Chemistry of bridging ketene from facile carbonylation of a ditungsten methylene complex with no metal-metal bond

Article abstract of DOI:10.1021/om9609980

The reaction of Cp(CO)₃W^- (Cp = η⁵-C₅H₅) with CH₂I₂ in CH₃CN at -20 °C gives the dinuclear acetylide complex Cp₂(CO)₆W₂(μ-C≡C) (2). When the same reaction is carried out in methanol at -20 °C, a dinuclear ketene complex, Cp₂(CO)₅W₂(μ,η¹,η ²-CH₂CO) (5), is isolated. The oxygen atom of the ketene unit in 5 is weakly coordinated to one of the tungsten metal centers. Upon dissolution in CH₃CN at room temperature, complex 5 transforms to 2. A bridging methylene complex, Cp₂(CO)₄[P(OMe)₃]₂W ₂(μ-CH₂) (4a), has been isolated, and its facile carbonylation gives a different ketene complex, Cp₂(CO)₂[P(OMe)₃]₂W ₂(μ,η¹,η^1- CH₂CO)(μ-CO) (6a), in CH₃CN. Treatment of 5 with CO affords Cp₂(CO)₆W₂(μ-CH₂CO) (8), which, upon reacting with H₂O, ROH (R = Me, Et, PhCH₂), and i-PrNH₂, generates mononuclear complexes Cp(CO)₃WCH₂COOH (9), Cp(CO)₃WCH₂COOR (12a-c), and Cp(CO)₃WCH₂CONH(i-Pr) (14), respectively. The more stable Cp′ (Cp′ = C₅H₄Me) analogues 2′, 5′, and 8′ are also prepared. An experiment using a mixture of 5 and 5′ to afford only 2 and 2′ without the crossover product shows that intermolecular coupling is not involved in this transformation. The reaction of 5 with PR₃ (R = OMe, Et, Ph) yields only the trans product Cp₂(CO)₅(PR₃)W₂(μ-CH ₂CO) (10a-c). But the reaction of 5 with t-BuNC gives both the trans and cis products of the ketene complex Cp₂(CO)₅(t-BuNC)W₂(μ-CH₂CO) (11). Complexes 2′, 5′, 8′, and 11 have been characterized by single-crystal X-ray diffraction analysis.

Full text of DOI:10.1021/om9609980

Organometallics 1997, 16, 1573-1580
1573
Ch em istr y of Br id gin g Keten e fr om F a cile Ca r bon yla tion
of a Ditu n gsten Meth ylen e Com p lex w ith No
Meta l-Meta l Bon d
Yu-Lee Yang, Luxti J un-J ieh Wang, Ying-Chih Lin,* Shou-Ling Huang,
Ming-Chou Chen, Gene-Hsiang Lee, and Yu Wang
Department of Chemistry, National Taiwan University, Taipei, Taiwan 10764,
Republic of China
Received November 26, 1996X
The reaction of Cp(CO)3W- (Cp ) η5-C5H5) with CH2I2 in CH3CN at -20 °C gives the
dinuclear acetylide complex Cp2(CO)6W2(µ-CtC) (2). When the same reaction is carried
out in methanol at -20 °C, a dinuclear ketene complex, Cp2(CO)5W2(µ,η1,η2-CH2CO) (5), is
isolated. The oxygen atom of the ketene unit in 5 is weakly coordinated to one of the tungsten
metal centers. Upon dissolution in CH3CN at room temperature, complex 5 transforms to
2. A bridging methylene complex, Cp2(CO)4[P(OMe)3]2W2(µ-CH2) (4a ), has been isolated,
and its facile carbonylation gives a different ketene complex, Cp2(CO)2[P(OMe)3]2W2(µ,η1,η1-
CH2CO)(µ-CO) (6a ), in CH3CN. Treatment of 5 with CO affords Cp2(CO)6W2(µ-CH2CO) (8),
which, upon reacting with H2O, ROH (R ) Me, Et, PhCH2), and i-PrNH2, generates
mononuclear complexes Cp(CO)3WCH2COOH (9), Cp(CO)3WCH2COOR (12a -c), and
Cp(CO)3WCH2CONH(i-Pr) (14), respectively. The more stable Cp′ (Cp′ ) C5H4Me) analogues
2′, 5′, and 8′ are also prepared. An experiment using a mixture of 5 and 5′ to afford only 2
and 2′ without the crossover product shows that intermolecular coupling is not involved in
this transformation. The reaction of 5 with PR3 (R ) OMe, Et, Ph) yields only the trans
product Cp2(CO)5(PR3)W2(µ-CH2CO) (10a -c). But the reaction of 5 with t-BuNC gives both
the trans and cis products of the ketene complex Cp2(CO)5(t-BuNC)W2(µ-CH2CO) (11).
Complexes 2′, 5′, 8′, and 11 have been characterized by single-crystal X-ray diffraction
analysis.
In tr od u ction
complexes either with a metal-metal bond6 or with
some other supplementary bridging ligand are not
commonly carbonylated into µ-ketene. In contrast, the
facile carbonylation of the dinuclear ruthenium µ-
methylene complex with no metal-metal bond leading
to the bridging ketene was first recognized in 1983.7
Thereafter, other ketene complexes derived from CO
insertion of compounds of this type have also been
reported.8 It is now accepted that, relative to dimetalla-
cyclopropane, the µ-methylene group with no metal-
metal bond displays higher reactivity especially through
CO insertion to result in C-C bond formation. From
the X-ray data of the first µ-methylene complex with
no metal-metal bond, the Ru-C-Ru bond angle of
123(3)° is observed.7a This feature might imitate the
structure of a bridging methylene group at the kink site
of a metallic surface while the dimetallacyclopropane
might model that at the smooth surface.9 The higher
reactivity of the µ-methylene complex with no metal-
Even though organic ketenes and their synthetic
applications have been recognized for nearly a century,1
only recently have metal-complexed ketenes been pre-
pared. A number of routes, including the coupling of
alkylidene and carbonyl moieties,2 addition of free
ketene to unsaturated metal systems,3 and deprotona-
tion of metal acyls,4 are known for preparation of the
metal-complexed ketenes. Heterobimetallic ketene com-
plexes have been prepared from the acylation of metal
anion, MLn-, by FpCH2COCl (Fp ) CpFe(CO)2).5 At-
tempts have been made to obtain the ketene moiety by
carbonylation of a dimetallacyclopropane. However,
owing to the extraordinary stability of such a three-
membered-ring skeleton, the well-known µ-methylene
X Abstract published in Advance ACS Abstracts, March 15, 1997.
(1) Brady, W. T. In The Chemistry of Ketenes, Allenes, and Related
Compounds; Patai, S., Ed.; Wiley: New York, 1980; Chapter 8.
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1978, 17, 525. (b) Bodner, T. W.; Cutler, A. R. J . Am. Chem. Soc. 1983,
105, 5926. (c) Barger, P. T.; Santarsiero, B. D.; Armantrout, J .; Bercaw,
J . E. J . Am. Chem. Soc. 1984, 106, 5178. (d) Curtis, M. D.; Messerle,
L.; D’Errico, J . J .; Solis, H. E.; Barcelo, I. D.; Butler, W. M. J . Am.
Chem. Soc. 1987, 109, 3603. (e) Geoffroy, G. L.; Bassner, S. L. Adv.
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H.; Straus, D. A.; Armantrout, J .; Schaefer, W. P.; Grubbs, R. H. J .
Am. Chem. Soc. 1984, 106, 2210. (c) Morrison, E. D.; Geoffroy, G. L.
J . Am. Chem. Soc. 1985, 107, 3541. (d) Holmgren, J . S.; Shapley, J .
R.; Wilson, S. R.; Pennington, W. T. J . Am. Chem. Soc. 1986, 108, 508.
(3) (a) Fermin, M. C.; Hneihen, A. S.; Maas, J . J .; Bruno, J . W.
Organometallics 1993, 12, 1845. (b) Fermin, M. C.; Bruno, J . W. J .
Am. Chem. Soc. 1993, 115, 7511.
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D.; Grubbs, R. H.; Bercaw, J . E. J . Am. Chem. Soc. 1983, 105, 2068.
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S0276-7333(96)00998-3 CCC: $14.00 © 1997 American Chemical Society

1574 Organometallics, Vol. 16, No. 8, 1997
Yang et al.
metal bond is thus a manifestation of the reactivity of
the same group attached to that kink site on an
irregular surface. On the basis of this belief, we set out
to study a similar organometallic system using tungsten
metal. In this paper we report the chemistry of various
dinuclear ketene complexes derived from facile car-
bonylation of a methylene complex of tungsten. Part
of the results has appeared in our preliminary
communication.7b
F igu r e 1. ORTEP drawing of (C5H4Me)2(CO)6W2(µ-CtC)
(2′) with thermal ellipsoids shown at the 50% probability
level. Selected bond distances (Å) and bond angles (deg)
are as follows: W-C(4), 2.135(9); C(4)-C(4a), 1.216(19);
W-C(4)-C(4a), 176.4(8).
Resu lts a n d Discu ssion
Rea ction of CH2I2 w ith Tu n gsten Ca r bon yla te
An ion . At -20 °C the reaction of Cp(CO)3W- (1) with
0.5 equiv of CH2I2 in CH3CN in 3 days affords the
ditungsten acetylide complex Cp2(CO)6W2(µ-CtC) (2) as
a dark red crystalline product. The yield of 2 is
generally ca. 25% if the reaction is carried out on a 5 g
scale and has been optimized to 31% (see Experimental
Section) when the reaction is carried out on a smaller
scale. Complexes Cp(CO)3WMe and Cp(CO)3WI, with
35% and 38% yields, respectively, are the two major side
products of this reaction. Complex 2 is soluble in polar
organic solvents and is air stable in the solid state at
room temperature. Some interesting physical proper-
ties are observed for 2; for example, analytically pure
solid compound displays either a yellow (amorphous
powder) or dark red color (crystalline) in the solid state,
but the solution always displays a yellow color. The
analogous complex Cp′2(CO)6W2(µ-CtC) (2′, Cp′ ) η5-
C5H4Me) could be similarly prepared in 30% yield.
Relative amounts of the reactants and solvent used in
the reaction change the product. If carried out in THF
with excess CH2I2, the reaction gives Cp(CO)3WCH2I
(3) as the major product. In the 13C NMR spectrum of
3 the resonance at δ -35.8 with J W-C ) 49.3 Hz is
assigned to the methylene group. Even though 3 can
be used for the synthesis of 2 by treatment with 1, the
yield is much lower (<10%).
of (CO)10Re2(µ-CtC) (1.19(3) Å),13 Cp3(PMe3)2ClRuZr-
(µ-CtC) (1.25(2) Å),14 (C5Me5)(PPh3)(NO)Re(µ-
CtC)Pd(PEt3)2Cl, (1.21(1) Å),15 and [Cl(PPh3)2Pt]2(µ-
CtC), (1.221(9) Å).16 The WsC(4)tC(4a) bond angle
in 2′ (176.4(8)°) differs only slightly from 180°. We have
previously reported in our preliminary communication
the structure of 2. All other bond distances and angles
lie in the expected range and deserve no further com-
ment. Complex 2 has also been reported as a trace
product from the reaction of ClCtCCl with Cp(CO)3W-.17
Great interest has focused on the chemistry of these
µ-ethynediyl compounds in past five years.18
Formation of complex 2 can be envisaged as proceed-
ing via the following steps: The initial reaction of CH2I2
with 1 presumably gives an unobserved dinuclear
µ-methylene complex, Cp2(CO)6W2(µ-CH2) (4), which
undergoes CO insertion to give a ketene intermediate.
The subsequent “formal dehydration” reaction and CO
abstraction from the other Cp(CO)3W moiety satisfac-
torily account for the formation of 2. The low yield of
this reaction may thus be interpreted in terms of this
CO abstraction step. The transformation of an acyl
ligand in a Re complex into a vinylidene ligand by triflic
anhydride was reported19 by Hughes and his co-workers.
The CO-induced conversion of η1-ketenyl ligands into
alkynyl ligands by a deoxygenation reaction has been
reported,20 but its mechanism is unknown. The reverse
1
Since there is only a singlet resonance in the H NMR
spectrum of 2, more data are required to define the
structure. The definitive characterization of 2′ came
from a single-crystal X-ray diffraction analysis. A view
of the molecular geometry of this compound is shown
in Figure 1. The W-C(4) distance (2.135(9) Å) is
slightly shorter than that of a regular W-C(sp3) single
bond,10 and the C(4)tC(4a) distance of 1.21(2) Å is very
close to the expected value for an organic CtC triple
(13) (a) Beck, W.; Niemer, B.; Mreimair, J .; Heidrich, J . J . Organo-
met. Chem. 1989, 372, 79. (b) Heidrich, J .; Steimann, M.; Appel, M.;
Beck, W. Organometallics 1990, 9, 1296.
(14) Lemke, F. R.; Szalda, D. J .; Bullock, R. M. J . Am. Chem. Soc.
1991, 113, 8466.
(15) Weng, W.; Bartik, T.; Brady, M.; Bartik, B.; Ramsden, J . A.;
Arif, A. M.; Gladysz, J . A. J . Am. Chem. Soc. 1995, 117, 11922.
(16) Su¨nkel, K.; Birk, U.; Robl, C. Organometallics 1994, 13, 1679.
(17) Ustynyuk, N. A.; Yinogradova, V. N.; Kravtsov, D. N. Metallo-
org. Khim. 1988, 1, 85; Organomet. Chem. USSR (Engl. Transl.) 1988,
1, 45.
bond,11 indicating
a
dimetallaalkyne with the
MsCtCsM form, instead of the alternative “dicarbide”
MdCdCdM form found in the Ta system.12 Very
similar distances are found in the acetylide complexes
(18) (a) Chisholm, M. H. Angew. Chem., Int. Ed. Engl. 1991, 30,
673. (b) Koutsantonis, G. A.; Selegue, J . P. J . Am. Chem. Soc. 1991,
113, 2316. (c) Beck, W.; Niemer, B.; Wieser, M. Angew. Chem., Int.
Ed. Engl. 1993, 32, 923. (d) Akita, M.; Morooka, Y. Bull. Chem. Soc.
J pn. 1995, 68, 420. (e) De Angelis, S.; Solari, E.; Floriani, C.; Chiesi-
Villa, A.; Rizzoli, R. Angew. Chem., Int. Ed. Engl. 1995, 34, 1092. (f)
Belanzoni, P.; Re, N.; Rosi, M.; Sgamellotti, A.; Floriani, C. Organo-
metallics 1996, 15, 4264.
(19) Boland-Lussier, B. E.; Churchill, M. R.; Hughes, R. P.; Rhein-
gold, A. L. Organometallics 1982, 1, 628.
(20) (a) Kreissl, F. R.; Eberl, K.; Uedelhoven, W. Angew. Chem., Int.
Ed. Engl. 1978, 17, 860. (b) Eberl, K.; Uedelhoven, W.; Wolfggruber,
M.; Kreissl, F. R. Chem. Ber. 1982, 115, 504.
(9) (a) Keim, W. Catalysis in C1 Chemistry; D. Reidel: Dordrecht,
The Netherlands, 1983. (b) Anderson, R. B. The Fischer-Tropsch
Synthesis; Academic Press: London, 1984. (c) Somorjai, G. A. Introduc-
tion of Surface Chemistry and Catalysis; J ohn Wiley & Sons: New
York, 1994.
(10) Templeton, J . L.; Winston, P. B.; Ward, B. C. J . Am. Chem.
Soc. 1981, 103, 7713.
(11) Allene, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 2 1987, S1-S19.
(12) Neithammer, D. R.; Lapointe, R. E.; Wheeler, R. A.; Richeson,
D. S.; Van Duyne, G. D.; Wolczanski, P. T. J . Am. Chem. Soc. 1989,
111, 9056.

Chemistry of Bridging Ketene
Sch em e 1
Organometallics, Vol. 16, No. 8, 1997 1575
resonance is expected for the CH2 of 5 because of free
rotation of the W-C bond and an AB type pattern for
that of 6. Indeed in the 1H NMR spectrum of 5, the
methylene protons appear as a broad singlet resonance
(with tungsten satellites) at δ 3.41 and the resonances
at δ 5.61 and 5.46 are assigned to the Cp groups. The
fact that the methylene protons display a singlet
resonance indicates a noncyclic structure of the ketene
unit for 5. At -40 °C, restricted rotation of the W-CH2
bond causes the singlet resonance to form two doublet
resonances at δ 3.13 and 3.56 with J H-H ) 3.4 Hz in
1
the H spectrum. The structure of 5 is also consistent
with its IR spectral data: in addition to the absorption
bands at 2020, 1922, 1903, and 1827 cm-1 assignable
to the stretching of the terminal CO group, an O-
coordinated νCdO stretching is observed at 1437 cm-1
,
much lower than the stretching absorption of a free
CdO group.
1
reaction has been observed in the transformation of
metal acetylide to metal acyl complex.21
When monitored by H NMR spectroscopy, the reac-
tion of 1 with CH2I2 in CD3CN at -25 °C is found to
yield three complexes, each containing diastereotopic
methylene protons with their resonances appearing at
δ 3.11, 3.52 (J H-H ) 3.7 Hz), 2.08, 2.23 (J H-H ) 7.5 Hz),
and 2.24, 2.62 (J H-H ) 6.6 Hz) with a ratio of 2:1:1. The
first set is almost identical to the low-temperature NMR
data of 5 (the slight variation may be due to the solvent
effect), and the other two sets at the upper field region
are believed to be due to isomers of the C,C-bonded
ketene complex 6 with a bridging CO ligand. The
upfield chemical shifts of the CH2 protons of 6 are
similar to those of a Ru complex.22 Thus we can
conclude that the proposed 4 undergoes CO insertion
to give a mixture of 5 and 6 in CH3CN with 6 being
much less stable. From a variable-temperature experi-
ment we could not tell if the transformation between 6
and 5 would ever occur. In the CD3OD solvent system,
due to the deuterium exchange of the methylene protons
and many other side products formed, we could not
firmly establish the presence of 6. Interestingly, with-
out CH3CN, no acetylide complex could be observed. The
“formal dehydration” of the ketene group thus requires
oxygen coordination and the presence of CH3CN.
Recrystallization of 5′ from hexane gives single crys-
tals suitable for X-ray diffraction analysis. The molec-
ular geometry and labeling scheme are shown in Figure
2. The two W atoms are connected by a bent µ,η1,η2-
ketene bridge with W(1)-C(6)-C(7) and W(2)-C(7)-
C(6) angles of 154.9(19) and 109.7(17)°, respectively.
Coordination of the oxygen atom is clearly shown, with
a W(1)-O(6) distance of 2.19(2) Å, comparable to the
W(1)-C(6) distance of 2.10(3) Å. The slightly shorter
C(6)-C(7) distance of 1.39(4) Å is probably due to this
oxygen coordination. The two metal centers exist as
mutually independent mononuclear states, and no
evidence for metal-metal interaction is detected. Pho-
tolysis of 5 would not yield the proposed dimetalla-
cyclopropane complex Cp2(CO)4W2(µ-CH2)(µ-CO) (7) but
only causes decomposition, indicating that the carbon-
ylation might be an irreversible process due to the
oxophilicity of the tungsten metal. Without O-coordina-
tion in the Ru system, formation of a dimetallacyclo-
propane complex Cp2(CO)2Ru2(µ-CH2)(µ-CO) has been
obtained by photolysis.23 In 5 and 5′, the oxygen atom
of the ketene unit is only weakly coordinated to one of
Isola tion of a n O-Coor d in a ted Keten e Com p lex.
Our attempts to prepare precursors of 2 led to isolation
of an O-coordinated ketene complex. Since the solvent
used for this reaction plays an important role in
determining the product, the attempted reactions are
therefore carried out in several different solvents. An
explicit intermediate is isolated from the reaction car-
ried out in MeOH. Treatment of 1 with CH2I2 in
methanol at -20 °C affords in 49% yield a dark red
product identified as a dinuclear ketene complex,
Cp2(CO)5W2(η1,η2,µ-CH2CO) (5). The same product is
also isolated from the reaction carried out in ethanol
but with
a lower yield. The analogous complex
Cp′2(CO)5W2(η1,η2,µ-CH2CO) (5′) is prepared similarly
in MeOH at -20 °C in 52% yield and in EtOH with a
lower yield. Complex 5′ is relatively more stable than
5. The two methylene protons of 5 are replaced by D
atoms for the reaction carried out in CH3OD. But the
CH2 protons of 5 and 5′ are not exchangeable with
CH3OD, indicating that an exchange process occurs at
the methylene complex. In addition to the structure of
5, there is an alternative structure 6 depicted in Scheme
1, obeying the 18-electron rule. On the basis of the
spectroscopic data, chemical reactivities, and X-ray
structure determination, complex 5 in its solid state
contains a bridging ketene with the η2-CO unit bonded
to one of the tungsten centers.22 However, when the
reaction carried out in CD3CN is monitored by NMR
spectroscopy at low temperature, the alternative species
6 is also observed. The cyclic structure of 6 imposes
restriction for rotation of the W-C bond, making the
two methylene protons inequivalent. Thus in the 1H
NMR spectra characteristic differences in the CH2
resonances of 5 and 6 would be expected: a singlet
(21) Bruce, M. I.; Swincer, A. G. Aust. J . Chem. 1980, 33, 1471.
(22) (a) Fachinetti, G.; Floriani, C.; Stoeckli-Evans, H. J . Chem. Soc.,
Dalton Trans. 1977, 2297. (b) Manriquez, J . M.; McAlister, D. R.;
Sanner, R. D.; Bercaw, J . E. J . Am. Chem. Soc. 1978, 100, 2716. (c)
Wolczanski, P. T.; Bercaw, J . E. Acc. Chem. Res. 1980, 13, 121. (d)
Richmond, T. G.; Basolo, F.; Schriver, D. F. Inorg. Chem. 1982, 21,
1272. (e) LaCroce, S. J .; Cutler, A. R. J . Am. Chem. Soc. 1982, 104,
2312. (f) Erker, G. Acc. Chem. Res. 1984, 17, 103. (g) Durfee, L. D.;
Rothwell, I. P. Chem. Rev. 1988, 88, 1059. (h) Gamble, A. S.; White,
P. S.; Templeton, J . L. Organometallics 1991, 10, 693. (i) Contreras,
L.; Monge, A.; Pizzano, A.; Ruiz, C.; Sanchez, L.; Carmona, E.
Organometallics 1992, 11, 3971. (j) Kriessl, W. J .; Sieber, W. J .;
Wolfggruber, M.; Riede, J . Angew. Chem., Int. Ed. Engl. 1994, 23, 640.
(k) Conejo, M. del M.; Pizzano, A.; Sanchez, L. J .; Carmona, E. J . Chem.
Soc., Dalton Trans. 1996, 3687.
(23) Lin, Y. C. J . Chin. Chem. Soc. 1985, 32, 295.

1576 Organometallics, Vol. 16, No. 8, 1997
Yang et al.
Sch em e 2
F igu r e 2. ORTEP drawing of (C5H4Me)2(CO)5W2(µ-CH2-
CO) (5′) with thermal ellipsoids shown at the 50% prob-
ability level. Selected bond distances (Å) and bond angles
(deg) are as follows: W(1)-C(6), 2.325(9); W(2)-O(6),
2.190(6); W(2)-C(7), 2.061(9); C(6)-C(7), 1.43(1); C(7)-
O(6), 1.27(1); W(2)-C(7)-C(6), 155.6(8); C(6)-C(7)-O(6),
126.0(8); W(2)-C(7)-O(6), 78.4(5); W(2)-O(6)-C(7), 67.2(5).
13C NMR spectrum are characteristic for such a CH2
group.7a For 6a , the two broad doublet resonances at δ
1
the tungsten metal centers. The carbonyl carbon of such
a ligand in 5 may not have carbene-like character.24
Weak coordination of the oxygen atom to tungsten is
somewhat surprising, since high oxophilicity has been
observed in many tungsten complexes.25
Complex 5 is a precursor of 2, since, upon dissolution
in CH3CN, 5 converts to 2 in 10 min at room temper-
ature. On the basis of the stoichiometry, it is not
surprising to have a low yield for this transformation.
In addition to the “formal dehydration” process that
affords 2, cleavage of the ketene unit followed by an
intermolecular coupling of two C1 units can possibly lead
to the C2 product. This possibility is excluded by the
following experiment: a mixture of 5 and 5′ in CH3CN
3.00 and 2.95 in the H NMR spectrum assignable to
the methylene group reveal the inequivalence of the gem
protons, indicating the cyclic structure. Two resonances
at δ 183.8 and 158.1 in the 31P NMR spectrum are
assigned to the two P(OMe)3 ligands. Better donor
ability of the phosphite ligand increases the electron
density at the metal center and thus hinders oxygen
coordination. The fact that no acetylide complex is
observed in the phosphite-substituted system reinforces
the concept of the importance of the O-coordination in
the formation of an acetylide complex.
Rea ction of 5 w ith Don or Liga n d . Treatment of
5 with CO affords Cp2(CO)6W2(µ-CH2CO) (8); see Scheme
2. Under 1 atm of CO pressure, the CH2Cl2 solution of
5 turned to yellowish-orange within 45 min, and by
cooling this solution to -20 °C, a yellow crystalline
product 8 is isolated in 55% yield. The weakly coordi-
nated oxygen atom relinquishes the coordination site
for the incoming CO ligand. In this reaction the
temperature control is critical: the optimum yield is
obtained at around 25 °C; at a higher temperature or
at a temperature below 15 °C, the reaction gives a
mixture of compounds, possibly due to the decomposi-
tion of 5. The reaction requires anhydrous conditions;
i.e., in the presence of water, the reaction yields
Cp(CO)3WCH2COOH (9) as a minor product which is
formed by the hydrolysis of 8. Complex 9 could be
separated from 8 by fractional crystallization. Treat-
ment of 8 with dehydration agents such as triflic
anhydride does not yield 2, further evidence supporting
the idea that O-coordination is required for the “formal
dehydration” to occur.
gives only
2 and 2′ with no crossover product
CpCp′(CO)6W2(µ-CtC), indicating that this transforma-
tion is an intramolecular process. Conversion of meth-
ylene to formaldehyde on rhenium had been reported.26
A Ditu n gsten Meth ylen e Com p lex. In reactions
using the Cp(CO)3W and Cp′(CO)3W groups, complex 4
cannot be observed even at low temperature. However,
in an experiment using a phosphite-substituted tung-
sten anion in the preparation, an unstable dinuclear
methylene complex with no metal-metal bond is iso-
lated. From the reaction of Cp(CO)2[P(OMe)3]W- (1a )
with CH2Br2 in THF are isolated the µ-methylene
complex Cp2(CO)4[P(OMe)3]2W2(µ-CH2) (4a ) as the ma-
jor product and its carbonylation product Cp2-
(CO)2[P(OMe)3]2W2(µ-CH2CO)(µ-CO) (6a ). Because car-
bonylation is so facile, 4a could not be obtained in pure
form. When the mixture of 4a and 6a is dissolved in
CH3CN, CO insertion of 4a takes place immediately,
yielding 6a . If the reaction of CH2Br2 with 1a is carried
out in CD3CN, 6a is obtained directly. This carbonyl-
ation gives a µ,η1,η1-ketene group, unlike the η1,η2-
bonding mode observed in 5. For 4a , the triplet signal
In the IR spectrum of 8, the absorption band at 1612
cm-1 is a typical νCdO stretching of a ketone or an acyl
ligand.27 In the 1H NMR spectrum, three singlet
resonances at δ 5.50, 5.44, and 3.20 are assigned to the
two Cp groups and the methylene group, respectively.
The 13C resonance of the CH2 group appears at δ 22.7
in the 13C NMR spectrum. Analogous complex 8′ could
1
at δ 2.34 (J P-H ) 5.1 Hz) in the H NMR spectrum and
the triplet resonance at δ -50.4 (J P-C ) 11.2 Hz) in the
(24) Yamamoto, A. Organotransition Metal Chemistry, Fundamental
Concepts and Application; Wiley: New York, 1990; p 250.
(25) Mayer, J . M. J . Am. Chem. Soc. 1987, 109, 2826.
(26) Buhro, W. E.; Georgious, S.; Ferndandez, J . M.; Patton, A. T.;
Strouse, C. E.; Gladysz, J . A. Organometallics 1986, 5, 956.
(27) 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 107.

Chemistry of Bridging Ketene
Organometallics, Vol. 16, No. 8, 1997 1577
F igu r e 4. ORTEP drawing of Cp2(CO)5(CNCMe3)W2(µ-
CH2CO) (11) with thermal ellipsoids shown at the 40%
probability level. Selected bond distances (Å) and bond
angles (deg): W(1)-C(6), 2.29(2); W(1)-C(8), 2.06(2); W(2)-
C(7), 2.36(2); C(6)-C(7), 1.50(3); C(6)-O(6), 1.19(3); W(2)-
C(7)-C(6), 114.6(14); W(1)-C(6)-C(7), 117.9(13); W(1)-
C(6)-O(6), 118.9(15); C(7)-C(6)-O(6), 122.9(18); W(1)-
C(8)-N, 178.9(20); C(8)-N-C(9), 176.4(25).
F igu r e 3. ORTEP drawing of (C5H4Me)2(CO)6W2(µ-CH2-
CO) (8′) with thermal ellipsoids shown at the 50% prob-
ability level. Selected bond distances (Å) and bond angles
(deg) are as follows: W(1)-C(7), 2.29(1); W(2)-C(8), 2.27(1);
C(7)-C(8), 1.49(1); C(7)-O(7), 1.24(1); W(1)-C(7)-C(8),
124.0(6); W(1)-C(7)-O(7), 114.4(7); C(8)-C(7)-O(7),
121.6(9); W(2)-C(8)-C(7), 121.9(7).
obtained. The crystal structure of the trans isomer
consists of an ordered arrangement of discrete molecular
units, which are seperated by normal van der Waals
distances. The molecular geometry and labeling scheme
are shown in Figure 4. The µ,η1,η1-coordination mode
of the ketene is clearly shown by the W(1)-C(6) distance
of 2.29(2) Å and the W(2)-C(7) distance of 2.36(2) Å.
The C(6)-C(7) distance of 1.50(3) Å is comparable to
that in 8′ and slightly longer than that in 5′. The two
W atoms are connected by a bent C2 ketene bridge with
W(1)-C(6)-C(7) and W(2)-C(7)-C(6) angles of 117.9(13)
and 114.6(14)°, respectively. The two metal centers
exist as mutually independent mononuclear states, and
no evidence for metal-metal interaction is detected.
Isonitriles form stable transition metal complexes29
analogous to metal carbonyls. The ketene-bridged
complexes 10 and 11 are inert and relatively more stable
than 8; while the latter decomposes at room tempera-
ture, the former complexes are stable. Thermolysis of
10a in CHCl3 gives the acyl complex Cp(CO)2[P(OMe)3]-
WCOCH3 (16a ) and Cp(CO)3WCl.
be similarly prepared, and with the same workup
procedure, single crystals suitable for X-ray diffraction
analysis are obtained. The molecular geometry and the
labeling scheme resulting from the analysis are shown
in Figure 3. The two W-C distances of the ketene
ligand are comparable (2.29(1) and 2.27(1) Å). The
µ,η1,η1-coordination mode of the ketene is clearly shown
since the O(7) is no longer coordinated to the W(1) metal.
Treatment of 5 with P(OMe)3 at -20 °C affords the
dinuclear ketene complex, trans-Cp2(CO)5[P(OMe)3]W2(µ-
CH2CO) (10a ), in 89% isolated yield. The term “trans”
refers to the configuration at the P(OMe)3-substituted
metal center; see Scheme 2. Spectroscopic data of 10a
1
are consistent with this formulation. In the H NMR
spectrum, the resonances of the two Cp groups appear
at δ 5.44 and 5.28, with the latter showing coupling with
P(OMe)3, J P-H ) 1.3 Hz, a typical coupling constant for
a piano stool Cp(CO)2LWR structure in a trans config-
uration;28 the resonance at δ 3.22 is assigned to the CH2
of the bridging ketene. Similar reactions are observed
for PEt3 and PPh3 giving Cp2(CO)5(PEt3)W2(µ-CH2CO)
(10b) and Cp2(CO)5(PPh3)W2(µ-CH2CO) (10c), respec-
tively. Only the trans isomer is observed for both 10b
and 10c. The 13C resonances of the CH2 and CO of the
bridging ketene unit appear at δ 20-30 and at δ 250,
respectively. Values of the two J W-C coupling constants
for the methylene carbon can be obtained from the 13C
NMR spectra of 10a -c and fall in the range of 30 and
25 Hz.
Rea ction s of 8 w ith Nu cleop h iles. The reaction
of 8 with MeOH in CH2Cl2 generates Cp(CO)3WCH2-
COOMe (12a , 50% yield) and [Cp(CO)3W]2 (13, 26%
yield); see Scheme 2. The other mononuclear complexes
Cp(CO)3WCH2COOR (12b, R ) Et; 12c, R ) CH2Ph)
and 13 are also obtained from EtOH and PhCH2OH,
respectively, all in high yield. Similarly, treatment of
8 with i-PrNH2 affords Cp(CO)3WCH2CONH(i-Pr) (14,
77% yield) and 13 as the final product. The 13C
resonances of the CH2 group of 14 appear at the upper-
field region (δ -10) and the amide CO appears at δ 180
in its 13C NMR spectrum. If the reactions are carried
out in C6D6 and monitored by NMR spectroscopy,
Cp(CO)3WH (15) is observed at the initial stage. As
mentioned previously, in the presence of water, 8
converts to 9 and 15. The nucleophiles attack the
carbonyl carbon of the ketene unit directly forming 9,
12, 14, and 15; the latter then dimerizes to give the
Treatment of 5 with tert-butyl isocyanide also affords
a high yield of Cp2(CO)5(t-BuNC)W2(µ-CH2CO) (11); see
Scheme 2. Both the trans and cis isomers are generated
from the reaction, with a slight excess of the trans
1
product. In the H NMR spectra, a singlet resonance
1
at δ 3.76 is assigned to the CH2 for the bridging ketene
of the trans isomer and an AB pattern at δ 3.60 and
3.40 with J H-H ) 13.5 Hz is assigned to the correspond-
ing CH2 of the cis isomer. In growing crystals suitable
for X-ray diffraction analysis, only the trans isomer is
observed tungsten dimer 13. In the H NMR spectrum
of 9 two resonances at δ 5.52 and 2.04 are assigned to
the Cp and the CH2 group.
Such a nucleophilic addition does not occur for the
substituted ketene complexes 10 and 11. It is not
(28) Stack, J . G.; Doney, J . J .; Bergman, R. G.; Heathcock, C. H.
Organometallics 1990, 9, 453.
(29) (a) Yamamoto, Y. Coord. Chem. Rev. 1980, 32, 193. (b)
Singleton, E.; Oosthuizen, M. E. Adv. Organomet. Chem. 1983, 22, 209.

1578 Organometallics, Vol. 16, No. 8, 1997
Yang et al.
CH2I2 (0.135 mL, 1.67 mmol). The solution was stored at -20
°C for 3 days, and dark red crystalline solids were found in
the flask. The solid was filtered and washed with hexane to
give Cp2(CO)6W2(µ-CtC) (2) (0.36 g, 0.53 mmol) in 31% yield
(based on W). Analytically pure 2 was recrystallized from slow
diffusion of hexane into a concentrated dichloromethane
solution at -20 °C. Spectroscopic data of 2 are as follows. IR,
CH2Cl2: 2034 (m), 2020 (m), 1933 (vs). 1H NMR, CDCl3: 5.54
(s, Cp). 13C NMR, CDCl3: 233.4, 213.3 (CO); 101.1 (CtC); 91.8
surprising to find no nucleophilic addition since the
better σ-donor phosphorus ligand and isonitrile ligand
enhance the electron density at the carbonyl group and
thus hinder addition of the nucleophiles. Also the donor
ligands make the W-COCH2 bond more stable such
that, in the thermolytic reaction of 10 in CHCl3, cleav-
age of the W-CH2 bond leads to the mononuclear
complexes Cp(CO)2LWCOMe and Cp(CO)3WCl in high
yield. Reactivity of 5 toward nucleophiles is not well
defined since attempted nucleophilic additions to 5
always give complex mixtures. The chemical reactivity
of complex 8 is somewhat different from that of di-
nuclear ruthenium complex Cp2(CO)2Ru2(µ-CH2CO)(µ-
CO).22 In the reactions of Ru-ketene complexes with
nucleophiles, free organic molecules such as MeCOOH
(from H2O) and MeCOOMe (from MeOH) were generally
observed as the final products.
Con clu d in g Rem a r k . The reaction of CH2I2 with
Cp(CO)3W- gives various products which provide a
system to study the rich chemistry of a dinuclear
tungsten methylene C1 complex with no metal-metal
bond. Facile carbonylation is the major reactivity
displayed by such a methylene complex. Thus when the
reaction is carried out in MeOH the key O-coordinated
µ,η1,η2-bridging ketene C2 intermediate is obtained. The
weakly bonded oxygen atom surrenders the coordination
site in the presence of a two-electron donor ligand to
form the µ,η1,η1-bridging ketene. However, such a weak
O-coordination is crucial to induce a “formal dehydra-
tion” to produce the acetylide complex which is obtain-
able from the reaction of CH2I2 with Cp(CO)3W- in
MeCN directly. The presence of an electron-donating
group in these complexes provides higher stability;
hence Cp′ analogues and phosphorus ligand substituted
complexes are more stable.
(Cps). MS, FAB (186W): 694 (M+), 666 (M+ - CO), 638 (M+
-
2CO), 610 (M+ - 3CO), 582 (M+ - 4CO), 554 (M+ - 5CO),
526 (M+ - 6CO). Anal. Calcd for C18H10O6W2: C, 31.33; H,
1.46. Found: C, 31.24; H, 1.40. Complex Cp′2(CO)6W2(µ-CtC)
(2′) (0.31 g) was similarly prepared in 30% yield (based on W)
from 13′ (1.00 g, 1.44 mmol) and CH2I2 (0.111 mL, 1.38 mmol).
Spectroscopic data of 2′ are as follows. IR, CH2Cl2: 2034 (m),
2019 (m), 1918 (vs). 1H NMR, CDCl3: 5.43-5.37 (m, 8H, CH);
2.58 (s, 6H, 2Me). 13C NMR, CD3CN: 235.0, 215.9 (CO); 106.3
(CtC); 94.4-88.6 (C5H4); 14.8 (Me). MS, FAB: 722 (M+), 694
(M+ - CO), 666 (M+ - 2CO), 638 (M+ - 3CO), 610 (M+ - 4CO),
582 (M+ - 5CO), 554 (M+ - 6CO). Anal. Calcd for
C
20H14O6W2: C, 33.46; H, 1.96. Found: C, 33.51; H, 2.01.
Rea ction of 1 w ith Excess CH2I2 in THF . To a solution
of 1 prepared from 13 (0.56 g, 0.84 mmol) in 20.0 mL of THF
was added CH2I2 (0.20 mL, 2.48 mmol) at -20 °C, and in 2
days the color turned to dark red; then the solvent was
removed under vacuum. The residue was extracted with 3 ×
15 mL of 1:1 hexane/CH2Cl2 and recrystallized to give the
product Cp(CO)3WCH2I (3) (0.51 g, 1.07 mmol) in 64% yield.
The solution part obtained from recrystallization also contains
Cp(CO)3WCH3 and Cp(CO)3WI as two minor products (ca.
10%). Spectroscopic data of 3 are as follows. IR, C6H6: 2025
(s), 1927 (vs) ν(CO). 1H NMR, CD3CN: 5.67 (s, 5H, Cp); 3.23
(CH2). 13C NMR, CD3CN: 229.8, 219.0 (CO); 95.2 (Cp); -35.8
(J W-C ) 49.3 Hz, CH2). MS, FAB: 476 (M+), 448 (M+ - CO),
420 (M+ - 2CO), 392 (M+ - 3CO), 349 (M+ - I), 335 (M+
-
CH2I). Anal. Calcd for C9H7O3IW: C, 22.81; H, 1.49.
Found: C, 22.96; H, 1.65.
Isola tion of Meth ylen e Com p lex fr om Rea ction of 1a
w ith CH2Br 2 in THF . To 20.0 mL of a THF solution of 1a
(0.53 g, 1.17 mmol) at -45 °C was added CH2Br2 (0.12 g). The
solution was stirred at -20 °C until the starting material was
completely consumed. The color of the solution turned from
yellow to deep red. The solvent was then removed under
vacuum, and the product was extracted with 2 × 10 mL of
benzene. After removal of the solvent the residue contains
Cp2(CO)4[P(OMe)3]2W2(µ-CH2) (4a ) as the major product and
Cp2(CO)2[P(OMe)3]2W2(µ-CH2CO)(µ-CO) (6a ) as the minor
product (5:1 from the 1H NMR data) in 36% total yield. An
attempt to purify 4a by careful recrystallization from benzene
at 10 °C gave a mixture of 4a and 6a in a 10:1 ratio.
Spectroscopic data of 4a are as follows. IR, C6H6: 1920 (s),
1858 (vs) ν(CO). 1H NMR, C6D6: 5.07 (s, 10H, Cp); 3.37 (d,
J P-H ) 11.6 Hz, 18H, Me); 2.33 (t, J P-H ) 5.1 Hz, 2H, CH2).
13C NMR, C6D6: 228.0 (d, J P-C ) 25.4 Hz, CO); 91.7 (2 Cps);
52.4 (d, J P-C ) 4.9 Hz, Me); -50.4 (t, J P-C ) 11.2 Hz, CH2).
MS, FAB: 876 (M+), 848 (M+ - CO), 820 (M+ - 2CO).
Complex 6a was obtained by dissolving the mixture of 4a and
6a in CH3CN. Spectroscopic data of 6a are as follows. IR,
CH3CN: 1950 (s), 1863 (vs), 1764 (m) ν(CO). 1H NMR, 250
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were performed
under nitrogen using a vacuum line, a drybox, and standard
Schlenk techniques. NMR spectra were recorded on Bruker
AC-200 and DMX-500 spectrometers and are reported in units
of δ with residual protons in the solvent as an internal
standard (CDCl3, δ 7.24; CD3CN, δ 1.93; C2D6CO, δ 2.04). IR
spectra were measured on a Perkin-Elmer 983 instrument, and
frequencies (cm-1) were assigned relative to a polystyrene
standard. FAB mass spectra were recorded on a J EOL SX-
102A spectrometer. Elemental analyses and X-ray diffraction
studies were carried out at the Regional Center of Analytical
Instrument located at the National Taiwan University. MeOH
was distilled from Mg prior to use. CH3CN and CH2Cl2 were
distilled from CaH2. Diethyl ether and THF were distilled
from Na/ketyl. All other solvents and reagents were reagent
grade and used as received. W(CO)6 and PEt3 were purchased
from Strem Chemical, and CH2I2, CH2Br2, P(OMe)3, PPh3,
t-BuNC, i-PrNH2, and PhCH2OH were purchased from Merck;
CH2I2 and CH2Br2 were distilled in small quantities before use.
The complexes [Cp(CO)3W]2 (13), [Cp′(CO)3W]2 (13′), and
[Cp(CO)2P(OMe)3W]2Hg were prepared according to the lit-
erature methods,30 and the metallate anions Cp(CO)3W- (1),
Cp′(CO)3W- (1′), and Cp(CO)2P(OMe)3W- (1a ) were prepared
from Na/Hg reduction of the corresponding tungsten dimers.
Rea ction of 1 w ith CH2I2 in CH3CN a t -20 °C. To a
flask containing a solution of Cp(CO)3W- (3.40 mmol, prepared
from Na/Hg reduction of 1.13 g of 13 and used immediately
after Hg was removed) in 15 mL of MeCN at -40 °C was added
K, CD3CN: 5.28 (d, J P-H ) 0.8 Hz, 5H, Cp); 5.24 (d, J P-H
)
1.8 Hz, 5H, Cp); 3.57 (d, J P-H ) 11.7 Hz, 9H, Me3); 3.53 (d,
J P-H ) 11.7 Hz, 9H, Me3); 3.00, 2.95 (d, br, J H-H ) 6.2 Hz, 2H,
CH2). 31P NMR, 250 K, CD3CN: 183.8 (J P-W ) 542.8 Hz);
158.1 (J P-W ) 370.3 Hz). 6a was also observed when the
reaction of CH2Br2 with 1a at -20 °C in CD3CN was monitored
1
by H NMR spectroscopy.
Rea ction of 1 w ith CH2I2 in MeOH. A sample of 1
prepared from Na/Hg reduction of 13 (1.41 g, 2.11 mmol) was
dissolved in 30.0 mL of CH3OH at -20 °C. Addition of CH2I2
(0.168 mL, 2.08 mmol) via a syringe caused formation of dark
red precipitates in 3 days at -20 °C, and the resulting solution
(30) Thomasson, J . E.; Robinson, P. W.; Ross, D. A.; Wojcicki, A.
Inorg. Chem. 1971, 10, 2130.

Chemistry of Bridging Ketene
Organometallics, Vol. 16, No. 8, 1997 1579
was filtered. The precipitates were washed with 3 × 30 mL
of hexane, giving the product Cp2(CO)5W2(η1,η2,µ-CH2CO) (5)
(0.70 g, 1.03 mmol) in 49% yield. Spectroscopic data of 5 are
as follows. IR, KBr: 2020 (m), 1922 (vs), 1903 (sh), 1827 (m),
1437 (m) ν(CO). 1H NMR, CDCl3: 5.61 (s, 5H, Cp); 5.46 (s,
5H, Cp); 3.41 (br, 2H, CH2). 1H NMR, 233 K, C2D6CO: 6.01,
5.71 (s, Cps); 3.56 (d, J H-H ) 3.4 Hz, 1H, CH2); 3.13 (d, J H-H
) 3.4 Hz, 1H, CH2). 13C NMR, CDCl3: 252.8 (CH2CO), 240.0,
227.2, 216.0 (CO); 93.3, 92.3 (2Cps); -5.46 (CH2). MS, FAB:
684 (M+), 656 (M+ - CO). Anal. Calcd for C17H12O6W2: C,
30.03; H, 1.78. Found: C, 30.21; H, 1.98. Complex
Cp′2(CO)5W2(η1,η2,µ-CH2CO) (5′) (0.60 g, 0.84 mmol) was
similarly prepared in 52% yield from the reaction of 1
(prepared from Na/Hg reduction of 13′ (1.12 g, 1.62 mmol))
with CH2I2 (0.129 mL, 1.60 mmol). Spectroscopic data of 5′
are as follows. IR, CH2Cl2: 2027 (m), 1927 (vs), 1814 (sh), 1488
(m) ν(CO). 1H NMR, 233 K, CDCl3: 6.17-5.06 (m, 8H, C5H4);
3.38 (d, J H-H ) 3.4 Hz, 1H, CH2); 2.91 (d, J H-H ) 3.4 Hz, 1H,
CH2), 2.08, 1.80 (s, 6H, 2Me). 13C NMR, 233 K, CDCl3: 249.0
(CH2CO); 242.7, 240.3 (t-CO); 228.5, 218.1 (t-CO); 119.3, 113.1
CH); 24.1 (CH2), 14.2, 13.9 (Me). MS, FAB: 740 (M+), 712
(M+ - CO), 684 (M+ - 2CO). Anal. Calcd for C20H16O7W2:
C, 32.64; H, 2.19. Found: C, 32.58; H, 2.25.
Rea ction of 5 w ith P (OMe)3 in CH2Cl2. Complex 5 (1.45
g, 2.13 mmol) was dissolved in 40.0 mL of CH2Cl2 at -20 °C,
P(OMe)3 (0.312 mL, 2.65 mmol) was added via a syringe, and
the resulting solution was stored at -20 °C for 2 days. The
solution turned from dark red into light yellow, and precipi-
tates formed. The resulting mixture was filtered. The solid
was collected after being washed with ether. The crude
product was further purified by recrystallization from CH2Cl2
to give Cp2(CO)5[P(OMe)3]W2(µ-CH2CO) (10a ) (1.52 g, 1.90
mmol) in 89% yield. Spectroscopic data of 10a are as follows.
IR, CHCl3: 2038 (m), 2013 (m), 1999 (w), 1922 (vs), 1844 (s),
1601 (m) ν(CO). 1H NMR, CDCl3: 5.44 (s, 5H, Cp); 5.28 (d,
J P-H ) 1.3 Hz, 5H, Cp); 3.62 (d, J P-H ) 12.0 Hz, 9H, P(OMe)3);
3.22 (s, 2H, CH2). 13C NMR, CDCl3: 250.9 (d, J P-C ) 12.0 Hz,
CO); 230.1, 229.3 (d, J P-C ) 27.2 Hz, CO); 218.3 (CO); 93.9,
90.9 (2 Cps); 52.7 (OMe); 23.6 (s, J W-C ) 33.6, 23.0 Hz, CH2).
31P NMR, CDCl3: 161.48 (s, J P-W ) 389.7 Hz). MS, FAB: 808
(M+), 780 (M+ - CO). Anal. Calcd for C20H21O9W2P: C, 29.87;
H, 2.63. Found: C, 30.01; H, 2.77.
(2 MeC); 95.4-86.3 (8 CHs); 13.8, 13.3 (2 Me); -1.92 (J W-C
)
24.7 Hz, CH2). MS, FAB: 712 (M+), 684 (M+ - CO). Anal.
Calcd for C19H16O6W2: C, 32.23; H, 2.28. Found: C, 31.97;
H, 2.11.
Cp2(CO)5(PEt3)W2(µ-CH2CO) (10b) was similarly prepared
in 85% yield. Spectroscopic data of 10b are as follows. IR,
CHCl3: 2011 (m), 1998 (w), 1918 (vs), 1823 (s), 1595 (m) ν(CO).
1H NMR, CDCl3: 5.41 (s, 5H, Cp); 5.16 (d, J P-H ) 0.9 Hz, 5H,
Cp); 3.22 (s, 2H, CH2); 1.85, 1.04 (m, P(Et)3). 13C NMR,
CDCl3: 252.8 (d, J P-C ) 9.5 Hz, CO); 232.9 (d, J P-C ) 17.6
NMR Mon itor in g of th e Rea ction of 1 w ith CH2I2 in
CD3CN a t -25 °C. Complex 1 prepared in 0.50 mL of CD3CN
from 13 (0.11 g, 0.17 mmol) was delivered into an NMR tube,
and CH2I2 (0.012 mL, 0.15 mmol) was added at -25 °C. The
NMR tube was quickly transferred into a precooled NMR probe
(-25 °C), and the reaction was monitored by 1H NMR
spectroscopy. The three major products, 5 and two isomers
of 6, were observed in the 1H NMR spectrum. Spectroscopic
data (1H NMR, -25 °C, CD3CN) are as follows. Isomers of 6:
5.56, (s, 5H, Cp); 4.87 (s, 5H, Cp); 2.23, 2.08 (AX, J H-H ) 7.5
Hz, CH2); 5.28, (s, 5H, Cp); 4.56 (s, 5H, Cp); 2.62, 2.24 (AX,
J H-H ) 6.6 Hz, CH2). 5: 5.66, (s, 5H, Cp); 5.63 (s, 5H, Cp);
3.52, 3.11 (AX, J H-H ) 3.7 Hz, CH2). The final products of
this experiment are Cp(CO)3WCH3 and Cp(CO)3WI, possibly
due to the temperature fluctuation while the tube is trans-
ferred into and out of the NMR probe.
Rea ction of 5 w ith CO in CH2Cl2. Complex 5 (1.00 g,
1.47 mmol) was dissolved in 15.0 mL of CO-saturated CH2Cl2
in a Schlenk flask at 25 °C, and to prevent decomposition of 5
at this temperature, CO was immediately passed through the
resulting solution. A slow reaction turned the color of the
solution from red into yellowish-orange. After 45 min, 15 mL
of cold hexane was added, and the solution was stored at -20
°C for 8 h to cause the first precipitation. The precipitate was
collected by filtration and was identified as Cp(CO)3WCH2-
COOH (9) (0.09 g, 16%). Spectroscopic data of 9 are as follows.
IR, CH2Cl2: 2028 (m), 1924 (vs), 1600 (m) ν(CO). 1H NMR,
CDCl3: 5.52 (s, 5H, Cp); 2.04 (s, CH2, J W-H ) 5.6 Hz). MS,
FAB: 394 (M+), 366 (M+ - CO), 338 (M+ - 2CO). Anal. Calcd
for C10H8O5W: C, 30.64; H, 2.06. Found: C, 30.45; H, 1.87.
The filtrate was further cooled to -20 °C to cause the second
precipitation. The solid was collected after filtration and
washing with ether. The crude product was further purified
by recrystallization from CH2Cl2 to give Cp2(CO)6W2(µ-CH2CO)
(8) (0.57 g) in 55% yield. Spectroscopic data of 8 are as follows.
IR, CH2Cl2: 2021 (m), 2005 (m), 1996 (m), 1917 (vs), 1612 (m)
ν(CO). 1H NMR, CDCl3: 5.50 (s, 5H, Cp); 5.44 (s, 5H, Cp);
3.20 (s, CH2, J W-H ) 4.6 Hz). 13C NMR, 0 °C, CDCl3: 245.2
(ketene CO); 228.9, 228.1, 221.0, 218.3 (CO); 94.8, 91.3 (2 Cps);
22.7 (CH2). MS, FAB: 712 (M+), 684 (M+ - CO). Anal. Calcd
for C18H12O7W2: C, 30.54; H, 1.71. Found: C, 30.50; H, 1.76.
Hz, CO); 230.7, 218.4 (CO); 93.6, 91.0 (2 Cps); 24.8 (s, J W-C
)
32.6, 22.9 Hz, CH2); 22.6 (d, J P-C ) 30.8 Hz, PCH2); 8.20 (d,
J P-C ) 2.2 Hz, CH3). 31P NMR, CDCl3: 15.10 (s, J P-W ) 217.4
Hz). MS, FAB: 802 (M+), 774 (M+ - CO). Anal. Calcd for
C
23H27O6PW2: C, 34.61; H, 3.41; found: C, 34.77; H, 3.27.
Cp2(CO)5(PPh3)W2(µ-CH2CO) (10c) was similarly prepared
in 76% yield. Spectroscopic data of 10c are as follows. IR,
KBr: 2004 (m), 1911 (vs), 1901 (vs), 1822 (s), 1591 (s) ν(CO).
1H NMR, CDCl3: 7.13-6.26 (m, P(Ph)3); 5.43 (s, 5H, Cp); 5.06
(d, J P-H ) 1.1 Hz, 5H, Cp); 3.32 (CH2). 13C NMR, CDCl3: 252.2
(d, J P-C ) 9.7 Hz, CO); 232.8 (d, J P-C ) 18.2 Hz, CO); 230.4,
218.6 (CO); 136-128 (m, Ph); 95.3, 91.0 (2 Cps); 24.3 (J W-C
)
32.0, 22.0 Hz, CH2). 31P NMR, CDCl3: 38.97 (s, J P-W ) 231.4
Hz). MS, FAB: 946 (M+), 918 (M+ - CO). Anal. Calcd for
C
35H27O6W2P: C, 44.61; H, 2.89. Found: C, 44.53; H, 2.92.
Rea ction of 5 w ith t-Bu NC in CH3CN. Complex 5 (0.50
g, 0.74 mmol) was suspended in 10.0 mL of CH3CN at -20
°C, t-BuNC (0.101 mL, 0.89 mmol) was added via a syringe,
and the resulting solution was stored at -20 °C for 2 days. A
slow reaction turned the dark red solid into a light yellow
precipitate, and the resulting mixture was filtered. The solid
was collected after being washed with ether to give Cp2(CO)5(t-
BuNC)W2(µ-CH2CO) (11) (0.52 g) in 93% yield. This product
contains cis and trans isomers of 11. Spectroscopic data of 11
are as follows. IR, CH2Cl4: 2112 (m) ν(CN); 2008 (m), 1998
(s), 1910 (vs), 1854 (s), 1589 (m) ν(CO). 1H NMR, C6D6: trans
isomer, 5.01 (s, 5H, Cp); 4.86 (s, 5H, Cp); 3.76 (s, CH2); 0.92
(s, 9H, CH3); cis isomer, 5.06 (s, 5H, Cp); 4.89 (s, 5H, Cp); 3.60,
3.40 (J H-H ) 13.5 Hz, CH2); 1.12 (s, 9H, CH3). 13C NMR,
CDCl3: 238.0, 234.2, 230.3, 230.2, 227.1, 219.5, 218.2, 217.6
(terminal CO); trans, 253.3 (CH2CO); 93.6, 91.1 (2 Cps); 59.2
(CMe3); 31.0 (Me3); 25.3 (s, J W-C ) 34.5 Hz, CH2); cis, 255.4
(CH2CO); 93.9, 91.4 (2 Cps); 58.5 (CMe3); 30.7 (Me3); 23.6 (s,
J W-C ) 21.0 Hz, CH2). MS, FAB: 767 (M+), 739 (M+ - CO).
The single crystals of the product were obtained by recrystal-
lization from CH2Cl2 to give only the trans isomer for diffrac-
tion analysis and elemental analysis. Anal. Calcd for
C
22H21O6NW2: C, 34.63; H, 2.77. Found: C, 34.65; H, 2.56.
Rea ction of 8 w ith ROH. Complex 8 (0.20 g, 0.28 mmol)
The complex Cp′2(CO)6W2(µ-CH2CO) (8′) was similarly
prepared in 60% yield. Spectroscopic data of 8′ are as follows.
IR, CH2Cl2: 2019 (s), 2004 (s), 1994 (sh), 1917 (vs), 1613 (m)
ν(CO). 1H NMR, CDCl3: 5.39-5.30 (m, 8H, 2C5H4); 3.15 (s,
J W-H ) 5.1 Hz, 2H, CH2); 2.17 (s, 3H, Me); 2.13 (s, 3H, Me).
13C NMR, -30 °C, CDCl3: 247.5 (ketene CO); 230.2, 229.6,
222.1, 219.6 (CO); 111.1, 109.0 (CMe); 95.8, 94.3, 92.2, 89.8 (8
was dissolved in 15.0 mL of CH2Cl2, and PhCH2OH (0.111 mL,
1.02 mmol) was added. The resulting solution was stirred at
room temperature for 2 days to give yellow precipitates. The
solid was collected after being washed with ether, to give
Cp(CO)3WCH2COOCH2Ph (12c) (0.09 g) in 65% yield. Two

1580 Organometallics, Vol. 16, No. 8, 1997
Yang et al.
dinuclear complexes, 13 and [Cp(CO)2W]2, were observed in
the solution part as the byproducts. 1H NMR for [Cp(CO)2W]2
in CDCl3: 5.36. The crude product of 12c was further purified
by recrystallization from CH2Cl2. Spectroscopic data of 12c
are as follows. IR, CH2Cl2: 2026 (m), 1923 (vs), 1679 (w)
ν(CO). 1H NMR, CDCl3: 7.43-7.28 (5H, Ph); 5.34 (s, 5H, Cp);
5.04 (s, 2H, OCH2); 2.07 (s, J W-H ) 5.5 Hz CH2). 13C NMR,
CDCl3: 228.2, 216.2 (CO); 181.7 (COO); 136.8, 128.9, 128.4,
128.0 (Ph); 91.8 (Cp); 65.5 (CH2); -15.2 (CH2, J W-C ) 34.9 Hz).
MS, FAB: 482 (M+), 454 (M+ - CO), 426 (M+ - 2CO). Anal.
Calcd for C17H14O5W: C, 42.35; H, 2.93. Found: C, 42.30; H,
2.90. Complexes Cp(CO)3WCH2COOCH3 (12a ) and Cp(CO)3-
WCH2COOC2H5 (12b) were similarly prepared in 50% and 48%
yields, respectively. Spectroscopic data of 12a are as follows.
IR, CH2Cl2: 2026 (m), 1920 (vs), 1682 (w) ν(CO). 1H NMR,
from the reaction mixture of 1′ with CH2I2 in CH3CN.
A
suitable single crystal of dimensions 0.25 × 0.35 × 0.50 mm3
was glued to a glass fiber and mounted on an Enraf-Nonius
CAD4 diffractometer. Initial lattice parameters were deter-
mined from a least-squares fit to 25 accurately centered
reflections 19.18° < 2θ < 31.08° and subsequently refined
using higher angle data. Cell constants and other pertinent
data are collected in Table I (in Supporting Information). Data
were collected using the θ-2θ scan method. The final scan
speed for each reflection was determined from the net intensity
gathered during an initial prescan and ranged from 2.75 to
8.24 deg/min. The scan angle was determined for each
reflection according to the expression 0.85 + 0.35 tan θ. Three
check reflections were measured every 60 min throughout the
data collection period and showed no apparent decay.
CDCl3: 5.49 (s, 5H, Cp); 3.58 (s, 3H, OMe); 2.03 (s, J W-H
)
The raw intensity data were converted to structure factor
amplitudes and their esd’s by correction for scan speed,
background, and Lorentz and polarization effects. An empiri-
cal correction for absorption (µ ) 119.17 cm-1), based on the
azimuthal scan data, was applied to the intensities. Crystal-
lographic computations were carried out on a Microvax III
computer using the NRCC structure determination package.
Merging of equivalent and duplicate reflections gave a total
of 1733 unique measured data, of which 1433 were considered
observed, I > 2.0σ(I). The structure was first solved by using
the heavy-atom method (Patterson synthesis), which revealed
the position of metal, and then refined via standard least-
squares and difference Fourier techniques. The quantity
minimized by the least-squares program was w(|Fo| - |Fc|)2,
where w is the weight of a given operation. The analytical
forms of the scattering factor tables for the neutral atoms were
used.31 All other non-hydrogen atoms were refined by using
anisotropic thermal parameters. Hydrogen atoms were in-
cluded in the structure factor calculations in their expected
positions on the basis of idealized bonding geometry but were
not refined in least squares. Final refinement using full-
matrix least squares converged smoothly to values of R ) 0.034
and Rw ) 0.035. Final values of all refined atomic positional
parameters (with esd’s) and tables of thermal parameters are
given in the Supporting Information.
5.6 Hz CH2). 13C NMR, CDCl3: 216.2, 202.7 (CO); 182.6
(COO); 91.9 (Cp); 50.7 (OMe); -15.4 (CH2). MS, FAB: 408
(M+), 380 (M+ - CO), 352 (M+ - 2CO). Anal. Calcd for
C
11H10O5W: C, 32.53; H, 2.48. Found: C, 32.73; H, 2.54.
Spectroscopic data of 12b are as follows. 1H NMR, CDCl3:
5.49 (s, 5H, Cp); 4.02 (q, J H-H ) 7.2 Hz, 2H, OCH2); 2.01 (s,
J W-H ) 5.2 Hz, CH2) 1.22 (t, J H-H ) 7.2 Hz, 3H, Me). MS,
FAB: 422 (M+), 394 (M+ - CO), 366 (M+ - 2CO), 338 (M+
-
3CO).
Rea ction of 8 w ith i-P r NH2. Reaction of complex 8 (0.20
g, 0.28 mmol) with i-PrNH2 was similarly carried out in 10.0
mL of CH2Cl2. The workup was the same as that used in the
reaction of PhCH2OH. Crude product was purified by recrys-
tallization from CH2Cl2 to give Cp(CO)3WCH2CONH(i-Pr) (14)
(0.10 g) in 77% yield. Spectroscopic data of 14 are as follows.
IR, CH2Cl2: 2019 (m), 1911 (vs), 1622 (w) ν(CO). 1H NMR,
CDCl3: 5.58 (s, 5H, Cp); 5.12 (br, 1H, NH); 3.96 (m, 1H, CH);
1.97 (s, 2H, CH2), 1.10 (d, J H-H ) 6.6 Hz, 6H, 2Me). 13C NMR,
CDCl3: 227.9, 217.8 (CO); 180.0 (CON); 92.1 (Cp); 41.3 (CH);
22.9 (Me); -10.9 (CH2). MS, FAB: 435 (M+), 407 (M+ - CO),
379 (M+ - 2CO), 342 (M+ - CH2CONH(i-Pr)). Anal. Calcd
for C13H15O4WN: C, 36.05; H, 3.49. Found: C, 36.27; H, 3.59.
Two dinuclear complexes, [Cp(CO)3W]2 and [Cp(CO)2W]2, were
also observed as products.
Th er m olysis of 10a . Complex 10a (0.14 g, 0.17 mmol) was
dissolved in 15 mL of CHCl3, and the solution was heated to
reflux for 8 h. The IR spectrum indicated complete consump-
tion of the starting material. The solvent was removed under
vacuum, and the residue was extracted with 2 × 20 mL of 1:1
hexane/CH2Cl2. After removal of the solvent, the product was
washed with 5 × 10 mL of hexane to remove Cp(CO)3WCl,
and then the residue was recrystallized from 1:1 hexane/
CH2Cl2 to give Cp(CO)2[P(OMe)3]WCOMe (16) (0.06 g, 0.13
mmol, 75% yield). Spectroscopic data of 16 are as follows. IR,
CH2Cl2: 1957 (vs), 1851 (s) ν(CO). 1H NMR, CDCl3: 5.30 (d,
J P-H ) 1.1 Hz, 5H, Cp); 3.64 (d, J P-H ) 11.8 Hz, 9H, OMe);
2.56 (s, 3H, Me). 13C NMR, CDCl3: 251.4 (d, J P-C ) 13.0 Hz,
CdO); 231.2 (d, J P-C ) 17.4 Hz, CO); 93.1 (Cp); 58.1 (Me); 53.2
(OMe). 31P NMR, CDCl3: 160.0 (J P-W ) 372.4 Hz). MS,
The procedures for the structure determination of 5′, 8′, and
11 are similar. The final residuals of the refinement are R,
Rw ) 0.031, 0.032; 0.032, 0.032; and 0.057, 0.065 for 5′, 8′, and
11, respectively. Final values of all refined atomic positional
parameters (with esd’s), thermal parameters, and bond dis-
tances and angles are given in the Supporting Information.
Ack n ow led gm en t. We are grateful for support of
this work by National Science Council, Republic of
China.
Su p p or tin g In for m a tion Ava ila ble: Tables of the struc-
tural determination for complexes 2′, 5′, 8′, and 11 including
data collection, positional and anisotropic thermal parameters,
and bond distances and angles (12 pages). Ordering informa-
tion is given on any current masthead page.
FAB: 474 (M+), 459 (M+ - Me), 446 (M+ - CO), 431 (M+
-
COMe), 418 (M+ - 2CO). Anal. Calcd for C12H17O6WP: C,
30.54; H, 3.63. Found: C, 30.35; H, 3.70.
OM9609980
Sin gle-Cr ysta l X-r a y An a lysis. Dark red single crystals
of 2′ suitable for X-ray diffraction study were grown directly
(31) International Tables for X-ray Crystallography; D. D. Reidel
Pub. Co.: Dordrecht, Boston, 1974; Vol. IV.