Iridium PCsp3P-type Complexes with a Hemilabile Anisole Tether

Article abstract of DOI:10.1021/acs.organomet.5b00165

A series of iridium PC_sp3P complexes based on bis(2-diisopropylphosphinophenyl)-2-anisoylmethane (PC^anisHP) is reported. (PC^anisP)Ir(H)Cl was generated from the C-H activation of the backbone by [Ir(COD)Cl]₂ (COD = 1,5-cyclooctadiene), while the dihydride (PC^anisP)Ir(H)₂ was generated by hydride metathesis from (PC^anisP)Ir(H)Cl. Both complexes are 18e octahedral complexes and water stable. The hemilability of the anisole tether was probed using CO and PMe₃; multiple isomers, in which the anisole substituent was displaced, were generated, showing the flexibility of the ligand backbone. (PC^anisP)Ir(H)₂ showed deuterium incorporation in the hydride, backbone, and anisole positions upon moderate heating in C₆D₆. Both (PC^anisP)Ir(H)Cl and (PC^anisP)Ir(H)₂ were precatalysts for transfer dehydrogenation of cyclooctane under moderate conditions.

Full text of DOI:10.1021/acs.organomet.5b00165

Article
pubs.acs.org/Organometallics
Iridium PC P‑type Complexes with a Hemilabile Anisole Tether
sp3
Dominic C. Babbini and Vlad M. Iluc*
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States
*
S Supporting Information
ABSTRACT: A series of iridium PC P complexes based on
sp3
bis(2-diisopropylphosphinophenyl)-2-anisoylmethane
anis
anis
(
PC HP) is reported. (PC P)Ir(H)Cl was generated from
the C−H activation of the backbone by [Ir(COD)Cl] (COD
2
anis
=
1,5-cyclooctadiene), while the dihydride (PC P)Ir(H) was
2
anis
generated by hydride metathesis from (PC P)Ir(H)Cl. Both
complexes are 18e octahedral complexes and water stable. The
hemilability of the anisole tether was probed using CO and
PMe ; multiple isomers, in which the anisole substituent was
3
displaced, were generated, showing the flexibility of the ligand
anis
backbone. (PC P)Ir(H) showed deuterium incorporation in the hydride, backbone, and anisole positions upon moderate
2
anis
anis
heating in C D . Both (PC P)Ir(H)Cl and (PC P)Ir(H) were precatalysts for transfer dehydrogenation of cyclooctane
6
6
2
under moderate conditions.
INTRODUCTION
Metal−ligand cooperation has been of much interest recently,
as it allows the observation of unique reactivity in several
was reduced using hydroiodic acid (Scheme 1) to give bis(2-
bromophenyl)-2-anisoylmethane (2). Compound 2, in turn,
■
Scheme 1. Synthesis of PCanisHP (3)
1
−16
organometallic systems.
For example, a new class of
ruthenium PNP-type pincer catalysts, which exhibit metal−
ligand cooperation, is capable of splitting water into O and
2
1
7
H . The metal−ligand cooperation in these compounds
enhances their reactivity toward bond activation and increases
the diversity of possible transformations.
Iridium complexes are active in a multitude of trans-
formations such as hydrogenation and dehydrogenation,
2
1
1
8
19
2
0
21−23
CO and CO insertion, borylation,
and olefin isomer-
2
2
4
ization. Complexes supported by PCP-type pincers possess
both inherent stability and good catalytic activity due to the
strong planar chelation and the ability to vary the electronic
25
properties of the ligand.
Unlike their PC P counterparts, examples of PC P-type
sp2
sp3
26−42
pincers are less common.
Even though the stability of the
resulting complexes is often attributed to the rigidity of the
backbone, the ability of such frameworks to adopt different
conformations may increase the versatility of specific catalytic
systems. In addition, iridium complexes supported by a flexible
i
reacted with n-BuLi, followed by the addition of Pr PCl to
2
PC P ligand, which incorporates a tethered anisole and is
afford the substituted bis(2-diisopropylphosphinophenyl)-2-
anisoylmethane (PC HP, 3) in good yield (Scheme 1).
sp3
anis
capable of hemilability, may provide enhancements to catalytic
behavior and bond activation via metal−ligand cooperation.
Compound 3 exhibits a phosphine-coupled triplet at 7.81 ppm
4
1
Herein, we describe a synthetic procedure for a PC P scaffold
( J = 6.6 Hz) in its H NMR spectrum corresponding to the
sp3
HP
that exhibits a weak internal ligand interaction with iridium and
its influence on the reactivity of the respective metal complexes.
triaryl methine position and broad peaks from 2.05 to 0.93 ppm
corresponding to the phosphine isopropyl groups. A broad
31
singlet at −6.32 ppm in the P spectrum was assigned to the
RESULTS AND DISCUSSION
Synthesis and Characterization of Iridium Complexes.
two phosphine environments. The broad peaks for the
■
1
31
isopropyl groups observed in the H and P NMR spectra
The novel PC P scaffold was synthesized starting with the
sp3
reaction of 2,2′-dibromobenzophenone with anisoyllithium to
Received: February 27, 2015
form bis(2-bromophenyl)-2-anisoylmethanol (1). This carbinol
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.5b00165
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Article
likely represent an averaged signal that characterizes an
inversion of the helicity of the triarylmethane moiety. Single
crystals were grown from a saturated n-pentane solution
geometric parameters (Figure 2). Both molecules exhibit a
square-planar geometry around the iridium center with the
(Figure 1). Compound 3 has a propeller-type structure with
Figure 2. Thermal ellipsoid (50% probability level) representation of
one of the two independent molecules in the unit cell of 4. Most
hydrogen atoms are omitted for clarity. Selected distances (Å) and
angles (deg): Ir(1)−P(11) 2.346(2), Ir(1)−Cl(1) 2.348(3), Ir(1)−
C(11) 2.133(10), Ir(1)−C(12) 2.088(10), Ir(1)−C(15) 2.147(9),
Ir(1)−C(16) 2.173(9); P(11)−Ir(1)−Cl(1) 91.28(9).
Figure 1. Thermal ellipsoid (50% probability level) representation of
. Most hydrogen atoms are omitted for clarity. Selected distances (Å)
and angles (deg): P(1)−C(12) 1.8517(15), C(22)−P(2) 1.811(3);
C(31)−C−C(21) 110.31(12), C(31)−C−C(11) 111.96(11), C(21)−
C−C(11) 112.16(11).
3
chloride ligand cis to one phosphine arm, P(21)−Ir(2)−Cl(2)
typical C −P distances (1.8517(15) and 1.811(3) Å) in
Ar
=
90.00(8)° and P(11)−Ir(1)−Cl(1) = 91.28(9)°, and typical
comparison to a similar PC P scaffold (C −P 1.838 and
sp3
Ar
2
metal−ligand distances, Ir(1)−P(11) = 2.346(2) Å, Ir(2)−
P(21) = 2.341(2) Å, Ir(1)−Cl(1) = 2.348(3) Å, and Ir(2)−
Cl(2) = 2.358(2) Å.
It was reasoned that a hydride complex would allow an easier
activation of the backbone than would the corresponding
chloride. The synthesis of a corresponding hydride was
accomplished by the metathesis reaction of 4 with 1 equiv of
1
.843 Å) and a tetrahedral geometry around the triaryl
methine carbon, with C−C−C angles between 110.31(12) and
12.16(11)°. Two unique phosphine environments are
observed in the solid state and represent the two averaged
1
3
1
phosphine environments observed in the P NMR spectrum.
The reaction of 3 with 1/2 equiv of [Ir(COD)Cl] (COD =
2
1
,5-cyclooctadiene) at 25 °C for 2 h led to the monocoordi-
1 anis 1
LiEt BH in Et O at −35 °C for 30 min (Scheme 2). In the
nated species (κ -PC HP)Ir(COD)Cl (4; Scheme 2). The H
3
2
2
anis
resulting complex, (κ -PC HP)Ir(COD)H (5), iridium
coordinates to the supporting ligand in a κ fashion through
2
Scheme 2. Synthesis of 4−6
both phosphorus atoms with a trigonal-bipyramidal geometry at
iridium. This structure is characterized in solution by
3
1
asymmetric phosphine environments that exhibit two
P
NMR resonances, one as a broad singlet at 4.87 ppm and the
2
other as a doublet at 2.66 ppm ( J = 17.0 Hz). A lack of
PP
resolution of the P−P coupling in the singlet resonance could
be attributed to the exchange of two unique phosphine
environments on one of the phosphine substituents. An upfield
resonance, representing the hydride environment, was observed
1
in the H NMR spectrum as a doublet of doublets at −14.23
2
ppm ( J = 26.3, 22.6 Hz), and a downfield resonance
HP
representing the backbone methine was observed as a doublet
4
of doublets at 7.68 ppm ( J
= 5.8, 2.7 Hz). X-ray
HP
crystallography supported the solution structure assignments
with a P(1)−Ir−P(2) angle of 100.971(16)° and Ir−P(1) and
Ir−P(2) distances of 2.3732(5) and 2.3543(5) Å, respectively
(
Figure 3). The hydride ligand was found in the electron
NMR spectrum of 4 exhibits a doublet of doublets at 8.06 ppm
density map and occupies an axial position relative to the
trigonal plane.
4
(
JHP = 13.2 and 7.7 Hz) corresponding to the methine position
of the backbone coupling to two inequivalent phosphine
environments. This assignment is supported by the presence of
two singlets in the P NMR spectrum at 49.87 and −12.40
ppm corresponding to the bound and free phosphine donors.
X-ray diffraction studies show that 4 crystallizes with two
independent molecules in the unit cell that have similar
Unfortunately, heating of 5 in C D at 80 °C in order to
6
6
promote backbone activation led to decomposition over several
days. However, heating 4 at 80 °C for 6 days led to the
oxidative addition of the methine C−H bond to form
3
1
anis
(PC P)Ir(H)Cl (6; Scheme 2) quantitatively. Complex 6
can also be formed by the direct reaction of 3 with
B
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Article
the electron difference map at 1.42(4) Å from iridium, is found
trans to the anisole substituent, consistent with the fact that the
−
−
two strong σ donors (R C and H ) occupy positions trans
3
−
with respect to the weaker σ donors (Oether and Cl ). Even
though the hydride was found in the electron density map, the
Ir−H distance is shorter than expected at 1.42(4) Å. This is
likely due to the large librational motion of the hydride ligand
and may not be representative of the true Ir−H distance. It is of
note that the methine carbon is nearly tetrahedral, with angles
ranging from 108.3(3) to 112.3(3)°, whereas previously
characterized triarylmethane PC P-type complexes exhibited
sp3
highly distorted tetrahedral geometries with angles as high as
45
1
29°.
The formation of the dihydride complex (PCanisP)Ir(H) (7)
2
was accomplished via a salt metathesis reaction using NaAlH
4
−
(
eq 1). Since any persistent Cl would allow the slow reversion
Figure 3. Thermal ellipsoid (50% probability level) representation of
5. Most hydrogen atoms are omitted, and isopropyl substituents are
shown in wireframe for clarity. Selected distances (Å) and angles
(
deg): Ir−P(1) 2.3732(5), Ir−P(2) 2.3543(5), Ir−C(61) 2.2581(18),
Ir−C(62) 2.2574(18), Ir−C(65) 2.1525(18), Ir−C(66) 2.1405(18);
P(1)−Ir−P(2) 100.971(16)°.
[
(
Ir(COD)Cl] at 80 °C for 6 days in benzene with a 90% yield
2
1
Scheme 2). The H NMR spectrum of 6 features a symmetric
2
phosphine-coupled triplet at −29.85 ppm ( J = 16.9 Hz)
corresponding to the hydride ligand. The corresponding
HP
of 7 back to 6, special care was taken to remove all NaCl
31
P
1
formed in the reaction. The H NMR spectrum exhibited two
spectrum shows a singlet at 37.77 ppm assigned to the
symmetrical phosphine donors.
Single crystals of 6 were grown from the diffusion of n-
pentane into a saturated toluene solution (Figure 4). The solid-
upfield hydride peaks as broad triplets of doublets at −11.39
2
2
2
(
J
= 13.2 Hz, J = 7.0 Hz) and −31.85 ppm ( J = 17.8
HH
HP
HH
HP
2
Hz, J
= 6.6 Hz) as a consequence of coupling to two
symmetrical phosphines and to each other. The upfield
resonance at −11.39 ppm is attributed to the hydride trans
3
to the sp backbone carbon, and the resonance at −31.9 ppm is
attributed to the hydride trans to the methoxy oxygen. The
drastic difference in chemical shift is associated with the trans
substituent: the moderately π donating ether ligand shifts the
4
4,46
trans hydride resonance upfield.
The presence of sym-
metrical phosphines is also supported by a singlet in the
corresponding 31P NMR spectrum at 58.6 ppm. Compound 7
was easily recrystallized from a saturated hexanes solution at
−
35 °C as light yellow crystals. The solid-state molecular
structure (Figure 5) exhibits a distorted-octahedral geometry
around iridium with the angle P(1)−Ir−P(2) = 152.55(2)°,
distances Ir−P(1) = 2.2529(7) and Ir−P(2) = 2.2748(7) Å, and
a slightly elongated distance Ir−O(3) = 2.2948(16) Å in
comparison to compound 6. Both hydride ligands were found
in the electron density map in a cis orientation relative to one
another.
Reactivity Studies. Heating 7 in C D at 80 °C for a
6
6
Figure 4. Thermal ellipsoid (50% probability level) representation of
prolonged time (up to 18 days) did not lead to the reductive
elimination of dihydrogen; however, the incorporation of
deuterium was observed in the hydride positions, the anisole
methyl positions, and backbone aromatic positions (eq 2). This
6. Most hydrogen atoms are omitted for clarity. Selected distances (Å)
and angles (deg): Ir−C 2.119(3), Ir−O 2.249(2), Ir−P(1) 2.2684(9),
Ir−P(2) 2.3032(9), Ir−Cl 2.4541(9); P(1)−Ir−P(2) 154.55(3), C−
Ir−Cl 171.46(9).
state molecular structure displays a distorted octahedral
geometry around the iridium center with a P(1)−Ir−P(2)
angle of 154.55(3)° and a C−Ir−Cl angle of 171.46(9)°. The
Ir−O distance of 2.249(2) Å indicates coordination of the
4
3,44
anisole oxygen.
The distances Ir−P(1) = 2.2684(9) Å, Ir−
P(2) = 2.3032(9) Å, and Ir−Cl = 2.4541(9) Å are in the
common range for iridium PC P pincer complexes. The
45
sp3
chloride ligand occupies the trans position with respect to the
central sp carbon, while the hydride ligand, which was found in
process was monitored by 1H NMR spectroscopy, which
indicated a broadening and gradual loss of the hydride
3
C
DOI: 10.1021/acs.organomet.5b00165
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Article
Scheme 3. Synthesis of 8−11
Figure 5. Thermal ellipsoid (50% probability level) representation of
7. Most hydrogen atoms are omitted for clarity. Selected distances (Å)
and angles (deg): Ir−P(1) 2.2529(7), Ir−P(2) 2.2748(7), Ir−C
5
8
2
.186(2), Ir−O(3) 2.2948(16); P(1)−Ir−P(2) 152.55(2), C−Ir−
mutually trans orientation. The carbonyl carbon was observed
O(3) 75.39(7).
13
in the C NMR spectrum as an unresolved doublet of doublets
apparent triplet) at 183.1 ppm ( J = 4.67 Hz) and exhibits a
CO stretching frequency at 1950.6 cm in the corresponding
IR spectrum. X-ray diffraction allowed the determination of the
solid-state molecular structure of 8 (Figure 6) and indicates a
2
(
PC
resonances corresponding to (PCanisP)Ir(H)(D) and the initial
formation of a deuterium-coupled multiplet at 3.71 ppm
−1
corresponding to partial deuteration of the anisole CH group.
3
The complete loss of hydride, anisole, and several backbone
aromatic peaks was apparent after 4 days. The formation of the
anis(D)
deuterated complex (PC
P)Ir(D) (7-d) was confirmed by
2
2
the corresponding H NMR spectrum, which showed a singlet
at 3.90 ppm for OCD and two broad singlets at −11.84 and
3
−
31.98 ppm for the two deuteride ligands. The deuterium
incorporation was found to be reversible on heating in C H for
6
6
a similar time with no decomposition. Hydrogen−deuterium
exchange between aromatic C−H bonds and deuterated
4
7−50
solvents was previously observed
for iridium dihydride
5
1
complexes, and the α-activation of alkyl ethers has been well
5
2,53
54,55
studied,
including deuterium incorporation.
At this
time, it is still unclear if this reaction takes place through an
intramolecular or intermolecular process. The intramolecular
55−57
mechanism is more likely,
due to the proximity of the
methyl group to the iridium center, and it likely involves
metal−ligand cooperation (Schemes S1 and S3 in the
Supporting Information). Due to inaccessibility, the incorpo-
ration of deuterium on the phenyl rings of the ligand must take
place through an intermolecular mechanism (Schemes S1 and
S2 in the Supporting Information).
In order to probe the hemilability of the anisole donor, a
Figure 6. Thermal ellipsoid (50% probability level) representation of
8. Most hydrogen atoms are omitted for clarity. Selected distances (Å)
and angles (deg): Ir−P(1) 2.2689(16), Ir−P(2) 2.2796(16), Ir−C
2.244(6), Ir−C(1) 1.881(7), C(1)−O(1) 1.148(7); C(1)−Ir−C
51
slight excess of CO was added to a solution of 7 in THF and
anis
9
8.8(2), P(1)−Ir−P(2) 158.90(6).
led to the formation of a new complex, (mer-PC P)Ir(CO)H2
1
(
8, Scheme 3). The H NMR spectrum of 8 exhibits a doublet
2
of doublets of doublets at −11.18 ppm ( J = 25.5, 15.4 Hz,
distorted-octahedral geometry around iridium with the angle
P(1)−Ir−P(2) = 158.90(6)°, the angle C(1)−Ir−C = 98.8(2)°,
the distance Ir−P(1) = 2.2689(16) Å, the distance Ir−P(2) =
2.2796(16) Å, the distance Ir−C = 2.244(6) Å, and the
carbonyl distance Ir−C(1) = 1.881(7) Å. Both hydride ligands
were found in the electron density map and retain the relative
cis orientation observed for 7.
HP
2
2
J
= 4.3 Hz) and a triplet of doublets at −14.22 ppm ( J
=
HH
HP
2
1
3.3 Hz, J = 4.4 Hz). The splitting of the first hydride peak
HH
(−11.18 ppm) is attributed to coupling with two inequivalent
phosphines and the other hydride. The upfield shift at −14.22
ppm was an apparent triplet of doublets due to the nearly
identical phosphine coupling constants as well as coupling to
the other hydride. Hydride coupling suggests nonsymmetrical
phosphine environments; this interpretation is supported by
Heating 8 at 80 °C for 7 days led to its isomerization to (fac-
anis
PC P)Ir(CO)H (9; Scheme 3) as well as some significant
2
3
1
the appearance of two doublets in the corresponding P NMR
decomposition, which was attributed to the reductive
elimination of H . As a consequence, heating under an H
2
2
spectrum at 59.95 ppm ( J = 272.3 Hz) and 42.61 ppm ( J
PP
PP
2
2
=
272.4 Hz), both exhibiting a coupling suggestive of a
atmosphere allowed the full conversion of 8 to 9 without
D
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Article
decomposition. Isomerization of 8 involved the rearrangement
of the carbonyl ligand trans to the backbone sp carbon as well
DIPPX ligand adopting a fac orientation in an intermediate
structure. This intermediate was proposed and spectroscopi-
3
60
as a rearrangement of the pincer ligand from a meridional to a
cally observed in an analogous system using variable-temper-
ature NMR experiments. Isomerization has also been
attributed to reversible oxidative addition/reductive elimination
6
1
facial binding mode. Complex 9 shows two doublets of
2
doublets at −7.52 ppm ( J = 127.2, 20.2 Hz) and −10.12
HP
2
1
ppm ( J = 127.9, 18.3 Hz) in its H NMR spectrum that
of H . In the DIPPX system, the trans rearrangement of the
HP
2
represent the two asymmetric hydrides, which both couple cis
and trans to the two nonsymmetrical phosphines. No H−H
coupling between hydrides was resolved, indicating a small
coupling constant. The nonequivalence of the phosphines was
further evidenced by the observation of two doublets in the
hydrides is most favorable due to the rigidity of the backbone
and instability of the intermediate; however, in our system the
more flexible backbone allows the more geometrically
optimized fac orientation, which preserves the cis dihydride.
Preservation of the cis dihydride orientation is considered
corresponding 31P NMR spectrum at 42.62 ppm ( J = 16.2
2
important in dehydrogenation catalytic cycles. These
62
PP
2
Hz) and 28.98 ppm ( J = 17.7 Hz). The carbonyl carbon was
observed in the C NMR spectrum as an apparent triplet at
76.73 ppm ( J = 4.3 Hz) and characterized by an IR
stretching frequency of 1920.8 cm . The solid-state molecular
observations describe the ability of the ligand to dissociate
through the weakly binding anisole substituent and open a
coordination site to allow the approach of a substrate, as well as
the flexibility of the backbone, which could allow unique
orientations to be accessible without the loss of the chelate
ligand.
PP
1
3
2
1
PC
−1
structure of 9 (Figure 7) indicates a distorted-octahedral
Displacement of the anisole substituent by trimethylphos-
phine was also studied. The reaction of 7 with PMe in C D at
3
6
6
2
5 °C for 5 min (Scheme 3) leads to a 1:3 mixture of two
anis anis
isomers, (mer-PC P)Ir(H) PMe (10) and (fac-PC P)Ir-
2
3
(
H) PMe (11). Because both compounds had comparable
2 3
solubility properties and decomposed on silica gel, they could
not be separated; however, they were characterized by
multinuclear NMR spectroscopy. A manual crystal separation
allowed the structural characterization of 11 (Figure 8).
Figure 7. Thermal ellipsoid (50% probability level) representation of
9. Most hydrogen atoms are omitted for clarity. Selected distances (Å)
and angles (deg): Ir−C 2.211(3), Ir−C(4) 1.866(3), Ir−P(1)
2
1
.3321(7), Ir−P(2) 2.3174(7), C(4)−O(4) 1.151(4); P(2)−Ir−P(1)
06.73(3), C(4)−Ir−C 174.61(12), Ir−C(4)−O(4) 176.9(3).
geometry around iridium with the angle P(1)−Ir−P(2) =
06.73(3)°; both hydride ligands were found in the electron
density map and retain their relative cis orientation. The shift of
1
−1
the carbonyl stretching frequency from 1950.6 cm in 8 to
920.8 cm− suggests a stronger metal interaction in the trans
1
1
Figure 8. Thermal ellipsoid (50% probability level) representation of
to the backbone orientation due to stronger π back-donation.
This could account for the thermodynamic preference of the
fac isomer but was not observed structurally. The Ir−C(4)
distance was 1.866(3) Å, in comparison to 1.881(7) Å for 8,
and the C(4)−O(4) distance was 1.151(4) Å, in comparison to
1
1. Most hydrogen atoms are omitted for clarity. Selected distances
Å) and angles (deg): Ir−C 2.2616(15), Ir−P(1) 2.3173(6), Ir−P(2)
.2723(5), Ir−P(4) 2.3082(6); P(2)−Ir−P(1) 103.302(18), P(2)−
Ir−P(4) 148.036(16), P(4)−Ir−P(1) 107.406(16), C−Ir−P(4)
08.45(4).
(
2
1
1
.148(7) Å for 8. Analogous rearrangements have been
described with the carbonyl dihydride (DIPPX)Ir(H) (CO)
2
(
DIPPX = diisopropylphosphino-m-xylene), in which the
Complex 10 is analogous to 8 and retains the mer orientation
carbonyl ligand rearranges similarly from a cis to a trans
of the backbone as well as the cis dihydride orientation.
Characterization by H NMR spectroscopy of 10 shows two
59
1
position with respect to the backbone carbon donor. In
DIPPX)Ir(H) (CO), the two hydrides also rearrange from cis
(
hydride resonances, one at −14.12 ppm as a doublet of
2
2
to trans with respect to each other to obtain the thermodynami-
cally favored orientation, in contrast to our system, which
maintains a mutually cis dihydride orientation. That rearrange-
ment was attributed to a nondissociative trigonal twist, with the
doublets of doublets ( J = 41.9, 29.3, 14.5 Hz) and another at
HP
−16.74 ppm as a complex multiplet. Assignment of the cis
orientation of the two hydrides is justified by the large coupling
2
constant ( J = 41.9 Hz) of the first hydride resonance that is
HP
E
DOI: 10.1021/acs.organomet.5b00165
Organometallics XXXX, XXX, XXX−XXX

Organometallics
indicative of trans H−P coupling. In the P NMR spectrum of
Article
3
1
Table 1. Transfer Dehydrogenation of Cyclooctane at High
a
1
0, two downfield doublets of doublets, having both cis and
Olefin Concentration
2
trans coupling, appear at 53.58 ppm ( J = 310.6, 19.1 Hz) and
PP
2
3
2.88 ppm ( J = 310.5, 15.1 Hz) consistent with a meridional
PP
geometry of the backbone. A third upfield doublet of doublets
was also observed for PMe at −60.48 ppm as an apparent
b
3
entry
cat.
olefin
base
amt, mol %
Ar/N2
TON
2
triplet exhibiting cis coupling ( J = 16.14 Hz).
PP
t
1
2
3
4
5
6
7
8
9
6
6
6
6
7
7
7
7
7
TBE
TBE
NBE
NBE
TBE
TBE
TBE
NBE
NBE
NaO Bu
0.1
0.1
0.1
0.1
0.1
0.1
1
N2
1.5
2.0
1.1
2.3
4.5
6.1
3.8
1.4
1.4
In the other isomer (11), the backbone occupies a facial
t
NaO Bu
Ar
orientation and PMe is trans to one of the phosphine donors
3
t
NaO Bu
N2
of the pincer ligand. The hydrides also retain their cis
t
NaO Bu
Ar
orientation. This cis dihydride fac backbone orientation is
consistent with 31P NMR resonances found at 36.31 ppm, as a
N
2
Ar
2
doublet of doublets ( J = 329.1, 14.8 Hz) with both cis and
PP
2
N2
trans phosphine coupling, and at 31.62 ppm ( J = 19.0, 15.4
PP
0.1
0.1
N2
2
Hz, J = 7.3 Hz), as a doublet of doublets of doublets, which
PH
Ar
contains a selectively resolved trans hydride coupling as well as
a
2
Reaction mixtures consisted of 17.0 mmol of COA and 17.0 mmol of
b
two cis phosphine couplings. A resonance at −55.83 ppm ( J
PP
acceptor and were heated to 150 °C for 24 h. Based on total number
=
329.1, 18.6 Hz) was assigned to PMe , and it indicates both
3
of double bonds formed to catalyst.
cis and trans phosphorus coupling. Two upfield hydride
1
resonances were observed in the H NMR spectrum of 11. A
atmosphere showed a small increase in activity, likely due to
coordination of dinitrogen, which has been observed to inhibit
previous iridium catalysts. A higher conversion was observed
at higher catalyst loadings. Complex 7 is slightly better than 6,
possibly due to side reactions with NaO Bu. A reaction using
doublet of doublets of doublets of doublets was observed at
2
2
−
11.49 ppm ( J = 120.3, 25.5, 20.0 Hz, J = 4.4 Hz) and
HP HH
63
exhibited coupling with the trans and the two cis phosphines as
well as the other hydride. A second hydride resonance was also
observed as an apparent doublet of triplets of doublets at
t
2
2
KN(TMS) as a base to dehydrohalogenate complex 6 did not
−
16.41 ppm ( J = 23.0, 11.9 Hz, J = 4.7 Hz), consistent
2
HP
HH
lead to any alkene products. Higher reactivity was observed
when TBE was used instead of NBE, likely a consequence of
steric differences between the two acceptors. It is likely that the
mechanism is similar to those for previously described,
analogous examples, wherein the coordinatively unsaturated
with coupling between the three cis phosphines as well as the
cis hydride.
Complex 11 was also characterized by X-ray diffraction
(
Figure 8) and exhibits a distorted-octahedral geometry with a
fac orientation of the backbone PCP fragment (P(1)−Ir−P(2)
103.302(18)°) and PMe in a trans-like orientation to one of
62,66
iridium(I) species is the active catalyst.
The dissociation of
=
3
anis
anisole in (PC P)IrH2 (7) is necessary for the alkene
insertion to take place and might limit the reactivity of the
system. The subsequent reductive elimination can generate the
coordinatively unsaturated (PC P)Ir fragment. This active
species should perform the C−H activation of cyclooctane to
form the (PC P)Ir(H)(cyclooctyl) intermediate, which could
the backbone phosphine donors (P(2)−Ir−P(4) =
148.036(16)°). The two hydride ligands were found in the
electron density map and have a relative cis orientation to each
other.
anis
The two isomers do not interchange thermally, suggesting
that the formation of 10 is not a prerequisite for the formation
anis
then undergo β-hydride elimination to form cyclooctene and 7,
followed by the hydrogenation of norbornene to norbornane.
of 11. The isomer containing PMe in the trans orientation
3
versus the backbone carbon was not observed, even though the
trans isomer was observed in complex 9. It is likely that the
stronger π-acceptor ligand CO cannot occupy a position trans
to the other phosphine π acceptors, while the weaker π
CONCLUSIONS
■
A novel PC P scaffold for iridium complexes was developed.
sp3
Substitution reactions with strongly coordinating ligands
showed the hemilability and flexibility of the ligand, since the
anisole group can be readily displaced and the backbone can
adopt both meridional and facial geometries. Deuterium
incorporation into the ligand and hydride positions of 7
suggests a ligand activation process. Transfer dehydrogenation
of cyclooctane is achieved through a coordinatively unsaturated
species obtained by the dehydrohalogenation of 6 with a strong
acceptor PMe is capable of this type of coordination.
3
Transfer Dehydrogenation Studies. Transfer dehydro-
genation of cyclooctane has often been used as a benchmark
catalytic reaction for iridium PCP-type complexes; therefore,
we decided to investigate this transformation using the newly
synthesized iridium complexes. A coordinatively unsaturated
catalyst was generated through the dehydrohalogenation of
anis
t
(
PC P)Ir(H)Cl (6) using an excess of NaO Bu or directly
anis
base or by the dehydrogenation of 7 with an acceptor. The
from (PC P)Ir(H) (7) in the presence of an acceptor (NBE
2
anis
(
PC P)Ir complexes discussed herein represent relatively air
=
norbornene or TBE = tert-butylethylene). Reactions were
and water stable precursors for active Ir(I) complexes.
tested using a 1:1 molar ratio of cyclooctane to acceptor and
showed low activity for both compounds (Table 1). This may
be attributed to high concentrations of the olefin, as this has
been shown to limit the reactivity of the catalyst in this
EXPERIMENTAL SECTION
■
General Conditions. All air-sensitive manipulations were con-
ducted in a glovebox or using Schlenk techniques under vacuum or an
inert atmosphere of nitrogen or argon. The reagent 2,2′-
6
3
transformation. Therefore, reactions were also run at a low
concentration of olefin and the results are described in Table 2.
Although the activity increased in comparison to that of
previous reactions, our systems display fairly low activity for
67
dibromobenzophenone was prepared following previous methods.
The solvents THF, Et O, toluene, n-pentane, and hexanes were dried
2
6
8
using a solvent column purification system. The solvents C H and
6
6
this transformation in comparison to other PC P iridium
C D were dried over CaH . All other reagents were purchased
sp3
6
6
2
6
4,65
examples.
Reactions that took place under an argon
commercially and used without further purification unless otherwise
F
DOI: 10.1021/acs.organomet.5b00165
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
a
Table 2. Transfer Dehydrogenation of Cyclooctane at Low Olefin Concentration
b
c
entry
cat.
olefin
base
amt, mol %
Ar/N2
conversion,
%
TON
t
1
2
3
4
5
6
7
8
9
6
6
6
6
6
6
6
7
7
7
7
7
7
TBE
NBE
NBE
TBE
TBE
TBE
NBE
TBE
NBE
NBE
TBE
TBE
TBE
NaO Bu
0.1
1
Ar
N2
Ar
N2
Ar
Ar
Ar
Ar
N2
Ar
N2
Ar
Ar
<1/1
1/3
t
NaO Bu
4
5
4
6
7
0
t
NaO Bu
1
3/2
t
NaO Bu
1
2/2
t
NaO Bu
1
4/2
t
NaO Bu
5
31/2
0/0
KN(TMS)2
1
0.1
1
<1/1
4/2
6
7
10
11
12
13
1
4/3
1
9/2
11
11
10.8
1
9/2
5
51/3
a
Reaction mixtures consisted of 4 mL of COA and 2.0 mmol of acceptor and were heated to 150 °C for 24 h. Catalyst loading was based on the
b
1
acceptor concentration. Conversion of double bonds determined by the integration of the olefin region in H NMR spectra; percent conversion
shown for cyclooctene/1,3-cyclooctadiene. Turnover number based on the total number of double bonds formed.
c
stated. H, H, 13C, and 31P NMR spectra were collected on Varian
1
2
ArH), 7.11 (td, J = 7.6, 4JHH = 1.9 Hz, 2H, ArH), 6.91 (dd, J
3
3
=
HH
HH
4
3
4
3
00 MHz, Bruker 400 MHz, and Bruker 500 MHz NMR
8.2, J = 1.0 Hz, 1H, ArH), 6.86 (td, J = 7.5, J = 1.1 Hz, 1H,
HH HH HH
1
2
13
3
4
3
spectrometers. H, H, and C NMR spectra were referenced to
residual solvent peaks; 31P NMR spectra were referenced indirectly to
H PO by referencing PPh in C D (−5 ppm). Mass spectra were
collected using a Bruker microTOF-Q II mass spectrometer. Infrared
spectra were collected as thin films using a Jasco FT-IR spectrometer
equipped with a micro-ATR attachment. Single-crystal X-ray
diffraction was conducted on Bruker Kappa and Duo instruments
with Mo Kα X-ray sources. CHN analyses were performed on a CE-
ArH), 6.81 (dd, J = 7.6, J = 1.8 Hz, 2H, ArH), 6.65 (dd, J
=
HH
HH
HH
4
7.5, J = 1.6 Hz, 1H, ArH), 6.41 (s, 1H, Ar CH), 3.74 (s, 3H,
HH
3
13
1
−OCH ). C{ H} NMR (100.5 MHz, CDCl , 20 °C): δ 157.60 (s,
3
4
3
6
6
3
3
ArC), 142.31 (s, ArC), 133.34 (s, ArC), 130.83 (s, ArC), 130.24 (s,
ArC), 130.11 (s, ArC), 128.28 (s, ArC), 128.22 (s, ArC), 127.24 (s,
ArC), 126.17 (s, ArC), 120.49 (s, ArC), 111.07 (s, ArC), 56.07 (s,
13
−OCH ), 50.17 (s, Ar CH). C NMR (100.5 MHz, CDCl , 20 °C): δ
3
3
3
1
50.17 (app d, J = 128.4 Hz, Ar CH). MS (QTOF) m/z 433
CH
3
+
4
40 Elemental Analyzer or by Midwest Microlab, LLC.
[C H Br O]H .
20 16 2
Synthesis of Bis(2-bromophenyl)-2-anisoylmethanol (1). To
Synthesis of Bis(2-diisopropylphosphinophenyl)-2-anisoyl-
anis
a solution of 2,2′-dibromobenzophenone (3.7 g, 11 mmol) in THF
50 mL) that was chilled to −35 °C was added 2-anisoyllithium
prepared from the reaction of n-BuLi and 2-bromoanisole in hexanes;
methane (PC HP) (3). A solution of bis(2-bromophenyl)-
(
(
1
anisoylmethane (2; 1.4 g, 3.2 mmol) in Et O (50 mL) was chilled
2
to −35 °C, and then 4.5 mL (7.2 mmol) of 1.6 M n-BuLi in hexanes
was added slowly under an inert atmosphere. The dark red solution
was warmed to ambient temperature and was stirred for 1 h; 1.1 mL
.3 g, 11 mmol). The dark red solution was stirred for 12 h and then
quenched using 2 mL of NH Cl(aq) and extracted with excess Et O.
4
2
The organic layer was separated and washed with NH Cl(aq),
(7.0 mmol) of Pi-Pr Cl was added slowly, and the resulting solution
2
4
followed by brine, and dried over Na SO . Excess solvent was then
was stirred for 12 h. The volume was reduced under reduced pressure;
2
4
removed via rotary evaporation. The crude material was purified via
flash column chromatography (silica gel, 95/5 hexanes/EtOAc),
extraction with n-pentane, filtration, and crystallization at −35 °C
1
yielded light yellow crystals (yield: 1.1 g, 67%). H NMR (300 MHz,
1
4
3
producing a light orange oil (yield: 3.3 g, 67%). H NMR (400 MHz,
C
6
D
6
, 20 °C): δ 7.81 (t, JHP = 6.6 Hz, 1H, Ar
3
CH), 7.43 (d, JHH
=
=
3
3
3
CDCl , 20 °C): δ 7.66−7.59 (m, 1H, ArH), 7.43 (d, J = 7.8 Hz,
7.3 Hz, 2H, ArH), 7.06 (m, 7H, ArH), 6.90 (dd, JHH = 7.6 Hz, JHP
1.8 Hz, 1H, ArH), 6.76 (td, JHH = 7.4 Hz, JHP = 0.8 Hz, 1H, ArH),
3
HH
3
4
1
7
H, ArH), 7.40−7.35 (m, 1H, ArH), 7.29−7.23 (m, 1H, ArH), 7.20−
3
4
.10 (m, 3H, ArH), 7.05−6.99 (m, 2H, ArH), 6.94−6.87 (m, 1H,
6.58 (dd, JHH = 8.2, JHP = 0.9 Hz, 1H, ArH), 3.28 (s, 3H, −OCH
2.05 (br., 2H, CH(CH ), 1.37 (br., 2H, CH(CH ), 1.09 (br., 12H,
CH(CH ), 0.93 (br., 12H, CH(CH ). C{ H} NMR (100.5 MHz,
C D , 20 °C): δ 157.47 (s, ArC), 151.91 (br., ArC), 137.81 (br., ArC),
6 6
3
),
3
4
ArH), 6.79 (dd, J = 7.8, J = 1.5 Hz, 1H, ArH), 5.53 (s, 1H,
3
)
2
)
3 2
HH
HH
13
1
13
1
Ar COH), 3.74 (s, 3H, −OCH ). C{ H} NMR (101 MHz, CDCl ,
0 °C): δ 157.65 (s, ArC), 143.18 (s, ArC), 142.59 (s, ArC), 135.75 (s,
3
)
2
)
3 2
3
3
3
2
ArC), 135.37 (s, ArC), 132.52 (s, ArC), 131.79 (s, ArC), 131.03 (s,
ArC), 129.65 (s, ArC), 129.15 (s, ArC), 128.41 (s, ArC), 127.95 (s,
ArC), 126.97 (s, ArC), 126.24 (s, ArC), 123.88 (s, ArC), 123.48 (s,
134.48 (s, ArC), 133.10 (s, ArC), 133.07 (s, ArC), 132.93 (s, ArC),
131.19 (br., ArC), 130.77 (br., ArC), 127.46 (s, ArC), 125.81 (s, ArC),
3
120.04 (s, ArC), 110.88 (s, ArC), 54.99 (s, −OCH
), 47.59 (t, JCP
=
3
1
1
ArC), 121.19 (s ArC), 112.27 (s ArC), 83.93 (s, Ar COH), 55.81 (s,
24.5 Hz, Ar
3
CH), 26.38 (d, JCP = 14.5 Hz, CH(CH
), 20.89 (s, CH(CH ), 20.61 (s, CH(CH
P{ H} NMR (121.3 MHz, C , 20 °C): δ −6.32 (br., P( Pr)
3
)
2
), 24.85 (d, JCP
).
). MS
3
+
−
OCH ). MS (QTOF): m/z 449 [C H Br O ]H .
= 13.7 Hz, CH(CH
3
)
2
3
)
2
)
3 2
3
20 16
2
2
31
1
i
Synthesis of Bis(2-bromophenyl)-2-anisoylmethane (2). To a
6
D
6
2
anis
+
solution of bis(2-bromophenyl)anisoyl methanol (1; 4.9 g, 11 mmol)
in glacial acetic acid (40 mL) was added HI (8.5 mL). The dark purple
solution was refluxed for 3 h, after which the solution was basified with
dilute NaOH(aq) and then extracted with excess EtOAc. The organic
layer was separated, washed with saturated aqueous sodium
metabisulfite and brine, and then dried with Na SO and filtered.
(QTOF): m/z 507 [(PC HP)]H .
1
anis
Synthesis of (κ -PC HP)Ir(COD)Cl (4). To a solution of 3 (31.8
mg, 0.063 mmol) in benzene (10 mL) was added [Ir(COD)Cl] (19.2
2
mg, 0.029 mmol). The bright orange solution was stirred at 25 °C for
2 h. The volatiles were removed under reduced pressure, and the
orange-yellow solid was recrystallized in a minimal amount of n-
pentane at −35 °C, producing light yellow crystals (yield: 48 mg,
2
4
Excess solvent was removed via rotary evaporation. Crude material was
1
4
purified via flash column chromatography (silica gel, 95/5 hexanes/
92%). H NMR (300 MHz, C D , 20 °C): δ 8.06 (dd, J = 13.2, 7.7
6 6 HP
3
1
EtOAc), producing a white powder (yield: 2.9 g, 61%). H NMR (300
Hz, 1H, Ar CH), 7.40 (d, J = 6.6 Hz, 1H, ArH), 7.13−6.86 (m, 9H,
ArH), 6.73 (t, J = 7.4 Hz, 1H, ArH), 6.49 (d, J = 8.0 Hz, 1H,
3
HH
3
4
3
3
MHz, CDCl , 20 °C): δ 7.59 (dd, J = 7.8, J = 1.4 Hz, 2H, ArH),
3
HH
HH
HH HH
3
4
7
.32−7.24 (m, 1H, ArH), 7.19 (td, JHH = 7.4, J = 1.5 Hz, 2H,
ArH), 5.40 (m, 2H, olefin), 4.46 (br., 1H, olefin), 3.49 (br., 1H, olefin),
HH
G
DOI: 10.1021/acs.organomet.5b00165
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
3
.22 (m, 1H, P−CH(CH ) ), 3.14 (s, 3H, −OCH ), 3.06 (m, 1H,
heated to 80 °C in an evacuated vessel for 6 days. The volatiles were
removed under reduced pressure, and the orange-yellow powder was
triturated with hexanes, filtered, and dried under reduced pressure
(yield: 819 mg, 90%). Analytically pure material was isolated by
crystallization from a concentrated dichloromethane solution layered
with n-pentane at −35 °C. Compound 6 could also be formed in
3
2
3
COD−CH ), 2.55 (m, 1H, P−CH(CH ) ), 2.42 (m, 3H, COD−
2
3 2
CH ), 2.19 (m, 1H, P−CH(CH ) ), 1.88 (m, 4H, COD−CH ), 1.57
2
3
2
2
(
J
m, 6H, P−CH(CH ) ), 1.33 (m, 6H, P−CH(CH ) ), 1.04 (app dd,
3
2
3 2
3
3
3
= 11.8 Hz, J = 6.9 Hz, 3H, P−CH(CH ) ), 0.92 (app dd, J
HP
HH
3
2
HP
3
3
=
1
14.0 Hz, J = 7.2 Hz, 3H, P−CH(CH ) ), 0.33 (app dd, J
=
HH
3
2
HP
3
1
2.1 Hz, J = 6.9 Hz, 3H, P−CH(CH ) ), 0.23 (br s, 3H, P−
similar yields by the heating of 4 in benzene for 6 days at 80 °C. H
HH
3 2
1
3
1
3
4
CH(CH ) ). C{ H} NMR (101 MHz, C D , 20 °C): δ 156.30 (s,
ArC), 151.85 (d, J = 28.1 Hz, ArC), 147.34 (s, ArC), 138.42 (d, J
=
NMR (300 MHz, C D , 20 °C): δ 7.49 (dd, J = 7.8 Hz, J = 1.2
6 6 HH HP
3
3
2
6
6
3
3
Hz, 2H, ArH), 7.10 (m, 2H, ArH), 6.90 (m, 5H, ArH), 6.66 (dd, J
HH
CP
CP
=
4
4
3
3
3
20.8 Hz, ArC), 138.18 (d, J = 19.64 Hz, ArC), 135.01 (d, J
= 7.4 Hz, J = 1.7 Hz, 1H, ArH), 6.63 (dd, J = 8.1 Hz, J = 1.8
CP
CP
HP HH HP
3
4
3
1
1
1
.9 Hz, ArC), 133.29 (s, ArC), 133.11 (s, ArC), 130.37 (s, ArC),
Hz, 1H, ArH), 6.55 (td, J = 7.4 Hz, J = 1.2 Hz, 1H, ArH), 6.22
HH HP
3
4
30.30 (s, ArC), 128.91 (s, ArC), 128.87 (s, ArC), 128.41 (s, ArC),
(dd, J = 8.2 Hz, J = 1.2 Hz, 1H, ArH), 3.97 (s, 3H, −OCH ),
HH
HP
3
4
27.94 (s, ArC), 127.46 (s, ArC), 126.57 (s, ArC), 123.56 (d, J
=
CP
2.52 (m, 2H, P−CH(CH ) ), 1.98 (m, 2H, P−CH(CH ) ), 1.61 (app
CP
3
2
3 2
2
3 3
HP
3.2 Hz, ArC), 120.18 (s, ArC), 110.47 (s, Ar CH), 89.12 (app t, J
dd, J = 14.8 Hz, J = 7.4 Hz, 6H, P−CH(CH ) ), 1.21 (app dd,
3
HH
3 2
3
3
3
=
13.1 Hz, olefin), 55.94 (s, P−CH(CH ) ), 54.56 (s, −OCH ), 53.81
JHP = 13.6 Hz, J = 6.8 Hz, 6H, P−CH(CH ) ), 1.08 (app dd, J
3
2
3
HH
3
2
HP
2
2
3
3
(
d, J = 16.0 Hz, olefin), 47.00 (d, J = 20.2 Hz, olefin), 35.49 (s,
= 14.6 Hz, J = 7.3 Hz, 6H, P−CH(CH ) ), 0.85 (app dd, J
=
CP
CP
HH
3
2
HP
3
2
P−CH(CH ) ), 31.71 (s, P−CH(CH ) ), 31.02 (s, P−CH(CH ) ),
14.7 Hz, J = 7.4 Hz, 6H, P−CH(CH ) ), −29.85 (t, J = 16.9 Hz,
3
2
3
2
3
2
HH
3
2
HP
2
13 1
2
8.08 (s, COD−CH ), 27.84 (d, J = 13.4 Hz, P−CH(CH ) ), 27.13
2
CP
3
2
1H, Ir-H). C{ H} NMR (100.5 MHz, C D , 20 °C): δ 164.18 (t,
6 6
2 1
2
2
(
d, J = 13.1 Hz, P−CH(CH ) ), 26.47 (d, J = 24.7 Hz, COD−
CP
3
2
CP
JCP = 14.0 Hz), 160.67 (s, ArC), 146.06 (s, ArC), 140.02 (t, J
=
CP
2
CH ), 25.87 (d, J = 27.1 Hz, COD−CH ), 22.08 (s, COD−CH ),
2
CP
2
2
22.0 Hz, ArC), 130.71 (s, ArC), 129.52 (s, ArC), 127.50 (s, ArC),
2
2
2
1.66 (d, J = 20.1 Hz, P−CH(CH ) ), 20.72 (d, J = 12.7 Hz, P−
3
CP
3
2
CP
127.41 (s, ArC), 127.32 (s, ArC), 125.75 (s, ArC), 125.00 (t, J = 3.2
CP
2
2
CH(CH ) ), 20.55 (d, J = 20.4 Hz, P−CH(CH ) ), 20.26 (d, J
1
CH(CH ) ). P{ H} NMR (121.3 MHz, C D , 20 °C): δ 49.87 (s,
Pbound), −12.40 (s, P
C, 53.10; H, 6.30. Found: C, 52.88; H, 6.29.
=
3
2
CP
3
2
CP
Hz, ArC), 121.52 (s, ArC), 110.09 (s, Ar C-Ir), 56.33 (s, −OCH ),
3
3
1.0 Hz, P−CH(CH ) ), 19.30 (s, P−CH(CH ) ), 18.65 (s, P−
1
1
3
2
3
2
27.04 (app t, J = 20.5 Hz, P−CH(CH ) ), 26.83 (app t, J = 11.0
CP
3
2
CP
31
1
2
3
2
6
6
Hz, P−CH(CH ) ), 19.73 (app t, J = 2.0 Hz, P−CH(CH ) ), 19.56
3
2
CP
3 2
). Anal. Calcd for C H ClIrOP ·CH Cl :
2
unbound
40 56
2
2
2
(s, P−CH(CH ) ), 19.02 (app t, J = 1.8 Hz, P−CH(CH ) ), 18.17
3
2
CP
3 2
31
1
(
(
s, P−CH(CH ) ). P{ H} NMR (121.3 MHz, C D , 20 °C): δ 37.77
2
anis
3
2
6
6
Synthesis of (κ -PC HP)Ir(COD)H (5). To a solution of 4
anis +
s, P). MS (QTOF): m/z 740 [(PC P)Ir(H)Cl]H . Anal. Calcd for
(
108.9 mg, 0.129 mmol) in Et O (50 mL) at −35 °C was added
2
C H ClIrOP ·0.5CH Cl : C, 50.52; H, 5.84. Found: C, 50.37; H,
32
44
2
2
2
LiEt BH (1.0 M in THF, 0.13 mL). The solution was warmed to
3
6
.04.
ambient temperature with stirring for 30 min, after which time it
produced a white precipitate. The solution was filtered and
concentrated. Recrystallization from n-pentane at −35 °C produced
Synthesis of (PCanisP)Ir(H) (7). To a solution of 6 (348 mg, 0.47
2
mmol) in Et O (50 mL) was added excess NaAlH (600 mg, 11
2
4
mmol) under an inert atmosphere. The solution was stirred for 30 min
1
a white powder (yield: 103 mg, 99%). H NMR (400 MHz, C D , 20
6
6
and then filtered through Celite, quenched with degassed H O, dried
4
2
°
C): δ 7.68 (dd, J = 5.8, 2.7 Hz, 1H, Ar CH), 7.42−7.36 (m, 1H,
HP
3
on Na SO , and filtered again. The solution was dried under reduced
3 4
HH
2
4
ArH), 7.26 (dt, J = 5.1 Hz, J = 3.5 Hz, 1H, ArH), 7.06−6.90 (m,
HP
pressure, triturated with n-pentane, and filtered through Celite. The
light yellow filtrate was chilled to −35 °C to produce light yellow
4
H, ArH), 6.90−6.84 (m, 3H, ArH), 6.84−6.80 (m, 1H, ArH), 6.65
3
4
3
(
td, J = 7.5 Hz, J = 1.1 Hz, 1H, ArH), 6.45 (dd, J = 8.1 Hz,
1
HH
HP
HH
crystals (yield: 178 mg, 54%). H NMR (300 MHz, C D , 20 °C): δ
4
6
6
JHP = 1.1 Hz, 1H, ArH), 4.68−4.51 (m, 1H, olefin), 4.29−4.13 (m,
3
4
7
7
6
.69 (d, J = 7.9 Hz, J = 0.8 Hz, 2H, ArH), 7.17 (m, 3H, ArH),
.07 (t, J = 7.5 Hz, 2H, ArH), 6.90 (t, J = 7.2 Hz, 2H, ArH),
HH HP
1
H, olefin), 3.79−3.70 (m, 1H, olefin), 3.70−3.59 (m, 1H, olefin),
.39−3.22 (m, 2H, COD−CH ), 3.10 (s, 3H, −OCH ), 2.87−2.74
3
3
HH
HH
2
3
.60 (m, 2H, ArH), 5.98 (m, 3H, ArH), 3.71 (s, 3H, −OCH ), 2.08
3
2
2
(
m, 2H, P−CH(CH ) ), 1.69 (m, 2H, P−CH(CH ) ), 1.28 (m, 6H,
3
2
3 2
H, P−CH(CH ) ), 2.34−2.19 (m, 2H, COD−CH ), 2.10−1.93 (m,
H, P−CH(CH ) ), 1.64−1.51 (m, 1H, COD−CH ), 1.43 (dd, J
3
3
2
2
P−CH(CH ) ), 0.92 (app q, J = 7.4 Hz, 6H, P−CH(CH ) ), 0.65
3
3
2
HH
3 2
=
3
2
3
2
2
HP
(
app q, J = 7.4 Hz, 6H, P−CH(CH ) ), −11.39 (td, J = 13.2 Hz,
3
HH
3
2
HP
3.7 Hz, J = 6.9 Hz, 3H, P−CH(CH ) ), 1.39−1.18 (m, 14H, P−
2
2 2
HH
3
2
JHH = 7.0 Hz, 1H, Ir−H), −31.85 (td, J = 17.8 Hz, J = 6.6 Hz,
3
3
HP
HH
CH(CH ) ), 0.90 (dd,
J
= 14.1 Hz,
J
HH
= 7.4 Hz, 3H, P−
13
1
3
2
HP
CH(CH ) ), 0.65 (dd, JHP = 9.9 Hz, 3JHH = 7.0 Hz, 3H, P−
3
1H, Ir−H). C{ H} NMR (126 MHz, C
3
6
D
6
, 20 °C): δ 164.50 (app t,
3
2
CH(CH ) ), 0.35 (dd, 3J = 10.4 Hz, 3JHH = 7.0 Hz, 3H, P−
J
CP = 14.0 Hz, ArC), 161.87 (s, ArC), 148.98 (s, ArC), 144.19 (app t,
3
2
HP
2
2
13
JCP = 21.8 Hz, ArC), 131.92 (s, ArC), 131.55 (s, ArC), 128.99 (app t,
CH(CH ) ), −14.23 (dd, J = 26.3, 22.6 Hz, 1H, Ir−H)2. C NMR
3
2
HP
3J = 6.4 Hz, ArC), 128.56 (s, ArC), 128.35 (s, ArC), 124.73 (s, ArC),
(
101 MHz, C D , 20 °C): δ 157.81 (s, ArC), 150.61 (d, J = 11.9
CP
6
6
CP
3
2
1
6
(
24.11 (t, J = 3.1 Hz, ArC), 121.49 (s, ArC), 109.44 (s, Ar C-Ir),
Hz, ArC), 146.75 (d, J = 12.4 Hz, ArC), 141.57 (s, ArC), 141.36 (s,
CP
3
CP
1
3
6.54 (s, −OCH ), 27.37 (app t, J = 11.0 Hz, P−CH(CH ) ), 26.26
ArC), 135.49 (d, J = 5.4 Hz, ArC), 134.19 (s, ArC), 131.36 (s, ArC),
3
CP
3 2
CP
1
3
app t, J = 17.9 Hz, P−CH(CH ) ), 21.18 (app t, J = 2.9 Hz, P−
1
1
1
31.10 (s, ArC), 130.40 (s, ArC), 130.27 (s, ArC), 128.35 (s, ArC),
28.29 (s, ArC), 127.52 (s, ArC), 124.61 (d, J = 3.7 Hz, ArC),
24.47 (d, J = 3.3 Hz, ArC), 119.82 (s, ArC), 110.43 (s, ArC), 77.32
CP
3
2
CP
3
3
CH(CH ) ), 20.65 (app t, J = 3.4 Hz, P−CH(CH ) ), 19.71 (s, P−
3
2
CP
3 2
CP
3
31
1
CH(CH
C
)
), 19.68 (s, P−CH(CH
)
2
). P{ H} NMR (121 MHz,
45IrOP : C, 54.92;
CP
3
2
3
(
s, olefin), 74.91 (s, olefin), 53.82 (s, −OCH ), 43.05 (s, P−
6
D
6
, 20 °C): δ 58.62 (s, P). Anal. Calcd for C32
H
2
3
1
1
CH(CH ) ), 42.05 (d, J = 10.4 Hz, P−CH(CH ) ), 41.88 (d, J
1
=
H, 6.48. Found: C, 54.33; H, 6.45.
3
2
CP
3
2
CP
2
anis(D)
0.3 Hz, P−CH(CH ) ), 39.95 (dd, J = 27.2, 6.4 Hz, olefin), 39.55
Synthesis of (PC
P)Ir(D)
2
(7-d). A solution of 7 (8 mg, 0.011
3
2
CP
dd, 2
J
= 29.7, 5.6 Hz, olefin), 36.48 (d, JCP = 8.2 Hz, P−
1
(
mmol) was dissolved in C D
6 6
(0.8 mL) in a J. Young NMR tube and
CP
2
CH(CH ) ), 34.17 (s, COD−CH ), 29.50 (d, J = 3.5 Hz, P−
CH(CH ) ), 26.83 (d, J = 21.5 Hz, P−CH(CH ) ), 26.37 (d, J
heated to 80 °C for 4 days. Proton reincorporation was achieved by
removing C under reduced pressure and heating the deuterated
product in C
°C): δ 7.71 (s, 2H, ArH), 7.19 (t, JHH = 3.6 Hz, 2H, ArH), 6.01 (s,
1H, ArH), 2.11 (m, 2H, P−CH(CH ), 1.72 (m, 2H, P−CH(CH ),
1.32 (app dd, JHP = 13.6 Hz, JHH = 6.9 Hz, 6H, P−CH(CH ), 1.26
3
2
2
CP
2
2
=
D
6 6
3
2
CP
3
2
CP
2
1
5
.2 Hz, P−CH(CH ) ), 26.15 (d, J = 5.0 Hz, P−CH(CH ) ), 22.24
H for 4 days at 80 °C. H NMR (400 MHz, C D , 20
6 6 6 6
3
3
2
CP
3 2
2
(
s, COD−CH ), 21.38 (s, COD−CH ), 20.01 (d, J = 4.8 Hz, P−
2
2
CP
2
2
CH(CH ) ), 19.88 (d, J = 5.0 Hz, P−CH(CH ) ), 19.27 (d, J
=
CP
3
)
2
)
3 2
3
2
CP
3
2
2
3
3
7
.0 Hz, P−CH(CH ) ), 18.63 (d, J = 6.8 Hz, P−CH(CH ) ), 12.67
)
3 2
3
2
CP
3 2
31
3
3
3
(
(
s, COD−CH ). P NMR (162 MHz, C D , 20 °C): δ 4.87 (s), 2.66
(dd, JHP = 15.7 Hz, JHH = 7.0 Hz, 6H, P−CH(CH ) ), 0.94 (dd, JHP
3 2
2
6
6
2
3
3
d, J = 17.0 Hz). Anal. Calcd for C H IrOP : C, 59.46; H, 7.11.
= 14.7 Hz, JHH = 7.3 Hz, 6H, P−CH(CH
3
)
2
), 0.67 (dd, JHP = 14.4
PP
40 57
2
3
2
Found: C, 59.81; H, 7.13.
Hz, JHH = 7.0 Hz, 6H, P−CH(CH
3
)
2
). H NMR (77 MHz, C , 20
H
6 6
Synthesis of (PCanisP)Ir(H)Cl (6). To a solution of 3 (696 mg, 1.37
°C): δ 3.90 (br s, 1H, −OCD ), −11.84 (br s, 1H, Ir−D), −31.98 (br
3
1
3
1
2
mmol) in benzene (50 mL) was added [Ir(COD)Cl] (420 mg, 0.63
mmol) under an inert atmosphere. The bright orange solution was
s, 1H, Ir−D). C{ H} NMR (101 MHz, C D ): δ 164.54 (t, J
=
2
6
6
CP
1
14.0 Hz, ArC), 161.90 (s, ArC), 148.92 (s, ArC), 144.17 (t, J = 22.0
CP
H
DOI: 10.1021/acs.organomet.5b00165
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
3
124.14 (d, 3JCP = 6.0 Hz, ArC), 118.91 (s, ArC), 111.89 (s, Ar C-Ir),
Hz, ArC), 131.75 (s, ArC), 131.45 (s, ArC), 128.90 (t, J = 6.4 Hz,
CP
3
1
1
ArC), 124.29 (dd, J = 37.9, 14.4 Hz, ArC), 124.20−123.38 (m,
54.21 (s, O−CH ), 28.55 (dd, J = 29.8, 4.8 Hz, P−CH(CH ) ),
CP
3
CP
3 2
1
1
ArC), 121.30−120.68 (m, ArC), 109.32 (s, Ar C-Ir), 66.45−64.82 (m-
28.13 (dd, J = 15.1, 1.9 Hz, P−CH(CH ) ), 27.49 (d, J = 18.6
3
CP
3
2
CP
1
1
1
OCD ), 27.35 (t, J = 11.0 Hz, P−CH(CH ) ), 26.28 (t, J = 17.9
Hz, P−CH(CH ) ), 25.61 (dd, J = 31.0, 2.5 Hz, P−CH(CH ) ),
3
CP
3
2
CP
3
2
CP
3 2
2
2
Hz, P−CH(CH ) ), 21.16 (t, J = 3.0 Hz, P−CH(CH ) ), 20.65 (t,
25.08 (d, J = 8.8 Hz, P−CH(CH ) ), 22.72 (s, P−CH(CH ) ),
3
2
CP
3
2
CP
3
2
3 2
2
2
2
2
J
= 3.5 Hz, P−CH(CH ) ), 19.74 (s, P−CH(CH ) ), 19.68 (t, J
20.39 (dd, J = 4.0, 3.2 Hz, P−CH(CH ) ), 19.79 (d, J = 1.4 Hz,
CP
3
3
2
1
3
2
CP
CP
3
2
CP
1
2
2
=
1.9 Hz, P−CH(CH ) ). P{ H} NMR (121 MHz, C D , 20 °C): δ
P−CH(CH ), 18.62 (d, JCP
= 7.1 Hz, P−CH(CH ), 18.39 (d, JCP = 5.6 Hz, P−CH(CH ),
14.27 (s, P−CH(CH ) ). P{ H} NMR (162 MHz, C D12, 20 °C): δ
3 2 6
3
)
2
), 19.37 (t, JCP = 2.6 Hz, P−CH(CH
3
)
2
3
2
6
6
2
5
8.03 (s).
3
)
2
)
3 2
Synthesis of (mer-PCanisP)Ir(CO)H (8). A solution of 7 (25.7 mg,
.037 mmol) in 5 mL of THF was placed in a septum-capped vial,
exposed to 1 atm of CO, and stirred for 10 min at ambient
temperature. The solution turned a darker yellow. The volatiles were
removed under reduced pressure producing a light yellow powder.
31
1
2
2
2
−1
0
42.62 (d, JPP = 16.2 Hz), 28.98 (d, JPP = 17.7 Hz). IR: 1920.8 cm
(νCO). Anal. Calcd for C33H45IrO P : C, 54.45; H, 6.23. Found: C,
2 2
54.53; H, 6.45.
Synthesis of (cis-mer-PCanisPIr(H)
PMe ) (10) and (cis-fac-
3
2
anis
1
PC P)Ir(H) PMe (11). To a solution of 7 (22.6 mg, 0.032 mmol) in
Yield: 26.5 mg, 99%. H NMR (300 MHz, C D , 20 °C): δ 7.33−7.25
2
3
6
6
3
3
toluene (10 mL) was added PMe (0.04 mmol in toluene). The
(
(
m, 1H, ArH), 7.20 (dd, J = 10.2 Hz, J = 6.0 Hz, 1H, ArH), 7.14
3
HH
HP
3
3
3
solution was stirred for 30 min, and then the volatiles were removed
under reduced pressure to produce a light yellow powder (mixture
dd, J = 8.1 Hz, J = 3.6 Hz, 1H, ArH), 7.07 (t, J = 7.6 Hz,
HH HP HH
3
3
1
6
7
7
H, ArH), 6.98 (dd, JHH = 4.0 Hz, J = 3.0 Hz, 2H, ArH), 6.96−
.86 (m, 2H, ArH), 6.76 (t, J = 7.0 Hz, 1H, ArH), 6.60 (t, J
.6 Hz, 1H, ArH), 6.54 (d, JHH = 8.0 Hz, 1H, ArH), 6.19 (d, J
HP
1
3
3
yield: 24.1 mg, 97%). H NMR (400 MHz, C D , 20 °C): δ 7.57 (dd,
=
=
6
6
HH
HH
3
3
3
3
JHH = 7.9 Hz, J = 2.5 Hz, ArH), 7.55−7.44 (m, ArH), 7.28 (td,
HP
HH
3JHH = 7.0 Hz, JHP = 1.6 Hz, ArH), 7.20 (td, JHH = 7.3 Hz, JHP = 1.2
3
3
3
.8 Hz, 1H, ArH), 2.99 (s, 3H, −OCH ), 2.31−2.20 (m, 2H, P−
3
3
3
CH(CH ) ), 2.14 (m, 2H, P−CH(CH ) ), 1.39−1.23 (m, 9H, P−
Hz, ArH), 7.08 (dd, J = 10.4 Hz, J = 3.9 Hz, ArH), 7.05−6.99
3 3 3
3
2
3
2
HH
HP
CH(CH ) ), 1.18−1.04 (m, 9H, P−CH(CH ) ), 0.69−0.60 (m, 3H,
(m, ArH), 6.94 (dt, J = 8.2 Hz, J = 4.2 Hz, ArH), 6.87 (tdd, J
HH HP HH
3
2
3
2
2
4
3
P−CH(CH ) ), 0.58−0.49 (m, 3H, P−CH(CH ) ), −11.18 (ddd, J
= 7.5, 5.8 Hz, J = 1.4 Hz, ArH), 6.80 (m, ArH), 6.68 (td, J = 7.8
3
2
3
2
HP
HP HH
2
2
4
3
4
=
25.5, 15.4 Hz, J = 4.3 Hz, 1H, Ir−H), −14.22 (td, J = 13.3, 4.4
Hz, J = 1.3 Hz, ArH), 6.64 (s, ArH), 6.50 (dd, J = 7.9 Hz, J
1.1 Hz, ArH), 6.39 (dd, J = 10.7 Hz, J = 4.5 Hz, ArH), 6.28 (dd,
=
HP
HH
HP
HP
HH
1
3
1
3
3
Hz, 1H, Ir−H). C{ H} NMR (101 MHz, C D , 20 °C): δ 183.14
6
6
HH HP
2
1
3
4
(
(
dd, J = 4.7 Hz, Ir−CO), 167.81 (d, J = 21.3 Hz, ArC), 164.19
JHH = 7.8 Hz, J = 1.6 Hz, ArH), 3.09 (s, O−CH (fac)), 2.72 (s,
CP
CP
HP
3
1
3
dd, J = 23.5, J = 3.9 Hz, ArC), 155.73 (s, ArC), 150.78 (s, ArC),
O−CH (mer)), 2.44 (m, P−CH(CH ) ), 2.35 (m, P−CH(CH ) ),
CP
CP
3
3
2
3 2
1
1
1
1
1
45.33 (d, J = 50.3 Hz, ArC), 142.13 (d, J = 48.9 Hz, ArC),
32.32 (d, J = 14.0 Hz, ArC), 131.19 (s, ArC), 130.84 (s, ArC),
29.33 (d, J = 2.3 Hz, ArC), 128.91 (s, ArC), 128.40 (d, J = 2.3
Hz, ArC), 126.88 (s, ArC), 124.90 (d, J = 6.6 Hz, ArC), 124.59 (d,
2.18 (m, P−CH(CH ) ), 2.10 (m, P−CH(CH ) ), 2.01 (m, P−
CP
CP
3
2
3 2
2
3
3
CP
CH(CH ) ), 1.52 (app ddd, J = 17.3, 13.3 Hz, J = 7.3 Hz, P−
3
2
HP
HH
3
3
CP
CP
CH(CH ) ), 1.33−1.26 (m, P−CH(CH ) ), 1.26−1.18 (m, P−
3
2
3 2
3
2
2
CP
CH(CH ) ), 1.15 (d, J = 1.9 Hz, P(CH ) ), 1.13 (d, J = 2.0
3 2 HP 3 3 HP
2
3
3
3
JCP = 12.5 Hz, ArC), 124.44 (s, ArC), 123.17 (d, J = 6.9 Hz, ArC),
Hz, P(CH ) ), 1.04 (app ddd, J = 13.2, 7.2 Hz, J = 3.6 Hz, P−
CP
3
3
HP
HH
3
3
1
18.61 (s, ArC), 112.00 (s, Ar C−Ir), 54.22 (s, −OCH ), 29.34 (app
CH(CH ) ), 0.86 (app ddd, J = 8.4, 6.3 Hz, J = 1.5 Hz, P−
3
3
3
2
HP
HH
1
1
3 3
dd, J = 23.6, 3.8 Hz, P−CH(CH ) ), 27.31 (app dd, J = 20.5, 3.4
CH(CH ) ), 0.71 (dd, J = 14.6 Hz, J = 6.6 Hz, P−CH(CH ) ),
CP
3
2
CP
3
2
HP
HH
3 2
1
3
3
3
Hz, P−CH(CH ) ), 25.88 (app dd,
J
= 37.0, 2.2 Hz, P−
0.53 (dd, J = 15.1 Hz, J = 6.8 Hz, P−CH(CH ) ), 0.18 (dd, J
3
2
CP
HP
HH
3
2
HP
2
3
2
CH(CH ) ), 22.23 (app d,
J
= 3.6 Hz, P−CH(CH ) ), 21.58
= 14.4 Hz, J = 7.0 Hz, P−CH(CH ) ), −11.49 (dddd, J = 120.3,
3
2
CP
3
2
HH
3
2
HP
2
2
2
2
(
app d, J = 4.7 Hz, P−CH(CH ) ), 20.91 (app dd, J = 33.9, 3.1
25.5, 20.0 Hz, J = 4.4 Hz, Ir−H(fac)), −14.12 (ddd, J = 117.6,
CP
3
2
CP
HH
HP
2
2
Hz, P−CH(CH ) ), 20.80 (app d, J = 3.9 Hz, P−CH(CH ) ),
29.2, 16.6 Hz, Ir−H(mer)), −16.41 (app dtd, J = 22.8, 12.0 Hz,
3
2
CP
3
2
HP
2
2
13
2
1
1
0.67 (s, P−CH(CH ) ), 19.81 (app d, J = 5.7 Hz, P−CH(CH ) ),
J
= 4.7 Hz, Ir−H(fac)), −16.74 (m, Ir−H(mer)). C NMR (101
3
2
CP
3
2
HH
2
2
9.30 (s, P−CH(CH ) ), 19.17 (app d, J = 1.3 Hz, P−CH(CH ) ),
MHz, C D , 20 °C): δ 170.42 (d, J = 24.0 Hz, ArC), 167.95−
3
2
CP
3
2
6
6
CP
2
31
1
3
2
7.06 (app dd, J = 5.1, 2.8 Hz, P−CH(CH ) ). P{ H} NMR (162
167.68 (m, ArC), 167.55 (d, J = 8.3 Hz, ArC), 166.92 (d, J
=
CP
3
2
CP
CP
2
2
MHz, C D , 20 °C): δ 59.95 (d, J = 272.3 Hz), 42.61 (d, J =
29.8 Hz, ArC), 154.87 (s, ArC), 154.59 (s, ArC), 154.28 (s, ArC),
6
6
PP
PP
−
1
2
2
2
5
72.4 Hz). IR: 1950.6 cm (νCO). Anal. Calcd for C H IrO P : C,
151.79 (s, ArC), 148.29 (d, J = 44.9 Hz, ArC), 147.62 (d, J
=
33
45
2
2
CP
CP
1
1
4.45; H, 6.23; Found: C, 54.52; H, 6.33.
35.5 Hz, ArC), 142.58 (d, J = 47.1 Hz, ArC), 139.32 (d, J = 48.5
CP CP
Synthesis of (fac-PCanisPIr)(H) (CO) (9). A solution of 8 (7.3 mg,
.01 mmol) in 10 mL of n-pentane was placed in a Schlenk tube,
evacuated, and then back-filled with 1 atm of H . The solution was
heated at 80 °C for 7 days then dried under reduced pressure to
produce a light yellow powder. Yield: 7.5 mg, 99%. The NMR sample
was prepared under an atmosphere of hydrogen to avoid
decomposition. H NMR (400 MHz, C D , 20 °C): δ 7.44 (dd,
3
4
2
Hz, ArC), 133.89 (d, J = 13.9 Hz, ArC), 131.97 (d, J = 7.1 Hz,
CP CP
3
4
0
ArC), 131.43 (d, J = 14.2 Hz, ArC), 130.92 (s, ArC), 129.27 (d, J
C
P
C
P
4
2
= 2.0 Hz, ArC), 129.06 (s, ArC), 128.97 (s, ArC), 128.90 (d, J = 2.2
Hz, ArC), 128.84 (s, ArC), 127.42 (d, J = 2.1 Hz, ArC), 127.04 (s,
CP
4
CP
ArC), 126.91 (s, ArC), 126.57 (s, ArC), 125.21 (s, ArC), 123.71 (d,
4
4
4
JCP = 4.6 Hz, ArC), 123.50 (d, J = 6.0 Hz, ArC), 123.04 (d, J
=
CP
CP
1
4
6
6
6.0 Hz, ArC), 122.06 (d, J = 6.1 Hz, ArC), 121.77 (s, ArC), 121.24
CP
3
3
JHH = 7.6 Hz, J = 2.8 Hz, 1H, ArH), 7.39−7.33 (m, 2H, ArH),
HP
(s, ArC), 120.33 (s, ArC), 120.02 (s, ArC), 113.99 (s, Ar C-Ir), 111.14
3
3
1
7
7
6
.09−6.99 (m, 3H, ArH), 6.97−6.85 (m, 3H, ArH), 6.70 (td, J
=
(s, Ar C-Ir), 53.89 (s, O−CH ), 53.10 (s, O−CH ), 29.67 (ddd, J
=
HH
3
3
3
CP
3
3
1
.8 Hz, J = 1.3 Hz, 1H, ArH), 6.64 (d, J = 8.0 Hz, 1H, ArH),
14.4, 7.1, 3.9 Hz, P−CH(CH ) ), 28.65 (app dt, J = 19.7, 5.3 Hz,
HP
HH
3
2
CP
3
3
1
.04 (dd, J = 7.8 Hz, J = 1.6 Hz, 1H, ArH), 3.33 (s, 3H,
P−CH(CH ) ), 28.27 (dd, J = 17.4, 1.3 Hz, P−CH(CH ) ), 27.98
HH
HP
3
2
CP
3 2
1
1
−
OCH ), 2.39−2.19 (m, 2H, P−CH(CH ) ), 2.16−2.07 (m, 1H, P−
(ddd, J = 13.7, 8.5, 1.8 Hz, P−CH(CH ) ), 26.41 (dd, J = 12.2,
3
3
2
CP
3
2
CP
2
CH(CH ) ), 2.07−1.97 (m, 1H, P−CH(CH ) ), 1.40−1.28 (m, 6H,
7.2 Hz, P−CH(CH ) ), 26.20 (app t, J = 4.0 Hz, P−CH(CH ) ),
3
2
3
2
3
2
CP
3 2
3
3
2
2
P−CH(CH ) ), 1.22 (dd, J = 17.1 Hz, J = 6.8 Hz, 3H, P−
25.88 (app t, J = 4.0 Hz, P−CH(CH ) ), 25.33 (d, J = 3.0 Hz,
3
2
HP
HH
CP
3
2
CP
3
3
CH(CH ) ), 1.11 (app td, J = 15.3 Hz, J = 6.8 Hz, 6H, P−
P−CH(CH ) ), 25.04 (s, P−CH(CH ) ), 24.95 (s, P−CH(CH ) ),
3
2
HP
HH
3
2
3
2
3 2
3
2
CH(CH ) ), 1.00−0.80 (m, 6H, P−CH(CH ) ), 0.09 (dd, J = 15.3,
24.89 (s, P−CH(CH ) ), 24.21 (s, P−CH(CH ) ), 24.05 (d, J = 4.7
3
2
3
2
HP
3
2
3
2
CP
3
2
2
J
HH
= 7.0 Hz, 3H, P−CH(CH ) ), −7.52 (dd, J = 127.2, 20.2 Hz,
Hz, P−CH(CH ) ), 23.97 (s, P−CH(CH ) ), 22.62 (d, J = 5.9 Hz,
3
2
HP
3
2
3
2
CP
2
13
1
2
2
1
H, Ir−H), −10.12 (dd, J = 127.9, 18.3 Hz, 1H, Ir−H). C{ H}
P−CH(CH ) ), 22.33 (d, J = 7.4 Hz, P−CH(CH ) ), 21.60 (d, J
HP
3
2
CP
3
2
CP
2
NMR (100.5 MHz, C D , 20 °C): δ 176.73 (t, J = 4.3 Hz, Ir−CO),
= 3.0 Hz, P−CH(CH ) ), 21.44 (s, P−CH(CH ) ), 21.09 (s, P−
6
6
CP
3
2
3 2
2
2
2
1
1
67.80 (d, J = 26.6 Hz, ArC), 166.38 (d, J = 33.1 Hz, ArC),
CH(CH ) ), 20.32 (d, J = 2.2 Hz, P−CH(CH ) ), 20.22−19.89 (m,
CP
CP
3
2
CP
3 2
3
1
2
2
55.95 (s, ArC), 152.53 (d, J = 5.4 Hz, ArC), 143.12 (d, J = 39.8
P−CH(CH ) ), 19.72 (d, J = 3.6 Hz, P−CH(CH ) ), 19.40 (d, J
CP
CP
3
2
CP
3
2
CP
1
3
31
Hz, ArC), 136.31 (d, J = 47.8 Hz, ArC), 132.64 (d, J = 15.3 Hz,
= 2.2 Hz, P−CH(CH ) ), 19.23 (s, P−CH(CH ) ). P NMR (162
CP
CP
3
2
3 2
4
2
ArC), 130.40 (s, ArC), 130.21 (d, J = 2.1 Hz, ArC), 130.13 (s, ArC),
29.99 (s, ArC), 129.46 (s, ArC), 128.58 (d, J = 2.1 Hz, ArC),
26.82 (s, ArC), 125.25 (d, JCP = 5.3 Hz, ArC), 124.31 (s, ArC),
MHz, C D ): δ 53.67 (dd, J = 310.5, 19.1 Hz, P(backbone, mer)),
6 6 PP
CP
4
2
2
1
1
36.34 (dd, J = 329.2, 14.9 Hz, P(backbone, fac)), 32.89 (dd, J
=
CP
PP
PP
3
2
310.5, 15.1 Hz, P(backbone, mer)), 31.62 (ddd, J = 19.2, 15.4, 7.2
PP
I
DOI: 10.1021/acs.organomet.5b00165
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
2
Hz, P(backbone, fac)), −55.83 (dd, J = 329.1, 18.8 Hz, PMe (fac)),
at −35 °C in the glovebox. The resulting crystals were light yellow
blocks. Crystal and refinement data for 7: C H IrOP ; M = 699.82;
PP
3
2
−60.49 (app t,
J
= 16.1 Hz, PMe (mer)). Anal. Calcd for
PP 3
C H IrOP : C, 54.18; H, 7.01. Found: C, 54.31; H, 7.12.
General Method for Transfer Dehydrogenation of Cyclo-
octane at High Olefin Concentration. A solution of 6 and NaO Bu
10 equiv) or 7 (0.1 or 1 mol % with respect to the acceptor) was
combined with norbornene or tert-butylethylene (17 mmol) in 17
mmol of cyclooctane in a Schlenk tube under nitrogen or argon. The
reaction mixture was heated in an oil bath at 150 °C for 24 h. A 0.1 mL
aliquot of the resulting solution was added to 0.6 mL of a 0.2 M
solution of trimethoxybenzene (as a standard) in CDCl , and the
percent conversion was determined by integration of the olefinic
32 45
2
r
triclinic; space group P1
̅
; a = 9.922(2) Å; b = 10.833(2) Å; c =
3
3
54
3
15.344(3) Å; α = 72.292(2)°; β = 85.131(3)°; γ = 68.382(2)°; V =
t
3
−1
1459.8(5) Å ; Z = 2; T = 120(2) K; λ = 0.71073 Å; μ = 4.706 mm ;
−3
(
dcalc = 1.592 g cm ; 15439 reflections collected; 5129 unique
reflections (Rint = 0.0135); R1 = 0.0135, wR2 = 0.0342 for 5029 data
with I > 2σ(I) and R1 = 0.0140, wR2 = 0.0343 for all 5129 data.
−3
Residual electron density (e Å ) max/min: 0.889/−0.552.
X-ray Crystal Structure of (mer-PC P)Ir(CO)H2 (8). X-ray-
anis
3
quality single crystals were obtained from a concentrated n-pentane
solution at −35 °C in the glovebox. The resulting crystals were light
yellow blocks. Crystal and refinement data for 8: C H IrO P ; M =
1
region in the H NMR spectrum.
33
45
2
2
r
General Method for Transfer Dehydrogenation of Cyclo-
727.83; monoclinic; space group P2 /c; a = 17.204(2) Å; b =
1
t
octane at Low Olefin Concentration. A solution of 6 and NaO Bu
(
12.4433(16) Å; c = 15.2830(17) Å; α = 90°; β = 107.233(3)°; γ = 90°;
3
10 equiv) or 7 (0.1, 1, or 5 mol % with respect to the acceptor) was
V = 3124.7(7) Å ; Z = 4; T = 120(2) K; λ = 0.71073 Å; μ = 4.403
−1
−3
combined with norbornene or tert-butylethylene (2 mmol) in 4 mL of
cyclooctane in a Schlenk tube under nitrogen or argon. The reaction
mixture was heated in an oil bath at 150 °C for 24 h. A 0.1 mL aliquot
of the resulting solution was added to 0.6 mL of a 0.2 M solution of
mm ; d = 1.547 g cm ; 38500 reflections collected; 5505 unique
calc
reflections (Rint = 0.1163); R1 = 0.0404, wR2 = 0.0668 for 3963 data
with I > 2σ(I) and R1 = 0.0748, wR2 = 0.0723 for all 5505 data.
−3
Residual electron density (e Å ) max/min: 0.984/−0.870.
anis
trimethoxybenzene (as a standard) in CDCl , and the percent
X-ray Crystal Structure of (fac-PC P)Ir(CO)H2 (9). X-ray-
3
conversion was determined by integration of the olefinic region in
quality single crystals were obtained from a concentrated n-pentane
solution at −35 °C in the glovebox. The resulting crystals were light
yellow blocks. Crystal and refinement data for 9: C H IrO P ; M =
1
the H NMR spectrum.
X-ray Crystal Structure of (PCanisHP) (3). X-ray-quality single
crystals were obtained from a concentrated n-pentane solution at −35
33
45
2
2
r
727.83; monoclinic; space group P2 /n; a = 10.8877(8) Å; b =
1
°
C in the glovebox. The resulting crystals were colorless blocks.
18.6255(13) Å; c = 15.2210(11) Å; α = 90°; β = 95.1787(13)°; γ =
3
Crystal and refinement data for 3: C H OP ; M = 506.61;
90°; V = 3074.0(4) Å ; Z = 4; T = 120(2) K; λ = 0.71073 Å; μ = 4.475
32
44
2
r
−1
−3
monoclinic; space group P2/c; a = 11.2267(9) Å; b = 13.8576(11)
Å; c = 20.1437(16) Å; α = 90°; β = 106.046(2)°; γ = 90°; V =
mm ; d = 1.573 g cm ; 33996 reflections collected; 5402 unique
calc
reflections (Rint = 0.0294); R1 = 0.0178, wR2 = 0.0388 for 4873 data
with I > 2σ(I) and R1 = 0.0220, wR2 = 0.0397 for all 5402 data.
3
−1
3
011.8(4) Å ; Z = 4; T = 120(2) K; λ = 0.71073 Å; μ = 0.166 mm ;
−3
−3
dcalc = 1.117 g cm ; 34582 reflections collected; 5025 unique
reflections (Rint = 0.0341); R1 = 0.0338, wR2 = 0.0817 for 4350 data
with I > 2σ(I) and R1 = 0.0419, wR2 = 0.0886 for all 5025 data.
Residual electron density (e Å ) max/min: 0.368/−0.392.
anis
X-ray Crystal Structure of (cis-fac-PC P)Ir(H) PMe (11). X-
2
3
ray-quality single crystals were obtained by manual separation of a
concentrated n-pentane solution of a mixture of 10 and 11 at −35 °C
in the glovebox. The resulting crystals were light yellow blocks. Crystal
−3
Residual electron density (e Å ) max/min: 0.303/−0.228.
1
anis
X-ray Crystal Structure of (κ -PC HP)Ir(COD)Cl (4). X-ray-
quality single crystals were obtained from a concentrated n-pentane
solution at −35 °C in the glovebox. The resulting crystals were light
yellow shards. Crystal and refinement data for 4: C H ClIrOP ; M =
and refinement data for 11: C35
space group P2 /n; a = 10.903(2) Å; b = 20.135(4) Å; c = 15.620(3)
Å; α = 90°; β = 94.941(3)°; γ = 90°; V = 3416.4(11) Å ; Z = 4; T =
H54IrOP ; M = 775.89; monoclinic;
3 r
1
3
40
56
2
r
−1
−3
8
=
=
42.44; triclinic; space group P1
̅
120(2) K; λ = 0.71073 Å; μ = 4.075 mm ; dcalc = 1.509 g cm ; 34798
reflections collected; 8477 unique reflections (Rint = 0.0167); R1 =
0.0144, wR2 = 0.0329 for 7924 data with I > 2σ(I) and R1 = 0.0165,
3
4028.8(17) Å ; Z = 4; T = 120(2) K; λ = 0.71073 Å; μ = 3.487
−1
−3
−3
mm ; d = 1.389 g cm ; 54455 reflections collected; 16593 unique
wR2 = 0.0336 for all 8477 data. Residual electron density (e Å )
calc
reflections (Rint = 0.1032); R1 = 0.0666, wR2 = 0.1556 for 10945 data
with I > 2σ(I) and R1 = 0.1080, wR2 = 0.1720 for all 16593 data.
max/min: 1.212/−1.323.
−3
Residual electron density (e Å ) max/min: 2.758/−3.709.
ASSOCIATED CONTENT
2
anis
■
X-ray Crystal Structure of (κ -PC HP)Ir(COD)H (5). X-ray-
quality single crystals were obtained from a concentrated n-pentane
solution at −35 °C in the glovebox. The resulting crystals were bright
yellow blocks. Crystal and refinement data for 5: C H IrOP ; M =
*
S
Supporting Information
Figures, tables, and CIF files giving NMR spectra for
compounds 1−11, IR spectra for 8 and 9, and crystallographic
data for compounds 3−9 and 11. The Supporting Information
is available free of charge on the ACS Publications website at
DOI: 10.1021/acs.organomet.5b00165.
43
60
2
r
8
47.05; triclinic; space group P1
c = 18.8352(15) Å; α = 93.4220(10)°; β = 91.7780(10)°; γ =
̅
; a = 10.3914(9) Å; b = 10.5136(9) Å;
3
1
14.5150(10)°; V = 1865.4(3) Å ; Z = 2; T = 120(2) K; λ = 0.71073
1
−
−3
Å; μ = 3.697 mm ; d = 1.508 g cm ; 26780 reflections collected;
calc
6
582 unique reflections (Rint = 0.0117); R1 = 0.0129, wR2 = 0.0298
for 6502 data with I > 2σ(I) and R1 = 0.0132, wR2 = 0.0303 for all
AUTHOR INFORMATION
■
−3
6
582 data. Residual electron density (e Å ) max/min: 0.676/−0.467.
anis
Corresponding Author
X-ray Crystal Structure of (PC P)Ir(H)Cl (6). X-ray-quality
*
E-mail for V.M.I.: viluc@nd.edu.
single crystals were obtained from a concentrated toluene solution
layered with n-pentane at −35 °C in the glovebox. The resulting
crystals were bright orange-yellow blocks. Crystal and refinement data
Notes
The authors declare no competing financial interest.
for 6: C H ClIrOP ; M = 734.26; triclinic; space group P1
̅
32
44
2
r
1
0.3699(9) Å; b = 10.6122(9) Å; c = 15.2348(13) Å; α =
6.7410(10)°; β = 86.0090(10)°; γ = 67.4240(10)°; V = 1506.5(2)
7
ACKNOWLEDGMENTS
■
3
−1
Å ; Z = 2; T = 120(2) K; λ = 0.71073 Å; μ = 4.650 mm ; d = 1.619
calc
We thank Dr. Allen Oliver for assistance with the
crystallography studies and the ND Energy Material Character-
ization facility for the use of the FT-IR spectrometer.
Acknowledgment is made to the donors of the American
Chemical Society Petroleum Research Fund for partial support
of this research (ACS PRF # 53536-DNI3).
−3
g cm ; 26526 reflections collected; 7526 unique reflections (R
0
.0443); R1 = 0.0292, wR2 = 0.0623 for 6723 data with I > 2σ(I) and
R1 = 0.0363, wR2 = 0.0665 for all 7526 data. Residual electron density
−
3
(
e Å ) max/min: 2.159/−1.253.
X-ray Crystal Structure of (PCanisP)Ir(H)2 (7). X-ray-quality
single crystals were obtained from a concentrated n-pentane solution
J
DOI: 10.1021/acs.organomet.5b00165
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(
38) Allen, O. R.; Field, L. D.; Magill, A. M.; Vuong, K. Q.;
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K
DOI: 10.1021/acs.organomet.5b00165
Organometallics XXXX, XXX, XXX−XXX