Chain extension and C-C bond formation on C4 polycarbon ligands: Novel chemistry of σ-π-butadiynyl complexes with carbene sources

Article abstract of DOI:10.1021/om9602217

Reaction of Reaction of Ru₂(CO)₆(μ-η¹:η² _α,β-C≡CC≡CR)-(μ-PPh₂) (1a, R = Bu^t; 1b, R = Ph) with the carbene precursors R′₂CN₂ (R′ = H, Ph) affords the 1-ynyl-

Full text of DOI:10.1021/om9602217

Organometallics 1996, 15, 2855-2857
2855
Ch a in Exten sion a n d C-C Bon d F or m a tion on C4
P olyca r bon Liga n d s: Novel Ch em istr y of σ-π-Bu ta d iyn yl
Com p lexes w ith Ca r ben e Sou r ces
Peter Blenkiron,† Gary D. Enright,† Nicholas J . Taylor,‡ and Arthur J . Carty*,†,‡
The Steacie Institute for Molecular Sciences, National Research Council of Canada,
100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6, and Guelph-Waterloo Centre for
Graduate Work in Chemistry, Waterloo Campus, Department of Chemistry, University of
Waterloo, Waterloo, Ontario, Canada N2L 3G1
Received March 25, 1996X
Summary: Reaction of Ru2(CO)6(µ-η1:η2R,â-CtCCtCR)-
Ch a r t 1
(µ-PPh2) (1a , R ) But; 1b, R ) Ph) with the carbene
precursors R′2CN2 (R′ ) H, Ph) affords the 1-ynyl-
allenyl complexes Ru2(CO)6(µ-η1:η2R,â-C(CtCR)dCdCR′2)-
(µ-PPh2) (2a , R ) But, R′ ) Ph; 2b, R ) Ph, R′ ) H; 2c,
R ) R′ ) Ph) via attack of the carbene group at CR of
the butadiynyl ligand. In the case of Ph2CN2, carbene
addition also occurs at Câ to give the η1-indenyl deriva-
tives Ru2(CO)6{µ-η1:η2-CH(C6H4)C(Ph)dCCtCBut}(µ-
PPh2) (3) or Ru2(CO)6{µ-η1:η2-CdC(Ph)CdC(Ph)(C6H4)-
CH}(µ-PPh2) (4) via two carbon-carbon bond-forming
processes. The molecular structures of 2a , 3, and 4 have
been determined by X-ray crystallography.
Ynyl and polyynyl ligands (-CtCR, -(CtC)x-) are
unrivaled in their ability to link metal centers into
linear chains via MsC(sp) bonds, and considerable effort
is being devoted to the synthesis of rodlike materials
and wires from these building blocks.1 However, the
full potential of the -(CtC)sR group lies in the
exploitation of π-interactions to construct two- and
three-dimensional multimetallic arrays. Yet despite an
extensive organometallic chemistry for monoalkynyl
ligands,2 the behavior of polycarbon ligands such as
butadiynyls (-CtCCtCR) or higher polyynyls
-(CtC)x-R with extended sp unsaturation at poly-
nuclear centers has only just begun to attract attention.3
We have recently described a route to the first series of
CtCCtCR′)(µ-PPh2) (R ) But, 1a ; R ) Ph, 1b; R )
SiMe3, 1c)3b,4 which possess one π-coordinated and one
pendant triple bond. In this communication we report
evidence for novel chemistry for these complexes. Reac-
tions with carbene sources result in exclusive attack at
the coordinated ynyl multiple bond, leading to new C5
ynyl-allenyl ligands via chain extension and η1:η2-
indenylacetylenes via intramolecular cyclization. These
results herald a rich and diverse chemistry for multi-
metal bound polyynyl ligands.
µ-η1:η2-butadiynyl complexes Ru2(CO)6(µ-η1,η2
-
R,â
* To whom correspondence should be addressed at the National
Research Council of Canada.
† National Research Council of Canada.
‡ University of Waterloo.
X Abstract published in Advance ACS Abstracts, May 15, 1996.
(1) (a) Khan, M. S.; Kakkar, A. K.; Ingham, S. L.; Raithby, P. R.;
Lewis, J .; Spencer, B.; Wittman, F.; Friend, R. H. J . Organomet. Chem.
1994, 472, 247. (b) Stang, P. J .; Tykwinski, R. J . Am. Chem. Soc. 1992,
114, 4411. (c) Coat, F.; Lapinte, C. Organometallics 1996, 15, 477. (d)
Brady, M.; Weng, W.; Gladysz, J . A. J . Chem. Soc., Chem. Commun.
1994, 2655. (e) Lang, H. Angew. Chem., Int. Ed. Engl. 1994, 33, 547.
(f) Weng, W.; Bartik, T.; Brady, M.; Bartik, B.; Ramsden, J . A.; Arif,
A. M.; Gladysz, J . A. J . Am. Chem. Soc. 1995, 117, 11931. (g) Fyfe, H.
B.; Mlekuz, M.; Zargarin, D.; Taylor, N. J .; Marder, T. B. J . Chem.
Soc., Chem. Commun. 1991, 188. (h) Irwin, M. J .; J ia, G.; Payne, N.
C.; Puddephatt, R. J . Organometallics 1996, 15, 51.
Treatment of the µ-η1:η2 , -butadiynyl complex 1b
R â
with diazomethane under CO at -10 °C in hexane
afforded, after thin-layer chromatography on silica,
yellow 2b (R ) Ph, R′ ) H, 35%)5 (Chart 1). Under
similar conditions 1a did not react with CH2N2 but 1a
and 1b on reaction with diphenyldiazomethane Ph2CN2
(80 °C, toluene) gave analogues 2a (R ) But, R′ ) Ph;
10%) and 2c (R ) R′ ) Ph; 22%)6 as well as a second
isomeric product 37 (R ) But; 22%) and 48 (R ) Ph; 15%),
respectively. Separation of 2a and 3, 2c and 4 was
(2) (a) Sappa, E.; Tiripicchio, A.; Braunstein, P. Chem. Rev. 1983,
83, 203. (b) Nast, R. Coord. Chem. Rev. 1982, 47, 89. (c) Cherkas, A.
A.; Doherty, S.; Cleroux, M.; Hogarth, G.; Randall, L. H.; Breckenridge,
S. M.; Taylor, N. J .; Carty, A. J .; Organometallics 1992, 11, 1701 and
references cited therein. (d) Akita, M.; Moro-oka, Y. Bull. Chem. Soc.
J pn. 1995, 68, 420.
(3) (a) Werner, H.; Gevert, O.; Steinert, P.; Wolf, J . Organometallics
1995, 14, 1786. (b) Blenkiron, P.; Corrigan, J . F.; Pilette, D.; Taylor,
N. J .; Carty, A. J . J . Chem. Soc., Chem. Commun. 1995, 2165. (c)
Blenkiron, P.; Taylor, N. J .; Carty, A. J . J . Chem. Soc., Chem. Commun.
1995, 327. (d) Worth, G. H.; Robinson, B. H.; Simpson, J . Organome-
tallics 1992, 11, 501. (e) Adams, C. J .; Bruce, M. I.; Horn, E.; Skelton,
B. W.; Tiekink, E. R. T.; White, A. H. J . Chem. Soc., Dalton Trans.
1993, 3299. (f) Ibid. 1993, 3313. (g) Weng, W.; Arif, A. M.; Gladysz, J .
A. J . Am. Chem. Soc. 1993, 115, 3824.
(4) Blenkiron, P.; Corrigan, J . F.; Pilette, D.; Taylor, N. J .; Carty,
A. J . Submitted for publication in Can. J . Chem.
(5) Spectroscopic data for 2b: IR (C6H14) ν(CO)/cm-1 2077 s, 2051
vs, 2016 s, 2000 m, 1984 w; 1H NMR (CDCl3) δ 7.54-7.01 (m, 15H,
Ph), 4.23 (d, J HH ) 1.9 Hz, 1H, CH2), 3.93 (d, J HH ) 1.9 Hz, 1H, CH2);
31P{1H} NMR (CDCl3) δ 127.6 (s). Anal. Calcd for C29H17O6PRu2: C,
50.15; H, 2.47. Found: C, 50.56; H, 2.87.
S0276-7333(96)00221-X CCC: $12.00 © 1996 American Chemical Society
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2856 Organometallics, Vol. 15, No. 13, 1996
Communications
of the new allenyl ligand closely resembles that in Ru2-
(CO)6(µ-η1:η2-C(Ph)dCdCPh2)(µ-PPh2)13 and is reflected
in the similarity of the CR-Câ-Cγ angles (144.0(4) vs
144.6(3)° in 2a ). Complexes 2b and 2c are assigned
similar ynyl-allenyl structures on the basis of close
correspondence of spectroscopic features to 2a . The
conversion of 1a ,b to 2a ,c is the first example of a C4 to
C5 chain extension at a -CtCCtCR ligand and repre-
sents a viable route to a new class of substituted allenyl
complexes. Although not synthesized via chain exten-
sion, other molecules with a cumulated C5 linkage
LnMdCdCdCdCdCR2, have recently been prepared14
via OR′ elimination from the pentadiynyl complexes Ln-
MCtCCtC-CR2OR′.
F igu r e 1. Molecular structure of [Ru2(CO)6(µ-η1,η2
-
R,â
An X-ray analysis of 3, the second CPh2 addition
product of 1a , revealed attack of the carbene group at
a Câ position, as shown in Figure 2. In this case the
ortho carbon atom of one of the phenyl rings has become
attached to CR of the original butadiynyl ligand, the
latter also becoming bonded to the liberated ortho
hydrogen atom to generate an η1-indenyl fragment (Ru-
(2)-C(7) ) 2.250(3) Å). Thus, compound 3, isomeric
with 2a , is derived from two C-C bond-forming pro-
cesses. Interestingly, the formerly free outer alkyne
group of the starting material is now coordinated in
π-fashion to the second Ru atom (Ru(1)-C(9) ) 2.361-
(3) Å, Ru(1)-C(10) ) 2.309(3) Å), effecting a small but
significant elongation of the C-C triple bond (C(9)-
C(10) ) 1.2335 Å, cf. 1.172(6) Å in 1a 3b). Complexes
containing η1-indenyl ligands are relatively rare,15 and
in the present case the η1-indenyl group may be stabi-
lized by the presence of a 2-alkynyl substituent coordi-
nated in π-fashion to the second ruthenium atom.
Compound 4 (Figure 3) is similarly formed from
attack of the carbene at Câ and coupling of CR and the
ortho carbon of a Ph2C phenyl ring. The latter leads to
fusion of an indene ring system onto CR and Câ of the
C4R ligand to give an η1-indenyl unit, the structural
data for which closely resemble that observed in 3. In
contrast to 3, however, the -CγtCδ- functionality of
the starting complex 1b has now been incorporated into
C(CtCBut)dCdCPh2)(µ-PPh2)] (2a ) with the non-hydrogen
atom labeling scheme. For clarity, only the ipso carbons of
the P-phenyl rings are drawn. Important bond lengths (Å)
and angles (deg) not mentioned in the text are as follows:
Ru(1)-Ru(2) ) 2.825(1), Ru(1)-C(7) ) 2.170(3), Ru(1)-
C(8) ) 2.297(3), C(8)-C(9) ) 1.438(5), C(10)-C(11) )
1.475(5); C(8)-C(7)-C(15) ) 144.6(3), C(7)-C(8)-C(9) )
114.3(3), C(8)-C(9)-C(10) ) 178.9(4), Ru(1)-P(1)-Ru(2)
) 73.6(1)°.
accomplished by thin-layer chromatography. Although
spectroscopic data for 2a -c were indicative of coordi-
nated allenyl and free alkyne functionalities, single-
crystal X-ray analyses of 2a ,9 3,10 and 411 were necessary
to fully establish the structures of the products.
The most striking feature of the structure of 2a
(Figure 1) is the presence of a five-carbon chain derived
from the original µ-η1:η2-CtCCtCBut ligand by adding
a :CPh2 fragment at CR.12 The polyunsaturated penta-
1-yne-3,4-dien-3-yl (or ynyl-allenyl) ligand is attached
to Ru(2) via a σ-bond to C(8) (Ru(2)-C(8) ) 2.095(3) Å),
the â-carbon of the original µ-η1:η2-CRtCâCγtCδBut
group, and to Ru(1) via an η2-interaction with the new
C(7)-C(8) allenyl double bond (C(7)-C(8) ) 1.411(5) Å).
The outer C(7)-C(15) double bond (C(7)-C(15) ) 1.323-
(5) Å) of the C(8)-C(7)-C(15) allenyl ligand is uncoor-
dinated, as is the alkyne functionality C(9)-C(10)
(1.191(5) Å) attached to C(8). The overall coordination
(10) Crystal data for 3: hexagonal cylinders grown from hexane at
-20 °C; C39H29O6PRu2, Mr ) 826.8; monoclinic, space group C2/c, a )
31.8406(9) Å, b ) 11.0622(4) Å, c ) 20.2768(5) Å, â ) 95.4480(23)°, V
) 7109.8(5) Å3, Z ) 8, T ) 295 K, Dc ) 1.545 g cm-3, F(000) ) 3322,
λ ) 1.540 56 Å, µ(Cu KR) ) 78.5 cm-1. Intensity data were collected
on a crystal of dimensions 0.16 × 0.32 × 0.30 mm mounted on an
Enraf-Nonius CAD4 diffractometer using the θ/2θ scan method (3.0 <
2θ < 140.0°). An absorption correction (face-indexed numerical) was
applied. Of 9242 reflections measured, 5891 were considered observed
(I > 2.5σ(I)). The structure was solved (direct methods) and refined
(full-matrix least squares) using the NRCVAX system, giving final R
and Rw values of 0.032 and 0.044, respectively.
(6) Spectroscopic data for 2a : IR (C6H14) ν(CO)/cm-1 2081 s, 2059
vs, 2021 s, 2003 m, 1986 w; 1H NMR (CDCl3) δ 7.50-6.22 (m, 20H,
Ph), 1.04 (s, 9H, But); 31P{1H} NMR (CDCl3) δ 122.8 (s). Anal. Calcd
for C39H29O6PRu2: C, 56.66; H, 3.54. Found: C, 56.87; H, 3.62. Mp:
169 °C. Spectroscopic data for 2c: IR (C6H14) ν(CO)/cm-1 2083 s, 2061
vs, 2023 s, 2005 m, 1989 w; 1H NMR (CDCl3) δ 7.49-6.26 (m, Ph);
31P{1H} NMR (CDCl3) δ 122.6 (s). Anal. Calcd for C41H25O6PRu2: C,
58.16; H, 2.98. Found: C, 58.07; H, 2.96. Mp: > 400 °C.
(7) Spectroscopic data for 3: IR (C6H14) ν(CO)/cm-1 2059 m, 2022 s,
1997 w, 1993 w, 1981 m; 1H NMR (CDCl3) δ 7.71-7.11 (m, 19H, Ph),
5.13 (d, J PH ) 6.8 Hz, 1H, CH), 1.28 (s, 9H, But); 31P{1H} NMR (CDCl3)
δ 162.6 (s). Anal. Calcd for C39H29O6PRu2: C, 56.66; H, 3.54. Found:
C, 56.87; H, 3.62. Mp: 155 °C.
(11) Crystal data for 4: red plates grown from hexane at -20 °C;
C41H25O6PRu2, Mr ) 846.7; triclinic, space group P1h, a ) 11.108(1) Å,
b ) 11.267(1) Å, c ) 15.642(1) Å, R ) 91.696(7)°, â ) 98.532(7)°, γ )
(8) Spectroscopic data for 4: IR (C6H14) ν(CO)/cm-1 2090 s, 2072
vs, 2036 s, 2030 m, 2009 s, 1973 w; 1H NMR (CDCl3) δ 7.70-6.99 (m,
24H, Ph), 3.27 (d, J PH ) 4.7 Hz, 1H, CH); 31P{1H} NMR (CDCl3) δ
88.8 (s). Anal. Calcd for C41H25O6PRu2: C, 58.16; H, 2.98. Found: C,
58.16; H, 2.91. Mp: 215 °C.
(9) Crystal data for 2a : yellow prisms grown from diethyl ether/
hexane at -20 °C; C39H29O6PRu2‚C4H10O, Mr ) 900.9; monoclinic,
space group P21/n, a ) 12.073(2) Å, b ) 9.735(2) Å, c ) 34.805(5) Å, â
112.496(8)°, V ) 1780.6(4) Å3, Z ) 2, T ) 295 K, Dc ) 1.579 g cm-3
,
F(000) ) 844, λ ) 0.710 73 Å, µ(Mo KR) ) 9.40 cm-1. Intensity data
were collected on a crystal of dimensions 0.20 × 0.12 × 0.10 × 0.045
mm mounted on a Siemens R3m/V diffractometer by the ω-scan method
(2θ < 50°). Of 6619 reflections measured, 4892 were considered
observed (F > 6.0σ(F)). The structure was solved and refined as for 2a
above, giving final R and Rw values of 0.0243 and 0.0262, respectively.
(12) See Chart 1 for designation of CR, Câ, Cγ, and Cδ.
) 93.05(1)°, V ) 4084.6(13) Å3, Z ) 4, T ) 200 K, Dc ) 1.465 g cm-3
,
F(000) ) 1824, λ ) 0.710 73 Å, µ(Mo KR) ) 8.26 cm-1. Intensity data
were collected on a crystal of dimensions 0.19 × 0.15 × 0.24 mm
mounted on a Siemens R3m/V diffractometer by the ω-scan method
(2θ < 48°). An absorption correction (face-indexed numerical) was
applied. Of 6431 reflections measured, 5266 were considered observed
(F > 6.0σ(F)). The structure was solved (Patterson and Fourier
(13) Nucciarone, D.; Taylor, N. J .; Carty, A. J . Organometallics 1986,
5, 1179.
(14) (a) Touchard, D.; Haquette, P.; Daridor, A.; Toupet, L.; Dixneuf,
P. H. J . Am. Chem. Soc. 1994, 116, 11157. (b) Lass, R. W.; Steinert,
P.; Wolf, J .; Werner, H. Chem. Eur. J . 1996, 2, 19.
(15) (a) For a review see: O’Connor, J . M.; Casey, C. P. Chem. Rev.
1987, 87, 307. (b) Bellomo, S.; Ceccon, A.; Gambaro, A.; Santi, S.; Venzo,
A. J . Organomet. Chem. 1993, 453, C4. (c) Casey, C. P.; O’Connor, J .
M. Organometallics 1985, 4, 384.
methods) and refined (full-matrix least squares) using the Siemens
2
SHELXTL PLUS program, giving final R and Rw values (based on Fo
)
of 0.0266 and 0.0302, respectively.
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Communications
Organometallics, Vol. 15, No. 13, 1996 2857
and co-workers.16 The position of the butadiynyl-
derived Ph substituent on C(9) occurs either as a result
of Câ-Cγ bond cleavage and subsequent coordination of
Cγ to the Ru-Ru unit or by 1,2-phenyl migration with
the original C4 ligand remaining intact. Accounts of
phenyl migration reactions are legion in organic chem-
istry,17 and although there is precedent in the literature
for metal-coordinated diyne cleavage,18 such accounts
are rare and the former seems a more likely course.
The generation of indenyl ring systems in 3 and 4
from 1a ,b via C-C bond formation at Câ and CR
resembles the recent synthesis of indenylidene from a
CPh2OSiMe3-substituted diynyl ruthenium complex.19
A plausible mechanism involves attack by the carbene
Ph2C: at Câ, creating a CâdCcarbene double bond and the
highly electrophilic carbene center CR. Subsequent
electrophilic attack on the ortho carbon of a phenyl ring
by CR leads to C-C coupling and proton transfer to CR.
The chemistry of 1a ,b toward amines3b and carbenes
demonstrates an exclusive preference for nucleophilic
attack at the coordinated and activated CR-Câ alkyne
bond over the unbound triple bond. Surprisingly, this
is the first instance in which competitive reactivity of
coordinated and free triple bonds in a diynyl complex
has been put to the test. EHMO calculations on Ru2-
(CO)6(µ-η1:η2R,â-CtCCtCH)(µ-PH2) suggest that in the
ground state attack at CR is favored on orbital control
grounds, as found for 1a ,b with NEt2H and :CH2.
Attack at CR for the bulky carbene :CPh2 is disfavored
on steric grounds. In the transition state for the
fluxional molecules, however, where the alkynyl frag-
ment is perpendicular to the Ru-Ru vector, attack at
Câ is favored on both orbital and charge grounds. We
are examining the reactions of these interesting mol-
ecules with organic and metal-based electrophiles to
further define their reactivity.
F igu r e 2. Molecular structure of [Ru2(CO)6{µ-η1,η2-CH-
(C6H4)C(Ph)dCCtCBut}(µ-PPh2)] (3) with the non-hydro-
gen atom labeling scheme. For clarity, only the ipso carbons
of the P-phenyl rings are drawn. Important bond lengths
(Å) and angles (deg) not mentioned in the text are as
follows: Ru(1)-Ru(2) ) 2.8928(4), C(7)-C(8) ) 1.478(4),
C(8)-C(9) ) 1.428(4), C(10)-C(11) ) 1.496(5), C(8)-C(15)
) 1.387(4), C(15)-C(22) ) 1.455(5), C(22)-C(27) ) 1.399-
(5), C(27)-C(7) ) 1.475(4); C(7)-C(8)-C(9) ) 122.5(3),
C(8)-C(9)-C(10) ) 166.5(3), C(9)-C(10)-C(11) ) 151.6-
(3), Ru(1)-P(1)-Ru(2) ) 76.88(3), C(8)-C(15)-C(22) )
106.9(3), C(15)-C(22)-C(27) ) 109.2(3), C(22)-C(27)-C(7)
) 109.2(3)°.
Ack n ow led gm en t. This work was supported by the
National Research Council of Canada and by the
Natural Sciences and Engineering Research Council
(NSERC). P.B. gratefully acknowledges the NSERC for
an International Fellowship Award. We thank Dr J ohn
F. Corrigan for his assistance with the EHMO calcula-
tions.
Su p p or tin g In for m a tion Ava ila ble: Text giving full
experimental details for the synthesis of compounds 2-4 and
tables giving the structure determination summary, atomic
coordinates, bond distances, bond angles, thermal parameters,
and hydrogen atom positions for 2a , 3, and 4 (24 pages).
Observed and calculated structure factor tables are available
from the authors upon request. Ordering information is given
on any current masthead page.
F igu r e 3. Molecular structure of [Ru2(CO)6{µ-η1,η2-CdC-
(Ph)CdC(Ph)(C6H4)CH}(µ-PPh2)] (4) with the non-hydro-
gen atom labeling scheme. For clarity, only the ipso carbons
of the P-phenyl rings are drawn. Important bond lengths
(Å) and angles (deg) not mentioned in the text are as
follows: Ru(1)-Ru(2) ) 2.826(1), Ru(1)-C(7) ) 2.291(3),
C(7)-C(8) ) 1.482(5), C(8)-C(9) ) 1.481(5), C(8)-C(11) )
1.362(4), C(11)-C(18) ) 1.464(5), C(18)-C(19) ) 1.415(4),
C(19)-C(7) ) 1.482(5); Ru(1)-C(7)-C(8) ) 99.9(2), C(7)-
C(8)-C(9) ) 114.6(2), C(8)-C(9)-C(10) ) 110.7(3), C(9)-
C(10)-Ru(1) ) 118.3(3), Ru(1)-C(10)-Ru(2) ) 84.7(1),
Ru(1)-P(1)-Ru(2) ) 73.4(1)°.
OM9602217
(16) Colborn, R. E.; Davies, D. L.; Dyke, A. F.; Endesfelder, A.; Knox,
S. A. R.; Orpen, A. G.; Plass, D. J . Chem. Soc., Dalton Trans. 1983,
2661.
(17) Murray, A. W. In Organic Reaction Mechanisms; Knipe, A. C.,
Watts, W. E., Eds.; Wiley: New York, 1984; Chapter 15, p 431. For
examples in organometallic chemistry see: Bly, R. S.; Zhong, Z; Kane,
C.; Bly, R. K. Organometallics 1994, 13, 899 and references cited
therein.
(18) (a) Pulst, S.; Arndt, P.; Baumann, W.; Tillack, A.; Kempe, R.;
Rosenthal, U.; J . Chem. Soc., Chem. Commun. 1995, 1753. (b) Hsu,
D. P.; Davis, W. M.; Buchwald, S. L. J . Am. Chem. Soc. 1993, 115,
10394. (c) Rosenthal, U.; Ohff, A.; Tillack, A.; Baumann, W.; Go¨rls, H.
J . Organomet. Chem. 1994, 468, C4.
(19) Touchard, D.; Pirio, N.; Toupet, L.; Fettouhi, M.; Ouahab, L.;
Dixneuf, P. H. Organometallics 1995, 14, 5263.
the organometallic structure with C(10) bridging the
metal-metal bond, somewhat asymmetrically (Ru(1)-
C(10) ) 2.181(4) Å, Ru(2)-C(10) ) 2.009(2) Å) to form
a µ2-vinylidene moiety (C(10)-C(9) ) 1.326(4) Å). These
bond parameters are in accord with those reported for
Cp2Ru2(CO)2(µ-CO)(µ-CCH2) (Ru(1)-CR ) 2.033(7) Å,
Ru(2)-CR ) 2.026(7) Å, CRdCâ ) 1.326(11) Å) by Knox
+
+