/2]), 516.0 (100%, [(C₁₈H₂₄N₂)Pt(C₇-

[(Bu^t₂bpy)Pd(l-NHAr)]₂(BF₄)₂(12). Ar = Ph

Method A. A solution of aniline (93.0 mg, 1.00 mmol) in

CH₂Cl₂(5 mL) was added to [(Bu^t₂bpy)Pd(l-OH)]₂(BF₄)₂(239 mg,

0.250 mmol) in CH₂Cl₂(50 mL). The mixture changed from yellow

to red within 30 min. The reaction was stirred for 4 h and then

ﬁltered. The ﬁltrate was concentrate in vacuo to ca. 15 mL. To

this solution ether (30 mL) was added and the resulting ﬁne

microcrystalline yellow product was isolated by ﬁltration. Yield:

221 mg (80%).

H₈N)/2]). ¹H NMR (300 MHz, CD₂Cl₂): 8.78 (d, 2H, J_HH

=

5.6 Hz, 6-H-bpy), 8.40 (d, 2H, J_HH= 5.9 Hz, 6^ꢀ-H-bpy), 8.14 (d,

2H, J_HH= 8.3 Hz, 2,2^ꢀ-H-p-tol), 7.86 (s, 2H, 3-H-bpy), 7.81 (s,

2H, 3^ꢀ-H-bpy), 7.78 (d, 2H, J_HH= 4.6 Hz, 5-H-bpy), 7.57 (d, 2H,

J_HH= 5.3 Hz, 5^ꢀ-H-bpy), 7.19 (d, 2H, J_HH= 8.2 Hz, 3,3^ꢀ-H-p-tol),

5.17 (s, 1H, NH), 2.55 (s, 1H, OH), 2.25 (s, 3H, Me-p-tol), 1.44 (s,

18H, Bu^t), 1.39 (s, 18H, Bu^t).

Method B. A CH₂Cl₂solution (5 mL) of LiPhNH (99.0 mg,

1.00 mmol) was added to a stirred solution of [(Bu^t₂bpy)Pd(l-

OH)]₂(BF₄)₂(239 mg, 0.250 mmol) in CH₂Cl₂(50 mL). Within

30 min the color of reaction changed from yellow to red. The

reaction was further stirred for 4 h and then ﬁltered. The ﬁltrate

was concentrate in vacuo to ca. 15 mL. Ether (30 mL) was

added and the resulting ﬁne microcrystalline yellow product was

isolated by ﬁltration. Yield: 219 mg (79%). Crystals for the X-

ray analysis were obtained by recrystallization from THF–ether at

−30 ^◦C. Anal. calcd (found) for C₄₈H₆₀B₂F₈N₆Pd₂·0.5(CH₂Cl₂): C,

50.66 (50.43); H. 5.35 (5.26); N, 7.31 (6.93%). ¹H NMR (250 MHz,

CD₂Cl₂): 8.59 (d, J_HH= 7.5 Hz, 4H, NC₆H₅), 8.17 (d, J_HH= 6.2 Hz,

4H, 6,6^ꢀ-H-bpy), 7.79 (d, J_HH= 1.8 Hz, 4H, 3,3^ꢀ-H-bpy), 7.55 (dd,

J_HH= 6.2 and 1.8 Hz, 4H, 5,5^ꢀ-H-bpy), 7.31 (t, J_HH= 8.8 Hz, 4H,

NC₆H₅), 7.03 (t, J_HH= 7.5 Hz, 2H, NC₆H₅), 2.89 (s, 2H, NH),

1.35 (s, 36H, Bu^t).

Ar = Ph

Method A.

A

solution of [(Bu^t₂bpy)Pt(l-OH)]₂(BF₄)₂

(283.5 mg, 0.250 mmol) in CH₂Cl₂(25 mL) was added to a stirred

solution of aniline (93.0 mg, 1.00 mmol) in CH₂Cl₂(5 mL). The

mixture changed from yellow to red within 20 min. The reaction

was further stirred for 4 h and then ﬁltered. The ﬁltrate was

concentrate in vacuo to ca. 10 mL. Ether (20 mL) was added

and the resulting ﬁne microcrystalline yellow-orange product was

isolated by ﬁltration. Yield: 245 mg (81%).

Method B. A solution of LiPhNH (99.0 mg, 1.00 mmol) in

CH₂Cl₂(5 mL) was added to a stirred solution of [(Bu^t₂bpy)Pt(l-

OH)]₂(BF₄)₂(283.5 mg, 0.250 mmol) in CH₂Cl₂(20 mL). Within

30 min the color of the mixture changed from yellow to red. The

mixture was further stirred for 4 h and then ﬁltered. The ﬁltrate

was concentrate in vacuo to ca. 10 mL. Ether (20 mL) was added

and the resulting ﬁne microcrystalline yellow-orange product was

isolated by ﬁltration. Yield: 240 mg (79%). Anal. calcd (found) for

C₄₂H₅₅N₅B₂F₈OPt₂·1.5CH₂Cl₂: C, 39.08 (39.11); H. 4.37 (4.48); N,

5.24 (5.04%). ¹H NMR (300 MHz, CD₂Cl₂): 8.78 (d, J_HH= 6.0 Hz,

Ar = 4-tol

A solution of [(Bu^t₂bpy)Pd(l-OH)]₂(BF₄)₂(239 mg, 0.250 mmol)

in CH₂Cl₂(50 mL) was reﬂux with p-toluidine (107 mg, 1.00 mmol)

with stirring for 20 h and then ﬁltered. The ﬁltrate was concentrate

2H, 6-H-bpy), 8.41 (d, J_HH= 6.3 Hz, 2H, 6^ꢀ-H-bpy), 8.26 (d, J_HH

2324 | Dalton Trans., 2008, 2314–2327

=

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in vacuo to ca. 15 mL. Ether (30 mL) was added and the resulting

ﬁne microcrystalline yellow product was isolated by ﬁltration.

Yield: 230 mg (81%). Crystals for the X-ray analysis were obtained

by recrystallization from CD₂Cl₂–ether at −30 ^◦C. Anal. calcd

(found) for C₅₀H₆₄N₆B₂F₈Pd₂: C, 52.86 (52.05); H. 5.63 (5.65);

N, 7.40 (7.20%). (The low carbon value probably results from

became deep yellow and an orange solid deposited. The orange

solid was collected by ﬁltration. Yield: 113.0 mg (45%).

Method C. A THF solution (2 mL) of proton sponge

(68.5 mg, 0.320 mmol) was added to a stirred solution/suspension

of [(Bu^t₂bpy)₂Pt₂(l-OH)(l-NHC₆H₄Me-4)](BF₄)₂(195 mg,

0.160 mmol) in THF (30 mL). The reaction mixture was

reﬂuxed with stirring for 6 h. The resulting solid product was

collected by ﬁltration. Yield: 137.0 mg (75%). The product

was recrystallized from CH₂Cl₂–ether. Anal. calcd (found) for

C₄₃H₅₆N₅BF₄OPt₂·0.5NaBF₄(method A): C, 43.37 (42.97); H. 4.74

(4.75); N, 5.88 (5.89%). MS (ESI/APC-direct infusion, CH₂Cl₂,

m/z): 1084.4 (90%, [(C₁₈H₂₄N₂)₂Pt₂(l-O)(l-NHC₆H₄CH₃-4)]⁺),

568.0 (100%, [(C₁₈H₂₄N₂)Pt(l-NC₆H₄CH₃-4)]), 268.9 (24%,

occluded CH₂Cl₂.) ¹H NMR (300 MHz, CD₂Cl₂): 8.52 (d, J_HH

=

8.2 Hz, 4H, H-p-tol), 8.26 (d, J_HH= 6.0 Hz, 4H, 6,6^ꢀ-H-bpy), 7.68

(d, J_HH= 1.8 Hz, 4H, 3,3^ꢀ-H-bpy), 7.55 (dd, J_HH= 6.0 & 1.8 Hz,

4H, 5,5^ꢀ-H-bpy), 7.09 (d, J_HH= 8.2 Hz, 4H, H-p-tol), 2.83 (s, 2H,

NH), 2.17 (s, 6H, Me-p-tol), 1.34 (s, 36H, Bu^t).

Ar = 4-C₆H₄NO₂

1

[C₁₈H₂₄N₂]). H NMR (300 MHz, CD₂Cl₂): 10.28 (d, 2H, 6-H-

A solution of [(Bu^t₂bpy)Pd(l-OH)]₂(BF₄)₂(150 mg, 0.157 mmol)

in CH₂Cl₂(50 mL) was reﬂuxed with 4-nitroaniline (87.0 mg,

0.630 mmol). The bright yellow solution was further reﬂuxed with

stirring for 5 h and then ﬁltered. The ﬁltrate was concentrate in

vacuo to ca. 15 mL. Ether (30 mL) was added and the resulting ﬁne

microcrystalline yellow product was isolated by ﬁltration. Yield:

172 mg (91%). The product was recrystallized from CH₂Cl₂–ether.

Anal. calcd (found) for C₄₈H₅₈N₈O₄B₂F₈Pd₂: C, 48.16 (48.34); H.

bpy), 8.14 (d, 2H, J_HH= 5.8 Hz, 2,2^ꢀ-H-p-tol), 7.68 (d, 2H, J_HH

=

4.4 Hz, 6^ꢀ-H-bpy), 7.60 (d, 2H, 3-H-bpy), 7.55 (d, 2H, 5-H-bpy),

7.43 (d, 2H, 3^ꢀ-H-bpy), 7.14 (d, 2H, 3,3^ꢀ-H-p-tol), 5.46 (s, 1H,

NH), 2.32 (s, 3H, Me-p-tol), 1.31 (s, 18H, Bu^t), 1.04 (s, 18H, Bu^t).

[(Bu^t₂bpy)Pt(l-N-4-tol)]₂(15)

A

solution of [(Bu^t₂bpy)Pt(l-NH-4-tol)]₂(BF₄)₂(91.8 mg,

1

4.84 (4.31); N, 9.36 (9.10%). H NMR (300 MHz, CD₂Cl₂): 8.79

0.070 mmol) in CH₂Cl₂(50 mL) was vigorously stirred with solid

Bu^tOK (17.0 mg, 0.070 mmol). The solution color changed from

yellow to black green within 10 min. Stirring was continued for

15 h and then the mixture was ﬁltered. The volume of the ﬁltrate

was reduced in vacuo to ca. 15 mL. Ether (30 mL) was added and

the resulting dark green product was isolated by ﬁltration. Yield:

68.0 mg (74%). Anal. calcd (found) for C₅₀H₆₂N₆Pt₂: C, 52.81

(d, J_HH= 8.8 Hz, 4H, H-p-nitroaniline), 8.19 (d, J_HH= 8.8 Hz, 4H,

H-p-nitroaniline), 8.14 (d, J_HH= 6.0 Hz, 4H, 6,6^ꢀ-H-bpy), 7.81 (d,

J_HH= 1.9 Hz, 4H, 3,3^ꢀ-H-bpy), 7.59 (dd, J_HH= 6.0, 4H, 1.9 Hz,

5,5^ꢀ-H-bpy), 3.54 (s, 2H, NH), 1.36 (s, 36H, Bu^t).

[(Bu^t₂bpy)Pt(l-NH-4-tol)]₂(BF₄)₂(13)

1

(52.35); H. 5.50 (5.12); N, 7.39 (7.05%). H NMR (300 MHz,

A solution of p-toluidine (42.8 mg, 0.400 mmol) was added to a

suspension of [(Bu^t₂bpy)₂Pt₂(l-OH)(l-NH-4-tol)](BF₄)₂(245 mg,

0.200 mmol) in CH₂Cl₂(50 mL). The solution was stirred for

20 h and then ﬁltered. The ﬁltrate was concentrate in vacuo to

ca. 15 mL. To this solution ether (30 mL) was added and the

amber product was isolated by ﬁltration. Yield: 210 mg (80%).

The product was recrystallized from CD₂Cl₂–ether. Anal. calcd

CD₂Cl₂): 9.06 (d, 4H, J_HH= 6.1 Hz, 6,6^ꢀ-H-bpy), 8.71 (d, 4H,

J_HH= 8.0 Hz, 2,2^ꢀ-H-p-tol), 7.73 (d, 4H, J_HH= 1.6 Hz, 3,3^ꢀ-H-

bpy), 7.61 (dd, 4H, J_HH= 6.0 AND Hz, 1.9-H-bpy), 7.07 (d, 4H,

J_HH= 7.9 Hz, 3,3^ꢀ-H-p-tol), 2.17 (s, 6H, Me-p-tol), 1.35 (s, 36H,

Bu^t).

(Bu^t₂bpy)Pd(OTf)₂(16). M = Pd

(found) for C₅₀H₆₄N₆B₂F₈Pt₂: C, 45.73 (45.14); H. 4.87 (4.99); N,

1

A solution of Pd(Bu^t₂bpy)Cl₂(44.5 mg, 0.100 mmol) in CH₂Cl₂

(3 mL) was stirred with solid AgSO₃CF₃(51.4 mg, 0.200 mmol)

for 1 h in the absence of light. The reaction mixture changed

from yellow to golden-yellow within 15 min with a pale purple

precipitate of AgCl. The yellow solution was collected by ﬁltration

and then dried in vacuo. The solid was recrystallized from CH₂Cl₂–

ether. Yield: 61.2 mg (91%). Crystals for X-ray analysis were

obtained by recrystallization from CD₂Cl₂–ether. Anal. calcd

(found) for C₂₀H₂₄N₂PdS₂O₆F₈: C, 35.71 (35.62); H. 3.57 (3.61);

6.40 (6.27%). H NMR (300 MHz, CD₂Cl₂): 8.47 (d, 4H, J_HH

=

6.1 Hz, 6,6^ꢀ-H-bpy), 8.31 (d, 4H, J_HH= 8.2 Hz, 2,2^ꢀ-H-p-tol), 7.81

(d, 4H, J_HH= 1.9 Hz, 3,3^ꢀ-H-bpy), 7.61 (dd, 4H, J_HH= 6.2 and

2.0 Hz, 5,5^ꢀ-H-bpy), 7.16 (d, 4H, J_HH= 8.1 Hz, 3,3^ꢀ-H-p-tol), 4.97

(s, 2H, NH), 2.25 (s, 6H, Me-p-tol), 1.40 (s, 36H, Bu^t).

[(Bu^t₂bpy)₂Pt₂(l-NH-4-tol)(l-O)]BF₄(14)

Method A. A solution of [(Bu^t₂bpy)₂Pt₂(l-OH)(l-NH-4-

tol)](BF₄)₂(122 mg, 0.100 mmol) in THF (50 mL) was vigorously

stirred with solid NaH (4.80 mg, 0.200 mmol). The solution

became orange within 30 min. Stirring was continued for 3 h and

then the mixture was ﬁltered. The ﬁltrate was reduced in vacuo

to ca. 15 mL. To this solution ether (30 mL) was added and the

resulting orange solid product was isolated by ﬁltration. Yield:

98.0 mg (87%).

N, 4.16 (3.97%). ¹H NMR (250 MHz, CD₂Cl₂): 8.69 (d, 2H, J_HH

=

6.3 Hz, 6,6^ꢀ-H-bpy), 7.83 (d, 2H, J_HH= 2.0 Hz, 3,3^ꢀ-H-bpy), 7.64

(dd, 2H, J_HH= 6.3 Hz, J_HH= 2.1 Hz, 5,5^ꢀ-H-bpy), 1.44 (s, 18H,

Bu^t).

M = Pt

This known complex⁵⁵was prepared similarly to the Pd ana-

log using Pt(Bu^t₂bpy)Cl₂(53.4 mg, 0.100 mmol) in place of

Pd(Bu^t₂bpy)Cl₂. Yield: 55.0 mg (90%). Anal. calcd (found) for

C₂₀H₂₄N₂PtS₂O₆F₈: C, 31.53 (31.43); H. 3.15 (3.29); N, 3.67

(3.46%). ¹H NMR (300 MHz, CD₂Cl₂): 8.64 (d, 2H, J_HH= 6.3 Hz,

Method B. A THF solution (5 mL) of p-toluidine (94.1 mg,

0.880 mmol) was added to a suspension of [(Bu^t₂bpy)Pt(l-

OH)]₂(BF₄)₂(249 mg, 0.220 mmol) in THF (50 mL). The reaction

mixture was brought to reﬂux with stirring. Over 6 h the solution

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6,6^ꢀ-H-bpy), 7.90 (d, 2H, J_HH= 1.9 Hz, 3,3^ꢀ-H-bpy), 7.69 (dd, 2H,

J_HH= 6.3 Hz, J_HH= 2.1 Hz, 5,5^ꢀ-H-bpy), 1.45 (s, 18H, Bu^t). ¹⁹⁵Pt

NMR (64 MHz, CD₂Cl₂): −3084.4 (s).

22 K. Noro, Y. Ozawa, M. Taguchia and A. Yagasaki, Chem. Commun.,

2002, 1770.

23 E. Szuromi, S. Hui and P. R. Sharp, J. Am. Chem. Soc., 2003, 124,

10522.

24 E. Szuromi, J. Wu and P. R. Sharp, J. Am. Chem. Soc., 2006, 128, 12088.

25 M. A. Cinellu, G. Minghetti, F. Cocco, S. Stoccoro, A. Zucca and M.

Manassero, Angew. Chem., Int. Ed., 2005, 44, 6892.

26 M. A. Cinellu, G. Minghetti, F. Cocco, S. Stoccoro, A. Zucca, M.

Manassero and M. Arca, Dalton Trans., 2006, 5703.

27 J. A. Keith, R. J. Nielsen, J. Oxgaard and W. A. Goddard, J. Am. Chem.

Soc., 2007, 129, 12342.

28 S. Kannan, A. J. James and P. R. Sharp, Polyhedron, 2000, 19, 155.

29 J. J. Li, W. Li and P. R. Sharp, Inorg. Chem., 1996, 35, 604.

30 A. Singh and P. R. Sharp, Dalton Trans., 2005, 2080–2081.

31 T. M. Anderson, R. Cao, E. Slonkina, B. Hedman, K. O. Hodgson,

K. I. Hardcastle, W. A. Neiwert, S. Wu, M. L. Kirk, S. Knottenbelt,

E. C. Depperman, B. Keita, L. Nadjo, D. G. Musaev, K. Morokuma

and C. L. Hill, J. Am. Chem. Soc., 2005, 127, 11948.

32 T. Hosokawa, M. Takano and S. I. Murahashi, J. Am. Chem. Soc.,

1996, 118, 3990.

[(Bu^t₂bpy)Pt(OH₂)₂](OTf)₂(17)

A solution of [(Bu^t₂bpy)Pt(OTf)₂] (20.0 mg, 0.025 mmol) in

CH₂Cl₂(6 mL) was stirred with 2 equiv of water. The reaction

was further stirred for 2 h and then concentrated in vacuo to

ca. 3 mL. Ether (6 mL) was added and the mixture was cooled

at −30 ^◦C for 24 h. The resulting ﬁne microcrystalline yellow

solid was isolated by ﬁltration. Yield: 19.7 mg (94%). Crystals for

◦

the X-ray analysis were obtained from CD₂Cl₂–ether at −30 C

(ether solvate) or by slow evaporation (in the drybox) of a CH₂Cl₂

solution (unsolvated). Anal. calcd (found) for C₂₀H₂₈N₂PtS₂O₈F₈:

C, 28.75 (28.19); H. 3.38 (3.21); N, 3.35 (3.10%). ¹H NMR

(250 MHz, CD₂Cl₂): 8.56 (d, 2H, J_HH= 6.2 Hz, 6,6^ꢀ-H-bpy), 8.27

(s, 4H, H₂O), 7.95 (d, 2H, J_HH= 1.9 Hz, 3,3^ꢀ-H-bpy), 7.72 (dd,

2H, J_HH= 6.3 Hz, J_HH= 2.1 Hz, 5,5^ꢀ-H-bpy), 1.47 (s, 18H, Bu^t).

33 Y. Zhang, R. J. Puddephatt, L. Manojlovic-Muir and K. W. Muir,

Chem. Commun., 1996, 2599.

34 N. W. Aboelella, J. T. York, A. M. Reynolds, K. Fujita, C. R. Kinsinger,

C. J. Cramer, C. G. Riordan and W. B. Tolman, Chem. Commun., 2004,

1716.

35 U. Anandhi and P. R. Sharp, Inorg. Chem., 2004, 43, 6780.

36 I. Kaljurand, A. Kutt, L. Soovali, T. Rodima, V. Maemets, I. Leito and

I. A. Koppel, J. Org. Chem., 2005, 70, 1019.

Acknowledgements

37 A. L. Llamas-Saiz, C. Foces-Foces and J. Elguero, J. Mol. Struct., 1994,

328, 297.

38 S. Wimmer, P. Castan, F. L. Wimmer and N. P. Johnson, J. Chem. Soc.,

Dalton Trans., 1989, 403.

Support from the Chemical Sciences, Geosciences and Biosciences

Division, Ofﬁce of Basic Energy Sciences, Ofﬁce of Science,

U. S. Department of Energy (DE-FG02-88ER13880) is gratefully

acknowledged. A grant from the National Science Foundation

(9221835) provided a portion of the funds for the purchase of

the NMR equipment. We thank Chad Magee for initial synthetic

work on 1 and Dr Charles Barns for X-ray data collection and

processing.

39 O. Crespo, A. Laguna, E. J. Fernandez, J. M. Lopez-de-Luzuriaga, P. G.

Jones, M. Teichert, M. Monge, P. Pyykko, N. Runeberg, M. Schutz and

H. J. Werner, Inorg. Chem., 2000, 39, 4786.

40 P. Pyykko¨, Chem. Rev., 1997, 97, 597.

41 D. S. Gill and B. Rosenberg, J. Am. Chem. Soc., 1982, 104, 4598.

42 R. Faggiani, B. Lippert, C. J. L. Lock and B. Rosenberg, Inorg. Chem.,

1978, 17, 1941.

43 R. Faggiani, B. Lippert, C. J. L. Lock and B. Rosenberg, Inorg. Chem.,

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