Hydrosilylation of carbonyl compounds with hydrosilyliron complexes catalyzed by cationic silyleneiron complexes

Article abstract of DOI:10.1021/om100398u

A hydride abstraction from the hydrosilyliron complexes Cp(OC) ₂FeSiR₂H (Cp = η⁵-C₅H ₅, R = p-tolyl (1a), Me (1b)) in CD₃CN afforded cationic silyleneiron complexes [Cp(OC)₂Fe=Si

Full text of DOI:10.1021/om100398u

Organometallics 2010, 29, 5423–5426 5423
DOI: 10.1021/om100398u
Hydrosilylation of Carbonyl Compounds with Hydrosilyliron Complexes
Catalyzed by Cationic Silyleneiron Complexes^
Takako Muraoka,† Yuusaku Shimizu,† Hideki Kobayashi,‡ Keiji Ueno,*,† and
Hiroshi Ogino§
†Department of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University,
1-5-1 Tenjin-cho, Kiryu 376-8515, Japan, ‡Department of Chemistry, Graduate School of Science,
Tohoku University, Aoba-ku, Sendai 980-8578, Japan, and The Open University of Japan,
Wakaba 2-11, Mihama-ku, Chiba 261-8586, Japan
§
Received May 1, 2010
A hydride abstraction from the hydrosilyliron complexes Cp(OC)2FeSiR2H (Cp = η5-C5H5, R = p-tolyl
(1a), Me (1b)) in CD3CN afforded cationic silyleneiron complexes [Cp(OC)2FedSiR2(NCCD3)][B(Arf)4]
(Arf=3,5-bis(trifluoromethyl)phenyl, R=p-tolyl (2a), Me (2b)). The cationic silylene complexes 2 cata-
lyzed hydrosilylation of aldehydes and ketones with 1 to give the corresponding alkoxysilyliron complexes
3-5 in moderate to high yield.
Introduction
as a catalyst for hydrosilylation.6 Tilley et al. reported
recently that cationic silyleneruthenium and -iridium com-
plexes show catalytic activity for hydrosilylation of alkenes
and carbonyl compounds with monosubstituted silanes
RSiH3.6
Transition metal silylene complexes1 have attracted much
attention because they have been proposed as an intermedi-
ate in dehydrogenative condensation of organosilicon
compounds,2 redistribution of substituents on organosilicon
compounds,3 and conversion of origosilanylmetal com-
plexes to monosilyl derivatives.4 Silylene complexes have
also been suggested as an intermediate or transition state in
catalytic hydrosilylation.5 However, there are only a few
reports on the application of well-defined silylene complexes
We previously reported the synthesis of cationic base-
stabilized silyleneiron complexes [Cp(OC)2FedSi(p-tolyl)2-
(HMPA)]þ and [Cp(OC)2FedSiMe{(2-CH2NMe2)C6H4}]þ
(Cp=η5-C5H5, HMPA = P(O)(NMe2)3) by a hydride abstrac-
tion from hydrosilyliron complexes Cp(OC)2FeSiH(p-tolyl)2
(1a) and [Cp(OC)2FeSiHMe{(2-CH2NMe2)C6H4}], res-
pectively.7 The silylene complex coordinated by CD3CN
[Cp(OC)2FedSi(p-tolyl)2(CD3CN)][B(Arf)4] (2a, Arf = 3,5-bis-
(trifluoromethyl)phenyl) was also obtained by a hydride abstrac-
tion from 1a with1 equiv of Ph3CB(Arf)4 in CD3CN. During the
course of the study on the reactivity of these silyleneiron com-
plexes, we found that 1a was converted to alkoxysilyliron
complexes by treatment with ketones in the presence of a
catalytic amount of 2a.
Hydrosilylation catalyzed by transition metal complexes is
one of the most powerful tools for synthesis of organosilicon
compounds and silicon polymers and has been applied for
various combinations of hydrosilanes and unsaturated or-
ganic substrates containing CdC, CtC, CtN, and CdO
bonds.8 However, there are almost no examples of catalytic
^ Part of the Dietmar Seyferth Festschrift. This paper is dedicated to
Professor Dietmar Seyferth for his dedicated service to Organometallics
and to the field of organometallic chemistry.
*To whom correspondence should be addressed. Tel & Fax: þ81-277-
30-1260. E-mail: ueno@chem-bio.gunma-u.ac.jp.
(1) (a) Tilley, T. D. In The Chemistry of Organosilicon Compounds;
Patai, S., Rappoport, Z., Eds.; Wiley: New York, 1989; p 1415. (b) Tilley,
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New York, 1991; pp 245 and 309. (c) Ogino, H. Chem. Rec. 2002, 2, 291. (d)
Okazaki, M.; Tobita, H.; Ogino, H. Dalton Trans. 2003, 493. (e) Waterman,
R.; Hayes, P. G.; Tilley, T. D. Acc. Chem. Res. 2007, 40, 712.
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Organomet. Chem. 1971, 27, C31. (c) Okinoshima, H.; Yamamoto, K.;
Kumada, M. J. Am. Chem. Soc. 1972, 94, 9263. (d) Okinoshima, H.;
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r
2010 American Chemical Society
Published on Web 07/19/2010
pubs.acs.org/Organometallics

5424 Organometallics, Vol. 29, No. 21, 2010
Muraoka et al.
and stoichiometric hydrosilylation directed to the functio-
nalization of hydrosilyl fragments in transition metal silyl
complexes.9
in 77% yield with a concomitant formation of unidentified
organic compounds (eq 4).
In this paper, we report the details of the hydrosilylation of
aldehydes and ketones with hydrosilyliron complexes 1
catalyzed by cationic silyleneiron complexes 2.
Results and Discussion
Dimethylsilyleneiron complex [Cp(OC)2FedSiMe2(NCCD3)]-
[B(Arf)4] (2b) was obtained almost quantitatively by the reac-
tion of Cp(OC)2FeSiMe2H (1b) and 1 equiv of Ph3CB(Arf)4 in
CD3CN, in a similar manner to the synthesis of 2a (eq 1). The
29Si NMR spectrum of 2a or 2b afforded a signal assignable to
the silylene fragment at 77.1 or 93.7 ppm, respectively. These
are in the range of the reported resonances for the base-
stabilized aryl- and alkyl-substituted silyleneiron complexes
(74-160 ppm).7,10
Catalytic hydrosilylation of acetone with 1a was achieved
by the following two steps: (i) addition of 0.1 equiv of
Ph3CB(Arf)4 to 1 equiv of 1a in CD3CN to afford a CD3CN
solution containing 0.9 equiv of 1a, 0.1 equiv of 2a, and 0.1
equiv of Ph3CH, and (ii) addition of 1.1 equiv of acetone to
the reaction mixture (eq 2). The NMR spectrum of the
resultant mixture revealed that it comprised Cp(OC)2FeSi-
(p-tolyl)2(OCHMe2) (3a) in 90% NMR yield and 0.1 equiv of
2a. No reactions took place between 1a and acetone in the
absence of 2a and between Ph3CB(Arf)4 and acetone in
CD3CN. Complex 2b was also relevant to the hydrosilylation
of acetone with hydrosilyliron complex 1b to afford Cp-
(OC)2FeSiMe2(OCHMe2) (3b) in 71% yield (eq 2). Benzo-
phenone and benzaldehyde were hydrosilylated by 1b in the
presence of 0.1 equiv of 2b to provide Cp(OC)2FeSiMe2-
(OCHPh2) (4) and Cp(OC)2FeSiMe2(OCH2Ph) (5) in 80%
and 83% NMR yields, respectively (eq 3). In contrast, the
reaction of 1b with methyl vinyl ketone under similar reaction
conditions afforded not the expected alkoxysilyliron complex but
O(SiMe2)2-bridged dimetallic complex [Cp(OC)2FeSiMe2]2O (6)
The catalytic hydrosilylation should proceed via activa-
tion of the CdO bond as a crucial process. It is well known
that the silylene fragment in transition metal silylene com-
plexes is electron deficient due to the low orbital overlapping
between the empty p orbital on Si and the filled dπ orbital on
the metal.1a Actually, silylene complexes 2 are stabilized by
the coordination of a Lewis base CD3CN on the silylene
fragment. Ketones and aldehydes could also coordinate to
the electron-deficient Si to give the corresponding silylene
complexes [Cp(OC)2FedSiR2(OdCR1R2)]þ (A), which con-
sequently activates the carbonyl compounds. A similar activa-
tion process via coordination of carbonyl compounds to a
cationic silyl fragment (silylium ion) was previously proposed
as a key step in the B(C6F5)3-catalyzed hydrosilylation.11 The
silylene complexes A were not observed by NMR; however,
formation of such complexes is strongly supported by the fact
that addition of 1 equiv of PPh3 to a mixture of silylene
(9) (a) Pannell., K. H.; Rozell, J. M.; Lii, J.; Tien-Mayr, S.-Y.
Organometallics 1988, 7, 2524. (b) Tanabe, M.; Osakada, K. Organome-
tallics 2001, 20, 2118.
(10) (a) Zybill., C.; Wilkinson, D. L.; Leis, C.; Muller, G. Angew.
Chem., Int. Ed. Engl. 1989, 28, 203. (b) Tobita, H.; Ueno, K.; Shimoi, M.;
Ogino, H. J. Am. Chem. Soc. 1990, 112, 3415. (c) Leis, C.; Wilkinson, D. L.;
Handwerker, H.; Zybill, C.; Muller, G. Organometallics 1992, 11, 514. (d)
Corriu, R. J. P.; Chauhan, B. P. S.; Lanneau, G. F. Organometallics 1995, 14,
1646. (e) Chauhan, B. P. S.; Corriu, R. J. P.; Lanneau, G. F.; Priou, C.; Auner,
N.; Handwerker, H.; Herdtweck, E. Organometallics 1995, 14, 1657. (f)
Ueno, K.; Nakano, K.; Ogino, H. Chem. Lett. 1996, 459. (g) Tobita, H.;
Kurita, H.; Ogino, H. Organometallics 1998, 17, 2850. (h) Tobita, H.; Sato,
T.; Okazaki, M.; Ogino, H. J. Organomet. Chem. 2000, 611, 314. (i) Sato, T.;
Okazaki, M.; Tobita, H. Chem. Lett. 2004, 868.
(11) (a) Parks, D. J.; Piers, W. E. J. Am. Chem. Soc. 1996, 118, 9440.
(b) Parks, D. J.; Blackwell, J. M.; Piers, W. E. J. Org. Chem. 2000, 65, 3090.

Article
Organometallics, Vol. 29, No. 21, 2010 5425
Scheme 1. Plausible Reaction Mechanism for the Silyleneiron
Complex-Catalyzed Hydrosilylation of Carbonyl Compounds
Chart 1
abstraction from 1 by complex A affords hydrosilylation
products 3-5 and regenerates silyleneiron complex 2.
Complex 6, obtained by the reaction with methyl vinyl
ketone (eq 4), would be provided via the following catalytic
mechanism: (i) formation of cationic disilyloxoniumdiiron
complex [{Cp(OC)2FeSiMe2}2{μ-OCH(CH3)CHdCH2}]þ
(Chart 1, B) from silyleneiron complex 2b and transiently
produced alkoxysilyl complex Cp(OC)2FeSiMe2(OCH-
(CH3)CHdCH2), (ii) immediate decomposition of B to
complex 6 and allylic cation (CH2dCHCHCH3þ), and (iii)
hydride abstraction by the allylic cation from complex 1b to
regenerate silyleneiron complex 2b.13 The allylic cation
would be converted to butene; however, it and related species
were not detected in 1H NMR or mass spectra. The forma-
tion of a cationic disilyloxoniumdiiron intermediate such as
B is further indicated by the fact that the alkoxyl group
transfer reaction takes place from the alkoxysilyliron complex
to the cationic silyleneiron complex, i.e., addition of 3a to
[(η5-MeC5H4)Fe(CO)2dSi(p-tolyl)2(NCCD3)][B(Arf)4] (2a0)
in CD3CN instantaneously gave a mixture of four silylene/
silyl iron complexes: 3a, 2a0, 2a, and (η5-MeC5H4)Fe(CO)2Si-
(p-tolyl)2(OCHMe2) (3a0) (eq 6).14
complexes 2 and acetone immediately afforded PPh3-incorpo-
rated complexes [Cp(OC)2FeSiR2{OC(PPh3)Me2}]þ (R =
p-tolyl (7a), Me (7b)) in high yield (eq 5). In the 13C{1H}
NMR spectrum of 7a or 7b, a doublet signal assignable to the
PPh3-introduced carbon was observed at 82.9 (1JPC = 64.8 Hz)
or 82.1 (1JPC = 66.2 Hz) ppm, respectively. These chemical
shifts and coupling constants are comparable to those observed
for [RCH(OSiMe3)PPh3]þ (R = H, Et, Ph, and 4-MeC6H4,
58-74 ppm, 1JPC = 62-70 Hz).12 The 29Si{1H} NMR spec-
trum of 7a or 7b also showed a doublet signal at 61.1 (3JPSi
10.8) or 76.5 (3JPSi = 7.3) ppm, respectively.
=
Experimental Section
General Procedures. All manipulations were performed using
either standard Schlenk tube techniques under nitrogen, vacuum
line techniques, or a drybox under nitrogen. Cp(OC)2FeSiR2H
(R = p-tolyl (1a),15 Me (1b)16), Cp(OC)2FeSiMe2Cl,16 and
Ph3CB(Arf)4 (Arf = 3,5-bis(trifluoromethyl)phenyl)17 were pre-
pared according to the published procedures. Acetone was dried
over Drierite followed by distillation under a nitrogen atmosphere
before use. Benzaldehyde, ethyl acetate, and methyl acetate were
The formation of complex 7 shows the strong electrophilic
character of the carbonyl carbon atom in A. The electro-
philicity of the carbonyl carbon is very important to drive the
catalytic cycle since no reaction occurred in the hydrosilyla-
tion for ethyl and methyl acetate with 1b in the presence of
2b. Thus, it is certain that complex A abstracts a hydride
from 1 to give the corresponding alkoxysilyliron complexes
and cationic silylene complexes 2.
On the basis of these results, a plausible reaction mechanism
for the silyleneiron complex-catalyzed hydrosilylation of carbo-
nyl compounds is shown in Scheme 1. In the first step, CD3CN-
coordinated silyleneiron complex 2 was formed by hydride
abstraction from hydrosilyliron complex 1 with Ph3CB(Arf)4.
A displacement of CD3CN with ketone or aldehyde in complex
2 resulted in the formation of intermediate A. A hydride
(13) Related hydride abstraction was reported from hydrosilane by
carbocation: Kira, M.; Hino, T.; Sakurai, H. Chem. Lett. 1992, 555.
(14) A similar thioalkoxyl exchange reaction was reported between
the thioalkoxysilylruthenium complex and a cationic silyleneruthenium
complex via the cationic disilylthiooxonium complex: Grumbine, S. K.;
Tilley, T. D. J. Am. Chem. Soc. 1994, 116, 6951.
(15) Shiozawa, R.; Tobita, H.; Ogino, H. Organometallics 1998, 17,
3497.
(16) King, R. B.; Pannell, K. H.; Bennett, C. R.; Ishaq, M. J.
Organomet. Chem. 1969, 19, 327.
(17) (a) Bahr, S. R.; Boudjouk, P. J. Org. Chem. 1992, 57, 5545. (b)
Straus, D. A.; Zhang, C.; Tilley, T. D. J. Organomet. Chem. 1989, 369, C13.
(12) Anders, E.; Hertlein, K.; Stankowiak, A.; Irmer, E. Synthesis
1992, 577.

5426 Organometallics, Vol. 29, No. 21, 2010
Muraoka et al.
dried over calcium hydride followed by distillation under a
nitrogen atmosphere before use. Methyl vinyl ketone was dried
over calcium chloride followed by distillation under a nitrogen
atmosphere before use. Benzophenone was recrystallized from dry
hexane before use. Toluene, Et2O, and THF were dried by
refluxing over sodium benzophenone ketyl followed by distillation
under a nitrogen atmosphere before use. CH3CN and CD3CN
were dried over calcium hydride followed by distillation under a
nitrogen atmosphere before use. C6D6 was dried over potassium
mirror followed by distillation in vacuo before use.
NMR spectra were recorded on a JEOL JNM-AL300 or a
JEOL JNM-AL500 Fourier transform spectrometer at room
temperature. IR spectra were recorded on a JASCO FT/IR-600
Plus spectrometer at room temperature. Elemental analyses
were performed by the Center for Material Research by Instru-
mental Analysis, Gunma University.
filtrated through a glass filter. The filtrate was concentrated in
vacuo, and the residue was purified by bulb-to-bulb distillation
(120 ꢀC/0.7 mmHg) to give Cp(OC)2FeSiMe2(OCHMe2) (3b)
(40%, 263 mg, 8.94 ꢀ 10-4 mol) as an orange liquid. 1H NMR
(300 MHz, CD3CN): δ/ppm 4.84 (s, 5H, Cp), 4.07 (sept, 3JHH
=
6.2 Hz, 1H, OCH), 1.11 (d, 3JHH = 6.2 Hz, 6H, CMe2), 0.48 (s, 6H,
SiMe2). 13C{1H} NMR (125.7 MHz, C6D6): δ/ppm 215.9 (CO),
83.6 (Cp), 65.3 (OCH), 26.0 (CMe2), 9.0 (SiMe2). 29Si{1H} NMR
(99.3 MHz, C6D6): δ/ppm 63.3. IR (KBr): νCO 1993 (vs), 1935 (vs);
νSiO 1017 (m) cm-1. Anal. Calcd for C12H18FeO3Si: C, 48.99; H,
6.17. Found: C, 49.47; H, 6.40. As a similar manner, Cp(OC)2FeSiMe2-
(OCH2Ph) (5) was prepared using Cp(OC)2FeSiMe2Cl16 (500 mg,
1.85 ꢀ 10-3 mol), sodium benzyloxide (1.8 ꢀ 10-3 mol), and THF
(10 mL); yield 19% (120 mg, 3.51 ꢀ 10-4 mol), 150 ꢀC/0.7 mmHg, an
orange liquid. 1H NMR (300 MHz, CD3CN): δ/ppm 7.20 (m, 5H,
Ph), 4.85 (s, 5H, Cp), 4.71 (s, 2H, OCH2), 0.53 (s, 6H, SiMe2).
13C{1H} NMR (125.7 MHz, C6D6): δ/ppm 215.7 (CO), 142.1 (ipso-
Ph), 128.5 (m-Ph), 127.1 (p-Ph), 126.6 (o-Ph), 83.6 (Cp), 65.1
(OCH2), 8.3 (SiMe2). 29Si{1H} NMR (99.3 MHz, C6D6): δ/ppm
69.2. IR (KBr): νCO 1991 (vs), 1932 (vs); νSiO 1065 (m) cm-1. Anal.
Calcd for C16H18FeO3Si: C, 56.15; H, 5.30. Found: C, 56.60; H, 5.38.
Preparation of [Cp(OC)2FeSiMe2]2O (6). To a solution of 1b
(184 mg, 7.79 ꢀ 10-4 mol) in CH3CN (5 mL) in a 50 mL round-
bottomed flask was added a CH3CN solution (10 mL) of
Ph3CB(Arf)4 (82 mg, 7.4 ꢀ 10-5 mol) with vigorous stirring.
To the resultant mixture was added a CH3CN solution (5 mL) of
benzaldehyde (100 μL, 9.8 ꢀ 10-4 mol), and then the solution
was stirred for 2 h at 25 ꢀC. After removal of volatiles from the
reaction mixture in vacuo, the residue was extracted with hexane
(2 mL ꢀ 5). The extract containing Cp(OC)2FeSiMe2(OCH2Ph)
(5) as a main product was hydrolyzed to afford [Cp(OC)2Fe-
SiMe2]2O (6) (21%, 40 mg, 8.2 ꢀ 10-5 mol) as yellow crystals. 1H
NMR (300 MHz, CD3CN): δ/ppm 4.82 (s, 10H, Cp), 0.52 (s,
12H, SiMe2). 13C{1H} NMR (125.7 MHz, C6D6): δ/ppm 216.0
(CO), 83.6 (Cp), 11.3 (SiMe2). 29Si{1H} NMR (99.3 MHz,
C6D6): δ/ppm 54.7. IR (KBr): νCO 1985 (vs), 1917 (vs); νSiO
1045 (m) cm-1. Anal. Calcd for C18H22Fe2O5Si2: C, 44.46; H,
4.56. Found: C, 44.70; H, 4.61.
General Procedure for Catalytic Hydrosilylation of Carbonyl
Compounds with Hydrosilyliron Complex 1. A CD3CN solution
of Ph3CB(Arf)4 (4 mg, 4 ꢀ 10-6 mol) was added to a CD3CN
solution (total 0.5 mL) of Cp(OC)2FeSiHMe2 (1b) (9 mg, 4 ꢀ
10-5 mol) in a NMR sample tube with a Teflon vacuum valve.
To this mixture was added acetone (5 μL, 7 ꢀ 10-5 mol), and the
resultant mixture was kept for 0.5 h. Cp(OC)2FeSiMe2-
(OCHMe2) (3b) was obtained in 71% yield with a trace amount
1
of 2b determined by H NMR spectrum. Characterization of
3-6 was achieved by isolation of the silyliron complexes from
the reaction mixture or comparing these spectroscopic data with
those of the authentic samples prepared by the reaction of
Cp(OC)2FeSiMe2Cl16 with the corresponding metal alkoxide.
Preparation of Cp(OC)2FeSiR2(OCHR02) (R = p-tolyl, R0 = Me
(3a),R=Me,R0 =Ph(4)).To a solution of Cp(OC)2FeSi(p-tolyl)2H
(1a) (155 mg, 4.00 ꢀ 10-4 mol) in CH3CN (4 mL) in a 50 mL round-
bottomed flask was added a CH3CNsolution(5mL) ofPh3CB(Arf)4
(44 mg, 4.0 ꢀ 10-5 mol) with vigorous stirring. To the resultant
mixture was added acetone (60.0 μL, 8.17 ꢀ 10-4 mol), and the
mixture was stirred for several hours at 25 ꢀC. After removal of
volatiles from the reaction mixture in vacuo, the residue was purified
by column chromatography (silica gel, eluent; toluene:hexane, 1:3),
and the yellow band (Rf = 0.32) was collected. Volatiles were
removed from the yellow solution to afford Cp(OC)2FeSi(p-tolyl)2-
(OCHMe2) (3a) (69%, 109 mg, 2.44 ꢀ 10-4 mol) as yellow solids. 1H
Observation of [Cp(OC)2FeSiR2{OC(PPh3)Me2}]þ (R = p-tolyl
(7a), R = Me (7b)). To a CD3CN solution of [Cp(OC)2FedSi-
(p-tolyl)2(NCCD3)][B(Arf)4] (2a) (25mg, 2.0ꢀ 10-5 mol) was added
a CD3CN solution (total 0.5 mL) of 1 equiv of acetone and PPh3 in a
NMR sample tube with a Teflon vacuum valve. The formation of 7a
3
NMR (300 MHz, CD3CN): δ/ppm 7.51 (d, JHH = 7.6 Hz, 4H,
C6H4), 7.20 (d, 3JHH = 7.6 Hz, 4H, C6H4), 4.68 (s, 5H, Cp), 3.97
(sept, 3JHH = 6.0 Hz, 1H, OCH), 2.34 (s, 6H, C6H4CH3), 1.04 (d,
3JHH = 6.0 Hz, 6H, CMe2). 13C{1H} NMR (75.5 MHz, C6D6):
δ/ppm 215.9 (CO), 140.5 (C6H4), 138.4 (C6H4), 134.8 (C6H4), 128.7
(C6H4), 84.5 (Cp), 65.3 (OCH), 25.7 (CMe2), 21.4 (C6H4CH3).
29Si{1H} NMR (59.6 MHz, CD3CN): δ/ppm 51.6. IR (KBr): νCO
1990 (vs), 1925 (vs) cm-1. Anal. Calcd for C24H26FeO3Si: C, 64.58;
H, 5.87. Found: C, 64.51; H, 5.75. In a similar manner, Cp(OC)2-
FeSiMe2(OCHPh2) (4) was prepared using 1b (187 mg, 7.92 ꢀ 10-4
mol), Ph3CB(Arf)4 (86 mg, 7.8 ꢀ 10-5 mol), benzophenone (166 mg,
9.11 ꢀ 10-4 mol), and CH3CN (14 mL); yield 24% (73 mg, 1.7 ꢀ
10-4 mol), yellow crystals. 1H NMR (300 MHz, CD3CN): δ/ppm
7.44 (d, 3JHH = 7.4 Hz, 4H, o-Ph), 7.29 (dd, 3JHH = 7.4 and 7.4 Hz,
4H, m-Ph), 7.20 (t, 3JHH = 7.4 Hz, 2H, p-Ph), 5.88 (s, 1H, OCH),
4.72 (s, 5H, Cp), 0.43 (s, 6H, SiMe2). 13C{1H} NMR (125.7 MHz,
C6D6): δ/ppm 215.8 (CO), 146.0 (ipso-Ph), 128.5 (m-Ph), 127.2 (p-
Ph), 126.7 (o-Ph), 83.7 (Cp), 77.3 (OCH), 8.7 (SiMe2). 29Si{1H}
NMR (99.3 MHz, C6D6): δ/ppm 69.6. IR (KBr) νCO 1983 (vs), 1925
(vs);νSiO 1061 (m) cm-1. Anal. Calcd for C22H22FeO3Si: C, 63.16; H,
5.30. Found: C, 63.18; H, 5.34.
1
was identified by NMR. H NMR (300 MHz, CD3CN): δ/ppm
7.78-7.14 (m, 15H, PPh3), 7.32-7.14(m, 4H, C6H4Me), 4.50 (s, 5H,
3
Cp), 2.33 (s, 6H, C6H4Me), 1.67 (d, JPH = 17.4 Hz, 6H,
CMe2). 13C{1H} NMR (75.5 MHz, CD3CN): δ/ppm 216.8 (CO),
140.2, 139.9 (p-, ipso-C6H4Me), 136.2 (p-PPh3), 136.1, 135.3 (o-, m-
C6H4Me), 131.1 (d, 3JPC = 11.8 Hz, m-PPh3), 129.4 (d, 2JPC = 12.2
Hz, o-PPh3), 118.1 (d, 1JPC = 78.0 Hz, ipso-PPh3), 86.6 (Cp), 82.9 (d,
2
1JPC = 64.8 Hz, OC(PPh3)Me2), 28.4 (d, JPC = 6.6 Hz, OC-
(PPh3)Me2), 21.4 (C6H4Me). 31P{1H} NMR (121 MHz, CD3CN):
δ/ppm 34.1. 29Si{1H} NMR (59.6 MHz, CD3CN): δ/ppm 61.1 (d,
3JPSi = 10.8 Hz). In a similar manner, 7b was identified by NMR. 1H
NMR (300 MHz, CD3CN): δ/ppm 8.0-7.0 (m, 15H, PPh3), 4.65 (s,
5H, Cp), 1.79 (d, 3JPH = 17.1 Hz, 6H, CMe2), 0.59 (S, 6H, SiMe2).
13C{1H} NMR (125.7 MHz, CD3CN): δ/ppm 216.1 (CO), 136-115
(PPh3), 85.1 (Cp), 82.1 (d, 1JPC = 66.2 Hz, OC(PPh3)Me2), 28.6 (d,
2JPC = 6.2 Hz, OC(PPh3)Me2), 12.3 (SiMe2). 31P{1H} NMR (202.5
MHz, CD3CN): δ/ppm 30.0. 29Si{1H} NMR (99.3 MHz, CD3CN):
δ/ppm 76.5 (d, 3JPSi = 7.3 Hz).
Preparation of Cp(OC)2FeSiMe2(OCHRR0) (R = R0 = Me
(3b), R = H, R0 = Ph (5)). To a solution of sodium isopropoxide
(2.3 ꢀ 10-3 mol) in 2-propanol (30 mL) in a 100 mL round-
(OC)2FeSiMe2Cl16 (610 mg, 2.25 ꢀ 10-3 mol) with vigorous
stirring. The resultant mixture was stirred for 3 h at 25 ꢀC. After
removal of volatiles from the reaction mixture in vacuo, the
residue was extracted with hexane (30 mL). The extract was
Acknowledgment. This work was supported by a Grant-
in-Aid for Scientific Research on Priority Areas (No.
20036011) and for Scientific Research (Nos. 21750056 and
20655011) from the Ministry of Education, Culture, Sports,
Science and Technology of Japan. K.U. expresses his sincere
thanks to Professor Dietmar Seyferth for continuing encour-
agement and support.
bottomed flask was added
a Et2O solution of Cp-