Toward an understanding of the mechanism of metal exchange in (propargyl alcohol)Co2(CO)6 clusters: Syntheses and structures of [η5-C5Ph2R2-C≡C-TMS)(Fe(CO )2(μ-H)]Co2(CO)6, R = Ph or Et

Article abstract of DOI:10.1021/om010494o

The reaction of (5-alkynylcyclopentadienol)Co₂(CO)₆ clusters with iron pentacarbonyl in acetone does not yield the expected product in which the hydroxyl substituent is lost and a tricarbonylcobalt vertex is replaced by an Fe(CO)₃ group. Instead, the product contains an (η⁵-C₅Ph₂R₂)Fe(CO)₂H moiety that is bridged to one of the cobalt vertexes of the intact dicobalt-alkyne cluster. The process is rationalized in terms of a decarboxylation rather than a dehydroxylation process, and the relevance to the mechanism of substitution of one metal vertex by another is discussed.

Full text of DOI:10.1021/om010494o

4690
Organometallics 2001, 20, 4690-4694
Tow a r d a n Un d er sta n d in g of th e Mech a n ism of Meta l
Exch a n ge in (P r op a r gyl Alcoh ol)Co2(CO)6 Clu ster s:
Syn th eses a n d Str u ctu r es of
[η5-C5P h 2R2-CtC-TMS)(F e(CO)2(µ-H)]Co2(CO)6, R ) P h
or Et
J ames A. Dunn,† J ames F. Britten,† J ean-Claude Daran,‡ and
Michael J . McGlinchey*,†
Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and
Laboratoire de Chimie de Coordination du CNRS, 205 Route de Narbonne,
31077 Toulouse Cedex 04, France
Received J une 11, 2001
The reaction of (5-alkynylcyclopentadienol)Co2(CO)6 clusters with iron pentacarbonyl in
acetone does not yield the expected product in which the hydroxyl substituent is lost and a
tricarbonylcobalt vertex is replaced by an Fe(CO)3 group. Instead, the product contains an
(η5-C5Ph2R2)Fe(CO)2H moiety that is bridged to one of the cobalt vertexes of the intact
dicobalt-alkyne cluster. The process is rationalized in terms of a decarboxylation rather than
a dehydroxylation process, and the relevance to the mechanism of substitution of one metal
vertex by another is discussed.
Ch a r t 1
In tr od u ction
In continuation of our studies on metal-stabilized
short-lived species,1 we have recently described the
syntheses and molecular dynamics of a series of anti-
aromatic cations.2 The fluorenyl, indenyl, and cyclopen-
tadienyl cations possess 12π, 8π, and 4π electron counts,
respectively, which do not conform to the Hu¨ckel rule
for planar aromatic systems.3 Nevertheless, these cat-
ions have been prepared as their alkynyl-dicobalt
clusters 1-4.2 The structures of such dicobalt species,
whereby the electron deficiency at the cationic site is
alleviated by direct overlap with a filled metal orbital,
are supported by NMR data,4 molecular orbital calcula-
tions,5 and the X-ray crystal structures of numerous
* Corresponding author. Tel: (905)-525-9140, ext 27318. Fax: (905)-
522-2509. E-mail: mcglinc@mcmaster.ca.
† McMaster University.
‡ Laboratoire de Chimie de Coordination.
(1) (a) Girard, L.; Decken, A.; Blecking, A.; McGlinchey, M. J . J .
Am. Chem. Soc. 1994, 116, 6427. (b) Gruselle, M.; El Hafa, H.; Nikolski,
M.; J aouen, G.; Vaissermann, J .; Li, L.; McGlinchey, M. J . Organo-
metallics 1993, 12, 4917. (c) Kondratenko, M.; El Hafa, H.; Gruselle,
M.; Vaissermann, J .; J aouen, G.; McGlinchey, M. J . J . Am. Chem. Soc.
1995, 117, 6907. (d) Downton, P. A.; Sayer, B. G.; McGlinchey, M. J .
Organometallics 1992, 11, 3281.
(2) Dunn, J . A.; Hunks, W. J .; Ruffolo, R.; Rigby, S. S.; Brook, M.
A.; McGlinchey, M. J . Organometallics 1999, 18, 3372.
(3) For a listing of the laser flash photolysis, mass spectrometric,
and reactivity studies on fluorenyl, indenyl, and cyclopentadienyl
cations, see ref 2.
(4) (a) Schreiber, S. L.; Klimas, M. T.; Sammakia, S. J . Am. Chem.
Soc. 1987, 109, 5749. (b) Padmanabhan, S.; Nicholas, K. M. J .
Organomet. Chem. 1983, 268, C23. (c) Edidin, R. T.; Norton, J . R.;
Mislow, K. Organometallics 1982, 1, 561. (d) D’Agostino, M. F.;
McGlinchey, M. J . Polyhedron 1988, 7, 807.
dimolybdenum or molybdenum-cobalt analogues.6 How-
ever, until very recently,7 no X-ray crystal structure of
a cobalt-stabilized carbocation had been reported, and
the most closely analogous systems that had been
structurally characterized were the neutral cobalt-iron
clusters in which a Co(CO)3+ vertex had been replaced
by the isolobal Fe(CO)3 moiety.8 Indeed, molecular
orbital calculations indicated that these neutral iron-
(5) (a) Schilling, B. E. R.; Hoffmann, R. J . Am. Chem. Soc. 1979,
101, 3456. (b) D’Agostino, M. F.; Mlekuz, M.; Kolis, J . W.; Sayer, B.
G.; Rodger, C. A.; Halet, J .-F.; Saillard, J .-Y.; McGlinchey, M. J .
Organometallics 1986, 5, 2345. (c) D’Agostino, M. F.; Frampton, C. S.;
McGlinchey, M. J . J . Organomet. Chem. 1990, 394, 145.
(6) Girard, L.; Lock, P. E.; El Amouri, H.; McGlinchey, M. J . J .
Organomet. Chem. 1994, 478, 189, and references therein.
(7) Melikyan, G. G.; Bright, S.; Monroe, T.; Hardcastle, K. I.;
Ciurash, J . Angew. Chem., Int. Ed. 1998, 37, 161.
(8) Victor, R. J . Organomet. Chem. 1977, 127, C25.
10.1021/om010494o CCC: $20.00 © 2001 American Chemical Society
Publication on Web 10/04/2001

(Propargyl Alcohol)Co2(CO)6 Clusters
Organometallics, Vol. 20, No. 22, 2001 4691
F igu r e 1. Molecular structure of [η5-C5Ph2Et2-CtC-
SiMe3](Fe(CO)2){µ-H}Co2(CO)6, 9 (50% probability).
F igu r e 2. Molecular structure of [η5-C5Ph4-CtC-SiMe3]-
(Fe(CO)2){µ-H}-Co2(CO)6, 10 (30% probability).
cobalt clusters were excellent structural models for the
cationic dicobalt systems.9 The mixed metal clusters are
conveniently prepared by treatment of the correspond-
ing (propargyl alcohol)Co2(CO)6 precursor with iron
pentacarbonyl in refluxing acetone.2,8,9
cyclopentadienyl ring. The iron is apparently linked to
one of the cobalt atoms, but the observed distance of
2.833(4) Å [2.866(4) Å in the other independent mol-
ecule] is too long to be considered a bond, and the
presence of a bridging metal hydride (which would also
account for the diamagnetism of the complex) is the
most probable explanation. Attempts to confirm this
The fluorenyl and indenyl Fe/Co clusters, 5 and 6,
exhibit Fe‚‚‚CR2 distances of 2.626(11) and 2.347(7) Å,
respectively,2 and one might anticipate that, since the
4π cyclopentadienyl cation has an even greater need for
electronic assistance from the metal center, the corre-
sponding cyclopentadienyl complexes, 7 and 8, would
possess even shorter Fe‚‚‚C bond lengths. Thus the syn-
theses of the cyclopentadienyl Fe/Co cluster complexes
7 and 8 were attempted. However, these experiments
yielded instead the trimetallic clusters [η5-C5Ph2R2-
CtC-SiMe3](Fe(CO)2){µ-H}Co2(CO)6, where R ) Et, 9,
or Ph, 10, and serendipitously may have led toward an
understanding of the mechanism of the Co(CO)3/
Fe(CO)3 vertex replacement process.
10
assumption through treatment with CCl4 to give CHCl3
were inconclusive. It is known that this process some-
times requires elevated temperatures; however, 9 de-
composes rapidly upon heating.
Since there is an interaction between the iron and
only one of the cobalt vertexes, the molecule does not
possess a mirror plane in the solid state, and this
1
asymmetry is maintained in solution such that the H
and 13C NMR spectra reveal the presence of two
nonequivalent ethyl groups, as well as two different iron
carbonyl resonances, even at room temperature.
Attempts to determine the barrier to migration of the
Fe-H bond between cobalt vertexes (which would have
equilibrated the ethyl environments, and Fe-CO’s) were
thwarted by the thermal instability of complex 9 in
solution. Nevertheless, the observation of these doubled
signals at room temperature reveals that the barrier
Resu lts a n d Discu ssion
Syn th etic a n d Str u ctu r a l Asp ects. With the intent
of preparing the iron-cobalt clusters 7 and 8 as
structural models of the [(alkynylcyclopentadienyl)Co2-
(CO)6]+ cations 3 and 4, respectively, the precursor
(alkynyl-cyclopentadienol)Co2(CO)6 complexes were
treated with iron pentacarbonyl and heated under reflux
in acetone for 2-3 days, and the products repeatedly
purified through multiple chromatographic separations.
Final yields of pure products ranged from 7 to 14%. The
13C NMR spectra of the products of both reactions
revealed the presence of iron carbonyls (δ 215-218) and
cobalt carbonyls (δ 200-202), but the appearance of
extra resonances in the region δ 80-95 suggested the
possibility of an η5-bonded cyclopentadienyliron carbo-
nyl moiety. The products, 9 and 10, were finally identi-
fied by means of X-ray crystallography, and the struc-
tures appear as Figures 1 and 2.
must exceed 15 kcal mol-1
.
The structure of 10 is shown in Figure 2, but because
of the relatively poor quality of the data,11 we merely
report the atom connectivity. As with 9, the iron-cobalt
vector in 10 is too long, 2.87 Å (mean value), to be
considered a bond, and the presence of a bridging
hydride is again invoked.
In each of these reactions, a further product, 11 or
12, respectively, was obtained and identified by NMR
and mass spectrometry as the Fe(CO)3 derivative of the
original 5-alkynylcyclopentadien-5-ol ligand. One can
readily visualize these complexes arising via reaction
of Fe(CO)5 with starting material that had lost its Co2-
(CO)6 group during the thermolysis.
There are two molecules of 9 in the asymmetric unit,
but their structures are very similar, and only one is
depicted in Figure 1. It reveals that in 9 both Co(CO)3
vertexes have been retained, the hydroxyl group has
been lost, and an Fe(CO)2 moiety is π-complexed to the
Mech a n istic Con sid er a tion s. The reaction of (pro-
pargyl alcohol)Co2(CO)6 clusters, 13, or their corre-
sponding diols (HOCR2CtCCR2OH)Co2(CO)6, 14, with
(10) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 2nd ed.; Wiley-Interscience: New York, 1993; p 62.
(11) Unit cell parameters for 10: a ) 17.173 Å, b ) 24.228 Å, c )
28.174 Å, a ) 104.69°, â ) 102.58°, γ ) 100.52°, V ) 10710 Å3, Z ) 10.
The only available crystals were of rather poor quality and apparently
exhibited multiple rotamers attributable to five different orientations
of the peripheral phenyl substituents.
(9) (a) Aime, S.; Osella, D.; Milone, L.; Tiripicchio, A. Polyhedron
1983, 2, 77. (b) Osella, D.; Dutto, G.; J aouen, G.; Vessie`res, A.; Raithby,
P. R.; De Benedetto, L.; McGlinchey, M. J . Organometallics 1993, 12,
4545. (c) Ruffolo, R.; Brook, M. A.; McGlinchey, M. J . Organometallics
1998, 17, 4992.

4692 Organometallics, Vol. 20, No. 22, 2001
Dunn et al.
Sch em e 1
Fe(CO)5 in refluxing acetone to yield iron-cobalt or di-
iron clusters, 15 or 16, respectively, was originally
reported by Victor in 1977.8 It was described as a
“dehydroxylation process”, and several such iron/cobalt9
or di-iron12 products have now been crystallographically
characterized.
Although the mechanism of this “dehydroxylation”
procedure remains unclear, speculation has focused on
the possible role of metal hydrides.13 For example, Chini
demonstrated that Co2(CO)8 and Fe(CO)5 in acetone
react to form HFeCo3(CO)12.14 Moreover, Geoffroy has
reported that MeCCo3(CO)9 and [Fe(CO)4]2- yield, upon
protonation, the hydride cluster MeCCo2FeH(CO)9.15
Thus the transformation of (HCtC-CH2OH)Co2(CO)6
into (HCdCdCH2)FeCo(CO)6 may involve the formation
of an intermediate metal hydride, 17; as depicted in
Scheme 1, subsequent elimination of water could give
the neutral iron-cobalt cluster 15.
However, the isolation of the trimetallic species 9 and
10 suggests another possibility: nucleophilic attack by
the hydroxyl group on a carbonyl ligand of Fe(CO)5 could
yield the hydrido metal carboxylate 18. It is, of course,
well known that the formation of the [HFe(CO)4]- anion
from Fe(CO)5 and KOH proceeds through an intermedi-
ate carboxylate species.16 It is relevant to note that
Osella has obtained the carboxylate-containing cluster
Fe2(CO)6[(EtCdCEt)C(dO)18O] from hex-3-yne, Fe2-
(CO)9, and 18OH2.17 Moreover, Sappa has convincingly
demonstrated that “deoxygenation” of the propargylic
alcohol HCtCC(Me)(Ph)OH by Fe3(CO)12 is really a
decarboxylation and proceeds with elimination of carbon
dioxide.18 It was tentatively suggested that the hydroxyl
substituent from the alkyne attacks a carbonyl ligand
on iron, and the current observations provide strong
support for such a proposal.
of the resulting loss of aromaticity in the six-membered
rings. Instead, one might invoke expansion of the
tetrahedral cluster to a square-based pyramidal struc-
ture 20. While the apical and basal plane cobalts in 20
would formally be assigned 19 and 17 electrons, respec-
tively, the overall skeletal electron count is appropriate
for a nido octahedral cluster,19 and numerous examples
of such cluster expansion20 or vertex replacement21
reactions are known. Finally, decarboxylation could
yield the observed mixed metal cluster 21, as typified
by 5 and 6.
Future work in this area will look at examining the
role of the solvent in these reactions to gain further
understanding of these fascinating processes.
Exp er im en ta l Section
Gen er a l Meth od s. All reactions were carried out under an
atmosphere of dry nitrogen employing conventional benchtop
and glovebag techniques. Silica gel (particle size: 20-45 µm)
was employed for flash column chromatography. 1H and 13C
NMR spectra were acquired on a Bruker DRX 500 spectrom-
eter and were referenced to the residual proton or 13C solvent
signal. Mass spectra were obtained using a Finnigan 4500
spectrometer by direct electron impact (DEI) or direct chemical
ionization (DCI) with NH3. Elemental analyses were performed
by Guelph Chemical Laboratories, Guelph, Ontario.
As depicted in Schemes 2 and 3, one can envision two
competing pathways. In the case of a cyclopentadiene
ligand, decarbonylation and η4-coordination to the five-
membered ring could precede decarboxylation to yield
19, which possesses an (η5-C5R4)Fe(CO)2H moiety and
corresponds to the observed product 9 or 10.
The alkynylcyclopentadienol)Co2(CO)6 complexes 22 and 23
were prepared as previously described.2
Rea ction of {5-(Tr im eth ylsilyl)eth yn yl)-1,4-d ieth yl-2,3-
diph en ylcyclopen tadien -5-ol}Co2(CO)6, 22, with Ir on P en -
ta ca r bon yl. Over a 25 min period, Fe(CO)5 (9.90 mL, 75.3
mmol) was added to 22 (5.0 g, 7.44 mmol) dissolved in acetone
(125 mL). The solution was heated to reflux and monitored
by TLC approximately every 5 h. Samples of the effluent gases
were shown by IR and mass spectrometry to contain traces of
CO2. After 60 h, the solution was allowed to cool and, after
removal of solvent, yielded a brown oil. The residue was
subjected to flash chromatography on silica gel with CH2Cl2
as eluent to remove inorganic salts arising from decomposed
metal carbonyls. A second purification (flash chromatography)
In contrast, coordination to the five-membered ring
of an indenyl or fluorenyl ligand is disfavored because
(12) (a) Gerlach, J , N.; Wing, R. M.; Ellgen, P. C. Inorg. Chem. 1976,
15, 2959. (b) Eigemann, S.-E.; Fo¨rtsch, W.; Hampel, F.; Schobert, R.
Organometallics 1996, 15, 1511. (c) Bright, D.; Mills, O. S. J . Chem.
Soc., Dalton Trans. 1972, 2465.
(13) McGlinchey, M. J .; Girard, L.; Ruffolo, R. Coord. Chem. Rev.
1995, 143, 331.
(14) Chini, P.; Colli, L.; Peraldo, M. Gazz. Chim. Ital. 1960, 90, 1005.
(15) Epstein, R. A.; Withers, H. W.; Geoffroy, G. L. Inorg. Chem.
1979, 18, 942.
(16) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987; p 403.
(17) Milone, L.; Osella, D.; Ravera, M.; Stanghellini, P. L.; Stein,
E. Gazz. Chim. Ital. 1992, 122, 451.
(19) Wade, K. Adv. Inorg. Chem. Radiochem. 1976, 18, 1.
(20) Adams, R. D. In The Chemistry of Metal Cluster Complexes;
Shriver, D. F., Kaesz, H. D., Adams, R. D., Eds.; VCH: New York,
1989; Chapter 3, pp 121-170.
(18) Gervasio, G.; Sappa, E. Organometallics 1993, 12, 1458.
(21) Vahrenkamp, H. Adv. Organomet. Chem. 1983, 22, 169.

(Propargyl Alcohol)Co2(CO)6 Clusters
Organometallics, Vol. 20, No. 22, 2001 4693
Sch em e 2
Sch em e 3
using hexanes yielded recovered 22 (730 mg, 1.09 mmol, 15%)
and the iron-dicobalt cluster 9, as well as 11 and other
unidentified decomposition products. The mixed metal cluster
9 was flash chromatographed a third time, with hexanes as
eluent, to yield brown microcrystals (338 mg, 0.44 mmol, 6.9%),
Crude 11 was also flash chromatographed a third time, using
hexanes on alumina, to yield an orange-red oil (26 mg, 0.05
mmol; 0.8%). 1H NMR (CD2Cl2): δ 7.31, 7.26 (m, 10 H, 2
phenyls), 6.56 (s, 1H, OH), 2.31 (m, 2H), 2.26 (m, 2H), 0.85 (t,
6H, CH3's), 0.13 (s, 9H, Me3Si). 13C NMR (CD2Cl2): δ 215.7
(Fe-CO’s), 153.1, 151.3 (C2,3), 132.4, 131.5, 128.4, 108.2 (CC-
TMS), 96.5 (C1), 86.7 (CC-TMS), 19.3 (CH2), 14.1 (CH3), 0.1
(Me3Si); IR (CH2Cl2) νCO 1997, 1921 cm-1. MS (DEI) m/z (%):
426 (11), ([M - Me - 3CO]+), 370 (9) ([M - Me - Fe(CO)3]+),
154 (16), 73 (100) ([Me3Si]+).
Reaction of {5-(Tr im eth ylsilyleth yn yl)-1,2,3,4-tetr aph e-
n ylcyclop en ta d ien -5-ol}Co2(CO)6, 23, w ith Ir on P en ta -
ca r bon yl. Over a 25 min period, Fe(CO)5 (17.0 mL, 131 mmol)
was added to 23 (7.00 g, 9.11 mmol) dissolved in acetone (125
mL). The solution was heated to reflux and monitored by TLC
approximately every 5 h. After 48 h, the solution was allowed
1
mp 110-113 °C. H NMR (CD2Cl2): δ 7.40, 7.31, 7.21 (m, 10
H, 2 phenyls); 2.47 (m, 1H) and 2.04 (m, 1H), (CH2); 1.57 (m,
1H) and 1.26 (m, 1H) (CH2′); 1.26 (t, 3H, CH3), 0.88 (t, 3H,
CH3′), 0.51 (s, 9 H, Me3Si). 13C NMR (CD2Cl2): δ 218.4, 215.6,
214.2, 202.2 (Fe-CO’s and Co-CO’s), 131.9, 131.3, 130.8,
128.8, 128.6, 128.5, 109.8, 109.7, 106.2, 100.1, 95.9, 81.4, 56.3,
18.6, 18.2, 17.2, 16.4, 2.4. IR (CH2Cl2): νCO at 2067, 2025, 1991,
1965 cm-1. MS (DCI) m/z (%): 624 (6) ([M - HCo(CO)3]+), 540
(11) ([M - Co(CO)3 - 3CO]+), 481 (9) ([M - HCo2(CO)6]+), 426
(14) ([M - FeCo(CO)6]+), 73 (100) ([Me3Si]+). Anal. Calcd for
C
34H30FeCo2SiO8: C, 53.15; H, 3.94. Found: C, 52.97; H, 4.13.

4694 Organometallics, Vol. 20, No. 22, 2001
Dunn et al.
to cool and, after removal of solvent, yielded a brown oil. The
residue was subjected to flash chromatography on silica gel
with CH2Cl2 as eluent to remove inorganic salts arising from
decomposed metal carbonyls. A second purification (flash
chromatography) using hexanes yielded recovered 23 (1.566
g, 2.04 mmol, 22%) and the iron-dicobalt cluster 10, as well
as 12 and other unidentified decomposition products. The
mixed metal cluster 10 was flash chromatographed a third
time, with CH2Cl2/hexanes (1:1) as eluent, to yield brown
microcrystals (847 mg, 0.98 mmol, 13.9%), mp 107-108 °C.
1H NMR (CD2Cl2): δ 7.32-6.89 (m, 20 H, 4 phenyls), 0.11 (s,
9 H, Me3Si). 13C NMR: (CD2Cl2) δ 218.4, 217.7 (Fe-CO’s),
200.1 (Co-CO’s), 135.7, 132.6-127.9 (∼17 overlapped peaks),
109.9, 109.2, 106.3, 101.5, 82.4, 59.7, 2.2 (Me3Si). IR (CH2-
Cl2): νCO at 2066, 2018, 1987, 1965 cm-1. MS (DCI) m/z (%):
636 (11) ([M - HCo(CO)3 - 3CO]+), 577 (14) ([M - HCo2-
(CO)6]+), 521 (9) ([M - HCo2(CO)8]+), 466 (15) ([M - FeCo2-
(CO)8]+), 267 (56) ([C3Ph3]+), 73 (100) ([Me3Si]+). Anal. Calcd
for C42H30FeCo2SiO8: C, 58.35; H, 3.50. Found: C, 58.47; H,
3.72. Crude 12 was also flash chromatographed a third time,
using hexanes on alumina, to yield an orange solid (287 mg,
processing was carried out by use of the program SAINT,23
while the program SADABS24 was utilized for the scaling of
diffraction data, the application of a decay correction, and an
empirical absorption correction based on redundant reflections.
Structures were solved by using the direct methods procedure
in the Siemens SHELXTL25 program library and refined by
full-matrix least-squares methods on F2.
Despite numerous attempts to obtain better crystals, the
structure of 9 could only be refined to a reasonable, though
high, R value of 0.137. However, there are high residual
electron densities in the vicinity of metal or carbons that could
not be attributed to solvent or water molecules. In 10, only
the heavy atoms Co, Fe, and Si were refined using anisotropic
thermal parameters. Hydrogen atoms were added as fixed
contributors at calculated positions, with isotropic thermal
parameters based on the carbon atom to which they are
bonded.
Ack n ow led gm en t. Financial support from Natural
Sciences and Engineering Research Council of Canada
and from the Petroleum Research Fund, administered
by the American Chemical Society, is gratefully ac-
knowledged. J .A.D. thanks NSERC for a Graduate
Fellowship. Mass spectra were acquired courtesy of Dr.
Kirk Green of the McMaster Regional Mass Spectrom-
etry Centre. We thank Professors Domenico Osella and
Enrico Sappa (Universita` del Piemonte Orientale,
Alessandria, Italy) for insightful comments.
1
0.46 mmol; 7%), mp 162-164 °C. H NMR (CD2Cl2): δ 7.49-
7.17 (m, 20H, 4 phenyls), 2.50 (s, 1H, OH), 0.58 (s, 9H, Me3-
Si). 13C NMR (CD2Cl2): δ 211.1 (Fe-CO’s), 155.0, 154.3 (C2,3),
132.6-126.8 (phenyls), 109.5 (CC-TMS), 90.2 (C1), 83.7 (CC-
TMS), -0.3 (Me3Si). IR (CH2Cl2) νCO at 1997, 1965, 1925 cm-1
.
MS (DCI) m/z (%): 606 (5) ([M + H - OH]+), 550 (8) ([M + H
- OH - 2CO]+), 522 (11) ([M + H - OH - 3CO]+), 466 (15)
([M + H - OH - Fe(CO)3]+), 450 (12), 436 (7), 380 (15), 315
(8), 289 (9), 73 (100) ([Me3Si]+). Anal. Calcd for C37H30FeSiO4:
C, 71.38; H, 4.86. Found: C, 71.66; H, 5.02.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data, atomic parameters, bond lengths and angles, and aniso-
tropic displacement parameters for 9. This material is avail-
able free of charge via the Internet at http://pubs.acs.org.
Cr ysta llogr a p h ic Da ta for 9 a n d 10. X-ray crystal-
lographic data for 9 and 10 were each collected from a suitable
sample mounted with epoxy on the end of a thin glass fiber.
Data were collected on a P4 Siemens diffractometer equipped
with a Siemens SMART 1K CCD area detector (employing the
program SMART22) and a rotating anode utilizing graphite-
monochromated Mo KR radiation (λ ) 0.71073 Å). Data
OM010494O
(23) Sheldrick, G. M. SAINT, Release 4.05; Siemens Energy and
Automation Inc.: Madison, WI 53719, 1996.
(24) Sheldrick, G. M. SADABS (Siemens Area Detector Absorption
Corrections); Siemens Energy and Automation Inc.: Madison, WI
53719, 1996.
(22) Sheldrick, G. M. SMART, Release 4.05; Siemens Energy and
Automation Inc.: Madison, WI 53719, 1996.
(25) Sheldrick, G. M. SHELXTL, Version 5.03; Siemens Crystal-
lographic Research Systems: Madison, WI, 1994.