Complexes derived from the reactions of diphenylphosphinoacetic acid. Part 4. Mononuclear complexes of Rh(I), Ir(I) and Ir(III) and some related chemistry involving the diphenyl(2,6-dimethylphenyl)-phosphine ligand

Article abstract of DOI:10.1016/S0020-1693(02)01190-8

The iridium complex [IrCl(COD)]₂ reacts with diphenylphosphinoacetic acid (1) in the presence of CO to afford the iridium(III) complex IrHCl(CO)(η²-Ph₂PCH₂CO₂) (η¹-Ph₂PCH₂CO₂H) (3) which in the solid state exists as a hydrogen-bonded dimer. Complex 3 converts to IrH(CO)(η²-Ph₂PCH₂CO₂) ₂ (4) when treated with AgO₃SCF₃ in dichloromethane. The tertiary phosphine PPh₂(Ph-2,6-Me₂) (2) reacts with solutions of [RhCl(CO)₂]₂ and [IrCl(COD)]₂ (in the presence of CO) in dichloromethane to give the square planar complexes MCl(CO)[PPh₂(Ph-2,6-Me₂)]₂ (M=Rh (5) or Ir (6)) in high yield. While the iridium(I) complex 6 undergoes an oxidative-addition reaction with HgCl₂ to yield the complex IrCl₂(HgCl)(CO)[PPh₂(Ph-2,6-Me₂)] ₂ (7), complex 5 is unreactive towards this reagent.

Full text of DOI:10.1016/S0020-1693(02)01190-8

Inorganica Chimica Acta 343 (2003) 275Á280
/
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Complexes derived from the reactions of diphenylphosphinoacetic
acid. Part 4. Mononuclear complexes of Rh(I), Ir(I) and Ir(III)
and some related chemistry involving
the diphenyl(2,6-dimethylphenyl)-phosphine ligand1
Shan-Ming Kuang a, Dennis A. Edwards b, Phillip E. Fanwick a, Richard A. Walton a,*
a Department of Chemistry, 1393 Brown Building, Purdue University, West Lafayette, IN 47907-1393, USA
b School of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
Received 20 May 2002; accepted 19 June 2002
Abstract
The iridium complex [IrCl(COD)]2 reacts with diphenylphosphinoacetic acid (1) in the presence of CO to afford the iridium(III)
complex IrHCl(CO)(h2-Ph2PCH2CO2)(h1-Ph2PCH2CO2H) (3) which in the solid state exists as a hydrogen-bonded dimer. Complex
3 converts to IrH(CO)(h2-Ph2PCH2CO2)2 (4) when treated with AgO3SCF3 in dichloromethane. The tertiary phosphine PPh2(Ph-
2,6-Me2) (2) reacts with solutions of [RhCl(CO)2]2 and [IrCl(COD)]2 (in the presence of CO) in dichloromethane to give the square
planar complexes MCl(CO)[PPh2(Ph-2,6-Me2)]2 (MꢀRh (5) or Ir (6)) in high yield. While the iridium(I) complex 6 undergoes an
/
oxidative-addition reaction with HgCl2 to yield the complex IrCl2(HgCl)(CO)[PPh2(Ph-2,6-Me2)]2 (7), complex 5 is unreactive
towards this reagent.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Crystal structures; Diphenylphosphinoacetic acid; Diphenyl(2,6-dimethylphenyl)phosphine; Rhodium(I) complexes; Iridium(I)
complexes; Iridium(III) complexes
1. Introduction
Cl5(Ph2PCH2CO2R)3 (RꢀMe or Et), in which the
/
Ph2PCH2CO2R ligands exhibit P,O-bridging and mono-
dentate P-bound modes, respectively.
The previously documented mononuclear transition
metal chemistry involving complexes of diphenylphos-
We now report a new mononuclear Ir(III) complex of
1, compare these results with literature data on Rh(I)
and Rh(III) complexes of this ligand [2,3], and describe
complexes of Rh(I), Ir(I) and Ir(III) that contain
diphenyl(2,6-dimethylphenyl)phosphine
phinoacetic acid (1) [1Á5] led us to examine the
/
complexes that are formed by the reactions of this
ligand with the quadruply bonded dimetal salts
K4Mo2Cl8 and (n-Bu4N)2Re2Cl8 [6]. With the use of
alcohol solvents we isolated the phosphineÁ
plexes Mo2Cl4(m-Ph2PCH2CO2Me)2 and
/
ester com-
Re2-
* Corresponding author. Tel.: ꢁ
0239
/
1-765-494 5464; fax: ꢁ
/
1-765-494
(2), a ligand that has the potential to undergo cyclome-
talation [7,8] to afford five-membered rings that could
resemble those formed by 1.
E-mail address: rawalton@purdue.edu (R.A. Walton).
1
Part 3 is Ref. [6].
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 1 9 0 - 8

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S.-M. Kuang et al. / Inorganica Chimica Acta 343 (2003) 275Á280
/
2. Experimental
2.5. Synthesis of IrCl(CO)[PPh2(Ph-2,6-Me2)]2 (6)
A CH2Cl2 solution (60 ml) that contained a mixture
of [IrCl(COD)]2 (68 mg, 0.10 mmol) and 2 (116 mg, 0.40
mmol) was treated with CO for 1 h and the mixture
filtered. The yellow filtrate was evaporated to leave a
2.1. Starting materials and reaction procedures
The starting material [RhCl(CO)2]2 was prepared by
the standard literature method [9] and [IrCl(COD)]2 was
purchased from Strem Chemicals. Samples of diphenyl-
phosphinoacetic acid (1) were available by use of the
procedure described in an earlier report [6], while the
phosphine ligand diphenyl(2,6-dimethylphenyl)phos-
phine [PPh2(Ph-2,6-Me2)] (2) was obtained by the
literature method [10]. All other reagents and solvents
were obtained from commercial sources. Solvents were
dried and degassed by standard methods and distilled
prior to use. Reactions were carried out under an
atmosphere of dry dinitrogen.
yellow powder that was washed with Et2O (3ꢂ10 ml);
/
yield: 150 mg (90%). Anal. Found: C, 57.85; H, 4.51.
Calc. for C41H38ClIrOP2: C, 58.88; H, 4.58%.
2.6. Synthesis of IrCl2(HgCl)(CO)[PPh2(Ph-2,6-
Me2)]2 (7)
A mixture of 6 (84 mg, 0.10 mmol) and HgCl2 (27 mg,
0.10 mmol) in CH2Cl2 (40 ml) was stirred at r.t. for 3 h
and filtered. The filtrate was evaporated to approxi-
mately 10 ml, then layered with 20 ml of MeOH and set
aside to allow for the separation of pale yellow crystals
of 7; yield: 73 mg (66%). Anal. Found: C, 42.92; H, 3.31.
Calc. for C41H38Cl3HgIrOP2: C, 44.45; H, 3.45%. The
bulk samples of 7 contain small amounts of CH2Cl2
2.2. Synthesis of IrHCl(CO)(h2-Ph2PCH2CO2)(h1-
Ph2PCH2CO2H) (3)
1
solvent molecules (shown by H NMR spectroscopy in
A slow stream of CO was bubbled for 1 h through a
solution that contained a mixture of [IrCl(COD)]2 (68
mg, 0.10 mmol) and 1 (100 mg, 0.40 mmol) in 60 ml of
CH2Cl2. The solvent was evaporated to leave a grey
CDCl3), thereby accounting for the low C and H
microanalyses. However, the crystal selected for the
single crystal X-ray structure determination was found
to be free of solvent.
residue that was washed with Et2O (3ꢂ10 ml); yield:
/
131 mg (88%). Anal. Found: C, 46.13; H, 3.57. Calc. for
C29H26ClIrO5P2: C, 46.81; H, 3.52%. X-ray quality
single crystals were grown by vapor diffusion of
diisopropyl ether into a solution of 3 in 1,2-dichlor-
oethane.
2.7. X-ray crystallography
Single crystals of compositions IrHCl(CO)(h2-
Ph2PCH2CO2)(h1-Ph2PCH2CO2H)×
/
0.5C2H4Cl2
(3),
C6H6 (5) and IrCl2-
RhCl(CO)[PPh2(Ph-2,6-Me2)]2×
/
(HgCl)(CO)[PPh2(Ph-2,6-Me2)]2 (7) were obtained as
described in the individual synthetic procedures outlined
in Sections 2.2, 2.4 and 2.6.
2.3. Synthesis of IrH(CO)(h2-Ph2PCH2CO2)2 (4)
The data were collected at 173 (9
(91) K for 5 and 7. All measurements were carried out
on a Nonius Kappa CCD diffractometer with graphite-
/
1) K for 3 and 150
A solution of 3 (74 mg, 0.10 mmol) in CH2Cl2 (50 ml)
was treated with AgO3SCF3 (29 mg, 0.10 mmol) and the
mixture stirred at room temperature (r.t.) for 30 min and
then filtered. The solvent was evaporated from the
filtrate to leave a pale yellow solid that was washed
with Et2O; yield: 48 mg (68%). This product did not give
satisfactory C and H microanalyses so its identity was
based upon its IR and NMR spectroscopic properties.
/
˚
0.71073 A).
monochromated Mo Ka radiation (lꢀ
/
Lorentz and polarization corrections were applied to
the data sets. The important crystallographic data are
given in Table 1.
The structure of 3 was solved using the structure
solution program PATTY in DIRDIF-92 [11] while the
structure of 5 was solved with the use of SHELXS-97 [12]
and DIRDIF-99 [13] was used for 7. The remaining atoms
were located in succeeding difference Fourier syntheses.
Hydrogen atoms were placed in calculated positions
2.4. Synthesis of RhCl(CO)[PPh2(Ph-2,6-Me2)]2 (5)
A solution of 2 (268 mg, 0.91 mmol) in CH2Cl2 (10
ml) was added to one of [RhCl(CO)2]2 (90 mg, 0.23
mmol) in this same solvent (20 ml). The mixture was
stirred at r.t. for 30 min to afford a yellow solution and
yellow microcrystals. The solid product was filtered off
and recrystallized from CH2Cl2/C6H6; yield: 328 mg
(87%). Anal. Found: C, 67.44; H, 5.40. Calc. for
according to idealized geometries with U(H)ꢀ
/
1.3Ueq(C). They were included in the refinement but
constrained to ride on the atom to which they are
bonded. An empirical absorption correction using
SCALEPACK [14] was applied in all cases. The final
refinements were performed by the use of the program
SHELXL-97 [15]. All non-hydrogen atoms were refined
with anisotropic thermal parameters unless indicated
C47H44ClOP2Rh (i.e. 5×
/
C6H6): C, 68.41; H, 5.38%.

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277
Table 1
squeeze option in PLATON [17]. The positions of the
hydrido ligands present in 3 (atoms H(1) and H(2)) were
calculated with the use of the program XHYDEX [18] and
they were not refined further. In this structure, carbon
atoms C(1), C(32), C(224) and C(426) were refined with
isotropic thermal parameters. The largest peak in the
final difference Fouriers of 3, 5, and 7 had a height of
Crystallographic
data
for
IrHCl(CO)(h2-Ph2PCH2CO2)(h1-
(3), RhCl(CO)[PPh2(Ph-2,6-
Me2)]2×C6H6 (5), and IrCl2(HgCl)(CO)[PPh2(Ph-2,6-Me2)]2 (7)
Ph2PCH2CO2H)×0.5C2H4Cl2
3
5
7
Empirical formula
C30H28Cl2- C47H44ClO-
IrO5P2
C
IrOP2
41H38Cl3Hg-
P2Rh
825.18
3.03, 0.44 and 1.47 e Aꢃ3, respectively.
˚
Formula weight
Space group
793.61 1107.86
¯
P1 (No. 2) C2/c (No. 15) P21/n (No. 14)
/
˚
a (A)
11.401(2)
14.939(3)
20.411(4)
11.40300(10)
14.5290(2)
23.6501(4)
12.4097(4)
17.3458(5)
18.0917(7)
90
2.8. Physical measurements
˚
b (A)
˚
c (A)
IR spectra were recorded as KBr pellets on a PerkinÁ
/
a (8)
b (8)
g (8)
103.579(15) 90
Elmer 2000 FT-IR spectrometer, while H and 31P{1H}
1
98.157(6)
99.063(13)
3278(2)
4
93.8612(6)
90
102.4719(12)
90
NMR spectra were obtained on a Varian INOVA 300
spectrometer. Proton resonances were referenced intern-
ally to the residual protons in the incompletely deu-
teriated solvent. The 31P{1H} spectra were recorded at
121.6 MHz, with 85% H3PO4 as an external standard.
Elemental microanalyses were performed by Dr H.D.
Lee of the Purdue University Microanalytical Labora-
tory.
3
˚
V (A )
Z
3909.32(16)
4
3802.5(4)
4
1.935
rcalc(g cmꢃ3
)
1.608
4.350
1.402
0.613
0.029
0.073
1.029
m(Mo Ka) (mmꢃ1
R(Fo)
)
7.843
0.047
a
0.065
0.151
0.977
2
)
b
Rw(Fo
Goodness-of-fit
0.105
0.953
a
Rꢀa jjFojꢃjFcjj/a jFoj with Fo2ꢀ2s(Fo2).
b
2
2
2 2 1/2
Rwꢀ[a w(jFo jꢃjFc j)2/a wjFo j ]
.
3. Results and discussion
otherwise. Crystallographic drawings were done using
the program ORTEP [16].
The reaction of [IrCl(COD)]2 with Ph2PCH2CO2H (1)
in the presence of CO affords pale yellow crystalline
IrHCl(CO)(h2-Ph2PCH2CO2)(h1-Ph2PCH2CO2H) (3).
This six-coordinate Ir(III) compound is the first iridium
complex of 1 to be isolated and structurally character-
ized. In contrast, several Rh(I) and Rh(III) complexes of
this ligand have been reported previously [2,3], including
the single crystal X-ray crystal structure determinations
The structure solutions and refinements of all three
compounds proceeded without major problem. Solvent
molecules were found to be present in the crystals of 3
and 5; these refined satisfactorily with anisotropic
thermal parameters. A badly disordered and unidenti-
fied solvent molecule was also present in the crystal of 3;
it could not be modeled and so was removed with the
Fig. 1. ORTEP [16] representation of the structure of IrHCl(CO)(h2-Ph2PCH2CO2)(h1-Ph2PCH2CO2H) (3) showing the linking of the two
independent iridium(III) molecules through a pair of hydrogen-bonds. The thermal ellipsoids are drawn at the 50% probability level except for the
carbon atoms of the phenyl groups which are circles of arbitrary radius.

278
S.-M. Kuang et al. / Inorganica Chimica Acta 343 (2003) 275Á280
/
of Rh(CO)(h2-Ph2PCH2CO2)(h1-Ph2PCH2CO2H) [2],
[3] and
Rh(CO)(h2-Ph2PCH2CO2)(h1-Ph2PCH2CO2H)
with
H)
fac-Rh(h2-Ph2PCH2CO2)3
RhHCl(h2-
identical Oꢀ ꢀ ꢀO distances of 2.67 A [2].
˚
Ph2PCH2CO2)(h1-Ph2PCH2CO2H)2 [3]; in all instances
the h2-anionic form of the ligand is bound as a P,O-
chelate ring while the h1-bound acid form involves
monodentate P-coordination. The crystal structure of 3
is shown in Fig. 1, and important bond distances and
angles are listed in Table 2.
The IR spectrum of 3 (KBr pellet) shows a n(Irꢀ
/
mode at 2192(w) cmꢃ1 and n(CO) at 2041(s) cmꢃ1
,
while the sets of n(COO) and n(COOH) vibrations of
the [Ph2PCH2CO2]ꢃ and Ph2PCH2CO2H ligands are at
1612(s) and1265(m) cmꢃ1 and 1719 (m-s) and 1333(m)
1
cmꢃ1, respectively. The H NMR spectrum of a CDCl3
The structure of 3 contains two molecules of
in
solution of 3 shows the Irꢀ
triplet at d ꢃ
15.2 (2JPꢀH
NMR spectrum in this same solvent consists of a simple
AB pattern at d ꢁ0.51 and ꢃ 340 Hz).
0.61 (2JPꢀP
When solutions of 3 in dichloromethane are treated
with AgO3SCF3 at room temperature, loss of HCl
occurs and a yellow product can be isolated that we
believe to be the complex IrH(CO)(h2-Ph2PCH2CO2)2
(4). Since we were unable to obtain single crystals that
were suitable for an X-ray structure determination, this
formulation is based upon the spectroscopic properties
/
H resonance as an apparent
IrHCl(CO)(h2-Ph2PCH2CO2)(h1-Ph2PCH2CO2H)
/
ꢀ
/
4.5 Hz), while the 31P{1H}
the asymmetric unit. These are linked to one another
in the solid state through two essentially identical
hydrogen-bonds formed between the unbound carbox-
ylate group O atom of the h2-Ph2PCH2CO2 ring of one
molecule and the free OH group of the h1-
Ph2PCH2CO2H ligand of the neighboring molecule.
/
/
ꢀ
/
The distances O(11)ꢀ
/
O(42) and O(22)ꢀ/O(32) are 2.64
˚
A but the CO2H group hydrogen atoms were not
located in the structure refinement. A similar type of
H-bonded structure was reported in the case of a-
of 4. The n(Irꢀ/H) and n(CO) modes of 4 are at 2213(w)
Table 2
2
1
a
˚
Important bond lengths (A) and bond angles (8) for IrHCl(CO)(h -Ph2PCH2CO2)(h -Ph2PCH2CO2H)×0.5C2H4Cl2 (3)
Bond lengths
Ir(1)ꢀH(1)
Ir(1)ꢀC(1)
Ir(1)ꢀO(21)
Ir(1)ꢀP(2)
1.6089(6)
1.837(15)
2.039(10)
2.313(4)
2.352(4)
2.476(4)
1.142(16)
1.301(19)
1.20(2)
Ir(2)ꢀH(2)
Ir(2)ꢀC(2)
Ir(2)ꢀO(41)
Ir(2)ꢀP(4)
1.6076(7)
1.799(17)
2.069(10)
2.331(4)
Ir(1)ꢀP(1)
Ir(2)ꢀP(3)
2.373(4)
2.468(4)
Ir(1)ꢀCl(1)
O(1)ꢀC(1)
O(11)ꢀC(12)
O(12)ꢀC(12)
O(21)ꢀC(22)
O(22)ꢀC(22)
Ir(2)ꢀCl(2)
O(2)ꢀC(2)
O(31)ꢀC(32)
O(32)ꢀC(32)
O(41)ꢀC(42)
O(42)ꢀC(42)
1.136(18)
1.232(18)
1.291(17)
1.288(19)
1.230(19)
1.279(18)
1.248(16)
Bond angles
H(1)ꢀIr(1)ꢀC(1)
H(1)ꢀIr(1)ꢀO(21)
C(1)ꢀIr(1)ꢀO(21)
H(1)ꢀIr(1)ꢀP(2)
C(1)ꢀIr(1)ꢀP(2)
O(21)ꢀIr(1)ꢀP(2)
H(1)ꢀIr(1)ꢀP(1)
C(1)ꢀIr(1)ꢀP(1)
O(21)ꢀIr(1)ꢀP(1)
P(2)ꢀIr(1)ꢀP(1)
H(1)ꢀIr(1)ꢀCl(1)
C(1)ꢀIr(1)ꢀCl(1)
O(21)ꢀIr(1)ꢀCl(1)
P(2)ꢀIr(1)ꢀCl(1)
P(1)ꢀIr(1)ꢀCl(1)
O(1)ꢀC(1)ꢀIr(1)
C(22)ꢀO(21)ꢀIr(1)
O(12)ꢀC(12)ꢀO(11)
O(12)ꢀC(12)ꢀC(11)
O(11)ꢀC(12)ꢀC(11)
O(22)ꢀC(22)ꢀO(21)
O(22)ꢀC(22)ꢀC(21)
O(21)ꢀC(22)ꢀC(21)
91.0(4)
83.6(3)
H(2)ꢀIr(2)ꢀC(2)
H(2)ꢀIr(2)ꢀO(41)
C(2)ꢀIr(2)ꢀO(41)
H(2)ꢀIr(2)ꢀP(4)
C(2)ꢀIr(2)ꢀP(4)
O(41)ꢀIr(2)ꢀP(4)
H(2)ꢀIr(2)ꢀP(3)
C(2)ꢀIr(2)ꢀP(3)
91.2(6)
84.1(3)
174.4(5)
93.43(10)
97.0(5)
175.3(7)
86.45(10)
99.4(5)
82.4(3)
80.7(3)
87.26(10)
96.0(5)
84.8(3)
94.11(10)
91.7(5)
88.3(3)
O(41)ꢀIr(2)ꢀP(3)
P(4)ꢀIr(2)ꢀP(3)
166.97(14)
170.33(10)
98.7(4)
168.90(14)
170.34(11)
98.4(6)
H(2)ꢀIr(2)ꢀCl(2)
C(2)ꢀIr(2)ꢀCl(2)
O(41)ꢀIr(2)ꢀCl(2)
P(4)ꢀIr(2)ꢀCl(2)
P(3)ꢀIr(2)ꢀCl(2)
O(2)ꢀC(2)ꢀIr(2)
C(42)ꢀO(41)ꢀIr(2)
O(31)ꢀC(32)ꢀO(32)
O(31)ꢀC(32)ꢀC(31)
O(32)ꢀC(32)ꢀC(31)
O(42)ꢀC(42)ꢀO(41)
O(42)ꢀC(42)ꢀC(41)
O(41)ꢀC(42)ꢀC(41)
86.8(3)
86.3(3)
84.57(14)
92.58(14)
177.2(14)
123.6(9)
121.6(17)
123.9(17)
114.4(15)
122.9(14)
117.6(15)
119.4(12)
91.18(14)
86.42(14)
178.7(15)
124.3(10)
122.0(15)
123.2(14)
114.8(15)
122.3(14)
121.1(15)
116.4(15)
a
Numbers in parentheses are estimated standard deviations in the least significant digits.

S.-M. Kuang et al. / Inorganica Chimica Acta 343 (2003) 275Á
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279
Fig. 3. ORTEP [16] representation of the structure of
IrCl2(HgCl)(CO)[PPh2(Ph-2,6-Me2)]2 (7) with the important atoms
labeled. Thermal ellipsoids are drawn at the 50% probability level.
Fig. 2. ORTEP [16] representation of the structure of trans-
RhCl(CO)[PPh2(Ph-2,6-Me2)]2 (5) with the important atoms labeled.
The CO and Cl ligands represent one-half of the disorder generated by
a twofold rotational axis perpendicular to the RhCl(CO)(P)2 plane.
The thermal ellipsoids are drawn at the 50% probability level.
Table 4
˚
Important bond lengths (A) and bond angles (8) for
IrCl2(HgCl)(CO)[PPh2(Ph-2,6-Me2)]2 (7)
a
Table 3
˚
Important bond lengths (A) and bond angles (8) for
Bond lengths
a
RhCl(CO)[PPh2(Ph-2,6-Me2)]2×C6H6 (5)
IrꢀC(1)
IrꢀP(2)
IrꢀP(1)
IrꢀCl(2)
1.917(8)
IrꢀCl(1)
HgꢀIr
HgꢀCl(3)
O(1)ꢀC(1)
2.462(2)
2.5596(4)
2.334(2)
1.019(8)
2.4000(19)
2.4045(19)
2.4221(18)
Bond lengths
RhꢀC(1)
RhꢀP
1.762(6)
2.3560(4)
RhꢀCl
C(1)ꢀO(1)
2.3779(19)
1.176(6)
Bond angles
Bond angles
C(1)ꢀRhꢀP
C(1)ꢀRhꢀP(a)
PꢀRhꢀP(a)
C(1)ꢀRhꢀCl
C(1)ꢀIrꢀP(2)
C(1)ꢀIrꢀP(1)
P(2)ꢀIrꢀP(1)
C(1)ꢀIrꢀCl(2)
P(2)ꢀIrꢀCl(2)
P(1)ꢀIrꢀCl(2)
C(1)ꢀIrꢀCl(1)
P(2)ꢀIrꢀCl(1)
P(1)ꢀIrꢀCl(1)
90.4(2)
88.5(2)
Cl(2)ꢀIrꢀCl(1)
C(1)ꢀIrꢀHg
P(2)ꢀIrꢀHg
P(1)ꢀIrꢀHg
Cl(2)ꢀIrꢀHg
Cl(1)ꢀIrꢀHg
O(1)ꢀC(1)ꢀIr
Cl(3)ꢀHgꢀIr
93.67(7)
94.2(2)
84.60(19)
95.41(19)
179.08(2)
178.83(19)
PꢀRhꢀCl
P(a)ꢀRhꢀCl
O(1)ꢀC(1)ꢀRh
96.55(3)
83.43(3)
177.1(7)
177.96(7)
173.2(2)
89.95(6)
90.86(6)
93.1(2)
89.95(5)
88.37(5)
79.03(5)
172.51(4)
178.3(8)
175.87(7)
a
Numbers in parentheses are estimated standard deviations in the
least significant digits.
91.73(7)
90.09(7)
and 2053(s) cmꢃ1, respectively. Its H NMR spectrum
1
a
(recorded in CDCl3) shows a multiplet centered at d ꢃ
18.85, that has the appearance of a very closely spaced
doubletÁofÁ
doublets, while its 31P{1H} NMR spectrum
is that of a AB pattern, the two most intense inner
components of which are at d ꢁ3.4 and ꢃ
0.3 (2JPꢀP
310 Hz).
/
Numbers in parentheses are estimated standard deviations in the
least significant digits.
/
/
whether any of these involve cyclometalation of the
ligand 2. The crystal structure of 5 is shown in Fig. 2 and
important bond distances and angles are listed in Table
3. The asymmetric unit contains a single molecule of 5
with the Rh atom located on a crystallographic twofold
rotational axis which is perpendicular to the
RhCl(CO)(P)2 plane, thereby leading to a disorder of
the CO and Cl ligands. This disorder was modeled
satisfactorily.
/
/
ꢀ
/
The reactions of [RhCl(CO)2]2 and [IrCl(COD)]2 (in
the presence of CO) with the phosphine ligand PPh2(Ph-
2,6-Me2) (2) at room temperature in dichloromethane
did not lead to cyclometalation [7,8]. Instead, the Rh(I)
and Ir(I) complexes MCl(CO)[PPh2(Ph-2,6-Me2)]2
(MꢀRh (5) or Ir(6)) were isolated in high yields.
/
Compounds 5 and 6 have very similar spectroscopic
properties thereby implying that they are probably
isostructural. Their IR spectra (KBr pellets) are essen-
When solutions of 5 and 6 in 1,2-dichloroethane were
refluxed for periods of up to 1 week, mixtures of
products were obtained as shown by 31P NMR spectro-
scopy. Further studies are underway to determine
tially identical, with n(CO) at 1951(s) and 1955(s) cmꢃ1
,

280
S.-M. Kuang et al. / Inorganica Chimica Acta 343 (2003) 275Á280
/
1
respectively. Similarities are also seen in their H NMR
spectra (recorded in CDCl3) with methyl resonances at d
References
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ꢁ
/
2.34 (5) and ꢁ
phenyl hydrogen resonances between d ꢁ
The 31P{1H} NMR spectrum of 5 shows a doublet at d
24.84 (JRhꢀP 124.2Hz) while 6 has a singlet at d ꢁ
19.04.
/
2.32 (6) and the exact same pattern of
/
7.0 and ꢁ8.0.
/
(c) J. Podlahova´, J. Loub, J. Jecˇny, Acta Crystallogr., B 35 (1979)
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An ORTEP [16] representation of the structure of 7 is
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/
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4. Supplementary material
Tables giving full details for the crystal data and data
collection parameters, atomic positional parameters,
anisotropic thermal parameters, bond distances and
bond angles for compounds 3, 5 and 7 are available
on request from the author (R.A.W.).
University of Gottingen, Gottingen, Germany, 1997.
¨ ¨
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¨
¨
Acknowledgements
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One of us (R.A.W.) thanks the John A. Leighty
Endowment Fund for support of this work.
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