Synthesis and structure of the {(2-phosphinoethyl)silyl}-tris(tertiary phosphine)iridium(I) complex Ir{η2-Me2Si(CH2)2PPh 2}(PMe3)3

Article abstract of DOI:10.1021/om9601312

The hydridomethyl(silyl)iridium(III) complex Ir{η²-Me₂Si(CH₂)₂PPh ₂}(PMe₃)₂ (2) reacted quantitatively with PMe₃ at 60 °C to give the {(2-phosphinoethyl)silyl}tris(ter

Full text of DOI:10.1021/om9601312

2790
Organometallics 1996, 15, 2790-2793
Syn th esis a n d Str u ctu r e of th e {(2-P h osp h in oeth yl)silyl}-
tr is(ter tia r y p h osp h in e)ir id iu m (I) Com p lex
Ir {η2-Me2Si(CH2)2P P h 2}(P Me3)3
Masaaki Okazaki, Hiromi Tobita,* and Hiroshi Ogino*
Department of Chemistry, Graduate School of Science, Tohoku University,
Sendai 980-77, J apan
Received February 20, 1996X
The hydridomethyl(silyl)iridium(III) complex Ir(H)(Me){η2-Me2Si(CH2)2PPh2}(PMe3)2 (2)
reacted quantitatively with PMe3 at 60 °C to give the {(2-phosphinoethyl)silyl}tris(tertiary
phosphine)iridium(I) complex Ir{η2-Me2Si(CH2)2PPh2}(PMe3)3 (3) as reddish orange crystals
through the reductive elimination of methane. X-ray crystal structure analysis revealed
that 3 adopts a slightly distorted five-coordinate, trigonal-bipyramidal geometry with the
silyl ligand occupying an axial site. Complex 3 generates the 16e silyliridium(I) complex
Ir{η2-Me2Si(CH2)2PPh2}(PMe3)2 (A) easily at room temperature.
In tr od u ction
(CH2)2PPh2}(PMe3)3. Moreover, this paper describes
that Ir{η2-Me2Si(CH2)2PPh2}(PMe3)3 liberates one mol-
ecule of PMe3 under very mild conditions to generate
the 16e silyliridium(I) complex Ir{η2-Me2Si(CH2)2PPh2}-
(PMe3)2.
Interest in transition-metal-catalyzed hydrosilation,1
silane oligomerization,2 and redistribution of substitu-
ents on silicon atoms3 has promoted the studies on
transition-metal silyl complexes. Silyliridium and -rhod-
ium complexes make one of the most important classes
of compounds among them, because many iridium and
rhodium complexes are known to become active cata-
lysts for these reactions,4 and silyliridium and -rhodium
complexes are assumed to play important roles in the
catalytic cycles. However, stable silyliridium(I) or
-rhodium(I) complexes have been rare. The first struc-
turally characterized silylrhodium(I) complex was Rh-
(tripsi)(CO) (tripsi ) Si(CH2CH2PPh2)3).5 In 1990,
Thorn and Harlow reported the first synthesis of a 16e
silylrhodium(I) complex, Rh(SiPh3)(PMe3)3.6 As for 16e
silyliridium(I) complexes, the 16e species L3Ir(SiR3) (L
) π-acidic two-electron-donor ligand) are attracting
increasing attention as key intermediates in some
stoichiometric reactions.7-9 However, only very recently
has a 16e silyliridium(I) complex, Ir{Si(SiMe3)3}(PMe3)3,
been detected in solution at -80 °C by 31P NMR
spectrocopy.9 Several 18e five-coordinate silyliridium(I)
complexes have been reported, but all of them are
stabilized by the coordination of strongly π-acidic car-
bonyl ligands.8,10 We report here the synthesis and
crystal structure of the first silyliridium(I) complex
containing no strongly π-acidic ligands, Ir{η2-Me2Si-
Exp er im en ta l Section
All manipulations were carried out under a dry nitrogen
atmosphere. Reagent-grade toluene and hexane were distilled
from sodium-benzophenone ketyl immediately before use.
Benzene-d6 and toluene-d8 were dried over a potassium mirror
and transferred into NMR tubes under vacuum. HMe2Si-
(CH2)2PPh2,11 PMe3,12 [Ir(CO)(PMe3)4]Cl,13 and P(CD3)314 were
prepared according to literature methods. Other chemicals
were purchased from Wako Pure Chemical Industries, Ltd.,
and used as received. All NMR spectra were recorded on a
Bruker ARX-300 spectrometer. 29Si NMR spectra were ob-
tained by the DEPT pulse sequence. IR spectra were recorded
on a Bruker IFS66v spectrometer.
Ir (Cl)(H){η2-Me2Si(CH2)2P P h 2}(P Me3)2 (1). A Pyrex tube
(20 mm o.d.) was charged with [Ir(CO)(PMe3)4]Cl (1.03 g, 1.84
mmol) and HMe2Si(CH2)2PPh2 (0.503 g, 1.85 mmol), and
toluene (10 mL) was introduced into this tube under high
vacuum by the trap-to-trap-transfer technique. The Pyrex
tube was flame-sealed. The sealed tube was placed in an oil
bath, where the sample was kept at 80 °C. After 36 h, the
tube was unsealed in a N2 glovebox. Removal of the volatiles
under reduced pressure resulted in a pale yellow oily residue,
which was extracted by toluene and hexane (2:1), and the
extract was filtered through a Celite pad. The solvent was
removed from the filtrate under reduced pressure. Recrys-
tallization of the residue from toluene-hexane yielded Ir(Cl)-
(H){η2-Me2Si(CH2)2PPh2}(PMe3)2 (1; 0.88 g, 1.35 mmol, 73%)
as colorless crystals. 1H NMR (300 MHz, C6D6): δ 8.28-8.22,
8.09-8.03 (m, 4H, o-PPh2), 7.14-7.07, 7.04-6.92 (m, 6H, m-
and p-PPh2), 2.27, 1.98 (m, 1H × 2, PCH2), 1.58 (dd, J (HP) )
2.3, 9.4 Hz, 9H, PMe3 (trans to PPh2)), 0.90 (d, J (HP) ) 7.8
Hz, 9H, PMe3 (trans to IrH)), 0.83, 0.71 (m, 1H × 2, SiCH2),
X Abstract published in Advance ACS Abstracts, May 15, 1996.
(1) See, for example: Ojima, I. In The Chemistry of Silicon Com-
pounds; Patai, S., Rappoprt, Z., Eds.; Wiley: New York, 1989; p 1479.
(2) See, for example, Corey, J . Y. In Advances in Silicon Chemistry;
Larson, G., Ed.; J AI Press: Greenwich, CT, 1991; Vol. 1, p 327.
(3) See, for example: Curtis, M. D.; Epstein, P. S. Adv. Organomet.
Chem. 1981, 19, 213.
(4) See, for example: Vaska, L. Acc. Chem. Res. 1968, 1, 335.
Halpern, J . Acc. Chem. Res. 1970, 3, 386.
(5) J oslin, F. L.; Stobart, S. R. J . Chem. Soc., Chem. Commun. 1989,
504.
(6) Thorn, D. L.; Harlow, R. L. Inorg. Chem. 1990, 29, 2017.
(7) Aizenberg, M.; Milstein, D. Angew. Chem., Int. Ed. Engl. 1994,
33, 317. Aizenberg, M.; Milstein, D. J . Am. Chem. Soc. 1995, 117, 6456.
(8) Esteruelas, M. A.; Lahoz, F. J .; Oliva´n, M.; On˜ate, E.; Oro, L. A.
Organometallics 1994, 13, 4246.
(9) Mitchell, G. P.; Tilley, T. D.; Yap, G. P. A.; Rheingold, A. L.
Organometallics 1995, 14, 5472.
(11) Holmes-Smith, R. D.; Osei, R. D.; Stobart, S. R. J . Chem. Soc.,
Perkin Trans. 1983, 861.
(12) Gibson, V. C.; Graimann, C. E.; Hare, P. M.; Green, M. L. H.;
Bandy, J . A.; Grebenik, P. D.; Prout, K. J . Chem. Soc., Dalton Trans.
1985, 2025.
(13) Labinger, J . A.; Osborn, J . A. Inorg. Synth. 1978, 18, 62.
(14) Our method of preparation is essentially the same as that
previously reported by Green et al.,12 except that we use CD3I instead
of CH3I.
(10) Auburn, M. J .; Grundy, S. L.; Stobart, S. R.; Zaworotko, M. J .
J . Am. Chem. Soc. 1985, 107, 266.
S0276-7333(96)00131-8 CCC: $12.00 © 1996 American Chemical Society

Ir{η2-Me2Si(CH2)2PPh2}(PMe3)3
Organometallics, Vol. 15, No. 12, 1996 2791
Ta ble 1. Cr ysta llogr a p h ic Da ta for
0.50, 0.33 (s, 3H × 2, SiMe2), -10.04 (dt, J (HPtrans) ) 126.7,
J (HPcis) ) 17.5 Hz, 1H, IrH). 13C NMR (75.5 Hz, C6D6): δ
139.7, 137.6, 134.7, 132.1, 129.5, 128.7, 128.4, 127.9 (Ar), 30.0
(d, J (CP) ) 38.9 Hz, PCH2), 20.0 (dd, J (CP) ) 3.4, 22.2 Hz,
SiCH2), 19.8 (dt, J (CP) ) 34.8, 3.5 Hz, PMe3), 17.7 (dt, J (CP)
) 27.5, 2.5 Hz, PMe3), 10.0 (dd, J (CP) ) 5.4, 2.1 Hz, SiMe),
4.9 (d, J (CP) ) 4.2 Hz, SiMe). 31P NMR (121.5 Hz, C6D6): δ
26.6 (dd, J (PPtrans) ) 334.6 Hz, J (PPcis) ) 18.2 Hz, PPh2),
-42.1 (dd, J (PPtrans) ) 334.6 Hz, J (PPcis) ) 20.9 Hz, PMe3
(trans to PPh2)), -49.9 (dd, PMe3 (trans to IrH)). 29Si NMR
(59.6 MHz, C6D6): δ 5.8 (ddd, J (SiPcis) ) 8.7, 5.7, 2.8 Hz). IR
(KBr): 2048 cm-1 (ν(IrH)). MS (70 eV, DEI): m/ z 652 (80,
M+), 650 (100, M+ - 2H), 616 (11, M+ - HCl). Anal. Calcd
for C22H39ClIrP3Si‚1/2(C6H5CH3): C, 43.86; H, 6.21; Cl, 5.08.
Found: C, 44.01; H, 6.05; Cl, 4.64.
Ir {η2-Me2Si(CH2)2P P h 2}(P Me3)3 (3)
formula
fw
C25H47IrP4Si
691.85
cryst syst
orthorhombic
space group
Pnaa (variant of No. 56)
a/Å
b/Å
c/Å
V/Å3
Z
14.176(2)
36.042(5)
11.884(3)
6072(2)
8
d
calcd/g cm-3
1.51
49.1
µ(Mo KR)/cm-1
cryst size/mm
T/°C
0.30 × 0.25 × 0.20
20
reflns measd
2θ range/deg
no. of unique data
no. of data used with |Fo| > 3σ(Fo)
no. of params refined
Ra
(h,k,l
3-50
Ir (H)(Me){η2-Me2Si(CH2)2P P h 2}(P Me3)2 (2). A diethyl
ether solution (2.7 mL) of MeLi (0.75 M, 2.0 mmol) was added
to the toluene (20 mL) solution of 1 (0.44 g, 0.67 mmol) at -48
°C, and the mixture was warmed to room temperature. The
reaction mixture was stirred at room temperature for 2 h.
Volatile material was removed under reduced pressure, and
the residue was extracted with a mixture of toluene and
hexane (2:1). The extract was filtered through an alumina
column. The solvent was removed from the filtrate under
reduced pressure. Recrystallization of the residue from tolu-
ene-hexane gave Ir(H)(Me){η2-Me2Si(CH2)2PPh2}(PMe3)2 (2;
0.29 g, 0.46 mmol, 69%) as colorless crystals. 1H NMR (300
MHz, C6D6): δ 7.90-7.84, 7.59-7.52 (m, 4H, o-PPh2), 7.13-
7.07, 7.04-6.96 (m, 6H, m- and p-PPh2), 2.68, 1.63 (m, 1H ×
2, PCH2), 1.46 (dd, J (HP) ) 2.3, 8.8 Hz, 9H, PMe3 (trans to
PPh2)), 0.82 (d, J (HP) ) 7.5 Hz, 9H, PMe3 (trans to IrH)), 1.08,
0.61 (m, 1H × 2, SiCH2), 0.72, 0.58 (s, 3H × 2, SiMe2), 0.27 (q,
J (HP) ) 4.4 Hz, 3H, IrMe), -12.60 (ddd, J (HPtrans) ) 120.6,
J (HPcis) ) 23.4, 17.7 Hz, 1H, IrH). 13C NMR (75.5 Hz, C6D6):
δ 140.6, 137.8, 134.2, 131.8, 129.2, 128.4, 127.9, 127.5 (Ar),
36.3 (dd, J (CP) ) 39.5, 1.9 Hz, PCH2), 21.6 (dd, J (CP) ) 20.5,
4.1 Hz, SiCH2), 21.2 (dt, J (CP) ) 33.4, 4.0 Hz, PMe3), 18.7 (dt,
J (CP) ) 27.3, 2.4 Hz, PMe3), 11.8 (d, J (CP) ) 6.0 Hz, SiMe),
6.6 (d, J (CP) ) 2.2 Hz, SiMe), -38.3 (ddd, J (CP) ) 14.8, 8.2,
6.5 Hz, IrMe). 31P NMR (121.5 Hz, C6D6): δ 35.2 (dd,
J (PPtrans) ) 349.7 Hz, J (PPcis) ) 19.2 Hz, PPh2), -48.4 (dd,
J (PPtrans) ) 349.7 Hz, J (PPcis) ) 20.7 Hz, PMe3 (trans to
PPh2)), -61.2 (dd, PMe3 (trans to IrH)). 29Si NMR (59.6 MHz,
C6D6): δ 10.5 (ddd, J (SiPcis) ) 17.7, 9.6, 8.1 Hz). IR (KBr):
2044 cm-1 (ν(IrH)). MS (70 eV, DEI): m/ z 632 (1, M+), 617
9708
3182
281
0.071
b
Rw
0.083
a
b
2
R ) ∑||Fo| - Fc||/∑|Fo|. Rw ) [∑w(|Fo| - Fc|)2/∑w|Fo| ]1/2; w
) [σ2(|Fo|) + aFo
]
-1, where a ) 0.001.
2
Sch em e 1
SiMe2). 31P NMR (121.5 MHz, C6D6, T ) -60 °C): δ 43.6 (m,
PPh2), -55, -56 (m, PMe3). 31P NMR (121.5 MHz, C6D6, T )
80 °C): δ 44.3 (br q, J (PP) ) 79 Hz, PPh2), -57.0 (br, d, J (PP)
) 79 Hz, PMe3). MS (70 eV, DEI): m/ z 692 (0.3, M+), 616
(100, M+ - PMe3). Anal. Calcd for C25H47IrP4Si: C, 43.40;
H, 6.85. Found: C, 43.66; H, 6.58.
X-r a y Cr ysta l Str u ctu r a l Deter m in a tion of 3. Intensity
data for X-ray crystal structure analysis were collected at 20
°C on a Rigaku AFC-6A diffractometer with graphite-mono-
chromated Mo KR radiation. A single crystal of 3 was sealed
in a glass capillary under a N2 atmosphere. The crystal
structure was solved by direct methods and refined anisotro-
pically using UNICS-III. A total of 9708 unique reflections
were collected by ω-scan in the range 3° < 2θ < 50°, with 3182
(|Fo| > 3σ(Fo)) used in calculations. None of the hydrogen
atoms were found. Crystallographic data for 3 are listed in
Table 1.
(100, M+ - CH3), 616 (71, M+ - CH4). Anal. Calcd for C23H42
-
IrP3Si‚1/8(C6H5CH3): C, 44.57; H, 6.74. Found: C, 44.69; H,
6.54.
Ir {η2-Me2Si(CH2)2P P h 2}(P Me3)3 (3). A Pyrex tube (12
mm o.d.) was charged with 2 (0.20 g, 0.32 mmol) and PMe3
(163 µL, 1.58 mmol), and toluene (2 mL) was introduced into
this tube under high vacuum by the trap-to-trap-transfer
technique. The Pyrex tube was flame-sealed. The sealed tube
was placed in the oil bath, where it was kept at 60 °C for 8 h.
The sample was cooled to -30 °C to allow the growing of red-
orange crystals, which were collected by filtration to give Ir-
Rea ction of 3 w ith P (CD3)3. A Pyrex NMR tube (5 mm
o.d.) was charged with 3 (15 mg, 0.022 mmol) and P(CD3)3 (11
µL, 0.11 mmol), and benzene-d6 (0.7 mL) was introduced into
this tube under high vacuum by the trap-to-trap-transfer
technique. The NMR tube was flame-sealed. The reaction was
1
{η2-Me2Si(CH2)2PPh2}(PMe3)3 (3; 0.17 g, 0.25 mmol, 78%). H
NMR (300 MHz, C6D6, T ) -60 °C) δ 7.80-7.74 (m, 4H,
o-PPh2), 7.26-6.94 (m, 6H, m- and p-PPh2), 2.59 (q, J ) 5.8
Hz, 2H, PCH2), 1.49 (br s, 9H × 2, PMe3 × 2 (equatorial)),
0.91 (s, 6H, SiMe2), 0.80 (d, 9H, J ) 6.3 Hz, PMe3 (axial)), 0.68
(dt, J ) 34.1, 6.9 Hz, 2H, SiCH2). 1H NMR (300 MHz, C6D6,
T ) 50 °C): δ 7.70-7.64 (m, 4H, o-PPh2), 7.13-7.00 (m, 6H,
m- and p-PPh2), 2.38 (q, J ) 7.6 Hz, 2H, PCH2), 1.33 (br, 9H
× 3, PMe3 × 3), 0.57 (dt, J ) 32.0, 7.6 Hz, 2H, SiCH2), 0.56 (s,
6H, SiMe2). 13C NMR (75.5 Hz, C6D6, T ) -60 °C): δ 143.4,
134.7, 127.7, 127.4 (Ar), 36.9 (d, J (CP) ) 25.8 Hz, PCH2), 27.8
(br, PMe3 × 2 (equatorial)), 24.5 (br, PMe3 (axial)), 22.0 (d,
J (CP) ) 29.4, SiCH2), 9.4 (q, J (CP) ) 6.7 Hz, SiMe2). 13C NMR
(75.5 Hz, C6D6, T ) 50 °C): δ 144.6, 134.2, 128.1, 127.2 (Ar),
37.4 (dd, J (CP) ) 33.5, 3.5 Hz, PCH2), 27.7 (br s, PMe3 × 3),
22.2 (dd, J (CP) ) 34.4, 3.3 Hz, SiCH2), 9.6 (q, J (CP) ) 6.2 Hz,
1
monitored by H and 31P NMR spectroscopy.
Resu lts a n d Discu ssion
Syn t h esis of Ir (H )(Me){η2-Me2Si(CH 2)2P P h 2}-
(P Me3)2 (2). The hydrido methyl complex Ir(H)(Me)-
{η2-Me2Si(CH2)2PPh2}(PMe3)2 (2) can be readily pre-
pared by the reactions shown in Scheme 1. Thermolysis
of the toluene solution of the ligand precursor HMe2Si-
(CH2)2PPh2 and the cationic iridium(I) complex [Ir(CO)-
(PMe3)4]Cl in a sealed tube at 80 °C for 36 h gave the

2792 Organometallics, Vol. 15, No. 12, 1996
Okazaki et al.
chlorohydridoiridium(III) complex Ir(Cl)(H){η2-Me2Si-
(CH2)2PPh2}(PMe3)2 (1) as colorless crystals in 73%
yield. The geometry of 1 can be uniquely determined
by the 1H, 31P, and 29Si NMR spectra. Addition of MeLi
to 1 in toluene at -48 °C resulted in the formation of
complex 2. Workup and recrystallization from toluene-
hexane afforded colorless crystals of 2 in 69% yield. The
1H, 31P, 13C, and 29Si NMR spectral data establish that
2 possesses hydrido, methyl, and silyl ligands in a mer
relationship. The 13C resonance of Ir-Me appears at
-38.3 ppm as a ddd coupled with three cis-31P (J (CPcis)
) 6.5, 8.2, 14.8 Hz). This chemical shift is characteristic
of the carbon directly bound to a transition metal
through a σ bond. In the complex fac-Ir(H)(Me)(SiR3)-
(PMe3)3 previously reported by Aizenberg and Milstein,7
a strongly trans-influencing silyl ligand15 is located
trans to the PMe3 ligand. In contrast, surprisingly the
silyl ligand in 3 is located trans to the strongly trans-
influencing methyl ligand.
Syn th esis of Ir {η2-Me2Si(CH2)2P P h 2}(P Me3)3 (3).
Reaction of 2 with 5 equiv of PMe3 in toluene at 60 °C
for 8 h resulted in an orange solution, from which
reddish orange crystals of Ir{η2-Me2Si(CH2)2PPh2}-
(PMe3)3 (3) were obtained in 78% yield (eq 1). The
F igu r e 1. ORTEP drawing of Ir{η2-Me2Si(CH2)2PPh2}-
(PMe3)3 (3).
Ta ble 2. Selected In ter a tom ic Dista n ces (Å) a n d
An gles (d eg) for Ir {η2-Me2Si(CH2)2P P h 2}(P Me3)3 (3)
Distances
Ir-P1
Ir-P3
Ir-Si
2.279(5)
2.290(5)
2.447(5)
Ir-P2
Ir-P4
2.289(5)
2.347(4)
Angles
P1-Ir-P2
P1-Ir-P4
P2-Ir-P3
P2-Ir-Si
P3-Ir-Si
130.4(2)
91.4(2)
109.5(2)
87.1(2)
91.4(2)
P1-Ir-P3
P1-Ir-Si
P2-Ir-P4
P3-Ir-P4
P4-Ir-Si
118.5(2)
80.6(2)
92.7(2)
98.8(2)
169.2(2)
structure of 3 has been determined by spectroscopic and
analytical methods and by X-ray crystal structure
analysis.
dium(I) complex Ir(PPh2CH2CH2SiMe2)(PPh3)(CO)2
(2.454(6) Å.10 The Ir-P(PPh2) bond length (2.279(5) Å)
of 3 is shorter than that of Ir(PPh2CH2CH2SiMe2)(PPh3)-
(CO)2 (2.342(5) Å).10 This indicates that back-donation
of d electrons from the iridium center to the phosphorus
atom in the former is more effective than that in the
latter because of the more electron-rich metal center in
the former. The overall structural features of 3 are
similar to those of structurally determined Ir(I) com-
plexes: Ir(PPh2CH2CH2SiMe2)(PPh3)(CO)2,10 Ir(H)(CO)2-
(PPh3)2,19 and Ir(COEt)(CO)2(dppe).20 All of these com-
plexes adopt distorted-trigonal-bipyramidal geometry
with a σ-donor ligand occupying an axial position.
There is only one 18e silylrhodium(I) complex that has
been structurally characterized by an X-ray diffraction
study, Rh(tripsi)(CO) (tripsi ) Si(CH2CH2PPh2)3), re-
ported by J oslin and Stobart, which also takes a
distorted-trigonal-bipyramidal geometry with the silyl
fragment and carbonyl ligand occupying the axial sites.5
We should mention that only two types of silyliridium(I)
compounds have been synthesized previously. One is
Ir(PPh2CH2CH2SiMe2)(PPh3)(CO)2,10 with two carbonyl
ligands in the equatorial plane. The other is Ir(SiR3)-
(PCy3)(CO)3 (R ) Et, Ph),8 with three carbonyl ligands
all in the equatorial plane according to the IR and NMR
spectroscopic data. Therefore, complex 3 is the first
example of a silyliridium(I) complex with no carbonyl
ligands. Complex 3 is expected to be more electron-rich
than other silyliridium(I) complexes previously reported
The five-coordinate complex 3 is fluxional in C6D5-
CD3 at room temperature. In the 1H NMR spectrum
at 50 °C, the three (one axial and two equatorial) PMe3
ligands appear equivalently at δ 1.33 ppm as a very
broad singlet. At -60 °C, the signals of one axial and
two equatorial PMe3 ligands appear nonequivalently at
δ 0.80 ppm as a doublet (J ) 6.3 Hz) and at 1.49 ppm
as a slightly broad singlet in the intensity ratio of 1:2,
respectively. At 80 °C, the 31P resonance of the PPh2
moiety appears at 44.3 ppm as a broad quartet coupled
with the 31P nuclei of three PMe3 ligands (J (PP) ) 79
Hz), which is consistent with the intramolecular ex-
change of three PMe3 ligands.16 It is known that the
analogous iridium(I) complex Ir(Me)(PMe3)4 exhibits an
intramolecular exchange process of PMe3 ligands.17
Str u ctu r e of 3. The ORTEP drawing for 3 is shown
in Figure 1. Selected bond distances and angles of 3
are listed in Table 2. The complex 3 takes a five-
coordinate, slightly distorted trigonal-bipyramidal ar-
rangement in which the silicon atom and a PMe3 ligand
occupy axial positions while the PPh2 moiety and two
PMe3 ligands are located in equatorial sites. The Ir-
Si bond length lies in the normal range (2.447(5) Å)18
and is close to that of the previously reported silyliri-
(15) Holmes-Smith, R. D.; Stobart, S. R.; Vefghi, R.; Zaworotko, M.
J .; J ochem, K.; Cameron, T. S. J . Chem. Soc., Dalton Trans. 1987, 969.
(16) Price, R. T.; Andersen, R. A.; Muetterties, E. L. J . Organomet.
Chem. 1989, 376, 407.
(17) Thorn, D. L. J . Am. Chem. Soc. 1980, 102, 7109. Thorn, D. L.
Organometallics 1982, 1, 197.
(18) See for example: Tilley, T. D. In The Silicon-Heteroatom Bond;
Patai, S., Rappoport, Z., Eds.; Wiley: New York, 1991; pp 264, 343.
Hays, M. K.; Eisenberg, R. Inorg. Chem. 1991, 30, 2623.
(19) Ciechanowicz, M.; Skapski, S. C.; Troughton, P. G. H. Acta
Crystallogr. 1976, B32, 1673.
(20) Deutsch, P. P.; Eisenberg, R. Organometallics 1990, 9, 709.

Ir{η2-Me2Si(CH2)2PPh2}(PMe3)3
Organometallics, Vol. 15, No. 12, 1996 2793
due to the coordination of four electron-releasing phos-
phine ligands and thus to be more reactive.
silylrhodium(III) complex Rh(H)(Me)(SiPh3)(PMe3)3 as
an intermediate, which eliminated methane to give Rh-
(SiPh3)(PMe3)3. Recently, Aisenberg and Milstein re-
ported that thermolysis of fac-(Me3P)3Ir(Me)(H)(SiPh3)
in C6D6 under relatively severe conditions (100 °C for
24 h) led to the formation of ortho-metalated product
(Me3P)3Ir{(C6H4)SiPh2}(H), and they assumed the gen-
eration of the 16e silyliridium(I) complex (Me3P)3Ir(SiPh3)
as a key intermediate by methane reductive elimination
from the hydrido methyl complex.7 Owing to the
unprecedentedly mild conditions for the dissociation of
PMe3 from 3, the complex 3 could be a convenient
precursor for generating a highly reactive 16e silyliri-
dium(I) species.
La bility of P Me3 Liga n d s in 3. To investigate the
lability of PMe3 ligands in complex 3, 5 equiv of P(CD3)3
was vacuum-transferred into the C6D6 solution of 3.
1
Instantly, the intensity of the H NMR signal of PMe3
ligands in 3 decreased at room temperature and the
signal of free PMe3 with the corresponding intensity
appeared. The intensity ratio of the 31P NMR reso-
nances of free PMe3 to free P(CD3)3 after 10 min was
5:4. After 30 min, the 31P NMR intensity ratio reached
ca. 3:5 and no further change of the ratio was observed
after this. This apparently means that a statistical
5
fraction, i.e. /8, of the PMe3 ligands in 3 was replaced
Con clu sion s
by P(CD3)3 at room temperature to give a mixture of
L′Ir(PMe3)3-m(P(CD3)3)m (3-d′: L′ ) SiMe2(CH2)2PPh2,
m ) 1-3) with the same geometry as that of 3 (eq 2).
We have prepared the novel silyliridium(I) complex
3 with no carbonyl ligand. X-ray crystal structure
analysis revealed that 3 takes a slightly distorted
trigonal bipyramidal geometry with the silyl and a PMe3
ligand occupying the axial positions. Complex 3 under-
goes an intramolecular fluxional process of PMe3 ligands
and also dissociates a PMe3 ligand under mild condi-
tions to generate a reactive 16e silyliridium(I) species.
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Scientific Research on Priority Area of
Reactive Organometallics (No. 07216206) from the
Ministry of Education, Science and Culture of J apan.
We thank Shin-Etsu Chemical Co., Ltd., and Toray Dow
Corning Silicone Co., Ltd., for the gifts of silicon
compounds.
These observations are consistent with the facile gen-
eration of the 16e silyliridium(I) complex Ir{η2-Me2Si-
(CH2)2PPh2}(PMe3)2 (A) from complex 3 even at room
temperature. The analogous Rh complex Rh(SiPh3)-
(PMe3)3 was isolated by the reaction of Rh(Me)(PMe3)3
with HSiPh3 at room temperature.6 They proposed the
Su p p or tin g In for m a tion Ava ila ble: Text giving details
of the X-ray structure determination and tables of crystal data,
atomic positional and thermal parameters, and bond distances
and angles for 3 (6 pages). Ordering information is given on
any current masthead page.
OM9601312