The π-(Hydroxyalkenyl)germane complexes Rh(acac){η2-(E)-Et3GeCH=CHC(OH)R2}(PCy 3) (R = Me, Ph) as intermediates in the hydrogermylation of alkynols catalyzed by Rh(acac)(cyclooctene)(PCy3)

Article abstract of DOI:10.1021/om981042n

The (hydroxyalkenyl)germanes (E)-R₃Ge-CH=CHC(OH)R′₂ (R = Et, Ph; R′ = Me, Ph) are prepared in quantitative yield, and in a catalytic manner, by addition of germanes to the alkynols HC≡CC-(OH)R′₂ (R′ = Me, Ph) in the presence of the complex Rh(acac)(cyclooctene)(PCy₃). During the reactions four cycles are evident. They have as a common point the intermediates Rh(acac){η²-(E)-CH(GeR₃)=~CHC(OH)-R′ ₂}(PCy₃), which have been isolated for R=Et and R′ = Me, Ph.

Full text of DOI:10.1021/om981042n

Organometallics 1999, 18, 2267-2270
2267
Notes
Th e π-(Hyd r oxya lk en yl)ger m a n e Com p lexes
Rh (a ca c){η2-(E)-Et3GeCHdCHC(OH)R2}(P Cy3) (R ) Me,
P h ) a s In ter m ed ia tes in th e Hyd r oger m yla tion of
Alk yn ols Ca ta lyzed by Rh (a ca c)(cycloocten e)(P Cy3)
Miguel A. Esteruelas,* Marta Mart´ın, and Luis A. Oro
Departamento de Quı´mica Inorga´nica-Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received December 28, 1998
Summary: The (hydroxyalkenyl)germanes (E)-R3Ge-
CHdCHC(OH)R′2 (R ) Et, Ph; R′ ) Me, Ph) are
prepared in quantitative yield, and in a catalytic man-
ner, by addition of germanes to the alkynols HCtCC-
(OH)R′2 (R′ ) Me, Ph) in the presence of the complex
Rh(acac)(cyclooctene)(PCy3). During the reactions four
cycles are evident. They have as a common point the
intermediates Rh(acac){η2-(E)-CH(GeR3)dCHC(OH)-
R′2}(PCy3), which have been isolated for R ) Et and R′
) Me, Ph.
lyzed hydrogermylation of alkynes is a field which has
not been previously investigated.
Previously, we have reported that the cyclooctene
complex Rh(acac)(cyclooctene)(PCy3) (1) reacts with
HGeEt3 to give the hydrido-germyl compound
Rh(acac)H(GeEt3)(PCy3) (2).5 As a part of our work on
the reactivity of transition-metal complexes toward
alkynols,6 we have investigated the use of 1 and 2 as
catalysts for the preparation of (hydroxyalkenyl)ger-
manes.
The compounds (E)-Et3GeCHdCHC(OH)R2 (R ) Me
(5), Ph (6)) can be synthesized via the stoichiometric
reactions shown in eq 1. The cyclooctene ligand of 1 is
Alkenylstannanes are very versatile organometallic
reagents in palladium-catalyzed coupling reactions.1
Some, however, are toxic. Alkenylgermanes show a very
low toxicity,2 and therefore, they could serve as alterna-
tives to the organotin reagents.
The hydrogermylation of alkynes is a simple route to
alkenylgermanes. These reactions take place readily in
the presence of catalytic amounts of a free radical
initiator such as azobis(isobutyronitrile), but such reac-
tions generally are not highly regio- and stereoselective.3
The stereoselective formation of alkenylgermanes by
addition of a germanium hydride to alkynes requires
the presence of transition-metal catalysts.4 From a
mechanistic point of view, the transition-metal-cata-
displaced by the alkynols HCtCC(OH)R2 (R ) Me (3),
Ph (4)) to afford the π-hydroxyalkyne compounds Rh-
(1) Stille, J . K. Angew. Chem., Int. Ed. Engl. 1986, 25, 508.
(2) Aldridge, W. N. In The Organometallic and Coordination Chem-
istry of Germanium, Tin and Lead; Gielen, M., Harrison, P. G., Eds.;
Freund: Tel Aviv, Israel, 1978; pp 9-31.
(3) Oshima, K. In Advances in Metal-Organic Chemistry; Liebeskind,
L. S., Ed.; J AI: Greenwich, CT, 1991; Vol. 2, pp 101-141.
(5) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Rodr´ıguez,
L. Organometallics 1996, 15, 3670.
(6) (a) Espuelas, J .; Esteruelas, M. A.; Lahoz, F. J .; Oro, L. A.; Ruiz,
N. J . Am. Chem. Soc. 1993, 115, 4683. (b) Esteruelas, M. A.; Lahoz, F.
J .; On˜ate, E.; Oro, L. A.; Zeier, B. Organometalllics 1994, 13, 1662. (c)
Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Zeier, B.
Organometallics 1994, 13, 4258. (d) Esteruelas, M. A.; Go´mez, A. V.;
Lahoz, F. J .; Lo´pez, A. M.; On˜ate, E.; Oro, L. A. Organometallics 1996,
15, 3423. (e) Edwards, A. J .; Esteruelas, M. A.; Lahoz, F. J .; Modrego,
J .; Oro, L. A.; Schrickel, J . Organometallics 1996, 15, 3556. (f)
Bourgault, M.; Castillo, A.; Esteruelas, M. A.; On˜ate, E.; Ruiz, N.
Organometallics 1997, 16, 636. (g) Esteruelas, M. A.; Oro, L. A.;
Schrickel, J . Organometallics 1997, 16, 796. (h) Esteruelas, M. A.;
Lo´pez, J . A.; Ruiz, N.; Tolosa, J . I. Organometallics 1997, 16, 4657. (i)
Bohanna, C.; Callejas, B.; Edwards, A. J .; Esteruelas, M. A.; Lahoz,
F. J .; Oro, L. A.; Ruiz, N. Valero, C. Organometallics 1998, 17, 373. (j)
Crochet, P.; Esteruelas, M. A.; Gutierrez-Puebla, E. Organometallics
1998, 17, 3114. (k) Crochet, P.; Esteruelas, M. A.; Lo´pez, A. M.; Ruiz,
N.; Tolosa, J . I. Organometallics 1998, 17, 3479.
(4) (a) Lesbre, M.; Satge´, J . C. R. Acad. Sci. Paris, Ser. C 1960, 250,
2220. (b) Dzhurinskaya, N. G.; Mironov, V. F.; Petrov, A. D. Dokl. Akad.
Nauk SSSR 1961, 138, 1107. (c) Gverdtsiteli, I. M.; Buachidze, M. A.
Dokl. Akad. Nauk SSSR 1964, 158, 147. (d) Gverdtsiteli, I. M.;
Guntsadze, T. P.; Petrov, A. D. Dokl. Akad. Nauk SSSR 1964, 157,
607. (e) Gverdtsiteli, I. M.; Buachidze, M. A. Soobshch. Akad. Nauk
Gruz. SSSR 1965, 37, 59. (f) Gverdtsiteli, I. M.; Buachidze, M. A.
Soobshch. Akad. Nauk Gruz. SSSR 1965, 37, 327. (g) Shikhiev, I. A.;
Abdullaev, N. D.; Aliev, M. I. Zh. Obshch. Khim. 1966, 36, 942. (h)
Shikhiev, I. A.; Aslanov, I. A.; Mekhmandarova, N. T. Zh. Obshch.
Khim. 1966, 36, 1295. (i) Lesbre, M.; Mazerolles, P.; Satge´, J . In The
Organic Compounds of Germanium; Seyferth, D., Ed.; Wiley: Chich-
ester, U.K., 1971; Chapter 2. (j) Corriu, R. J . P.; Moreau, J . J . E. J .
Organomet. Chem. 1972, 40, 73. (k) Ichinose, Y.; Oda, H.; Oshima, K.;
Utimoto, K. Bull. Chem. Soc. J pn. 1987, 60, 3468. (l) Wada, F.; Abe,
S.; Yonemaru, N.; Kikukawa, K.; Matsuda, T. Bull. Chem. Soc. J pn.
1991, 64, 1701. (m) Lukevics, E.; Barabanov, D. I.; Ignatovich, L. M.
Appl. Organomet. Chem. 1991, 5, 379.
(7) This complex has been previously reported; see: Esteruelas, M.
A.; Lahoz, F. J .; Mart´ın, M.; On˜ate, E.; Oro, L. A. Organometallics 1997,
16, 4572.
10.1021/om981042n CCC: $18.00 © 1999 American Chemical Society
Publication on Web 04/28/1999

2268 Organometallics, Vol. 18, No. 11, 1999
Notes
Sch em e 1
Sch em e 2
(acac){η2-ΗCtCC(OH)R2}(PCy3) (R ) Me (7), Ph (8)7)
(Scheme 1). The reactions were carried out at -78 °C,
in pentane as solvent, and the reaction products were
isolated as yellow solids in 84% (7) and 71% (8) yields.
Treatment of toluene solutions of 7 and 8 with 1 equiv
of HGeEt3 at room temperature leads to the π-(hydroxy-
alkenyl)germane derivatives Rh(acac){η2-(E)-Et3GeCHd
CHC(OH)R2}(PCy3) (R ) Me (9), Ph (10)), which were
isolated as orange solids in 65% (9) and 60% (10) yields.
Complexes 9 and 10 can also be obtained by addition of
1 equiv of the alkynols 3 and 4 to toluene solutions of
2. By this route, 9 and 10 were obtained in 55% and
50% yields, respectively.
Ta ble 1. P r od u ct Yield s a fter 48 h of Rea ction for
th e Hyd r oger m yla tion s of Alk yn es Ca ta lyzed by
Rh (a ca c)(cycloocten e)(P Cy3) (1)
yield
alkyne
germane
product
(%)
HCtCC(OH)Ph2 HGeEt3 (E)-Et3GeCHdCHC(OH)Ph2 100
HCtCC(OH)Ph2 HGePh3 (E)-Ph3GeCHdCHC(OH)Ph2
CH2dC(GePh3)C(OH)Ph2
71
12
HCtCC(OH)Me2 HGeEt3 (E)-Et3GeCHdCHC(OH)Me2 100
HCtCPh
HGeEt3 (E)-Et3GeCHdCHPh
CH2dC(GeEt3)Ph
HGeEt3 (E)-Et3GeCHdCHCy
CH2dC(GeEt3)Cy
87
10
81
17
97
The presence in 9 and 10 of π-(hydroxyalkenyl)-
germane ligands with E stereochemistry at the carbon-
carbon double bond is strongly supported by the 1H
NMR spectra of these compounds, which show olefinic
resonances at 4.49 and 2.33 (9) and 4.96 and 2.72 (10)
ppm, with H-H coupling constants of 13.8 (9) and 13.5
(10) Hz. In the 13C{1H} NMR spectra, the resonances
due to the sp2 carbons appear at 91.0 and 36.9 (9) and
86.6 and 40.0 (10) ppm.
HCtCCy
HCtCSiMe3
HGeEt3 (E)-Et3GeCHdCHSiMe3
temperature, leads after 48 h to 0.67 mmol of the
(hydroxyalkenyl)germanes 5 and 6, according to eq 1.
Complex 1 catalyzes not only the addition of HGeEt3
to 2-methyl-3-butyn-2-ol and 1,1-diphenyl-2-propyn-1-
ol but also the addition of HGeEt3 to phenylacetylene,
cyclohexylacetylene, and (trimethylsilyl)acetylene and
the addition of HGePh3 to 1,1-diphenyl-2-propyn-1-ol
(Table 1). These reactions are less selective than those
shown in eq 1. Thus, in addition to the E isomer the
gem isomers are also obtained.
In conclusion, (hydroxyalkenyl)germanes, (E)-R3-
GeCHdCHC(OH)R′2, can be prepared in a catalytic
process, by addition of R3GeH to the alkynols in the
presence of the complex Rh(acac)(cyclooctene)(PCy3).
Four cycles (A and B in Scheme 1 and C and D in
Scheme 2) seem to be involved in the catalytic reaction.
Interestingly, they have as a common point the inter-
mediates Rh(acac){η2-(E)-R3GeCHdCHC(OH)R′2}(PCy3),
which have been isolated for R ) Et and R′ ) Me and
Ph. These compounds are the first isolated transition-
metal complexes containing (hydroxyalkenyl)germane
ligands.
The (hydroxyalkenyl)germane ligands of 9 and 10 can
be displaced by cyclooctene to give 5 and 6 and to
regenerate 1. These reactions along with those previ-
ously mentioned constitute two stoichiometric cycles (A
and B in Scheme 1) for the formation of the (hydroxy-
alkenyl)germanes 5 and 6 by addition of HGeEt3 to the
alkynols 3 and 4, using the cyclooctene complex 1 as a
template. These cycles, which differ in the entry order
of the reagents into 1, have the complexes 9 and 10 as
common intermediates.
The hydrido-germyl complex 2 and the π-hydroxy-
alkyne compounds 7 and 8 can also be used as templates
for the stoichiometric synthesis of 5 and 6 (cycles C and
D in Scheme 2). Thus, we have also observed that, in
the absence of cyclooctene and in toluene at room
temperature, complexes 9 and 10 react with 1 equiv of
HGeEt3 to give the (hydroxyalkenyl)germanes 5 and 6
in 70% and 78% yields, respectively, and that the
addition at -78 °C of the alkynols 3 and 4 to pentane
solutions of 9 and 10 affords 5 and 6 and the π-hydroxy-
alkyne compounds 7 and 8.
Exp er im en ta l Section
All reactions were carried out under an atmosphere
of argon using Schlenk-tube techniques. Solvents were
dried by the usual procedures and distilled under argon
As expected from the chemistry described above,
complex 1 efficiently catalyzes the addition of HGeEt3
to the alkynols 3 and 4. In fact, treatment of 0.67 mmol
of 3 and 4 with 0.67 mmol of HGeEt3 in 0.5 mL of
benzene-d6 and in the presence of 6.7 µmol of 1, at room
(8) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Rodr´ıguez,
L.; Steinert, P.; Werner, H. Organometallics 1996, 15, 3436.

Notes
Organometallics, Vol. 18, No. 11, 1999 2269
prior to use. The starting material Rh(acac)(cyclooctene)-
PCH), 31.2, 30.2, 28.6, 28.5, 28.3, 28.2, and 27.0 (all s,
PCy3), 27.8 (d, J PC ) 5.8 Hz, CH3 of acac), 26.5 (s, CH3
of acac), 9.6 (s, GeCH2CH3), 6.6 (s, GeCH2CH3).
(PCy3) (1) was prepared by a published method.8
P r ep a r a tion of Rh (a ca c){η2-ΗCtCC(OH)Me2}-
(P Cy3) (7). A solution of Rh(acac)(cyclooctene)(PCy3) (1;
148.2 mg, 0.25 mmol) in 15 mL of pentane was cooled
to -78 °C, and then a stoichiometric amount of 2-meth-
yl-3-butyn-2-ol (3; 25 µL, 0.25 mmol) was added. After
the mixture was stirred for 1 h, a yellow solid was
formed, which was separated by decantation, washed
with pentane, and dried in vacuo. Yield: 119 mg (84%).
Anal. Calcd for C28H48O3PRh: C, 59.36; H, 8.54.
Found: C, 59.12; H, 8.08. IR (KBr, cm-1): ν(OH) 3416,
The compounds 9 and 10 can also be prepared by
reaction of 0.5 mmol of the alkynols 3 and 4 with toluene
solutions of 0.5 mmol of compound 2 (yields 200.0 mg
(55%) and 212.9 mg (50%), respectively).
P r ep a r a tion of (E)-Et3GeCHdCHC(OH)R2 (R )
Me (5), P h (6)). To a solution of 9 (218.1 mg, 0.3 mmol)
or 10 (255.4 mg, 0.3 mmol) in 10 mL of toluene was
added a stoichiometric amount of cyclooctene (39 µL,
0.3 mmol). After it was stirred for 1 h, the solution was
concentrated to dryness. The residual oil was dissolved
in ca. 0.5 mL of pentane and chromatographed on Al2O3
(neutral, activity grade I, column length 7 cm). With
diethyl ether a colorless fraction was eluted, from which
the solvent was removed in vacuo. A colorless oil was
obtained.
1
ν(CtC) 1837, ν(CO)acac 1580 and 1520. H NMR (300
MHz, toluene-d8, 293 K): δ 5.14 (s, 1H, CH of acac),
4.29 (s, 1H, OH), 3.89 (s, 1H, HCtC), 1.9-1.1 (m, 33H,
C6H11), 1.92 (s, 6H, Me), 1.88 and 1.70 (both s, 6H, CH3
of acac). 31P{1H} NMR (121.4 MHz, toluene-d8, 233 K):
δ 50.5 (d, J RhP ) 179.7 Hz). 13C{1H} NMR (75.4 MHz,
toluene-d8, 233 K): δ 186.7 and 184.2 (both s, CO of
acac), 99.9 (s, CH of acac), 92.4 (d, J RhC ) 15.7 Hz, HCt
C), 66.3 (s, COH), 66.0 (dd, J RhC ) 18.0 Hz, J PC ) 6.5
Data for 5 are as follows. NMR (C6D6): 1H, δ 6.12
(part A of an AB system, 1H, J HH ) 18.6 Hz, dCH), 5.95
(part B of an AB system, 1H, J HH ) 18.6 Hz, d
Hz, HCtC), 32.9 and 32.0 (both s, Me), 31.8 (d, J PC
22.5 Hz, PCH), 30.3, 28.8, 28.4, 28.3, 28.2, 28.1, and 26.9
)
CHGeEt3), 1.17 (s, 7H, Me and OH), 1.06 (t, 9H, J HH
)
7.9 Hz, GeCH2CH3), 0.79 (q, 6H, J HH ) 7.9 Hz, GeCH2-
CH3); 13C{1H}, δ 154.1 (s, dCH), 120.9 (s, dCHGeEt3),
71.6 (s, COH), 29.7 (s, Me), 9.1 (s, GeCH2CH3), 4.6 (s,
GeCH2CH3). MS: m/z 246 (M+).
(all s, PCy3), 27.9 and 27.2 (both s, CH3 of acac).
P r ep a r a tion of Rh (a ca c){η2-(E)-Et3GeCHdCHC-
(OH)R2}(P Cy3) (R ) Me (9), P h (10)). To a solution
of 7 (141.6 mg, 0.25 mmol) or 8 (172.7 mg, 0.25 mmol)
in 15 mL of toluene was added a stoichiometric amount
of HGeEt3 (161 µL, 0.25 mmol). A change in color from
yellow to orange occurred almost instantaneously. The
solution was concentrated to ca. 0.1 mL in vacuo;
addition of methanol caused the precipitation of orange-
yellow solids. The solids were separated by decantation,
washed with methanol, and dried in vacuo.
Data for 6 are as follows. NMR (C6D6): 1H, δ 7.5-7.0
(m, 10H, Ph), 6.63 (part A of an AB system, 1H, J HH
)
18.6 Hz, dCH), 6.16 (part B of an AB system, 1H, J HH
) 18.6 Hz, dCHGeEt3), 1.96 (s, 1H, OH), 1.01 (t, 9H,
J HH ) 7.7 Hz, GeCH2CH3), 0.76 (q, 6H, J HH ) 7.7 Hz,
GeCH2CH3); 13C{1H}, δ 150.9 (s, dCH), 146.8 (s, Cipso-Ph),
128.3, 127.5 and 127.3 (all s, Co,m,p-Ph), 125.0 (s, d
CHGeEt3), 80.6 (s, COH), 9.1 (s, GeCH2CH3), 4.6 (s,
GeCH2CH3). MS: m/z 370 (M+).
Data for 9 are as follows. Yield: 118 mg (65%). Anal.
Calcd for C34H64GeO3PRh: C, 56.14; H, 8.87. Found: C,
56.58; H, 9.19. IR (KBr, cm-1): ν(OH) 3600, ν(CO)acac
1580 and 1516. NMR (C6D6): 1H, δ 5.16 (s, 1H, CH of
acac), 4.44 (d, 1H, J HH ) 13.8 Hz, dCH), 2.33 (dd, 1H,
J HH ) 13.8, J PH ) 6.0 Hz, dCHGeEt3), 2.1-1.2 (m, 33H,
C6H11), 1.94 (s, 3H, Me), 1.80 and 1.75 (both s, 6H, CH3
of acac), 1.43 (s, 3H, Me), 1.01 (s, 1H, OH); 31P{1H}, δ
41.0 (d, J RhP ) 182.7 Hz); 13C{1H}, δ 185.8 and 183.0
The compounds 5 and 6 can also be obtained by
reaction of 0.5 mmol of complexes 9 and 10 with 0.5
mmol of HGeEt3 (yields: 85.4 mg (70%) and 143.9 mg
(78%), respectively).
Ca ta lytic Stu d ies. The catalytic reactions were
carried out at room temperature in NMR tubes contain-
ing 0.0067 mmol of 1, 0.67 mmol of HGeR3, and 0.67
mmol of alkyne in 0.5 mL of benzene-d6.
(both s, CO of acac), 99.3 (s, CH of acac), 91.0 (d, J PC
)
Selected NMR spectroscopic data are as follows. (E)-
P h 3GeCHdCHC(OH)P h 2: 1H, δ 6.97 (part A of an AB
system, 1 H, J HH ) 18.3, dCH), 6.77 (part B of an AB
system, 1 H, J HH ) 18.3, dCHGePh3); 13C{1H}, δ 154.5
(s, dCH), 122.5 (s, dCHGePh3), 80.7 (s, COH).
16.7 Hz, dCH), 72.2 (s, COH), 39.6 (dd, J PC ) 15.3 Hz,
J RhC ) 3.3 Hz, dCHGeEt3), 34.5 (d, J PC ) 19.5 Hz,
PCH), 32.6 and 31.5 (both s, Me), 31.8, 30.6, 28.6, 28.5
28.4, 28.3, and 26.9 (all s, PCy3), 27.8 (d, J PC ) 5.7 Hz,
CH3 of acac), 26.4 (s, CH3 of acac), 9.9 (s, GeCH2CH3),
7.0 (s, GeCH2CH3).
CH2dC(GeP h 3)C(OH)P h 2: 1H, δ 5.86 (d, 1 H, J HH
)
0.9, dCH2), 5.56 (d, 1 H, J HH ) 0.9, dCH2). (E)-
Et3GeCHdCHP h : 1H, δ 6.90 (part A of an AB system,
1 H, J HH ) 19.2, dCH), 6.61 (part B of an AB system,
1 H, J HH ) 19.2, dCHGeEt3); 13C{1H}, δ 144.3 (s,
dCH), 127.3 (s, dCHGeEt3), 9.0 (s, GeCH2CH3), 4.5 (s,
GeCH2CH3). CH2dC(GeEt3)P h : 1H, δ 5.90 (d, 1 H, J HH
) 2.8, dCH2), 5.40 (d, 1 H, J HH ) 2.8, dCH2). (E)-
Et3GeCHdCHCy: 1H, δ 5.95 (dd, 1 H, J HH ) 18.6, J HH′
) 5.7, dCH), 5.73 (dd, 1 H, J HH ) 18.6, J HH′ ) 1.2,
dCHGeEt3); 13C{1H}, δ 152.8 (s, dCH), 123.0 (s,
dCHGeEt3), 9.0 (s, GeCH2CH3), 4.4 (s, GeCH2CH3).
CH2dC(GeEt3)Cy: 1H, δ 5.65 (dd, 1 H, J HH ) 2.2, J HH′
) 1.2, dCH2), 5.19 (dd, 1 H, J HH ) 2.2, J HH′ ) 0.7,
dCH2). (E)-Et3GeCHdCHSiMe3: 1H, δ 6.85 (part A
Data for 10 are as follows. Yield: 128 mg (60%). Anal.
Calcd for C44H68GeO3PRh: C, 62.06; H, 8.05. Found: C,
62.31; H, 8.24. IR (KBr, cm-1): ν(OH) 3613, ν(CO)acac
1582 and 1518. NMR (C6D6): 1H, δ 8.6-7.0 (m, 10H,
Ph), 5.23 (s, 1H, CH of acac), 4.96 (d, 1H, J HH ) 13.5
Hz, dCH), 2.72 (dd, 1H, J HH ) 13.5 Hz, dCHGeEt3),
2.1-1.1 (m, 33H, C6H11), 1.97 (s, 1H, OH), 1.81 and 1.78
(both s, 6H, CH3 of acac); 31P{1H}, δ 42.6 (d, J RhP ) 183.5
Hz); 13C{1H}, δ 186.3 and 183.5 (both s, CO of acac),
150.2 and 149.0 (both s, Cipso-Ph), 129.6, 128.1, 127.2 and
126.4 (all s, Co,m,p-Ph), 99.4 (s, CH of acac), 86.6 (d, J PC
) 17.3 Hz, dCH), 80.5 (s, COH), 40.0 (dd, J PC ) 17.3
Hz, J RhC ) 4.6 Hz, dCHGeEt3), 34.3 (d, J PC ) 19.6 Hz,

2270 Organometallics, Vol. 18, No. 11, 1999
Notes
of an AB system, 1 H, J HH ) 21.9, dCH), 6.61 (part B
of an AB system, 1 H, J HH ) 21.9, dCHGeEt3); 13C{1H},
δ151.2 (s, dCH), 148.1 (s, dCHGeEt3), 8.9 (s, GeCH2CH3),
4.2 (s, GeCH2CH3).
Ack n ow led gm en t. We thank the DGICYT (Projects
PB 94-1186 and PB 95-0806, Programa de Promocio´n
General del Conocimiento) for financial support.
OM981042N