Thermal reactions of alkyl(hydrido)(hydrosilyl)iridium(III) complexes: Generation of a hydrido(silylene)iridium(I) species via the reductive elimination of alkane and 1,2-H-shift from the silicon atom to the Ir(I) metal center

Article abstract of DOI:10.1016/S0022-328X(97)00370-7

Heating of alkyl(hydrido)(hydrosilyl)iridium(III) complexes L_nIr(R)(H) [L_n={η²-MesHSi(CH₂)₂PPh ₂}(PMe₃)₂, Mes=2,4,6-C₆H₂Me₃, R=Me, Et] led to the reductive elimination of alkane. Subsequently, the resulting hydrosilyliridium(I) intermediate L_nIr (A) activated the intramolecular carbon-hydrogen bond to give Ir(H){η³-CH₂C₆H₂(CH ₃)₂SiH(CH₂)₂PPh ₂}(PMe₃)₂. In the presence of MeOH, A was quickly trapped with MeOH to give a methoxysilyliridium(III) complex Ir(H)₂{η²-Mes(MeO)Si(CH₂) ₂PPh₂}(PMe₃)₂. This reactivity of A with MeOH clearly supports the occurrence of a 1,2-H-shift from the silyl silicon atom to the iridium center to generate a hydrido(silylene)iridium(I) species Ir(H)[η²-{=SiMes(CH₂)₂PPh ₂}](PMe₃)₂.

Full text of DOI:10.1016/S0022-328X(97)00370-7

Ž
.
Journal of Organometallic Chemistry 553 1998 1–13
ž
/ž
/
ž /
Thermal reactions of alkyl hydrido hydrosilyl iridium III complexes:
ž
/
ž /
generation of a hydrido silylene iridium I species via the reductive
elimination of alkane and 1,2-H-shift from the silicon atom to the Ir I
ž /
metal center
)
Masaaki Okazaki, Hiromi Tobita , Yasuro Kawano, Shinji Inomata, Hiroshi Ogino1
Department of Chemistry, Graduate School of Science, Tohoku UniÕersity, Sendai 980-77, Japan
Abstract
2
Ž
.Ž
.
Ž
.
Ž .Ž . w
Ä
Ž
.
4Ž
.
Heating of alkyl hydrido hydrosilyl iridium III complexes LnIr R H Lns h -MesHSi CH2 2 PPh2 PMe3 2 , Mess2,4,6-
x
Ž . Ž .
C6H2Me3, RsMe, Et led to the reductive elimination of alkane. Subsequently, the resulting hydrosilyliridium I intermediate LnIr A
3
Ž .Ä
Ž
.
Ž
.
4Ž
.
activated the intramolecular carbon–hydrogen bond to give Ir H h -CH2C6H2 CH3 2SiH CH2 22PPh2 PMe3 2. In the presence of
Ž
.
Ž . Ä 4Ž
Ž
.
Ž
.
.
MeOH, A was quickly trapped with MeOH to give a methoxysilyliridium III complex Ir H 2 h -Mes MeO Si CH2 2PPh2 PMe3 .
2
This reactivity of A with MeOH clearly supports the occurrence of a 1,2-H-shift from the silyl silicon atom to the iridium center to
2
Ž
.
Ž .
Ž .w
Ä
Ž
.
4xŽ
.
generate a hydrido silylene iridium I species Ir H h - sSiMes CH2 2PPh2 PMe3 2. q 1998 Elsevier Science S.A.
Keywords: Silyliridium; Silylene complex; 1,2-migration; Carbon–hydrogen bond activation
1. Introduction
been focused on silyl complexes with no Si–H bond,
and the reactivities of hydrosilyl complexes are rela-
Transition-metal silyl complexes have attracted much
attention as intermediates in the catalytic transformation
tively unexplored. This paper describes the thermal
2
Ž
.Ž
.
Ä
Ž
.
reactivities of Ir R
H
h -M esH Si C H
2
2
w
x
4
Ž
. Ž
.
Ž
of hydrosilanes 1,2 . In particular, hydrosilyl com-
plexes M–SiHR2 have been assumed to be key interme-
diates formed in transition-metal-catalyzed dehydro-
genative condensation of hydrosilanes and redistribution
PPh2 PMe3
RsMe, Et, H . In these systems Rs
2
.
Ž .
Me, Et , we revealed that a 16e-hydrosilyliridium I
2
Ž
Ž
.
4
Ž
.
complex Ir h -MesHSi CH2 2 PPh2 PMe3
2
resulting
from reductive elimination of alkane undergoes a 1,2-
2
w
x
Ž
.
Ž .
w
Ä
of substituents on silicon atoms 1–4 . In many of these
catalytic reactions, hydrosilyl hydrido complexes, re-
sulting from oxidative addition of dihydrosilanes to
H-shift to give a hydrido silylene species Ir H h - s
Ž
.
Ž . 4xŽ
.
2
SiMes CH2 2 PPh2 PMe3 under relatively mild con-
2
Ž .
w
Ä
ditions. In the presence of MeOH, Ir H h - s
Ž . 4xŽ
.
2
.
transition-metals, undergo dissociation of dihydrogen to
SiMes CH2 2 PPh2 PMe3 reacts quickly with MeOH
2
2
w
x
Ž .
Ä
Ž
Ž
.
4
Ž
.
give a silylene intermediate 5–8 . 1,2-Migration of
hydrogen on a hydrosilyl silicon atom to a transition-
metal and subsequent dissociation of dihydrogen can be
to give Ir H h -Mes MeO Si CH2 2 PPh2 PMe3 2. In
2
2
Ž
. Ä
h -
2
contrast, dihydrido com plex Ir H
Ž
.
4
Ž
.
MesHSi CH2 2 PPh2 PMe3 is inert to the thermal
2
Ž
assumed to be a possible route for dehydrogenation Eq.
1 , 9,10 . Nevertheless, the most intense studies have
reductive elimination of dihydrogen. A part of this work
has been published as a preliminary communication
3
Ž .
w
x
Ž
w
x.
11,12 .
)
Corresponding author.
1 Also corresponding author.
2 The formation of silylene complexes via dehydrogenation has
w
x
been reported in Refs. 5,6 .
3 The generation of a hydrido–silylene complex via the 1,2-H-shift
from the silyl silicon atom to the metal center is reported in Refs.
Ž .
1
w
x
9,10 .
0022-328Xr98r$19.00 q 1998 Elsevier Science S.A. All rights reserved.

(
)
2
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
Ž
.
Ž
.
Ž
.
Ž
2. Experimental
p-ArMe , 23.4 o-ArMe2 , 125.7 ipso-Ar , 128.1 m-
.
Ž
.
Ž
.
Ar , 130.9 CHsCH2 , 135.6 CHsCH2 , 139.7
29
Ž
.
Ž
Ž
.
.
Ä1
4
Ž
.
p-Ar , 144.7 o-Ar . Si H NMR 59.6 MHz, C6 D6
All manipulations were carried out under a dry nitro-
gen atmosphere. Reagent-grade toluene, hexane, diethyl
ether, and THF were distilled from sodium–benzo-
phenone ketyl immediately before use. Benzene-d6 was
dried over a potassium mirror and transferred into an
y1
y1
Ž Ž
..
d y52.0. IR KBr 2150 cm
n SiH , 855 cm
Ž
Ž
..
v CH2 . Anal. found: C, 74.36; H, 9.34. C11H16Si.
Calc.: C, 74.93; H, 9.15%. Exact mass found: 176.1025.
C11H16Si. Calc.: 176.1021.
w
x
NMR tube under vacuum. MesLi 13 and
w
Ž
.Ž
.
x
w x
Ir CO PMe3 Cl 14 were prepared according to lit-
(
)
4
2.3. MesH2 Si CH2 2 PPh2
erature methods. Other chemicals were purchased from
Wako Pure Chemical Industries and used as received.
NMR spectra were recorded on a Bruker ARX-300
spectrometer. 29Si NMR spectra were obtained using the
DEPT pulse sequence. IR spectra were recorded on a
Bruker IFS66v spectrometer.
Ž
.
A deoxygenated solution of MesSiH2 CHsCH2
Ž
.
Ž
.
1.08 g, 6.12 mmol and HPPh2 1.14 g, 6.12 mmol in
Ž
.
toluene 5 ml was irradiated with a 450 W medium
pressure Hg lamp through a Pyrex sleeve at 08C for 12
h with stirring. Removal of solvent from the reaction
mixture under reduced pressure followed by crystalliza-
tion from toluene–hexane at y308C gave colorless
(
)
2.1. MesSiCl2 CHsCH2
Ž
.
Ž
.
needles of MesH2 Si CH2 2 PPh2. Yield 2.06 g 93% .
1H NMR 300 MHz, C6 D6 d 0.80–0.91 m, 2H,
Ž
.
Ž
Ž
.
Ž
.
To a toluene solution 120 ml of SiCl3 CHsCH2
.
Ž
.
Ž
Ž
.
Ž
.
SiCH2 , 2.08 s, 3H, p-ArMe , 1.99–2.20 m, 2H,
22 ml, 0.17 mol was added a suspension 150 ml of
.
Ž
Ž
.
Ž
Ž
.
Ž
.
PCH2 , 2.31 s, 6H, o-ArMe2 , 4.34 t, Js2.7 Hz, 2H,
MesLi 22 g, 0.17 mol in toluene 150 ml at room
temperature. After stirring for 12 h, the resulting mix-
ture was filtered through a Celite pad. The solvent was
removed from the filtrate under reduced pressure.
.
.
Ž
SiH2 , 6.76 s, 2H, C6 H2 Me3 , 7.00–7.41 m, 10H,
13
.
Ä1
4
Ž
.
Ž
Ž
PPh2 . C H NMR 50.3 MHz, C6 D6 d 6.5 d,
Ž
.
.
Ž
.
J CP s13 Hz, SiCH2 , 21.3 p-ArMe , 23.9 o-
.
Ž
Ž
.
.
Ž
.
ArMe2 , 24.0 d, J CP s16 Hz, PCH2 , 126.9, 128.6,
Molecular distillation of the residue 1208C, 2 mm Hg
31
Ž
.
Ä1
4
Ž
.
128.7, 133.1, 139.3, 139.6, 144.6 Ar . P H NMR
gave MesSiCl2 CHsCH2 as a colorless oil. Yield
29
1
Ž
.
Ä1
4
Ž
Ž
.
.
Ž
.
Ž
36.3 MHz, C6 D6 d y11.3. Si H NMR 59.6
10.0 g 21% . H NMR 300 MHz, CDCl3 d 2.28 s,
.
Ž
Ž
.
.
Ž
.
Ž
.
Ž
MHz, C6 D6 d y43.4 d, J SiP s23 Hz . IR toluene
3H, p-ArMe , 2.56 s, 6H, o-ArMe2 , 6.18–6.48 m,
13
2150 cmy1 n SiH . Exact mass found: 362.1621.
Ä1
4
Ž
Ž Ž
..
.
Ž
.
3H, CHsCH2 , 6.87 s, 2H, ArH . C H NMR
Ž
.
Ž
.
.
C13 H27 PSi. Calc.: 362.1620.
75.5 MHz, CDCl3 d 21.1 p-ArMe , 24.8 o-ArMe2 ,
Ž
Ž
.
Ž
.
Ž
Ž
.
126.8 ipso-Ar , 129.8 m-Ar , 134.9 CHsCH2 ,
.
.
Ž
.
2
136.1 CH s CH2 , 141.8 p-Ar , 144.6 o-Ar .
(
)( )
{
(
)
}
(
) ( )
2.4. Ir Cl H h -MesHSi CH2 2 PPh2 PMe3
1
2
29
Ä1
4
Ž
Ž
.
Ž
.
Si H NMR 59.6 MHz, CDCl3 d 2.3. IR KBr 854
..
cmy1 v CH2
C11H14Cl2 Si. Calc.: 244.0242.
.
Exact mass found: 244.0240.
Ž
w
Ž
Ž
.Ž
.
.
x
Ž
.
To Ir CO PMe3 Cl 0.71 g, 1.27 mmol and
4 Ž
.
MesH2 Si CH2 2 PPh2 0.46 g, 1.27 mmol in a Pyrex
Ž
.
tube 20 mm o.d. connected to a vacuum line was
(
)
2.2. MesSiH2 CHsCH2
Ž
.
introduced toluene 3 ml by the trap-to-trap-transfer
technique. The tube was flame-sealed under vacuum
and then heated to 808C for 24 h. The tube was opened
in an N2 glove bag. Removal of the volatiles under
reduced pressure resulted in a pale yellow oily residue,
which was extracted using a toluene–hexane 2:1 mix-
ture. The solvent was removed under reduced pressure.
Recrystallization from toluene–hexane gave a white
Ž
. Ž
.
MesSiCl2 CHsCH2 10.0 g, 0.040 mol in THF
Ž
Ž
.
30 ml was added dropwise to a suspension of LiAlH4
3.0 g, 0.079 mol in THF 80 ml over a period of 30
.
Ž
.
Ž
.
min. After addition was complete, the mixture was
refluxed for 2 h. The flask was then cooled in an ice
Ž
.
bath and 5% sulfuric acid solution 100 ml was care-
fully added to the reaction mixture. The resulting pre-
cipitate was filtered, and the filtrate was placed in a
separatory funnel and washed with a saturated NaHCO3
solution, a dilute NaCl solution, and water, respectively.
The organic layer was dried over anhydrous MgSO4.
2
Ž
.Ž .
Ä
Ž
.
4
Ž
.
powder of Ir Cl H h -MesHSi CH2 2 PPh2 PMe3
2
1
Ž . .
Ž
.
Ž
1 . Yield 0.76 g 80% . H NMR 300 MHz, C6 D6 d
Ž
Ž
.
Ž .
s130 Hz, J HPcis 17 Hz, 1H,
y9.41 dt, J HP
.
Žtrans
.
Ž
Ž
.
IrH , 1.06, 1.29 m, 2H, SiCH2 , 1.09 d, J HP s7.9
Ž
..
Ž
Ž
.
Hz, 9H, PMe3 trans to IrH , 1.34 dd, J HP s9.7,
Ž
.
Ž
..
Ž
Molecular distillation 1308C, 15 mm Hg afforded
2.3 Hz, 9H, PMe3 trans to PPh2 , 1.84, 2.62 m, 2H,
Ž
.
.
Ž
Ž
.
Ž
MesSiH2 CHsCH2 as a colorless oil. Yield 6.0 g
PCH2 , 2.13 s, 3H, p-ArMe , 2.64, 2.68 s, 6H, o-
1
3
Ž
.
Ž
.
Ž
.
.
Ž
.
.
85% . H NMR 300 MHz, C6 D6 d 2.09 s, 3H,
ArMe2 , 4.77 dd, J HH s6.4, 20.1 Hz, 2H, SiH2 ,
.
Ž
.
Ž
Ž
Ž
.
Ž
p-ArMe , 2.38 s, 6H, o-ArMe2 , 4.83 d, J HH s2.3
6.72, 6.83 s, 2H, m-Mes , 6.90–7.16 m, 6H, m,
13
.
Ž
.
Ä1
4
Ž
.
Ž
.
.
Ž
Hz, 2H, SiH2 , 5.74–6.07 m, 3H, CHsCH2 , 6.72 s,
p-PPh2 , 8.36 m, 4H, o-PPh2 . C H NMR 75.5
MHz, C6 D6 d 12.5 d, J CP s20.1 Hz, SiCH2 , 16.1
13
.
Ä1
4
Ž
.
Ž
Ž
.
.
2H, ArH . C H NMR 75.5 MHz, C6 D6 d 21.1

(
)
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
3
Table 1
Ž
Ž
.
.
Ž
Ž
.
dt, J CP s27.9, 2.4 Hz, PMe3 , 18.7 dt, J CP s
2
Ž .Ž .Ä
Ž
.
4Ž
.
Crystallographic Data for Ir H Cl h -MesHSi CH2 2 PPh2 PMe3
Ž .
2
.
Ž
.
Ž
Ž
.
2
35.6, 3.3 Hz, PMe3 , 21.1 p-ArMe , 23.5 d, J CP s
.
Ž
.
Ž
Ž
.
3.2 Hz, o-ArMe , 26.2 o-ArMe , 28.0 d, J CP 37.4
Formula
fw
Crystal system
Space group
C29 H45ClIrP3Si
742.36
Orthorhombic
Pnca
Ž .
14.279 2
Ž .
31.943 5
.
Hz, PCH2 , 128.1, 128.5, 128.6, 128.9, 129.6, 129.6,
131.2, 132.6, 134.1, 134.7, 135.8, 136.5, 137.7, 139.8,
143.6, 145.1 Ar . P H NMR 36.3 MHz, C6 D6
31
Ž
Ž
.
Ä1
4
Ž
.
d
Ž
.
Ž
y49.4 dd, J PPcis s11. 1, 22.2 Hz, PMe3 trans to
˚
Ž .
a A
..
Ž
Ž
.
Ž
.
IrH , y43.5 dd, J PP
s329.0 Hz, J PPcis
s
˚
Ž .
b A
trans
Žtrans
..
Ž
Ž
.
22.2 Hz, PMe3
to PPh2 , 19.7 dd, J PP
˚
Ž .
c A
Ž .
13.951 2
Ž .
6363 2
trans
29
Ž
.
.
Ä1
4
Ž
329.0 Hz, J PPcis 11.1 Hz, PPh2 . Si H NMR 59.6
3
˚
Ž
.
V A
.
Ž
Ž
.
.
MHz, C6 D6 d y19.8 ddd, J SiPcis 5.8, 6.7, 7.4 Hz .
Z
8
y1
y3
Ž
.
Ž
.
Ž Ž
.
Ž
..
Ž
dcalc. g cm
. Ž
1.55
47.2
IR KBr 2058, 2129 cm
n SiH , n IrH . MS 70
y1
q
q
Ž
.
m Mo K a cm
.
Ž
.
Ž
Ž
eV, EI mrz 742 18, M , 662 100, M – C6 H5 q
Ž
.
Crystal size mm
0.20=0.20=0.10
..
3H . Anal. found: C, 47.29; H, 5.85; Cl, 4.57.
Ž
.
T 8C
2u range 8
No. of unique data
20
C29 H45ClIrP3Si. Calc.: C, 46.92; H, 6.11; Cl, 4.78%.
Ž .
3–55
12569
3836
317
0.072
0.078
<
<
Ž
.
No. of data used with Fo )3s Fo
2
(
)( )
{
(
)
2.5. Photolysis of Ir Cl H h -MesHSi CH2
) ( )
PPh2 PMe3 1
2
No. of params refined
2
Ra
}
(
Rbw
2
a
Ž
.Ž .
Ä
Ž
.
4
Ž
.
Ž .
5
<
<
5
<
<
<
To Ir Cl H h -MesHSi CH2 2 PPh2 PMe3
1
RsÝ Fo y Fc Ý Fo .
2
2
1r2
w
Ž<
<
<.2
<
< x
Rw s Ýv Fo y Fc rÝv Fo
vs s Fo qaFo
.
Ž
.
Ž
.
30 mg, 0.040 mmol in a Pyrex NMR tube 5 mm o.d.
connected to a vacuum line was added benzene-d6 0.7
ml by the trap-to-trap-transfer technique. The tube was
2
w
2Ž< <.
xy1
, where as0.001.
Ž
.
flame-sealed under vacuum and irradiated. The reaction
was monitored by 1H NMR spectroscopy. The photosta-
tionary state of the geometric isomerization was attained
between 1 and its geometric isomer 2, after irradiation
for 1 h with the ratio of 1:2s5:3. The resulting solu-
tion was concentrated under reduced pressure. Careful
crystallization from benzene-d6 at room temperature
2.6. X-ray crystal structure determination of 2
Intensity data from the X-ray crystal structure analy-
sis were collected at 208C on a Rigaku AFC-6A diffrac-
tometer with graphite-monochromated Mo–K a radia-
tion. The crystal structure was solved by direct methods
and refined anisotropically using UNICS-III. 12569
unique reflections were collected by v scan in the range
gave colorless crystals of 2, which were suitable for
1
Ž
.
X-ray crystal structure analysis. Yield 11 mg 37% . H
Ž
.
Ž
Ž
.
NMR 300 MHz, CD2Cl2 d y10.27 dt, J HP
s
trans Ž
Ž
<
<
Ž
..
38-2u-558, with 3836 Fo )3s Fo used in calcu-
lations. None of the hydrogen atoms was found. Crystal-
lographic data for 2 are listed in Table 1. The final
atomic coordinates and temperature factors of non-hy-
drogen atoms are listed in Table 2.
Ž
.
.
134.0 Hz, J HPcis 21.3 Hz, 1H, IrH , 0.97, 1.75 m,
.
Ž
Ž
.
1H=2, SiCH2 , 0.98 dd, J HP 1.6, 5.8 Hz, 9H,
Ž
..
Ž
Ž
.
PMe3 syn to Mes , 1.27 dd, J HP s1.7, 5.7 Hz,
Ž
..
Ž
.
9H, PMe3 anti to Mes , 2.16, 3.13 m, 1H=2, PCH2 ,
Ž
.
Ž
.
2.21 s, 3H, p-ArMe , 2.54 s, 6H, o-ArMe2 , 3.13,
Ž
.
Ž
.
Ž
.
2.16 m, 2H, PCH2 , 4.04 t, J HH s13.4 Hz, 1H,
2
( )(
)
{
(
)
}
(
) ( )
.
Ž
Ž
2.7. Ir H Me h -MesHSi CH2 2 PPh2 PMe3
3
SiH , 6.75 s, 2H, m-Mes , 7.42–7.24 m, 6H, m,
2
13
.
Ž
.
Ä1
4
p-PPh2 , 8.32, 7.90 m, 4H, o-PPh2 . C H NMR
2
Ž
.
.
Ž
Ž
.
.
Ž
. Ž
. Ä
H h
75.5 MHz, C6 D6 d 13.7 d, J CP s23.9 Hz, SiCH2 ,
T o
a
s o lu tio n
o f Ir C l
1
-
.
Ž
Ž
.
Ž
.
4
Ž
.
Ž . Ž
16.0 ddd, J CP s25.0, 14.1, 3.1 Hz, PMe3 , 18.0
MesHSi CH2 2 PPh2 PMe3
0.21 g, 0.28 mmol
2
Ž
Ž
.
.
Ž
Ž
ddd, J CP s25.3, 14.2, 3.5 Hz, PMe3 , 19.7 p-
in 10 ml of toluene was added MeLi 0.6 M, 0.75 ml,
.
.
Ž
.
Ž
Ž
.
.
ArMe , 23.1 o-ArMe2 , 25.6 d, J CP s35.3 Hz,
1.6 equiv. via syringe at y488C. The reaction mixture
PCH2 , 127.4, 127.5, 127.6, 127.8, 128.2, 128.6, 129.0,
was slowly warmed up to room temperature and stirred
for 1 h. The volatiles were removed under reduced
pressure. The residue was extracted using toluene–
Ž
.
.
129.4, 130.8, 133.9, 136.7, 139.1, 139.5, 140.0 Ar .
31
Ä1
4
Ž
.
Ž
Ž
P H NMR 36.3 MHz, C6 D6 d y48.9 d, J PPcis
.
Ž
Ž
.
Ž
.
19.5 Hz, PMe3 =2 , y1.9 t, J PPcis s19.5 Hz,
hexane 2:1, 40 ml . The extract was filtered through an
29
.
Ä1
4
Ž
.
Ž
PPh2 . Si H NMR 59.6 MHz, C6 D6 d y16.2 dt,
alumina column. After removal of solvent, recrystalliza-
y1
2
Ž
.
.
Ž
.
Ž .Ž
.Ä
J SiPcis s1.7, 12.1 Hz . IR KBr 2054, 2065 cm
tion from toluene–hexane afforded Ir H Me h -
q
Ž Ž
.
Ž
..
Ž
.
Ž
.
Ž
.
4
Ž
.
Ž .
3 as colorless crystals.
n SiH , n IrH . MS 70 eV, EI mrz 742 19, M ,
MesHSi CH2 2 PPh2 PMe3
2
1
q
Ž
Ž
..
Ž
.
Ž
.
662 100, M – C6 H5 q3H . Anal. found: C, 47.68;
H, 6.07; Cl, 4.52. C29 H45ClIrP3Si. Calc.: C, 46.92; H,
6.11; Cl, 4.78%.
Yield 115 mg 57% . H NMR 300 MHz, C6 D6 d
Ž
Ž
.
Ž .
s122.7 Hz, J HPcis s19.1 Hz,
y12.00 dt, J HP
.
Ž
tranŽs
.
.
1H, IrH , 0.43 q, J HPcis s6.2 Hz, 3H, IrMe , 1.01

(
)
4
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
29
Table 2
.
Ä1
4
Ž
.
15.8 Hz, PPh2 . Si H NMR 59.6 MHz, C6 D6
d
Final atomic coordinates and temperature factors of the non-hydrogen
atoms of Ir H Cl h -MesHSi CH2 2 PPh2 PMe3
Ž
Ž
.
.
Ž
.
y14.3 dt, J SiPcis s7.2, 10.6 Hz . IR KBr 2004,
2
Ž .Ž .Ä
Ž
.
4Ž
. Ž .
2
2087 cmy1 n SiH , n IrH . MS 70 eV, DEI mrz
2
Ž Ž ..
.
Ž
Ž
Ž
.
Atom
x
y
z
Beq
q
q
Ž
.
.
722 3, M , 706 100, M –CH4 . Anal. found: C,
Ž .
Ž .
Ž .
Ž .
2816.0 4
Ir
Cl
3597.0 4
1567.2 1
1820 1
855 1
1764 1
1594 1
1355 1
1477 4
1892 4
2024 5
1736 5
1327 5
1182 4
2233 4
1883 6
704 4
598 4
2.4
4.1
2.8
3.2
3.1
3.1
3.1
3.0
3.9
3.9
3.6
3.5
4.1
6.5
4.6
2.8
4.3
4.8
4.7
4.9
3.7
3.5
4.7
6.0
6.3
7.3
4.4
4.2
3.3
4.1
4.4
4.9
4.2
4.8
4.4
Ž
.
52.78; H, 7.18. C30 H48 IrP3SiP1r2 C6 H5CH3 . Calc.:
Ž .
Ž .
4034 3
4795 3
C, 52.39; H, 6.82%.
Ž .
Ž .
Ž .
Ž .
2946 3
P 1
3991 3
Ž .
Ž .
Ž .
Ž .
1618 3
P 2
4647 3
2
( )( )
{
(
)
}
(
) ( )
2.8. Ir H Et h -MesHSi CH2 2 PPh2 PMe3
4
Ž .
Ž .
Ž .
Ž .
4012 3
P 3
2454 3
2
Ž .
Ž .
Ž .
1589 3
Si
Ž .
2572 3
Ž .
Ž .
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
C 1
1247 9
1654 11
Ž
A diethyl ether solution of EtMgBr 2.0 M, 0.24 ml,
2.0 equiv. was added to a toluene solution 10 ml of
.Ž . . Ž . Ž
Ir Cl H h -MesHSi CH2 2 PPh2 PMe3 1 0.18 g,
2
0.24 mmol at y488C, and the mixture was stirred at
room temperature for 1 h. The volatiles were removed
under reduced pressure. The residue was extracted with
toluene–hexane 2:1 . The extract was filtered through
an alumina column and concentrated. Recrystallization
Ž .
Ž .
39 11
Ž .
Ž
1473 11
C 2
991 9
.
Ž
.
Ž .
Ž
.
Ž .
Ž
1545 11
C 3
2
Ž
Ä
Ž
.
4
Ž
Ž .
Ž
.
.
Ž .
Ž
1764 12
C 4
Ž .
y655 10
y406 10
.
Ž
Ž .
Ž
1901 11
C 5
Ž .
Ž
.
Ž .
Ž
1821 11
C 6
502 11
1707 10
Ž .
Ž
.
Ž .
Ž
1190 13
C 7
Ž .
Ž
.
Ž .
Ž
1861 16
C 8
Ž .
C 10
y1707 12
Ž
.
Ž
.
Ž .
Ž
1865 12
C 9
Ž
655 13
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ž .
Ž .
Ž
3979 9
4137 11
4241 13
5137 13
5944 14
5832 13
Ž
4916 12
2521 11
3019 13
of the residue from toluene–hexane afforded
Ir H Et h -MesHSi CH2 2 PPh2 PMe3 4 as color-
Ž
Ž
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
Ž .
Ž
C 11
3697 12
3705 12
3967 11
4257 13
4271 11
5172 11
5943 11
6871 11
7010 14
6227 15
5307 12
3117 11
2876 10
4310 11
4921 12
5838 10
175 4
2
Ž
Ž
Ž .
Ž
Ž .Ž
.
Ä
Ž
.
4
Ž
. Ž .
C 12
5 5
2
1
Ž
Ž
Ž .
Ž
C 13
231 5
653 5
833 4
700 4
Ž
.
Ž
less crystals. Yield 110 mg 62% . H NMR 300 MHz,
Ž
Ž
Ž .
Ž
C 14
.
Ž
Ž
.
Ž
.
C6 D6 d y12.23 ddd, J HP
s120.0 Hz, J HPcis
trans
Ž
Ž
Ž .
C 15
.
Ž
Ž
.
22.4, 14.9 Hz, 1H, IrH , 0.95 d, J HP s7.6 Hz, 9H,
Ž
Ž
Ž .
Ž
C 16
Ž
..
Ž
.
PMe3 trans to IrH , 0.95, 1.35 m, 1H=2, SiCH2 ,
Ž
Ž
Ž .
Ž
C 17
880 5
Ž
Ž
Ž .
Ž
Ž
.
Ž
Ž
.
C 18
787 5
Ž .
2672 16
1912 16
1464 17
1.03, 1.49 m, 1H=2, IrC H2CH3 , 1.30 dd, J HP s
Ž
Ž
Ž
C 19
528 6
Ž
.
Ž
Ž
.
.
.
8.9, 1.6 Hz, 9H, PMe3 trans to PPh2 , 2.00 t, J HH
Ž
Ž
Ž .
Ž
C 20
334 6
435 5
.
Ž
7.6 Hz, 3H, IrCH2C H3 , 2.03, 2.53 m, 1H=2, PCH2 ,
2.23 s, 3H, p-ArMe , 2.81, 2.87 s, 3H=2, o-ArMe2 ,
Ž
Ž
Ž .
Ž
1755 13
C 21
Ž
Ž
.
Ž
Ž
Ž
Ž .
Ž
2243 12
C 22
536 4
Ž .
Ž
.
.
5.06 dd, J HH s17.7, 5.0 Hz, 1H, SiH , 6.88, 6.96
Ž
Ž
Ž
1301 11
C 23
780 4
Ž
Ž
Ž .
Ž
.
.
Ž
.
Ž
.
C 24
2251 4
1413 4
967 12
Ž
601 12
2003 14
s, 1H=2, m-Mes , 6.99–7.11 m, 6H, m, p-PPh2 ,
13
Ž
.
Ä1
4
Ž
Ž
Ž .
C 25
7.52–7.57, 8.05–8.11 m, 4H, o-PPh2 . C H NMR
Ž
Ž
Ž .
Ž
.
.
.
.
C 26
1925 5
Ž .
Ž
.
Ž
Ž
.
75.5 MHz, C6 D6 d y18.3 q, J CPcis s7.1 Hz,
Ž
Ž
Ž
5217 12
C 27
2840 11
1732 11
1565 10
1717 5
.
Ž
Ž
Ž
.
.
.
IrCH2CH3 , 9.3 dd, J CP s19.6, 2.1 Hz, SiCH2 ,
Ž
Ž
Ž .
Ž .
Ž
4224 13
C 28
1130 5
1996 5
Ž
.
.
Ž
Ž
16.7 dt, J CP s26.9, 2.4 Hz, PMe3 , 21.0 dt, J CP
Ž
Ž
Ž
3845 13
C 29
.
Ž
.
Ž
Ž
.
33.0, 4.0 Hz, PMe3 , 21.3 p-ArMe , 24.5 d, J CP s
aAtomic coordinates are multiplied by 104. Thermal parameters are
given by the equivalent temperature factors A .
.
Ž
Ž
.
Ž
.
2.3 Hz, o-ArMe , 26.3 d, J CP s9.7 Hz, o-ArMe ,
2
˚
Ž
.
Ž
.
.
Ž
.
26.6 IrCH2CH3 35.4 dd, J CP s37.0, 2.3 Hz,
PCH2 , 127.6, 127.7, 128.1, 128.8, 129.0, 129.2, 129.4,
Ž
Ž
.
Ž
..
d, J HP s7.6 Hz, 9H, PMe3 trans to IrH , 1.02,
132.5, 134.6, 136.2, 136.3, 138.5, 140.2, 143.4, 145.0
31
Ž
.
Ä1
4
Ž
.
Ž
Ž
.
Ž
Ž
.
1.39 m, 1H=2, SiCH2 , 1.21 dd, J HP s9.0, 2.2
Ar . P H NMR 36.3 MHz, C6 D6 d y64.3 dd,
Ž
.
Ž
.
Ž
.
Ž
..
Hz, 9H, PMe3 trans to PPh2 , 2.22 s, 3H, p-ArMe ,
J PPcis s22.2, 29.0 Hz, PMe3 trans to IrH , y51.9
Ž
.
.
Ž
Ž
Ž
Ž
.
Ž .
340.3 Hz, J PPcis s22.2 Hz, PMe3
2.31 m, 1H=2, PCH2 , 2.81, 2.82 s, 3H=2, o-
dd, J PP
trans
.
Ž
Ž
.
..
Ž
Ž
.
ArMe2 , 5.19 dt, J HP s16.6, 4.1 Hz, 1H, SiH ,
trans to PPh2 , 29.0 dd, J PP
s340.3 Hz,
trans
29
Ä1
4
Ž
Ž
.
Ž
Ž
.
.
6.85, 6.94 s, 1H=2, m-Mes , 6.85–7.15 m, 6H, m,
J PPcis s11.1 Hz, PPh2 . Si H NMR 59.6 MHz,
.
Ž
.
.
.
Ž
Ž
.
.
Ž
.
.
p-PPh2 , 7.60–7.66, 7.95–8.01 m, 4H, o-PPh2 .
C6 D6 d y20.0 dt, J SiPcis s9.3, 11.8 Hz . IR KBr
13
Ä1
4
Ž
Ž
2031, 2125 cmy1 v SiH , v IrH . MS DEI, 70 eV
Ž Ž ..
.
Ž
Ž
C H NMR 75.5 MHz, C6 D6 d y37.2 ddd,
q
q
Ž
.
.
Ž
Ž
.
Ž
.
Ž
.
J CPcis s6.2, 8.8, 14.5 Hz, IrMe , 12.2 ddd, J CP s
mrz 736 4, M , 706 100, M –C2 H6 . Anal. found:
.
Ž
Ž
.
Ž
.
19.4, 3.1, 1.2 Hz, SiCH2 , 17.3 ddd, J CP s27.3,
C, 53.05; H, 6.93. C30 H48 IrP3SiP1r2 C6 H5CH3 .
.
Ž
Ž
.
3.0, 2.3 Hz, PMe3 , 20.1 ddd, J CP s34.3, 4.1, 3.5
Calc.: C, 52.99; H, 6.96%.
.
Ž
.
Ž
Ž
.
Hz, PMe3 , 21.2 p-ArMe , 24.0 d, J CP s2.8 Hz,
2
.
Ž
.
Ž
Ž
.
( )
{
(
)
}
(
) ( )
o-ArMe , 26.5 o-ArMe , 35.5 dd, J CP s37.7, 2.2
2.9. Ir H 2 h -MesHSi CH2 2 PPh2 PMe3
5
2
.
Hz, PCH2 , 128.2, 128.8, 129.1, 129.3, 132.1, 134.1,
31
.
Ä1
4
s
Ž
.
Ž
136.2, 137.5, 140.4, 140.9, 143.3, 144.8 Ar . P H
To a THF suspension 25 ml of LiAlH4 160 mg,
4.21 mmol was added a THF solution 25 ml of
Ir Cl H h -MesHSi CH2 2 PPh2 PMe3
0.35 mmol . The reaction mixture was stirred at room
temperature for 5 h, and then refluxed for 2 h. Volatiles
Ž
.
Ž
Ž
.
.
Ž
1
.
NMR 121.5 MHz, C6 D6 d y62.0 dd, J PPcis
2
Ž
..
Ž
Ž
.Ž .
Ä
Ž
.
4
Ž
.
Ž . Ž
0.26 g,
15.8, 22.4 Hz, PMe3 trans to IrH , y49.4 dd,
2
Ž
.
..
Ž . Ž
s344.2 Hz, J PPcis s22.4 Hz, PMe3 trans
.
J PP
trans
Ž
Ž
.
Ž
.
to PPh2 , 31.3 dd, J PP
s344.2 Hz, J PPcis s
trans

(
)
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
5
Ž
.
.
Ž
Ž
.
were evaporated under reduced pressure, and the residue
was extracted with toluene–hexane 2:1 . The extract
was filtered through an alumina column and concen-
J CPcis s4.7 Hz, IrCH2 , 14.0 dd, J CP s25.5, 3.8
Ž
.
.
Ž
Ž
.
.
Hz, SiCH2 , 21.1 dt, J CP s23.6, 1.9 Hz, PMe3 ,
Ž
.
Ž
Ž
.
21.5, 22.9 s, ArMe , 23.5 dt, J CP s30.2, 3.8 Hz,
.
Ž
Ž
.
.
trated under reduced pressure. Crystallization from
PMe3 , 29.4 dd, J CP s36.9, 11.3 Hz, PCH2 , 125.8,
2
Ž
. Ä
h
2
to lu e n e – h e x a n e
a ffo rd e d
Ir H
-
126.8, 129.2, 129.6, 131.7, 132.1, 132.6, 137.9, 139.7,
31
Ž
.
Ä1
4
Ž
.
Ž
.
4
Ž
.
MesHSi CH2 2 PPh2 PMe3
2
Ž .
5 as a white powder.
Yield 156 mg 63% . H NMR 300 MHz, C6 D6 d
141.7, 142.3 Ar . P H NMR 121.5 MHz, C6 D6
d
1
Ž
.
Ž
.
Ž
Ž
.
.
Ž
y60.9 t, J PPcis s20.1 Hz, PMe3 , y59.6 dd,
Ž
Ž
.
Ž .
s106.2 Hz, J HPcis s15.6 Hz,
Ž
.
.
Ž
Ž
.
y12.51 dt, J HP
J PPcis s13.7, 20.1 Hz, PMe3 , 24.0 dd, J PPcis
s
trans
29
.
Ž
Ž
.
.
Ä1
4
Ž
.
1H, IrH , y11.93 dt, J HPtrans s 113.4 Hz,
13.7, 20.1 Hz, PPh2 . Si H NMR 59.6 MHz, C6 D6
Ž
.
.
Ž
Ž
.
Ž
.
Ž
.
Ž
.
Ž
J HPcis s20.7 Hz, 1H, IrH , 1.11 d, J HP s8.0 Hz,
d 21.7 ddd, J SiP
10.7 Hz , IR KBr 2023, 2054 cm
Exact mass found: 706.2057. C29 H44 P3Si. Calc.:
706.2055. Anal. found: C, 48.55; H, 6.41. C29 H44 IrP3Si.
s131.1 Hz, J SiPcis s7.9,
trans
y1
Ž
..
Ž
Ž
.
Ž Ž
.
..
9H, PMe3 trans to IrH , 1.15, 1.42 m, 1H=2,
v IrH , v SiH .
.
Ž
Ž
.
Ž
SiCH2 , 1.23 d, J HP s7.7 Hz, 9H, PMe3 trans to
..
Ž
.
Ž
Ž
Si , 2.22, 2.54 m, 1H=2, PCH2 , 2.26 s, 3H, p-
1
.
Ž
.
Ž
.
Ž
ArMe , 2.88 s, 6H, o-ArMe2 , 5.24 dd, J HH s17.3,
Calc.: C, 49.34; H, 6.28%. Data for 6b: H NMR 300
.
Ž
.
Ž
.
Ž
Ž
.
7.8 Hz, 1H, SiH , 6.92 s, 2H, m-Mes , 7.01–7.13 m,
MHz, C6 D6 d y12.09 dt, J HP
s105 Hz,
trans
13
.
Ž
.
Ä1
4
Ž
.
.
Ž
Ž
.
6H, m, p-PPh2 , 7.45, 7.82 m, 4H, o-PPh2 . C H
J HPcis s18 Hz, 1H, IrH , 1.03 d, J HP s7.3 Hz,
Ž
.
Ž
Ž
.
Ž
.
Ž
Ž
.
.
NMR 75.5 MHz, C6 D6 d 15.0 dd, J CP s23.7, 3.1
9H, PMe3 , 1.11 d, J HP s6.8 Hz, 9H, PMe3 , 2.39,
2.81 s, 3H=2, ArMe2 , 5.23 m, 1H, SiH . 13C NMR
.
Ž
.
Ž
.
Ž
.
Ž
.
Hz, SiCH2 , 21.1 p-ArMe , 21.4 dt, J CP s29.3,
.
Ž
Ž
.
.
Ž
.
Ž
Ž
.
4.6 Hz, PMe3 , 26.0 dt, J CP s25.8, 3.6 Hz, PMe3 ,
75.5 MHz, C6 D6 d 2.8 dt, J CP
s62.8 Hz,
Ž trans
Ž
.
29
Ž
.
.
Ž
Ž
.
Ž
.
Ž
.
24.4 o-ArMe2 , 37.6 dd, J CP s37.0, 11.4 Hz,
J CPcis s5.1 Hz, IrCH2 . Si NMR 59.6 MHz, C6 D6
Ž
.
.
PCH2 , 127.9, 128.2, 128.5, 128.8, 129.2, 132.0, 133.3,
d 18.9 ddd, J SiP
s134.0 Hz, J SiPcis 18.0, 4.4
.
Ž trans
.
Ž
31
Hz . 31 P NMR 121.5 MHz, C6 D6 d y59.6 dd,
Ž
.
Ä1
4
Ž
135.9, 140.5, 143.1 Ar . P H NMR 36.3 MHz,
.
Ž
Ž
.
.
Ž
.
Ž
..
C6 D6 d y61.4 dd, J PPcis s16.2, 20.3 Hz, PMe3 ,
J PPcis s6.9, 13.7 Hz, PMe3 trans to Si , y59.4
Ž
Ž
.
.
Ž
Ž
Ž
Ž
Ž
.
.
Ž
.
..
y59.0 dd, J PPcis s16.2, 20.3 Hz, PMe3 , 35.2 t,
dd, J PPcis s6.9, 8.4 Hz, PMe3 trans to IrH , 25.8
29
Ž
.
.
Ä1
.
4
Ž
J PPcis s16.2 Hz, PPh2 . Si H NMR 59.6 MHz,
dd, J PPcis s8.4, 13.7 Hz, PPh2 .
.
Ž
Ž
Ž
.
C6 D6 d y4.4 ddd, J SiP
123.8 Hz, J SiPcis
10.6, 5.5 Hz . IR KBr 2007, 2029, 2042 cm
..
s
trans
y1
2
.
Ž
.
Ž Ž
.
(
)( ){
n IrH ,
2 .1 1 . T h e r m o ly s is o f Ir H E t h
) ( )
MesHSi CH2 2 PPh2 PMe3 4
2
-
q
Ž
Ž
.
Ž
.
(
)
}
(
n SiH . MS DEI, 70 eV mrz 708 37, M , 706
q
Ž
.
100, M –H2 . Anal. found: C, 43.78; H, 6.26.
Ž
.
Ž
.
C22 H40 IrP3SiP1r8 C6 H5CH3 . Calc.: C, 43.66; H,
A Pyrex sample tube 15 mm o.d. with a greaseless
2
Ž .Ž
.Ä
6.57%.
vacuum valve was charged with Ir H Et h -
Ž . Ž .
0.30 g, 0.40 mmol
Ž
.
Ž
4
.
Ž
.
MesHSi CH2 2 PPh2 PMe3
4
2
and toluene 5.0 ml . The solution was degassed on a
vacuum line by the conventional freeze–pump–thaw
method. The tube was flame-sealed under vacuum and
then heated at 608C for 6 h. The procedure gave 6. The
isolation of the product 6a was the same as the method
2
(
)( ){
2 .1 0 . T h e r m o ly s is o f Ir H M e h
-
(
)
}
(
) ( )
MesHSi CH2 2 PPh2 PMe3 3
2
Ž
.
A Pyrex sample tube 15 mm o.d. with a greaseless
2
Ž .Ž
.Ä
Ž
.
vacuum valve was charged with Ir H Me h -
MesHSi CH2 2 PPh2 PMe3
described above. Yield 0.15 g 55% .
Ž
.
Ž
4
.
Ž
.
Ž . Ž
3
.
0.25 g, 0.35 mmol
2
2
( )
{
and toluene 5.0 ml . The solution was degassed on a
vacuum line by the conventional freeze–pump–thaw
method. The tube was flame-sealed under vacuum and
then heated at 608C for 80 h. It was then opened in an
N2 glove box. Volatiles were removed under reduced
2.12. Attempted thermal reaction of Ir H h -
) ( )
MesHSi CH2 2 PPh2 PMe3 5
2
2
(
)
}
(
Ž
.
.
A Pyrex NMR tube 5 mm o.d. was charged with
2
Ž .
Ä
Ž
4
Ž
. Ž . Ž .
Ir H h -MesHSi CH2 2 PPh2 PMe3
5 8 mg , and
2
2
Ž
.
pressure to give a mixture of an isomeric pair of
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 moni-
tored by the H and P H NMR spectroscopy r.t. to
808C . No change was observed on the H and P H
NMR spectra at 808C for 12 h.
3
Ž .
Ä
Ž
.
Ž
.
4
Ž
.
Ir H h -CH 2C6 H 2 CH 3 2 SiH CH 2 2 PPh2 PMe3
2
Ž
.
6a and 6b . Crystallization from toluene–hexane at
y308C gave colorless crystals of 6a. Yield 0.13 g
1
31
Ä1
4
Ž
1
1
31
.
Ä1
4
Ž
.
Ž
.
53% . Data for 6a: H NMR 500 MHz, C6 D6 d
Ž
Ž
.
Ž .
s132.2 Hz, J HPcis s17.8 Hz,
y11.59 dt, J HP
trans
.
Ž
.
.
Ž
1H, IrH , 0.88, 1.50 m, 1H=2, SiCH2 , 1.23 d,
2
Ž
.
.
Ž
Ž
(
) {
h
2
J HP s7.8 Hz, 9H, PMe3 , 1.23 d, J HP s7.3 Hz,
2 . 1 3 .
MesHSi CH2 2 PPh2 PMe3
P h o t o l y s i s
o f
) ( )
I r H
-
.
Ž
.
(
)
}(
9H, PMe3 , 1.66, 2.56 m, 1H=2, PCH2 , 2.66, 3.28
5
2
Ž
Ž
Ž
.
Ž
.
m, 1H=2, IrCH2 , 2.35, 2.85 s, 6H, o-ArMe2 , 5.58
m, 1H, SiH , 6.90–7.55 m, 12H, ArH . C H NMR
75.5 MHz, C6 D6 d 3.3 dt, J CP
13
.
Ž
.
Ä1
4
Ž
.
.
A Pyrex NMR tube 5 mm o.d. was charged with
2
.
Ž
Ž
.
s61.4 Hz,
trans
Ž . Ž
Ž
4
Ž
. Ž . Ž .
5 8 mg , and
Ir H h -MesHSi CH2 2 PPh2 PMe3
2
2

(
)
6
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
Ž
.
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 photo reaction was
2.16. Thermal geometric isomerization of 6
Ž
.
A Pyrex NMR tube was charged with 6a 8 mg , and
monitored by H and 31 P NMR spectroscopy.
1
Ž
.
benzene-d6 0.7 ml was introduced into the tube under
vacuum by the trap-to-trap-transfer technique. The NMR
tube was flame-sealed under vacuum. The thermal geo-
metric isomerization at 608C was monitored periodically
by 1H NMR spectroscopy. After 3 h, the geometric
isomerization reached to an equilibrium with a ratio of
6a: 6bs5:3.
2
(
) (
) {
R h
2 .1 4 . T h e r m o ly s is
MesHSi CH2 2 PPh2 PMe3
the presence of PMe3
o f I r H
) ( ( )
-
(
)
}
(
( ))
RsMe 3 , Et 4 in
2
Ž
.
A Pyrex NMR tube 5 mm o.d. was charged with 3
or 4 and PMe3 5 equiv. via syringe, and benzene-d6
0.7 ml was introduced into the tube under high vac-
Ž
.
2.17. Thermal reaction of 6a with CO
Ž
.
uum by the trap-to-trap-transfer technique. The NMR
Ž
.
Ž
.
A C6 D6 solution 0.7 ml of 6a 8 mg was placed in
a 5 mm o.d. NMR tube, and CO was bubbled through
the solution via a needle. This sample was kept at 608C
in an oil bath, and the reaction was monitored periodi-
tube was flame-sealed. The tube was heated to 608C and
1
the reaction was monitored by H and 31 P NMR spec-
troscopy. The clean formation of 6 was observed.
1
cally by H NMR spectroscopy. The clean formation of
2
(
)( )
( ))
{
7 was observed.
2.15. Therm al reaction of Ir H
R
h -
(
)
}
(
) (
( )
MesHSi CH2 2 PPh2 PMe3 RsMe 3 , Et 4 with
2
2
CO
(
)( )
R
{
2.18. Therm al reaction of Ir H
h -
(
)
}
(
) (
)
MesHSi CH2 2 PPh2 PMe3
with MeOH
3: RsMe, 4: RsEt
2
Ž
.
A solution of 3 or 4 in C6 D6 0.7 ml was placed in a
5 mm o.d. NMR tube which was sealed by a septum.
Carbon monoxide was bubbled through the solution via
a needle at room temperature. The sealed NMR tube
Ž
.
A Pyrex NMR tube 5 mm o.d. was charged with 3
or 4 and MeOH 5 equiv. via syringe, and benzene-d6
0.7 ml was introduced into the tube under high vac-
uum by the trap-to-trap-transfer technique. The NMR
Ž
.
Ž
.
was heated to 608C and the reaction was monitored by
2
Ä
NMR spectroscopy. The formation of Ir h -
Ž
.
4
Ž
.Ž
.
Ž .
7 was confirmed
MesHSi CH2 2 PPh2 PMe3 CO
tube was flame-sealed. The reaction was monitored by
2
1H and P H NMR spectroscopy. The formation of
31
Ä1
4
Ž
Ž
Ž .
Ž ..
carried out as follows: A solution of Ir H Et h -
Ž . Ž
at 608C for 80 h 3 , 6 h 4 . The isolation of 7 was
2
2
Ž .Ž
.
0.15 g, 0.20 mmol
.Ä
Ž .
Ä
.
Ž
.
4
Ž
.
Ž .
8
Ir H h -Mes MeO Si CH2 2 PPh2 PMe3
at
Ž ..
4 was confirmed. The
2
2 Ž
Ž .
Ž
.
4
Ž
.
MesHSi CH2 2 PPh2 PMe3
4
608C for 80 h 3 , 6 h
2
in toluene was stirred under CO at 608C for 6 h, and the
resulting colorless solution was concentrated in vacuo.
Crystallization from toluene–hexane gave a white pow-
isolation of the product 8 was carried out as follows: A
Ž
.
Pyrex tube 20 mm o.d. was charged with
2
Ž .Ž . Ž . Ž
Ir H Et h -MesHSi CH2 2 PPh2 PMe3 4 0.29 g,
2
.
Ä
Ž
.
4
Ž
2
Ž
Ž
.
4
Ž
.Ž
.
Ž .
.
Ž
.
der of Ir h -MesHSi CH2 2 PPh2 PMe3 CO
7 .
0.40 mmol and MeOH 8.1 ml, 5 equiv. via syringe,
and benzene-d6 was introduced into the tube under high
vacuum by the trap-to-trap-transfer technique. The tube
was flame-sealed. The sample was placed in an oil-bath
at 608C for 6 h. The tube was opened in the glove bag,
and volatiles were removed under reduced pressure.
Crystallization of the residue from toluene–hexane gave
c r y s t a l s
Mes MeO Si CH2 2 PPh2 PMe3
2
1
Ž
.
Ž
.
Yield 0.11 g 80% . H NMR 300 MHz, C6 D6 d 0.89
Ž
Ž
.
.
Ž
Ž
d, J HP s9.4 Hz, 9H, PMe3 , 0.98, 1.15 m, 1H=2,
.
Ž
.
SiCH2 , 2.17 s, 3H, p-ArMe , 2.18, 2.66 m, 1H=2,
.
Ž
.
Ž
.
PCH2 , 2.70 s, 6H, o-ArMe2 , 5.38 m, 1H, SiH , 6.85
13
Ž
.
Ž
.
Ä
4
s, 2H, m-Mes , 6.97–7.61 m, 10H, ArH . C 1H
Ž
.
Ž
Ž
.
NMR 75.5 MHz, C6 D6 d 11.9 dd, J CP s27.0, 2.5
2
.
Ž
Ž
.
.
Ž
. Ä
h
2
Hz, SiCH2 , 21.1 dt, J CP s31.5, 4.3 Hz, PMe3 ,
c o l o r l e s s
o f
I r H
8 . Yield 0.23 g
-
Ž
.
Ž
.
Ž
Ž
.
Ž
.
Ž
.
4
Ž
.
Ž .
21.5 p-ArMe , 24.5 o-ArMe2 , 37.7 dd, J CP s
2
1
.
Ž
.
Ž
.
Ž
35.3, 8.8 Hz, PCH2 , 128.4, 128.5, 128.9, 129.3, 129.5,
78% . H NMR 300 MHz, C6 D6 d y12.79 dt,
Ž
.
Ž
Ž
.
Ž . .
s100.2 Hz, J HPcis s18.0 Hz, 1H, IrH ,
130.2, 132.1, 134.2, 137.5, 143.8 Ar , 185.3 dd,
J HP
trans
Ž
.
.
Ž
Ž
.
Ž
Ž
.
Ž .
s112.7 Hz, J HPcis s21.0 Hz,
J CP s27.5, 11.7 Hz, CO , 186.0 dd, J CP s31.1,
y11.46 dt, J HP
31
.
Ä1
4
Ž
.
.
Ž
traŽns
.
.
Ž
11.4 Hz, CO . P H NMR 121.5 MHz, C6 D6
d
.
d
1H, IrH , 1.20 d, J HP s7.5 Hz, 9H, PMe3 , 1.22 d,
Ž
Ž
.
.
Ž
Ž
Ž
.
.
Ž
y60.8 d, J PPcis s27.1 Hz, PMe3 , 31.6 d, J PPcis
J HP s8.3 Hz, 9H, PMe3 , 1.42, 1.52 m, 1H=2,
29
.
Ä1
4
Ž
.
.
Ž
.
Ž
Ž
s27.1 Hz, PPh2 . Si H NMR 59.6 MHz, C6 D6
SiCH2 , 2.10, 2.52 m, 1H=2, PCH2 , 2.24 s, 3H,
Ž
.
Ž
.
Ž Ž
Ž . .
.
Ž
.
13.1 dd, J SiP
s74.4 Hz, J SiPcis s9.6 Hz . IR
p-ArMe , 2.92 br. s, 6H, o-ArMe2 , 3.40 s, 3H,
SiOMe , 6.91 s, 2H, m-Mes , 6.98–7.14, 7.50–7.57,
7.77–7.83 m, 10H, PPh2 . C H NMR 75.5 MHz,
trans
y1
Ž
Ž
..
Ž Ž ..
.
Ž
.
KBr 2079 cm
v SiH , 1903, 1959 v CO . Mass
13
q
q
Ž
.
Ä1
4
Ž
.
Ž
.
Ž
.
DEI, 70 Ev mrz 686 11, M , 658 100, M –CO ,
q
Ž
.
.
Ž
.
Ž
Ž
.
630 54, M –2CO . Anal. found: C, 49.41; H, 5.38.
C28 H35IrO2 P2 Si. Calc.: C, 49.04; H, 5.14%.
C6 D6 d 21.0 p-ArMe , 21.4 dd, J CP s24.0, 7.9
.
Ž
Ž
.
Hz, SiCH2 , 22.7 ddd, J CP s29.2, 5.1, 3.3 Hz,

(
)
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
7
.
Ž
.
Ž
Ž
.
Ž .
Ž
.
PMe3 , 24.6 br. s, o-ArMe2 , 25.4 dt, J CP s25.1,
Eq. 3 . The IR spectrum shows a n IrH absorption in
the usual metal–hydrido region. The IrH resonance
appears in the 1H NMR spectrum as a doublet of triplets
at y9.41 ppm with one large trans and two identical
.
Ž
Ž
.
.
3.5 Hz, PMe3 , 34.1 dd, J CP s36.4, 10.2 Hz, PCH2 ,
Ž
Ž
.
.
49.5 d, J CP s5.0 Hz, SiOMe , 127.8, 128.4, 128.5,
129.0, 129.5, 132.1, 132.5, 133.4, 140.3, 140.4, 142.8,
31
Ž
.
Ä1
4
Ž
.
Ž Ž
.
s130 Hz,
143.6 Ar . P H NMR 121.5 MHz, C6 D6 d y63.0
cis P–H coupling constants J HP
trans
1
Ž
Ž
.
.
Ž
Ž
.
Ž
.
.
t, J PPcis s19 Hz, PMe3 , y55.3 t, J PPcis s19
J HPcis s17 Hz . The H NMR spectrum also contains
29
.
Ž
Ž
.
.
Ä1
4
s
Ž Ž
.
Hz, PMe3 , 33.3 t, J PPcis s19 Hz, PPh2 . Si H
a doublet of doub1et signal at 4.77 ppm J HH s1.9,
31
.
Ä1
4
Ž
.
Ž
.
Ž
Ž
.
NMR 59.6 MHz, C6 D6 d 46.2 ddd, J SiP
6.8 Hz assigned to that of SiH. The P H NMR
trans
Ž
.
.
146.2 Hz, J SiPcis s9.6, 6.5 Hz . IR KBr 2013
spectrum established that 1 possesses three phosphoros
atoms in a mer-geometry. The resonance of the PPh2
moiety in the P H NMR spectrum appears at 19.7
ppm as a doublet of doublets with one typical large
y1
cmy1 n IrH , 1066 cm
n Si–O . MS 70 eV,
Ž Ž ..
Ž Ž
..
Ž
31
q
Ä1
4
.
Ž
.
DEI mrz 738 21, M . Anal. found: C, 50.07; H,
Ž
.
6.63. C30 H48 IrOP3Si P 1r4 C6 H5CH3 . Calc.: C,
Ž Ž
.
s
50.11; H, 6.62%.
trans and one cis P–P coupling constants J PP
trans
329.0 Hz, J PPcis s11.1 Hz . In the 29Si NMR spec-
trum, the 29Si resonance appears at y19.8 ppm as a ddd
with three nearly identical cis Si–P coupling constants
Ž
.
.
2
(
) ( ) {
2 . 1 9 .
R e a c t i o n
)
o f
I r H C l h
-
(
}
(
) ( )
MesHSi CH2 2 PPh2 PMe3 1 with NaOMe
2
Ž Ž
.
.
J SiPcis s5.8, 6.7, 7.4 Hz . The structure of 1 was
also confirmed by the elemental analysis and mass
spectral data.
A single crystal of a geometric isomer of 1 suitable
for X-ray crystal structure analysis was obtained. Com-
plex 1 underwent geometric isomerization on photolysis
2
Ž .Ž
.
Ä
Ž
.
4
Ž
.
Ž . Ž
1
Ir H Cl h -MesHSi CH2 2 PPh2 PMe3
15
2
.
Ž
mg, 0.020 mmol and a MeOH solution of NaOMe 1.5
M, 40 ml, 3 equiv. was placed in a Pyrex NMR tube 5
mm o.d. connected to a vacuum line. Benzene-d6 0.7
ml was transferred into the NMR tube by the trap-to-
trap-transfer technique. The sample was flame-sealed
under vacuum. The clean formation of Ir H h -
MesHSi CH2 2 PPh2 PMe3
NMR spectroscopy.
.
Ž
.
Ž
.
Ž
Ž ..
to give 2 Eq. 4 . This photoreaction reached a photo-
stationary state within 2 h. The molar ratio of 1 to 2 is
29:71. Careful crystallization of the resulting solution
afforded colorless crystals of 2. The 31 P resonances for
the two nearly chemically equivalent PMe3 ligands
overlap each other and appear as a doublet at y48.9
2
Ž .
Ä
2
Ž
.
4
Ž
.
Ž .
5 was confirmed by
2
Ž Ž
.
3. Results and discussion
ppm with a cis P–P coupling constant J PPcis s19.5
.
Hz . Other spectroscopic data for 2 are similar to those
3.1. Preparation of chelate ligand precursor
for 1.
Ž
.
MesH2 Si CH2 2 PPh2 can be prepared as colorless
crystals according to the preparative method reported by
31
Ž
w
x
Ž ..
Ä1
4
Holmes-Smith et al. 15 , Eq. 2 . In the P H NMR
Ž .
3
spectrum, the signal of PPh2 appears at y11.3 ppm as
29
Ä1
4
.
a singlet. The Si H NMR spectrum shows a doublet
Ž Ž
.
at y43.4 ppm J SiP s23 Hz . These chemical shifts
are characteristic of RPPh2 and R2 SiH2 , respectively.
Ž .
2
Ž .
4
(
)(
)
3.2. Preparation of chloro hydrido hydrosilyl complex
1
Ž .
Heating the toluene solution of the cationic iridium I
w
Ž
.Ž
.
x
Ž
.
3.3. X-ray structure of complex 2
The geometry of 2 was unequivocally determined by
X-ray crystal structure analysis Fig. 1 . Selected bond
distances and angles are listed in Tables 3 and 4.
Although the hydrido ligand could not be located crys-
complex Ir CO PMe3 Cl with MesH2 Si CH2 2 PPh2
4
at 808C for 36 h in a sealed-tube resulted in the
formation of the relatively air-stable complex
2
Ž
.Ž .
Ä
Ž
.
4
Ž
.
Ž .
Ž
.
Ir Cl H h -MesSiH CH2 2 PPh2 PMe3
1 in 80%
2
Ž
Ž ..
yield as a white powder Eq. 3 . The IR and NMR
spectra of 1 strongly support the structure as shown in

(
)
8
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
Table 4
2
Ž .
8
Ž
.Ž .Ä
S e le c te d b o n d a n g le s
4Ž . Ž .
MesHSi CH2 2 PPh2 PMe3 2
2
fo r Ir H C l h -
Ž
.
Ž .
Ž .
95.4 1
88.9 1
Ž .
Ž .
87.8 2
Cl–Ir–P 1
Cl–Ir–P 2
Cl–Ir–Si
Ž .
Ž .
Ž .
Ž .
Ž .
175.2 2
Cl–Ir–P 3
Ž .
Ž .
Ž .
Ž .
Ž .
Ž .
98.5 1
P 1 –Ir–P 2
99.3 I
P 1 –Ir–P 3
Ž .
Ž .
Ž .
162.1 2
P 1 –Ir–Si
P 2 –Ir–Si
85.8 1
P 2 –Ir–P 3
Ž .
P 3 –Ir–Si
Ž .
Ž .
Ž .
95.5 2
87.5 2
usual metal–hydride region. The 1H NMR spectrum
Ž Ž
.
shows pseudo quartets at 0.43 ppm J HPcis s6.2 Hz,
.
3H , which is assigned to the signal of IrMe. The IrMe
resonance in the C H NMR spectrum appears as a
13
Ä1
4
ddd at y37.2 ppm with three nearly identical C–P cis
Ž Ž
.
.
coupling constants J CPcis s6.2, 8.8, 14.5 Hz . The
chemical shift is characteristic of carbon directly bound
to a transition-metal through a s-bond. The 31 P reso-
nance of the PPh2 moiety appears as a doublet of
doublets at 31.3 ppm with one large trans and small cis
Ž Ž
.
s 344.2 Hz,
P–P coupling constants J PP
tran s
2
Ž
.
.
J PPcis s15.8 Hz , which indicates that the three phos-
phorus atoms in 3 are located in a mer-geometry.
Recently, Aizenberg and Milstein reported the synthesis
Ž
. Ž . Ä
F ig . 1 . O R T E P
d ra w in g
4Ž . Ž .
MesHSi CH2 2 PPh2 PMe3
2
o f Ir H C l h
-
Ž
.
2 .
Ž
.Ž
.
Ž
.
of methyl hydrido silyl iridium III complexes fac-
tallographically, NMR data clearly indicate that the
hydrido ligand occupies the position opposite to the
PPh2 moiety. Therefore, one can easily see that the
coordination geometry around iridium is a slightly dis-
torted six-coordinate octahedron. The Ir–Si bond length
is relatively short compared to that of previously re-
Ž
.Ž .Ž .Ž
.
3
Ir Me H SiR3 PMe3 by the thermal reaction of
MeIr PMe3 with HSiR3 17 . In these complexes, a
strongly trans-influencing silyl ligand is located at the
Ž
.
w x
4
w
x
position trans to the PMe3 ligand 17,18 . In contrast,
surprisingly, the silyl ligand in 3 is located trans to the
strongly trans-influencing methyl ligand.
w
x
ported silyl–iridium compounds 1,2,16,17 . This may
be due to the coordination of a weakly trans-influenc-
ing chloro ligand opposite the silyl ligand.
Ethyl–hydrido complex 4 was also prepared as color-
less crystals in 62% isolated yield by adding EtMgBr to
1 in toluene at 488C Eq. 6 . The spectroscopic data
Ž .
support the geometry shown in Eq. 6 . The resonance
Ž
Ž ..
2
(
) (
) {
R h
3 . 4 .
S y n t h e s i s
o f
I r H
( )
-
13
Ä1
4
of IrCH2 in the C H NMR spectrum appears as
(
)
}
(
) (
( )
MesHSi CH2 2 PPh2 PMe3
( ))
5
RsMe 3 , Et 4 , H
2
a pseudo quartet at y18.3 ppm with three identical
Ž Ž
.
.
cis C–P coupling constants J CPcis s 7.1 Hz .
In the C–1H HETCOR spectrum, the 13C signal of
13
Methyl–hydrido complex 3 was prepared as colorless
crystals in 57% isolated yield by the reaction of 1 with
1
IrCH2 at y18.3 ppm correlates with the H signals at
1
1.03 and 1.49 ppm. In the H–1H COSY spectrum, the
Ž
Ž ..
MeLi in toluene at y488C Eq. 5 . The NMR and IR
signals of IrCH2 at 1.03 and 1.49 ppm correlate with
the signal at 2.00 ppm t, J HH s7.6 Hz, 3H , which
data are in good agreement with the structure shown in
Eq. 5 . The IR spectrum shows a v IrH band in the
Ž
Ž
.
.
Ž .
Ž
.
is assigned to IrCH2C H3.
Complex 1 reacted with LiAlH4 in THF to give a
Table 3
Ž
.
Ž
Ž ..
dihydridoiridium III complex 5 Eq. 7 . Crystalliza-
tion of 5 from toluene–hexane afforded a white powder
in 63% isolated yield. The spectroscopic data are con-
2
˚
Ž
.
Ž
.Ž .Ä
S elected b o n d d istan ces
4Ž Ž .
A
fo r Ir H C l
h
-
Ž
.
.
MesHSi CH2 2 PPh2 PMe3
2
2
Ž .
2.542 4
Ž .
Ž .
2.349 3
Ž .
2.336 4
Ir–Cl
Ir–P 1
Ž .
sistent with the geometry shown in Eq. 7 . The IrH
Ž .
Ž .
2.331 4
Ž .
Ir–P 2
Ir–Si
Ir–P 3
signals appear in the 1H NMR spectrum as two doublets
Ž .
2.352 5
y
y
Ž Ž
.
Ž
.
of triplets at y12.51 J HP
s106.2 Hz, J HPcis
Ž .
Ž
.
.
.
.
.
Ž .
Ž .
Ž
.
.
.
.
Ž .
1.85 2
P 1 –C 10
1.86 2
P 1 –C 16
P 2 –C 24
P 2 –C 26
P 3 –C 28
tranŽs Ž
.
Ž .
Ž
Ž .
Ž .
Ž
Ž .
1.87 2
P 1 –C 22
1.89 2
.
s15.6 Hz and y11.93 ppm J HP
s113.4 Hz,
trans
Ž .
Ž
Ž .
Ž .
Ž
Ž .
1.86 2
P 2 –C 25
1.85 2
Ž
.
.
J HPcis s20.7 Hz splitted by P–H couplings. The
Ž .
Ž
Ž .
Ž .
Ž
Ž .
1.83 2
31
P 3 –C 27
1.81 2
Ä1
4
P H NMR spectrum exhibits signals of three in-
equivalent mutually coupled phosphorus atoms with
nearly identical cis P–P coupling constants, which es-
Ž .
Ž
Ž .
P 3 –C 29
1.82 2
y
y
Ž .
Si–C 1
Ž .
1.93 1
Ž
.
Ž .
1.93 1
Si–C 23

(
)
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
9
tablishes that 5 possesses three phosphorus atoms in a
Ž .
fac-relationship as shown in Eq. 7 .
Ž .
5
1
Ä31
Fig. 2. H P NMR spectrum of 6a.
4
Ž .
6
trum, the 13C signal of IrCH2 at 3.3 ppm correlates with
1
two H signals at 2.66 and 3.28 ppm. Furthermore, the
1
Ä31
4
P NMR spectrum
resonance of IrCH2 in the
H
appears as an AB splitting pattern as shown in Fig. 2.
The 29Si H NMR spectrum shows a ddd signal at 21.7
Ä1
4
ppm with one large trans and two nearly identical cis
Ž Ž
.
Ž
.
coupling constants J SiP
s131.1 Hz, J SiPcis s
trans
Ž .
7
.
10.7, 7.9 Hz . The NMR data for 6b are similar to those
for 6a.
In contrast to complexes 3 and 4, complex 5 is
Ž
Ž ..
thermally stable at 808C for 12 h Eq. 9 . This order of
thermal stability is in accordance with that of the typical
Ž
. w x
bond strength of LnM-X XsH)Me)Et 20 . We
2
(
( )
)( )
R
{
Ž
Ž ..
3.5. Therm al reactions of Ir H
h -
carried out the photolysis of 5 in C6 D6 Eq. 9 . The
reaction proceeded with the evolution of H2 to give
several unidentified products. The formation of H2 was
(
)
}
(
) (
( ) ( ))
MesHSi CH2 2 PPh2 PMe3 RsMe 3 , Et 4 , H 5
2
confirmed by 1H NMR spectroscopy 4.46 ppm in
Ž
Thermolysis of 3 at 608C for 80 h resulted in the
clean formation of 6 via reductive elimination of
methane and the intramolecular carbon–hydrogen bond
activation Eq. 8 . The H NMR spectrum contains a
very sharp singlet at 0.15 ppm, which is assigned to free
CH4 in C6 D6. The thermal reaction of 4 proceeded
.
C6 D6 .
1
Ž
Ž ..
Ž
.
more quickly 608C, 6 h to give the same product 6.
The evolution of ethane was also confirmed by 1H
Ž
.
NMR spectroscopy 0.79 ppm in C6 D6 . Interestingly,
complex 4 is inert to b-hydrogen elimination under
these conditions, although many transition-metal ethyl
complexes are known to undergo b-hydrogen elimina-
Ž .
8
w
x
tion even at room temperature 19 . Product 6 was a
mixture of the geometric isomers 6a and 6b in the ratio
of 5:3. Recrystallization of 6 from toluene–hexane at
y308C gave colorless crystals of only 6a. The spectro-
scopic data clearly support the geometries of 6a and 6b
Ž .
shown in Eq. 8 . The arrangement of three coordinating
Ž
.
atoms C, Si, and P of the tridentate ligand around Ir III
are facial for 6a and meridional for 6b. The C H
13
Ä1
4
spectrum of 6a contains a doublet of triplets at d 3.3
Ž Ž
.
Ž . .
s61.4 Hz, J CPcis s4.7 Hz , which
ppm J CP
trans
can be assigned to the methylene carbon directly bound
13
to the iridium center. In the C–1H HETCOR spec-
Ž .
9

(
)
10
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
Ž
Ž
..
3.6. Attempted reaction of 3 or 4 with PMe3
equilibrium with the ratio of 6a and 6bs5:3 Eq. 11 .
Several octahedral, tertiary phosphine complexes are
known to undergo geometric isomerization on photoly-
sis or thermolysis. In most cases, the mechanism in-
volves the dissociation of a phosphine ligand, and the
addition of tertiary phosphine retards the isomerization
In a previous paper, we described the generation of a
2
Ä
Ž
.
4
Ž
.
16e-Ir h -M e 2 Si CH 2 2 PPh 2 PM e 3
from
2
2
Ž .Ž .
Ä
Ž
.
4
Ž
.
Ž
.
RsMe, Et
Ir H R h -Me2 Si CH2 2 PPh2 PMe
w
3 x2
via reductive elimination of alkane 21 . We succeeded
in trapping the 16e-Ir h -Me2 Si CH2 2 PPh2 PMe3
.
by adding PMe3 as Ir h -Me2 Si CH2 2 PPh2 PMe3
3
2
Ä
Ž
Ž
.
4
4
Ž
.
w
x
24 . Interestingly, addition of 5 equiv. of trimeth-
ylphosphine did not retard the isomerization of 6a.
2
.
2
Ä
.
Ž
Therefore, we also carried out the thermal reactions of 3
and 4 with excess PMe3 at 608C. Even in the presence
of PMe3, intramolecular carbon–hydrogen bond activa-
Ž
.
11
tion took place in both reactions to give 6 quantita-
2
Ä
tively. The formation of a PMe3 adduct Ir h -
Ž
.
4
Ž
.
MesHSi CH2 2 PPh2 PMe3 was not observed, be-
3
3.9. Thermal reaction of 6a with CO
cause 6 is thermodynamically more stable than the
PMe3 adduct due to the chelate effect.
The thermal reaction of 6a with CO proceeded at
Ž .
Ž
608C to give a dicarbonyliridium I complex 7 Eq.
3.7. Thermal reaction of 3 or 4 with CO
Ž
..
12 . The observation is consistent with the hypothesis
that the C–H bond oxidative addition is reversible at
The reactions of 3 and 4 were carried out in the
presence of more sterically favorable carbon monoxide.
The reaction proceeded at 608C cleanly to give a dicar-
2
Ä
Ž
.
4
Ž
.
Ž .
A
2
608C between Ir h -MesHSi CH2 2 PPh2 PMe3
Ž
.
and 6 see Scheme 1 . Recently, Aizenberg and Milstein
reported the reversible ortho-metalation of the transient
2
Ž .
Ä
b o n y l i r i d i u m
I
c o m p l e x
I r h
-
2
Ž
.
Ž
.
Ž
.
Ä
Ž
Me3P Ir SiMe2 Ph to give fac- Me3P Ir h - o-
4
3
3
Ž
.
4
Ž
. Ž
. Ž . Ž
Ž
..
MesHSi CH2 2 PPh2 CO PMe3
7
Eq. 10 . The
2
.4Ž . w x
C6 H4SiMe2 H 23 . Importantly, in the course of the
2
Ä
formation of
MesHSi CH2 2 PPh2 CO PMe3 was not observed.
a monocarbonyl compound Ir h -
reaction, the isomerization to 6b was completely inhib-
ited, which seems to demonstrate that the geometric
isomerization between 6a and 6b takes place via the
intermediate A.
Ž
.
4
Ž
.Ž
.
2
Assignment of the coordination geometry of 7 is based
on the NMR and IR spectroscopic data. The IR spec-
Ž
.
trum shows two n CO bands in the terminal carbonyl
13
y1
Ž
.
Ä1
4
region 1959, 1903 cm . In the C H NMR spec-
trum, the signals of two carbonyl ligands appear in-
Ž Ž
.
.
equivalently at 185.3 ppm J HP s27.5, 11.7 Hz and
Ž Ž
.
.
186.0 ppm J HP s31.1, 11.4 Hz as two doublets of
doublets. In agreement with the cis geometry of two
phosphorus atoms, the signal of a PMe3 ligand in the
31
Ä1
4
P H NMR spectrum appears at y60.8 ppm as a
Ž Ž
.
s
doublet with a P–Pcis coupling constant J PPcis
27.1 Hz . The 29Si resonance shows a doublet of dou-
Ž
.
12
.
blets at 13.1 ppm coupled with one trans and one
31
Ž Ž
.
Ž . .
s74.4, J SiPcis s9.6 Hz .
cis- P nuclei J SiP
3.10. A possible formation mechanism of 6 and 7
trans
Scheme 1 shows one possible mechanism that allows
the formation of 6 and 7. Complex 3 or complex 4
eliminates the corresponding alkane via reductive elimi-
Ž
.
10
Ž .
nation to give a 16e-silyliridium I complex A. In the
absence of any trapping agent, A activates an intra-
molecular C–H bond to give 6 reversibly. In the pres-
ence of carbon monoxide, CO traps the intermediate A
Ž .
to give a dicarbonyliridium I complex 7. Aizenberg
3.8. Thermal geometric isomerization of 6
w
x
w x
and Milstein 17 and also Mitchell et al. 25 indepen-
dently described the generation of unsaturated silylirid-
ium I complexes that undergo intramolecular carbon–
hydrogen bond activation to give silyliridium III com-
plexes. These results suggest that unsaturated silylirid-
Thermolysis of isolated complex 6a at 608C resulted
in geometric isomerization to 6b which reached to an
Ž .
Ž
.
4
Ž .
ium I species should be quite reactive compared with
Ž
.
Ž .
The synthesis of silyldicarbonylbis tertiary phosphine iridium I
other four-coordinate complexes of d8 metals.
w
x
complexes is reported in Refs. 22,23 .

(
)
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
11
Scheme 1.
3.11. Thermal reactions of 3 or 4 with MeOH
likely to demonstrate the facile migration of a hydrogen
from the silyl silicon atom to the iridium center.
An alternative mechanism involving the generation
Complexes 3 and 4 reacted with MeOH at 608C to
Ž
.
Ž
.
Ž
.
Ž
.
give a dihydrido methoxysilyl iridium III complex
of a hydrido methoxy iridium III complex C could be
considered as shown in Scheme 3. According to path A,
intermediate C undergoes reductive elimination of the
2
Ž .
Ä
Ž
.
Ž
.
4
Ž
.
Ž . Ž
Ir H h -Mes MeO Si CH2 2 PPh2 PMe3
13 . The formation of the corresponding alkane was
confirmed by H NMR spectroscopy. The IR and NMR
8 Eq.
2
Ž
..2
1
Ž .
Si–OMe bond to give the chelate-ring-opened iridium I
Ž
.
data clearly support the geometry depicted in Eq. 13 .
intermediate D. Subsequently, intramolecular Si–H ox-
idative addition takes place to give 8. By path B, the
intermediate C loses a PMe3 ligand and then undergoes
a 1,2-H-shift to give a silylene species E. The interme-
diate E causes the migration of the methoxy ligand on
the silylene silicon atom and the ligation of PMe3 to
give 8. Esteruelas et al. described the reaction of
Ž
.
The IR spectrum shows a n Si–O absorption at 1066
1
cmy1. The H NMR spectrum exhibits a singlet at 3.40
31
Ä1
4
ppm assigned to SiOMe. The P H NMR spectrum
established that 8 has three phosphorus atoms in a
fac-relationship. The 31 P resonance of the PMe3 ligand
trans to the silyl moiety appears as a pseudo-triplet at
y63.0 ppm coupled with two cis 31 P nuclei. The
Ž .Ž
. Ž . Ž
.
Ir H SiHPh2 CO PCy3 with ROH. They proposed
2
2
29
Ä1
4
Si H NMR spectrum contains a ddd at 46.2 ppm
a mechanism comprising the initial generation of
Ž Ž
.
.
Ž .Ž .Ž
.Ž
.
coupled with one trans J SiP
s146.2 Hz and
Ir H OR SiHPh2 CO followed by the 1,2-H-shift to
trans
2
two cis 31 P nuclei J SiPcis s9.6, 6.5 Hz . In the
NOESY spectrum, the 1H NMR signal of a SiOMe
moiety correlates with the signal of a PMe3 ligand trans
to IrH, which is consistent with the geometry in Eq.
Ž Ž
.
.
Ž
.
13 .
One possible mechanism for the formation of 8 is
illustrated in Scheme 2. In this mechanism, it is as-
sumed that the intermediate A is in quick equilibrium
Ž
.
with a hydrido silylene complex B through the re-
versible 1,2-H-shift from the silyl silicon atom to the
unsaturated iridium center of A. In the presence of
MeOH, MeOH attacks the silylene silicon atom of B
Ž
.
nucleophilically to afford a methoxysilyl iridium III
complex 8. MeOH is known to be an effective trapping
w
x
agent for silylene complexes 26 , since the M5Si bond
is fairly polarized in the MdySidq fashion 27,28 .
Introduction of a methoxyl group to the silicon atom is
Ž
w
x.
Scheme 2.

(
)
12
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
Ž
.
14
A listing of additional bond distances, bond angles,
thermal parameters, and tables of observed and calcu-
lated structure factors is available from the authors.
4. Conclusion
Scheme 3.
Ž
.Ž
.
Ž
.
Thermolysis of alkyl hydrido hydrosilyl iridium III
2
Ž .Ž . .
Ä
Ž
.
4
Ž
complexes Ir R H h -MesHSi CH2 2 PPh2 PMe3
R5Me 3 , Et 4 proceeded by reductive elimination
of alkane to give the transient unsaturated silyliridium I
complex Ir h -MesHSi CH2 2 PPh2 PMe3 A . Reac-
2
w
Ž .
Ž .x
Ž .
2
Ä
Ž
.
4
Ž
. Ž .
2
tive intermediate A activated the intramolecular car-
Ž . Ž .Ž .
give a silylene intermediate Ir H OR 5SiPh2 CO
2
as in path B 10 .
To get information about the possibility of Scheme 3,
we carried out the reaction of 1 with NaOMe. Transi-
tion-metal chloro complexes are known to give alkoxy
.Ž
2
3
Ž
.Ž
bon – hydrogen bond to give Ir H h -
w
x
Ž
.
Ž
.
4
Ž
.
Ž .
6 . In the
CH2C6 H2 CH3 2 SiH CH2 2 PPh2 PMe3
2
presence of MeOH, A reacted with MeOH to give a
2
Ž
.
Ž
.
Ž .
Ä
dihydrido methoxysilyl iridium III complex Ir H h -
2
Ž
.
Ž
.
4
Ž
.
Ž .
8 . The latter ob-
Mes MeO Si CH2 2 PPh2 PMe3
2
w
x
complexes on addition of NaOR 29 . The reaction
proceeded at room temperature to give a dihydrido
servation clearly supports facile and reversible 1,2-
migration of hydrogen on A from the silyl silicon atom
Ž
.
Ž .
5 quantitatively Eq. l4 .
1
iridium III complex
to the unsaturated iridium center to give the
Formaldehyde was detected by H NMR spectroscopy.
Hydrido–methoxy complexes are known to cause b-hy-
drogen elimination to give a dihydrido complex and
2
Ž
.
Ž
. Ä
h y d rid o s ily le n e
c o m p le x
. Ž .
2
Ir H h
-
Ž
.
4
Ž
MesSi CH2 2 PPh2 PMe3
conditions.
B under relatively mild
w
x
formaldehyde 30 . In this reaction, the formation of 8
was not observed at all. Based on these observations we
could rule out the mechanism involving the generation
Ž
.
of a hydrido–methoxy iridium III complex.
Acknowledgements
This work was supported by the Kurata research
grant from the Kurata Foundation.
References
w x
1
T.D. Tilley, The Chemistry of Organic Silicon Compounds, in:
Ž
.
S. Patai, Z. Rappoport Eds. , Wiley, New York, 1989, p. 1415.
T.D. Tilley, The Silicon-Heteroatom Bond, in: S. Patai, Z.
w x
2
Ž
.
Rappoport Eds. , Wiley, New York, 1991, pp. 245 and 309.
w x
3
Ž
.
J.Y. Corey, Advances in Silicon Chemistry, in: G. Larson Ed. ,
JAI Press, Greenwich, CT, 1991, p. 327.
Ž
.
13

(
)
M. Okazaki et al.rJournal of Organometallic Chemistry 553 1998 1–13
13
w x
Ž
.
w
w
w
x Ž .
4
M.D. Curtis, P.S. Epstein, Adv. Organomet. Chem. 19 1981
213.
16 M.K. Hays, R. Eisenberg, Inorg. Chem. 30 1991 2623.
x Ž .
17 M. Aizenberg, D. Milstein, J. Am. Chem. Soc. 117 1995 6456.
w x
5
x
18 R.N. Haszeldine, R.V. Parish, J.H. Setchfield, J. Organomet.
H. Handwerker, C. Leis, R. Probst, P. Bissinger, A. Grohman,
P. Kiprof, E. Herdtweck, J. Blumel, N. Auner, C. Zybill,
Ž
.
Chem. 57 1973 279.
¨
Ž
.
w
w
w
w
x
Organometallics 12 1993 2162.
19 R.H. Crabtree, The Organometallic Chemistry of the Transition
w x
6
B.P.S. Chauhan, R.J.P. Corriu, G.F. Lanneau, C. Priou,
Metals, Wiley, New York, 1993.
Ž
.
x
Ž
.
.
Organometallics 14 1994 1657.
20 H.E. Bryndza, J.E. Bercaw, J. Am. Chem. Soc. 109 1987
1444.
21 M. Okazaki, H. Tobita, H. Ogino, Organometallics 15 1996
2790.
w x
7
Ž
.
I. Ojima, S. Inaba, T. Kogure, J. Organomet. Chem. 55 1973
x
Ž
C7.
w x
8
T. Sakakura, O. Kumberger, R.P. Tan, M.-P. Arthur, M. Tanaka,
Ž
.
x
J. Chem. Soc. Chem. Commun. 1995 193.
22 M.J. Auburn, S.L. Grundy, S.R. Stobart, M.J. Zaworotko, J.
w x
9
Ž
.
Ž .
Am. Chem. Soc. 107 1985 266.
P. Burger, R.G. Bergman, J. Am. Chem. Soc. 115 1993
w
w
w
x
Ž
.
10462.
23 M. Aizenberg, D. Milstein, Organometallics 15 1996 3317.
24 G.L. Geoffroy, Prog. Inorg. Chem. 27 1980 123.
x
25 G.P. Mitchell, T.D. Tiley, G.P.A. Yap, A.L. Rheingold,
w
w
x
x Ž .
10 M.A. Esteruelas, F.J. Lahoz, M. Olivan, E. Offate, L.A. Oro,
Ž
.
Organometallics 13 1994 4246.
x
Ž .
Organometallics 14 1995 5472.
11 M. Okazaki, Y. Kawano, H. Tobita, S. Inomata, H. Ogino,
Ž
.
w
w
x
Ž
.
Chem. Lett. 1995 1005.
26 K. Ueno, H. Tobita, S. Seki, H. Ogino, Chem. Lett. 1993
w
w
x
Ž
.
12 M. Okazaki, H. Tobita, H. Ogino, Chem. Lett. 1996 477
1723.
x
x
27 H. Nakatsuji, J. Ushio, T. Yonezawa, J. Organomet. Chem. 258
13 G.R. Gillette, H.B. Yokelson, R. West, Organometallic Synthe-
Ž
.
Ž
.
Ž
.
ses, in: R.B. King, J.J. Eisch Eds. , Elsevier, Vol. 4 1988 p.
529.
1983 C1.
w
w
w
x
Ž
.
28 H. Jacobsen, T. Ziegler, Inorg. Chem. 35 1996 775.
29 H.E. Bryndza, W. Tam, Chem. Rev. 88 1988 1163.
x Ž .
30 O. Blum, D. Milstein, J. Am. Chem. Soc. 117 1995 4582.
w
w
x
Ž
.
x Ž .
14 J.A. Labinger, J.A. Osborn, Inorg. Synth. 18 1978 62.
x
15 R.D. Holmes-Smith, R.D. Osei, S.R.J. Stobart, Chem. Soc.
Ž
.
Perkin. Trans. 1983 861.