Heterometallic derivatives of the unsaturated methyl-bridged complex [Mo2(η5-C5H5) 2(μ-CH3)(μ-PCy2)(CO)2]. Photochemical generation of methylidyne-bridged clusters

Article abstract of DOI:10.1021/om900961u

The photochemical reactions of the methyl-bridged complex [Mo ₂Cp₂(μ-CH₃)(μ-PCy₂)(CO) ₂] (1) (Cp = η⁵-C₅H₅) with the carbonyl complexes [M(CO)₆] (M = Cr, Mo, W) and [MnCp'(CO) ₃] (Cp' = η⁵-C₅H₄CH₃) give the corresponding electron-precise methylidyne-bridged derivatives [MMo₂Cp₂(μ₃CH)(μ-PCy₂)(CO) ₇](Mo-Mo = 2.9340(13) A for M = W) and [MnMo₂Cp ₂Cp'(μ₃-CH)(μ-PCy₂)(CO)₄] (Mo-Mo = 2.9678(6) A in good yields. Under similar conditions, the reaction of 1 with [Ru₃(CO)₁₂] gives the 46-electron methylidyne-bridged cluster [Mo₂RuCp₂(μ₃-CH) (μ-PCy₂)(CO)S] (Mo-Mo = 2.6824(7) A), along with a small amount of the methoxy-bridged analogue [Mo₂RuCp₂(μ ₃-OCH₃)(μPCy₂)(CO)₅]. A related iron species [FeMo₂Cp₂(μ₃-OCH ₃)(μ-PCy₂)(CO)₅] (Mo-Mo = 2.667(I) A) can be prepared in moderate yield from the reaction of the 30-electron methyl complex [Mo₂Cp₂(μ-K¹ : η²CH₃)(μ-PCy₂)(μ-CO)] and [Fe ₂(CO)₉] Compound 1 reacts with [Fe₂(CO) ₉] at room temperature to give the acetyl-bridged cluster [FeMo ₂Cp₂{μ₃-K¹:η²: k¹-C(O)CH₃} (μ-PCy₂)(CO)₅] (Mo-Mo = 2.8474(5) A) in high yield, which undergoes full cleavage of the acetyl C-O bond under thermal or photolytic activation to give the oxoethylidyne derivative [FeMo₂Cp₂(μ₃-CCH ₃)(μ-PCy₂)(O)(CO)₄] (Mo-Mo = 2.8469(4) A). Under photochemical conditions, however, compound 1 reacts with [Fe₂(CO)₉] to give the methylidyne-bridged compound [Fe₂Mo₂Cp₂(μ₄-CH)(μ-PCy ₂)(CO)₈] (Mo-Mo = 2.8351(7) A) as major species. This 60-electron cluster displays a butterfly Mo₂Fe₂ core with no agostic interactions of the methylidyne ligand.

Full text of DOI:10.1021/om900961u

904 Organometallics 2010, 29, 904–916
DOI: 10.1021/om900961u
Heterometallic Derivatives of the Unsaturated Methyl-Bridged Complex
[Mo2(η5-C5H5)2(μ-CH3)(μ-PCy2)(CO)2]. Photochemical Generation of
Methylidyne-Bridged Clusters
M. Angeles Alvarez, M. Esther Garcıa, M. Eugenia Martınez, and Miguel A. Ruiz*
´
ꢀ
Departamento de Quımica Organica e Inorganica/IUQOEM, Universidad de Oviedo, E-33071 Oviedo, Spain
ꢀ
Received November 3, 2009
The photochemical reactions of the methyl-bridged complex [Mo2Cp2(μ-CH3)(μ-PCy2)(CO)2] (1)
(Cp = η5-C5H5) with the carbonyl complexes [M(CO)6] (M = Cr, Mo, W) and [MnCp0(CO)3] (Cp0 =
η5-C5H4CH3) give the corresponding electron-precise methylidyne-bridged derivatives [MMo2Cp2(μ3-
0
˚
CH)(μ-PCy2)(CO)7] (Mo-Mo = 2.9340(13) A for M = W) and [MnMo2Cp2Cp (μ3-CH)(μ-PCy2)(CO)4]
˚
(Mo-Mo = 2.9678(6) A) in good yields. Under similar conditions, the reaction of 1 with [Ru3(CO)12]
gives the 46-electron methylidyne-bridged cluster [Mo2RuCp2(μ3-CH)(μ-PCy2)(CO)5] (Mo-Mo =
˚
2.6824(7) A), along with a small amount of the methoxy-bridged analogue [Mo2RuCp2(μ3-OCH3)(μ-
˚
PCy2)(CO)5]. Arelatedironspecies[FeMo2Cp2(μ3-OCH3)(μ-PCy2)(CO)5] (Mo-Mo=2.667(1) A) can
be prepared in moderate yield from the reaction of the 30-electron methyl complex [Mo2Cp2(μ-κ1:η2-
CH3)(μ-PCy2)(μ-CO)] and [Fe2(CO)9]. Compound 1 reacts with [Fe2(CO)9] at room temperature to give
1
2 1
˚
the acetyl-bridged cluster [FeMo2Cp2{μ3-κ :η :κ -C(O)CH3}(μ-PCy2)(CO)5] (Mo-Mo = 2.8474(5) A)
in high yield, which undergoes full cleavage of the acetyl C-O bond under thermal or photolytic
activation to give the oxoethylidyne derivative [FeMo2Cp2(μ3-CCH3)(μ-PCy2)(O)(CO)4] (Mo-Mo =
˚
2.8469(4) A). Under photochemical conditions, however, compound 1 reacts with [Fe2(CO)9] to give
˚
the methylidyne-bridged compound [Fe2Mo2Cp2(μ4-CH)(μ-PCy2)(CO)8] (Mo-Mo = 2.8351(7) A) as
major species. This 60-electron cluster displays a butterfly Mo2Fe2 core with no agostic interactions of
the methylidyne ligand.
Chart 1
Introduction
Recently we reported the preparation, structure, and
bonding of the unsaturated methyl-bridged complex
[Mo2Cp2(μ-CH3)(μ-PCy2)(CO)2] (1), which revealed that in
the solid state the methyl ligand is involved in a very weak
agostic interaction with the dimetal center. This interaction
is retained in solution, but there the agostic form A probably
coexists with small amounts of the nonagostic form B
(Chart 1), only slightly higher in energy (as computed for
the analogous benzyl complex).1 Because of the weakness of
the C-H Mo interaction in the agostic form, the real
3 3 3
unsaturation of the dimetal center in both structures is likely
to be essentially the same and close to that expected for a
triply bonded molecule. In any case, compound 1 provides
an excellent opportunity to examine the chemistry of a
bridging methyl ligand at a highly unsaturated dimetal site
at the molecular level. Alkyl-bridged complexes are species
of general interest for several reasons: they serve as models
both for intermediates in alkyl-transfer processes and for
adsorbates in several heterogeneously catalyzed reactions
such as the Fischer-Tropsch synthesis, and they are also
implied as catalysts or precursors of the homogeneous
catalysts used in the polymerization of olefins.2,3 Although
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Organometallics 2009, 28, 3225. (b) Li, S.; Miao, W.; Tang, T.; Dong, W.;
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*To whom correspondence should be addressed. E-mail: mara@
uniovi.es.
(1) (a) Garcıa, M. E.; Ramos, A.; Ruiz, M. A.; Lanfranchi, M.;
ꢀ
€
Marchio, L. Organometallics 2007, 26, 6197. (b) García, M. E.; Melon, S.;
Chem. Soc. 2006, 128, 15005. (e) Dietrich, H. M.; Grove, H.; Tornroos, K. W.;
Ramos, A.; Riera, V.; Ruiz, M. A.; Belletti, D.; Graiff, C.; Tiripicchio, A.
Organometallics 2003, 22, 1983.
Anwander, R. J. Am. Chem. Soc. 2006, 128, 1458. (f) Weng, Z.; Teo, S.; Koh,
L. L.; Hor, T. S. A. Chem. Commun. 2006, 1319.
r
pubs.acs.org/Organometallics
Published on Web 01/15/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 4, 2010 905
a large number of such binuclear complexes have been
reported so far, only some of them display metal-metal
bonds, these generally exhibiting an agostic interaction with
one of the metal atoms. The reactivity reported so far for the
alkyl ligands in the latter complexes includes the oxidative
addition of the agostic C-H bond at trimetal centers,4
rearrangement of the ligand to a terminal coordination
mode,5 deprotonation,6 reductive elimination with other
ligands,7 and insertion of CO.5c,d,8 Among all the alkyl-
bridged complexes described so far, however, only a few of
them display multiple intermetallic bonding,9 and the reac-
tivity of the latter unsaturated species has not been explored.
In a preliminary study on the chemical behavior of the
methyl-bridged complex 1 we found that, while a molecule of
CO could be removed photochemically to yield the carbonyl
derivative [Mo2Cp2(μ-κ1:η2-CH3)(μ-PCy2)(μ-CO)] (2), hav-
ing a strengthened agostic interaction (Chart 1), the photo-
chemical treatment of 1 in the presence of [Mo(CO)6] or
[Fe2(CO)9] gave methylidyne-bridged heterometallic clus-
ters, thus revealing the occurrence of easy dehydrogena-
tion steps in these reations.10 This is an unusual evolution
of a bridging agostic methyl ligand. Actually, we can quote
only a couple of precedents of related μ-CH3/μ-CH trans-
formations involving agostic ligands, these reported to occur
at room temperature at Ru2 (through dehydrogenation)11
and Fe3 (through double oxidative addition of C-H bonds)
metal centers.4b In addition, related μ-CH2R/μ-CH/μ-CR
transformations (R = CH2Ph) were reported recently to
occur at 120 °C in a Ru3 cluster.12 Besides this we note that
Chart 2
methylidyne clusters are relatively scarce molecules related
to the surface species following methane activation by metal
atoms and surfaces and to those involved in relevant
heterogeneously catalyzed industrial processes such as the
Fischer-Tropsch synthesis.13 Moreover only a few hetero-
metallic methylidyne clusters containing molybdenum have
been reported previously, these displaying MoCo2,14
Mo2Co,15 MoCoRu,16 and Mo2Ru4 metal cores.17 We thus
decided to study in more detail the reactions of the methyl
complex 1 with different metal-carbonyl substrates as a
likely rational route to heterometallic clusters bridged by
methylidyne or related ligands. As it will be shown below, the
reactions of 1 with 16-electron metal carbonyl fragments has
allowed us to prepare in good yields new methylidyne-
bridged clusters having trinuclear Mo2M (M=Cr, Mo, W,
Mn, Fe, Ru) and tetranuclear Mo2Fe2 metal skeletons. In
contrast, those reactions with metal-metal bonded dimers
of type [M2Cp2(CO)2n] or [M2(CO)2n] led to no new products
(M=Mo, Co, Mn) or complex mixtures of products (M=
Fe, Ni) that could not be characterized.
(4) (a) Calvert, R. B.; Shapley, J. R. J. Am. Chem. Soc. 1977, 99, 5225.
(b) Dutta, T. K.; Vites, J. C.; Jacobsen, G. B.; Fehlner, T. P. Organometallics
1987, 6, 842.
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Bierenstiel, M.; McDonald, R.; Ferguson, M. J.; Cowie, M. Organome-
tallics 2009, 28, 3407. (b) Wigginton, J. R.; Trepanier, S. J.; McDonald, R.;
Ferguson, M. J.; Cowie, M. Organometallics 2005, 24, 6194. (c) Rowsell,
B. D.; McDonald, R.; Cowie, M. Organometallics 2004, 23, 3873.
(d) Trepanier, S. J.; McDonald, R.; Cowie, M. Organometallics 2003, 22,
2638.
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Orpen, A. G. J. Chem. Soc., Chem. Commun. 1984, 841. (b) Casey, C. P.;
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Bierenstiel, M.; McDonald, R.; Ferguson, M. J.; Cowie, M. Organome-
tallics 2009, 28, 3407. (b) Gao, Y.; Jennings, M. C.; Puddephatt, R. J.
Organometallics 2001, 20, 1882. (c) Jeffery, J. C.; Orpen, A. G.; Stone,
F. G. A.; Went, M. J. J. Chem. Soc., Dalton Trans. 1986, 173.
(9) Apparently only a few complexes (all dichromium ones) have
been reported to have methyl bridges over multiple metal-metal bonds:
(a) Horvath, S.; Gorelsky, S. I.; Gambarotta, S.; Korobkov, I. Angew.
Chem., Int. Ed. 2008, 47, 1. (b) Heintz, R. A.; Ostrander, R. L.; Rheingold,
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P. M.; Spencer, M. D.; Wilson, S. R.; Girolami, G. Organometallics 1994, 13,
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Trans. 1978, 446.
Results and Discussion
Reactions of Compound 1 with [M(CO)6] (M=Cr, Mo, W).
The photolysis of toluene solutions of 1 and the hexacarbo-
nyls [M(CO)6] (M=Mo, W) using visible-UV light gives the
trinuclear methylidyne clusters [MMo2Cp2(μ3-CH)(μ-PCy2)-
(CO)7] [M=Mo (3a), W (3b)] in good yield (Chart 2). No
reaction took place, however, when using tetrahydrofuran
(THF) as solvent. In the same line, our attempts to prepare
ꢀ
(10) Alvarez, M. A.; Garcıa-Vivo, D.; Garcıa, M. E.; Martınez,
M. E.; Ramos, A.; Ruiz, M. A. Organometallics 2008, 27, 1973.
(11) Connelly, N. G.; Forrow, N. J.; Gracey, B. P.; Knox, S. A. R.;
Orpen, A. G. J. Chem. Soc., Chem. Commun. 1985, 14.
(12) Temjimbayashi, R.; Murotani, E.; Takemori, T.; Takao, T.;
Suzuki, H. J. Organomet. Chem. 2007, 692, 442.
(13) (a) Cho, H.-G.; Lester, A. J. Phys. Chem. A 2006, 110, 3886, and
references therein. (b) Marsh, A. L.; Becraft, K. A.; Somorjai, G. A. J. Phys.
Chem. B 2005, 109, 13619, and references therein. (c) Maitlis, P. M.;
Zanotti, V. Chem. Commun. 2009, 1619. (d) Maitlis, P. M. J. Organomet.
Chem. 2004, 689, 4366. (e) Maitlis, P. M. J. Mol. Catal. A 2003, 204-205,
55. (f) Dry, M. E. Catal. Today 2002, 71, 227.
(14) (a) Zhang, W.; Watson, W. H.; Richmond, M. G. J. Chem.
Crystallogr. 2008, 38, 437. (b) Watson, W. H.; Poola, B.; Richmond, M. G.
J. Organomet. Chem. 2006, 691, 5567. (c) Zhang, W. Q.; Zhu, B. H.; Hu, B.;
Zhang, Y. H.; Zhao, Q. Y.; Ying, Y. Q.; Sun, J. J. Organomet. Chem. 2004,
689, 714. (d) Beurich, H.; Vahrenkamp, H. Chem. Ber. 1982, 116, 2385.
(15) Duffy, D. N.; Kassis, M. M.; Rae, A. D. J. Organomet. Chem.
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4182.

906 Organometallics, Vol. 29, No. 4, 2010
Alvarez et al.
Table 1. Selected Bond Lengths and Angles for Compounds 3a10
and 3b
3a (M = Mo)
3b (M = W)
Mo(1)-Mo(2)
Mo(1)-M
Mo(2)-M
Mo(1)-C(8)
Mo(2)-C(8)
M-C(8)
2.9283(3)
3.1245(3)
3.0938(3)
2.040(3)
2.053(3)
2.316(3)
2.410(1)
2.425(1)
0.99(3)
2.934(1)
3.113(1)
3.086(1)
2.06(1)
2.06(1)
2.32(1)
2.410(3)
2.422(3)
1.02(13)
Mo(1)-P
Mo(2)-P
C(8)-H(8)
Mo(1)-M-Mo(2)
Mo(1)-Mo(2)-C(2)
Mo(2)-Mo(1)-C(1)
Mo(2)-P-Mo(1)
Mo(1)-C(1)-O(1)
Mo(2)-C(2)-O(2)
Mo(1)-C(8)-Mo(2)
Mo(1)-C(8)-H(8)
Mo(2)-C(8)-H(8)
P-Mo(1)-C(8)
56.2(1)
87.0(1)
86.7(1)
74.5(1)
170.9(2)
170.5(2)
91.4(1)
129(2)
56.5(1)
87.6(3)
86.6(3)
74.8(1)
171(1)
172(1)
90.8(4)
129(8)
127(7)
78.5(3)
78.0(3)
Figure 1. ORTEP diagram (30% probability) of compound 3b,
with Cy rings (except the C1 atoms) and H atoms (except H8)
omitted for clarity.
these clusters through the thermal reaction of 1 with the
adducts [M(CO)5(THF)] were also unsuccessful, suggesting
that the methyl complex 1 lacks the electron-donor ability
needed to displace the coordinated THF molecule. Unlike the
above reactions with [Mo(CO)6] and [W(CO)6], the photolytic
reaction of 1 with [Cr(CO)6], under the same conditions, gives
a mixture of three isomeric methylidyne derivatives, [CrMo2-
Cp2(μ3-CH)(μ-PCy2)(CO)7] (3c, 4) and [CrMo2Cp2(μ-CH)(μ-
PCy2)(CO)7] (5), differing in the relative positioning of the
bridging (and even carbonyl) ligands (Chart 2). These pro-
ducts were found to interconvert in solution, with the equi-
librium ratio being 1:15:5, respectively, in CD2Cl2 solution, as
shown by NMR measurements (see Experimental Section).
Moreover, the ratio 4/5 increases to 4:1 in C6D6 solution
(3c being present only in trace amounts here), whereas
compound 4 is the unique isomer present in acetone-d6
solution. We should finally note that, although the formation
of the methylidyne complexes 3 to 5 from the methyl complex
1 requires the elimination of hydrogen at some intermediate
stage, to be discussed later on, we have been unable to
characterize any intermediate species in these reactions.
Solid-State and Solution Structure of Compounds 3. The
structure of the trimolybdenum compound 3a was deter-
mined by X-ray diffraction methods in our preliminary
study.10 We have now determined that of the Mo2W com-
pound 3b, which is very similar (Figure 1 and Table 1). In
both cases the molecule can be viewed as resulting from the
addition of a M(CO)5 fragment (M = Mo, W) to the unsatu-
rated dimetal center of a dehydrogenated molecule of 1 (thus
transformed into a methylidyne-bridged substrate) opposite
the dicyclohexylphosphide ligand. This is accompanied by a
trans to cis rearrangement of the Mo2Cp2(CO)2 moiety, not
unexpected under photochemical conditions,18 while the
M(CO)5 fragments display octahedral geometry, with the
sixth coordination position roughly pointing to the center of
126(2)
79.0(1)
78.4(1)
P-Mo(2)-C(8)
CH2 depending on the partner,20 the above intermetallic
distances suggest a methylenic behavior of this fragment in
compounds 3a,b so as to render an electron-precise cluster. In
contrast, we have previously found that in the related hydride-
bridged cluster [WMo2Cp2(μ3-H)(μ-PCy2)(CO)7], having two
fewer cluster electrons, the W(CO)5 fragment acts essentially as
an acceptor group (CH3þ-like behavior), then exhibiting quite
˚
large Mo-W lengths (ca. 3.35 A), as expected for a 3c-2e
interaction.21 We finally note the largely asymmetric coordina-
tion of the methylidyne ligand in 3b, strongly bound to the Mo
˚
atoms, as indicated by the short Mo-C lengths of ca. 2.05 A,
but more weakly bound to the W(CO)5 fragment (M-C ca.
˚
2.30 A). The above Mo-C lengths are comparable to those
measured for the trimolybdenum compounds [Mo3Cp3(μ3-
CH)(CO)6]22 and [Mo3Cp*3(μ3-CH)(μ-CH2)(μ-O)2].23
Spectroscopic data in solution for compounds 3a,b are
consistent with the structure found in the solid state for these
molecules, but only limited data are available for compound 3c
due to its low proportion in the corresponding mixture of
isomers. The IR spectra for 3a,b display a strong band at
ca. 2040 cm-1, characteristic of the presence of M(CO)5
fragments (M = Cr, Mo, W).24 As for the 31P NMR spectra,
these complexes exhibit resonances ranging from 164 to 173
ppm. These chemical shifts are somewhat lower than the values
of ca. 170-210 ppm previously found by us for the unsaturated
clusters derived from the complexes [Mo2Cp2(μ-H)(μ-PCy2)-
(CO)2]21 and [Mo2Cp2(μ-COMe)(μ-PCy2)(μ-CO)]25 and are
thus consistent with the formulation of compounds 3 as
electron-precise molecules. Their 1H NMR spectra display in
each case a single cyclopentadienyl resonance, indicative of the
˚
the Mo2C(8) triangle. The Mo-Mo separation of ca. 2.93 A is
˚
significantly shorter than the Mo-W ones (ca. 3.10 A). Yet, all
(20) (a) Hoffmann, R. Angew. Chem., Int. Ed. Engl. 1982, 21, 711.
(b) Stone, F. G. A. Angew. Chem., Int. Ed. Engl. 1984, 23, 89.
(21) Alvarez, C. M.; Alvarez, M. A.; Garcıa, M. E.; Ramos, A.; Ruiz,
M. A.; Graiff, C.; Tiripicchio, A. Organometallics 2007, 26, 321.
(22) (a) Akida, M.; Noda, K.; Moro-oka, Y. Organometallics 1994,
13, 4145. (b) Akida, M.; Noda, K.; Takahashi, Y.; Moro-oka, Y. Organome-
tallics 1995, 14, 5209.
these values can be considered consistent with the presence of
single intermetallic bonds and are comparable to the interme-
tallic lengths found for the electron-precise (48-electron) clus-
ters [MMo2(μ3-S)(CO)12][PPN]2 (M=Mo, W).19 Although the
þ
M(CO)5 fragments can be isolobal-related to either CH3 or
(23) Guzyr, O. I.; Prust, J.; Roesky, H. W.; Lehman, C.; Teicher, M.;
Cimpoesu, F. Organometallics 2000, 19, 1549.
(18) (a) Alvarez, C. M.; Garcıa, M. E.; Ruiz, M. A.; Connelly, N. G.
Organometallics 2004, 23, 4750. (b) Bitterwolf, T. E.; Scallorn, W. B.; Li,
B. H. Organometallics 2000, 19, 3280.
(24) Braterman, P. S. Metal Carbonyl Spectra; Academic Press:
London, U.K., 1975.
ꢀ
(25) (a) Garcıa, M. E.; Garcıa-Vivo, D.; Ruiz, M. A. Organometallics
ꢀ
ꢀ
(19) Darensbourg, D. J.; Zalewski, D. J.; Sanchez, K. M.; Delord, T.
2009, 28, 4385. (b) García, M. E.; García-Vivo, D.; Ruiz, M. A. Organome-
Inorg. Chem. 1988, 27, 821.
tallics 2008, 27, 169.

Article
Organometallics, Vol. 29, No. 4, 2010 907
Table 2. Selected IRa and NMRb Data for New Compounds
compound
ν(CO)a
δ(P)b
δ(CH)b
δ(CH)b
[Mo3Cp2(μ3-CH)(μ-PCy2)(CO)7] (3a)
[Mo2WCp2(μ3-CH)(μ-PCy2)(CO)7] (3b)
2042 (s), 1949 (s, sh), 1935 (vs), 1825 (w)
2041 (s), 1963 (m, sh), 1945 (s, sh), 1932 (vs),
1917 (m, sh), 1890 (w, sh), 1815(w)
172.8
169.7
12.26[5]
12.05[5]
244.7[21]
[CrMo2Cp2(μ3-CH)(μ-PCy2)(CO)7] (3c)
[CrMo2Cp2(μ3-CH)(μ-PCy2)(CO)7] (4)
164.2
272.9
11.67[14]
13.47
2006 (m, sh), 1999(m), 1979 (w, sh), 1962 (vs),
1932 (s), 1897 (s), 1868 (m, sh)c
273.5[3]
270.6[2]
[CrMo2Cp2(μ2-CH)(μ-PCy2)(CO)7] (5)
[MnMo2Cp2Cp0(μ3-CH)(μ-PCy2)(CO)4] (6)
[Mo2RuCp2(μ3-CH)(μ-PCy2)(CO)5] (7)
[Mo2RuCp2(μ3-OCH3)(μ-PCy2)(CO)5] (8d)
[FeMo2Cp2(μ3-OCH3)(μ-PCy2)(CO)5] (8e)
[FeMo2Cp2{μ3-C(O)CH3}(μ-PCy2)(CO)5] (9)
[FeMo2Cp2(μ-CCH3)(μ-PCy2)(O)(CO)4] (10)
[Fe2Mo2Cp2(μ4-CH)(μ-PCy2)(CO)8] (11)
147.7
144.9
180.9
179.1
179.1
154.1
182.6
164.2
9.47[14]
12.79[7]
13.59
1927 (vs), 1862 (w), 1813 (w), 1773 (w)
2039 (vs), 1978 (s), 1949 (m), 1901 (w), 1870 (w)d
2040 (vs), 1979 (s), 1949 (m), 1900 (w), 1850 (w)e
2007 (vs), 1943 (s), 1920 (m)
1995 (vs), 1945 (s), 1906 (m), 1600 (w)
2002 (vs), 1933 (s), 1818 (w)
2022 (s), 1984 (m, sh), 1972 (vs), 1944 (s), 1911 (m),
1870 (w)
1986 (vs), 1928 (vs), 1858 (w)
4.24[2]
15.47
234.3[11]
330.0[7]
[FeMo2Cp2(μ2-CH)(μ-PCy2)(CO)5] (12)
244.8
aRecorded in dichloromethane solution, ν in cm-1 b Recorded in CD2Cl2 solutions at 290 K and 121.50 (31P) or 100.63 (13C) MHz, δ in ppm relative
.
to internal TMS (13C) or external 85% aqueous H3PO4 (31P); coupling constants to 31P for the methyne resonances are shown in square brackets and are
given in Hz. c Bands corresponding to a mixture of compounds 3c, 4, and 5 in a 1:15:5 ratio. d Recorded in petroleum ether solution. e Estimated from
mixtures 7/8d in petroleum ether solution.
retention of the cisoid geometry of the Mo2Cp2(CO)2 moiety
in solution, and a strongly deshielded methylidyne resonance
at ca. 12 ppm. This chemical shift is comparable to those
measured for different molecules displaying CH ligands sym-
metrically bridging three metal atoms,15,22,23,26 thus suggesting
that compounds 3 in solution might display a more symme-
trical coordination of the CH ligand over the trimetal triangle,
compared to the solid state. In line with this, the methylidyne
ligand of 3a gives rise to a relatively shielded 13C NMR
resonance (δ 244.7 ppm), as usually found for μ3-CH ligands.
This spectrum also exhibits three resonances for the Mo(CO)5
fragment in agreement with the static structure, this being
indicative of the absence of fast rotation of this fragment,
which in turn is consistent with its strong binding in the cluster
(carbene-like behavior).
Solution Structure of Compounds 4 and 5. The IR spectra of
the mixture of the chromium isomers 4 and 5 (recall that the
isomer 3c is present only in very small amounts) lack
the high-frequency band at ca. 2050 cm-1 characteristic of
M(CO)5 fragments (Table 2). Thus we propose that a CO
ligand has been transferred from chromium to the Mo atoms
in these isomers, leaving Cr(CO)4, Mo(CO)2, and Mo(CO)
fragments in both cases (Chart 2). In agreement with this, the
cyclopentadienyl ligands are inequivalent in both cases (see
Experimental Section). The major isomer 4 displays methy-
lidyne resonances (δH 13.47 ppm, δC 270.6 ppm) comparable
to those of the ruthenium complex [Mo2RuCp2(μ-CH)(μ-
PCy2)(CO)5] (7) to be discussed later (Table 2), this being
indicative of a rather symmetrical coordination of the CH
ligand over the metal triangle. However, its 31P{1H} NMR
spectrum exhibits a strongly deshielded resonance at 272.9
ppm, which we take as indicative of its coordination to the
lighter chromium atom.27 For instance, the 13P chemical
shifts of the complexes [M2Cp2(μ-H)(μ-PEt2)(CO)4] are
237.4 ppm (Cr)28 and 179.8 ppm (Mo), respectively.29 In
agreement with all this, the carbonyl ligands bound to
chromium exhibit a 5 to 15 Hz P-C coupling, not observed
in the structures of type 3 (see Experimental Section), and
two of the Mo-bound carbonyls exhibit no P-C coupling at
all. As for the isomer 5, it exhibits a relatively shielded 31P
NMR resonance at 147.7 ppm, close to that of the electron-
precise cluster [MnMo2Cp2Cp0(μ3-CH)(μ-PCy2)(CO)4] (6),
to be discussed later (Table 2), and to those of the isoelectronic
methoxycarbyne complexes [MnMo2Cp2L(μ3-COMe)(μ-PCy2)-
(CO)4] (ca. 142 ppm, L=Cp, Cp0).25 We take this as indica-
tive that the phosphide ligand in 5 still bridges the Mo-Mo
edge (as in isomers 3). To balance the electronic distribution
of the cluster, we propose that the methylidyne ligand should
act as an essentially edge-bridging ligand connecting the
Cr(CO)4 and Mo(CO) fragments (Chart 2). Unfortunately
we could not locate the methylidyne resonance of this minor
isomer in the 13C{1H} NMR spectrum of the mixture of
isomers, so as to check the proposed change in the coordina-
tion mode of this ligand.
Reaction of Compound 1 with [MnCp0(CO)3]. The photo-
lysis of toluene solutions of 1 and [MnCp0(CO)3] using
visible-UV light gives the trinuclear methylidyne cluster
[MnMo2Cp2Cp0(μ3-CH)(μ-PCy2)(CO)4] (6) in good yield
(Chart 1). This electron-precise cluster can be viewed again
as resulting from the addition of a 16-electron MnCp0(CO)2
fragment to the unsaturated dimetal center of a dehydroge-
nated molecule of 1.
The molecular structure of 6 in the crystal (Figure 2 and
Table 3) displays a metal triangle made up of two MoCp(CO)
fragments and a MnCp0(CO)2 fragment, with a dicyclohex-
ylphosphide ligand bridging the Mo atoms and a methyli-
dyne ligand bridging the metal triangle rather symmetri-
˚
cally, if we allow for the ca. 0.1 A difference in the covalent
radii of Mo and Mn. The Mn-bound carbonyls are involved
in bent-semibridging interactions with the Mo atoms
(26) (a) Kolis, J. W.; Holt, E. M.; Shriver, D. F. J. Am. Chem. Soc.
1983, 105, 7307. (b) Vites, J. C.; Jacobsen, G.; Dutta, T. K.; Fehlner, T. P.
J. Am. Chem. Soc. 1985, 107, 5563.
˚
˚
(Mo(1)-C(4)=2.468(6) A, Mo(2)-C(3)=2.527(6) A), thus
balancing the electron densities at the Mo and Mn atoms.
Actually, the structure of 6 is very similar to that of the
isoelectronic methoxycarbyne cluster [MnMo2Cp3(μ3-COMe)-
(μ-PCy2)(CO)4] recently reported by us,25 and no further
discussion is therefore needed. We just note that the Mo-Mo
(27) Carty, A. J.; MacLaughlin, S. A.; Nucciarone, D. In Phosphorus-
31 NMR Spectroscopy in Stereochemical Analysis; Verkade, J. G., Quin,
L. D., Eds.; VCH: Deerfield Beach, FL, 1987; Chapter 16.
(28) Weng, Z.; Leong, W. K.; Vittal, J. J.; Goh, L. Y. Organometallics
2002, 21, 5287.
ꢀ
(29) Garcıa, M. E.; Riera, V.; Ruiz, M. A.; Saez, D. Organometallics
˚
2002, 21, 5515.
length of 2.9678(6) A is comparable to those measured in the

908 Organometallics, Vol. 29, No. 4, 2010
Alvarez et al.
Chart 3
Scheme 1
Figure 2. ORTEP diagram (30% probability) of compound 6,
with Cy rings (except the C1 atoms) and H atoms (except H5)
omitted for clarity.
˚
Table 3. Selected Bond Lengths (A) and Angles (deg) for
Compound 6
purification of the major product 7. The formation of 8d is
obviously originated from trace amounts of oxygen during
photolysis, although we have not investigated this side
reaction in detail.
Mo(1)-Mo(2)
Mo(1)-Mn(1)
Mo(2)-Mn(1)
Mo(1)-C(5)
Mo(2)-C(5)
Mn(1)-C(5)
Mo(1)-P(1)
Mo(2)-P(1)
Mo(1)-C(1)
Mo(2)-C(2)
C(1)-Ο(1)
2.9678(6)
2.840(1)
2.843(1)
2.074(5)
2.063(5)
1.970(5)
2.422(1)
2.428(1)
1.966(6)
1.971(6)
1.154(7)
1.152(7)
2.468(6)
2.527(6)
1.808(6)
1.809(6)
1.173(7)
1.184(7)
0.96(2)
Mo(1)-Mn(1)-Μο(2)
Mo(1)-P(1)-Mo(2)
Mo(1)-Μο(2)-C(2)
Mo(2)-Mo(1)-C(1)
Mo(1)-C(1)-O(1)
Mo(2)-C(2)-Ο(2)
Mo(1)-C(5)-Mo(2)
Mo(1)-C(5)-Mn(1)
Mo(2)-C(5)-Mn(1)
P(1)-Mo(1)-C(5)
P(1)-Mo(2)-C(5)
P(1)-Mo(1)-C(1)
P(1)-Mo(2)-C(2)
Mn(1)-C(4)-O(4)
Mn(1)-C(3)-C(3)
Mo(1)-Mn(1) -C(4)
Mo(2)-Mn(1) -C(3)
62.9(1)
75.5(1)
87.4(1)
86.6(2)
The formation of 7 could be viewed again as resulting from
the addition of a 16-electron fragment (Ru(CO)4 in this case)
to the unsaturated dimetal center of a dehydrogenated mole-
cule of 1, then followed by further decarbonylation of the
resulting 48-electron cluster thus generated. In an attempt to
prepare a related iron species, we examined the room-tem-
perature reaction of 1 with [Fe2(CO)9], the latter acting as a
source of the Fe(CO)4 fragment in the absence of light.
However, this reaction instead gives the acetyl-bridged cluster
[FeMo2Cp2{μ3-κ1:η2:κ1-C(O)Me}(μ-PCy2)(CO)5] (9), derived
from CO insertion into the Mo-Me bond possibly after the
incorporation ofthe iron fragment, asitwillbe discussed later.
Since compound 9 displays an acetyl ligand C,O,O-bound
over the metal triangle, we were interested in determining
whether a full C-O bond cleavage could be induced, as had
previously been shown by Shapley et al. in the tetranuclear
cluster [WOs3Cp{μ3-C(O)CH2(p-tol)}(CO)11].30 Indeed, se-
parate experiments revealed that compound 9 can be trans-
formed into the corresponding oxoethylidyne derivative
[FeMo2Cp2(μ3-CMe)(μ-PCy2)(O)(CO)4] (10) in refluxing to-
luene, although a more selective transformation is achieved
upon photolysis at 288 K (Scheme 1).
The above results suggest that the dehydrogenation steps
leading to methylidyne derivatives most likely require photo-
lytic conditions even if a 16-electron metal fragment can be
added thermally to the unsaturated dimetal center present in
1. In line with this, the photolysis of toluene solutions of 1 in
the presence of [Fe2(CO)9] gave the tetranuclear methylidyne
cluster [Fe2Mo2Cp2(μ4-CH)(μ-PCy2)(CO)8] (11) as a major
product, along with small and variable amounts of the
oxo complex 10 and the trinuclear methylidyne cluster
[FeMo2Cp2(μ-CH)(μ-PCy2)(CO)5] (12) (Chart 4). The major
product 11 could be fully purified by column chromatogra-
phy and characterized completely. However, the minor
171.4(5)
171.4(5)
91.7(2)
89.2(2)
89.6(2)
77.8(1)
77.8(1)
C(2)-O(2)
86.94(17)
86.94(17)
155.1(5)
155.5(5)
59.28(19)
61.09(19)
Mo(1)-C(4)
Mo(2)-C(3)
Mn(1)-C(4)
Mn(1)-C(3)
C(3)-O(3)
C(4)-O(4)
C(5)-H(5)
48-electron clusters 3a,b, as expected, while the relatively short
˚
Mo-Mn distances (ca. 2.84 A) can be related to the presence of
small-sized C-donor bridging ligands, notably the triply brid-
ging methylidyne ligand, but also the carbonyl ligands acting as
semibridging groups.25
Spectroscopic data in solution for compound 6 are con-
sistent with the structure found in the crystal and are very
similar to those of the methoxycarbyne-bridged Mn2Fe
cluster mentioned above;25 therefore a detailed analysis is
not needed. We just note the retention in solution of the
semibridging interactions of the carbonyl ligands, as indi-
cated by the presence of a low-frequency (1773 cm-1) C-O
stretching band in the IR spectrum. The presence of the triply
bridging methylidyne ligand in 6 is denoted by the appear-
ance of a strongly deshielded resonance at 12.79 ppm in its
1H NMR spectrum, a position comparable to those of the
clusters 3 and 5.
Reactions of Compound 1 with Group 8 Metal Carbonyls.
The photolysis of toluene solutions of 1 and [Ru3(CO)12]
using visible-UV light gives the 46-electron methylidyne-
bridged cluster [Mo2RuCp2(μ3-CH)(μ-PCy2)(CO)5] (7) in
good yield, along with small and variable amounts of the
methoxy-bridged analogue [Mo2RuCp2(μ3-OMe)(μ-PCy2)-
(CO)5] (8d) (Chart 3). Although these compounds could
not be separated from each other using chromatographic
procedures, crystallization of these mixtures allowed the
(30) (a) Shapley, J. R.; Park, J. T; Churchill, M. R.; Zieller, J. W.;
Beanan, L. R. J. Am. Chem. Soc. 1984, 106, 1144. (b) Churchill, M. R.;
Zieller, J. W.; Beanan, L. R. J. Organomet. Chem. 1985, 287, 235. (c) Park,
J. T.; Chi, Y.; Shapley, J. R.; Churchill, M. R.; Zieller, J. W. Organometallics
1994, 13, 813.

Article
Organometallics, Vol. 29, No. 4, 2010 909
Chart 4
methylidyne cluster 12 could not be separated from the oxo
complex 10, and therefore it was not isolated as a pure
material.
Togaincomplementaryinformationontheformationofthe
above iron derivatives of 1, we also examined the thermal
reaction of the monocarbonyl methyl complex [Mo2Cp2-
(μ-η1:κ2-CH3)(μ-PCy2)(μ-CO)] (2) with [Fe2(CO)9]. Unfortu-
nately, this reaction gave a mixture of products, with the major
one being the methoxy-bridged cluster [FeMo2Cp2(μ3-OMe)-
(μ-PCy2)(CO)5] (8e), isostructural with the ruthenium com-
pound 8d. As we noted in our preliminary report, the triply
bonded compound 2 is extremely air-sensitive,10 so it seems
that 2 first reacts with trace amounts of oxygen, and the
formation of 8e then follows from the addition of the Fe(CO)4
fragment to the major oxoderivatives of 2, yet to be investi-
gated.
Figure 3. ORTEP diagram (30% probability) of compound 7,
with Cy rings (except the C1 atoms) and H atoms (except H6)
omitted for clarity.
˚
Table 4. Selected Bond Lengths (A) and Angles (deg) for
Compound 7
Mo(1)-Mo(2)
Mo(1)-Ru(1)
Mo(2)-Ru(1)
Mo(1)-C(6)
Mo(2)-C(6)
Ru(1)-C(6)
Mo(1)-P(1)
Mo(2)-P(1)
Mo(1)-C(1)
Mo(2)-C(2)
Ru(1)-C(3)
Ru(1)-C(4)
Ru(1)-C(5)
C(6)-H(6)
2.6824(7)
2.8793(7)
2.8789(7)
2.091(6)
2.089(6)
2.012(7)
2.401(2)
2.398(2)
1.986(7)
1.970(7)
1.884(7)
1.895(8)
1.960(7)
0.98(2)
Mo(1)-Ru(1)-Μο(2)
Mo(1)-P(1)-Mo(2)
Mo(1)-Μο(2)-C(2)
Mo(2)-Mo(1)-C(1)
Ru(1)-Μο(2)-C(2)
Ru(1)-Mo(1)-C(1)
Mo(1)-C(1)-O(1)
Mo(2)-C(2)-Ο(2)
Mo(1)-C(6)-Mo(2)
Mo(1)-C(6)-Ru(1)
Mo(2)-C(6)-Ru(1)
P(1)-Mo(1)-C(6)
P(1)-Mo(2)-C(6)
P(1)-Mo(1)-C(1)
P(1)-Mo(2)-C(2)
55.5(1)
68.0(1)
91.3(2)
91.9(2)
65.9(2)
67.7(2)
168.8(6)
166.4(5)
79.9(2)
89.1(3)
89.2(3)
102.6(2)
102.8(2)
90.1(2)
91.1(2)
Solid-State and Solution Structure of Compound 7. The
molecular structure of this Mo2Ru cluster (Figure 3 and
Table 4) can be derived from that of 6, after replacing the
MnCp0(CO)2 fragment with a Ru(CO)3 fragment. This,
however, removes two electronsfrom the system, thenleaving
an unsaturated (46-electron) cluster. This unsaturation seems
to be localized on the Mo2 center, since the short Mo-Mo
˚
length of 2.6824(7) A is consistent with the presence of a
double metal-metal bond. In fact, the structure of 7 is very
similar to that of the isoelectronic methoxycarbyne-bridged
cluster [FeMo2Cp2(μ3-COMe)(μ-PCy2)(CO)5] (Mo-Mo =
(M = Fe, Ru).25 We note that the Mo-bound carbonyls give
rise to very weak bands, an effect also observed in the above
methoxycarbyne clusters and in compounds 3a,b. As ex-
pected, the methylidyne ligand in 7 gives rise to quite de-
shielded 1H and 13C NMR resonances (δH 13.59 ppm, δC =
270.6 ppm), and the low value of the P-C coupling in the
latter (2 Hz) is consistent with the conformation found in the
crystal, implying P-Mo-C angles (ca. 103°) substantially
larger than those in the electron-precise clusters 3 and 6
(ca. 78°, JPC = 21 Hz for 3a). Besides this, the relative deshield-
ing of the 13C carbyne and 31P resonances in 7 (compared to
those in the clusters 3) is attributed to the unsaturation of the
cluster. We finally note that the Ru(CO)3 fragment in this
molecule gives rise to a single 13C resonance at room tempera-
ture, which is indicative of the occurrence of a fast fluxional
process effectively exchanging the carbonyl positions, a feature
commonly found for pyramidal M(CO)3 fragments in cluster
compounds.32
25a
˚
2.688(3) A) recently reported by us,
and therefore a
detailed analysis is not needed here. We just note that the
intermetallic lengths in 7 are also comparable to those
measured in the unsaturated clusters [Mo2RuCp2{μ-η3-
RCC(R’)CPh}{μ3-η3-HCC(Ph)CH}(μ3-S)(CO)2] (R = Ph, H;
31
0
˚
˚
R = H, Ph; Mo-Ru ca. 2.83 A and Mo-Mo ca. 2.68 A).
Another structural feature of 7 is the absence of semibridging
carbonyls and a change in the conformation of the Mo-bound
carbonyls (when compared to that in 6), since now these ligands
are directed toward the ruthenium atom in a very incipient
˚
semibridging interaction (Ru C separations of ca. 2.75 A)
3 3 3
so as to partially balance the electron densities at the Ru and
Mo atoms. This effect was also observed in the mentioned
methoxycarbyne-bridged Mo2Fe cluster.25a Such conforma-
tional modification (compared to that in the electron-precise
cluster 6) is accompanied by a change of the phosphide
position, which moves away from the bridging carbyne ligand,
this implying an increase in the P-Mo-C(carbyne) angles
from ca. 78° to 103°.
The IR spectrum of compound 7 exhibits five C-O stretch-
ing bands in the region of terminal carbonyls, when recorded
in petroleum ether solution. The three bands of higher fre-
quency and intensity are characteristic of pyramidal M(CO)3
fragments24 and are comparable to those observed for the
mentioned clusters [MMo2Cp2(μ3-COMe)(μ-PCy2)(CO)5]
Solid-State and Solution Structure of Compounds 8. The
crystal structure of compound 8e (Figure 4 and Table 5) is
essentially identical to that of the isoelectronic methylidyne
cluster 7, after replacing Ru by Fe and the methylidyne by a
methoxy ligand, and no detailed comments are therefore
˚
needed. We just note that the Mo-Mo length (2.667(1) A) is
even shorter than that in 7, thus indicating that the unsatura-
tion of the cluster also is essentially localized at the Mo2
edge. As for the methoxy ligand, the M-O separations are
(31) Adams, R. D.; Babin, J. E.; Tasi, M.; Wang, J. G. Organome-
tallics 1988, 7, 755.
(32) Orrel, K. G.; Sik, V. Ann. Rep. NMR 1987, 19, 79.

910 Organometallics, Vol. 29, No. 4, 2010
Alvarez et al.
Figure 5. ORTEP diagram (30% probability) of compound 9,
with Cy rings (except the C1 atoms) and H atoms omitted for
clarity.
Figure 4. ORTEP diagram (30% probability) of compound 8e,
with Cy rings (except the C1 atoms) and H atoms omitted for
clarity.
˚
Table 5. Selected Bond Lengths (A) and Angles (deg) for
Compound 8e
˚
Table 6. Selected Bond Lengths (A) and Angles (deg) for
Compound 9
Mo(1)-Mo(2)
Mo(1)-Fe(1)
Mo(2)-Fe(1)
Mo(1)-O(6)
Mo(2)-O(6)
Fe(1)-O(6)
Mo(1)-P(1)
Mo(2)-P(1)
Mo(1)-C(1)
Mo(2)-C(2)
Fe(1)-C(1)
Fe(1)-C(2)
Fe(1)-C(3)
Fe(1)-C(4)
Fe(1)-C(5)
O(6)-C(6)
2.667(1)
2.766(2)
2.799(2)
2.20(2)
2.25(2)
1.88(1)
2.409(3)
2.390(3)
1.99(1)
1.97(1)
2.60(1)
2.90(1)
1.81(1)
1.75(1)
1.78(1)
1.40(2)
Mo(1)-Fe(1)-Μο(2)
Mo(1)-P(1)-Mo(2)
Mo(1)-Μο(2)-C(2)
Mo(2)-Mo(1)-C(1)
Mo(1)-C(1)-O(1)
Mo(2)-C(2)-Ο(2)
Mo(1)-O(6)-Mo(2)
Mo(1)-O(6)-Fe(1)
Mo(2)-O(6)-Fe(1)
P(1)-Mo(1)-C(1)
P(1)-Mo(2)-C(2)
P(1)-Mo(1)-O(6)
Fe(1)-Mo(1)-C(1)
Fe(1)-C(3)-O(3)
Fe(1)-C(4)-O(4)
Fe(1)-C(5)-C(5)
57.3(1)
67.5(1)
90.2(3)
91.2(3)
165(1)
170.8(9)
73.7(6)
84.9(6)
84.8(6)
100.6(3)
91.3(4)
104.1(4)
63.7(4)
175(1)
Mo(1)-Mo(2)
Mo(1)-Fe(1)
Mo(2)-Fe(1)
Mo(1)-O(6)
Mo(2)-O(6)
Mo(1)-C(6)
Fe(1)-C(6)
Mo(1)-P(1)
Mo(2)-P(1)
Mo(1)-C(1)
Mo(2)-C(2)
C(1)-Ο(1)
2.8474(5)
2.7417(8)
2.7603(8)
2.139(3)
2.121(3)
2.131(5)
1.935(5)
2.445(1)
2.434(1)
1.972(5)
2.000(6)
1.168(6)
1.154(6)
1.736(6)
1.796(6)
1.805(6)
2.518(6)
1.386(6)
1.507(7)
Mo(1)-Fe(1)-Μο(2)
Mo(1)-P(1)-Mo(2)
Mo(1)-Μο(2)-C(2)
Mo(2)-Mo(1)-C(1)
Mo(1)-C(1)-O(1)
Mo(2)-C(2)-Ο(2)
Mo(1)-O(6)-Mo(2)
Mo(1)-C(6)-Fe(1)
Fe(1)-C(6)-C(7)
Fe(1)-C(6)-O(6)
O(6)-C(6)-C(7)
P(1)-Mo(1)-C(1)
P(1)-Mo(2)-C(2)
P(1)-Mo(1)-O(6)
Fe(1)-Mo(1)-C(1)
Fe(1)-C(3)-O(3)
Fe(1)-C(4)-O(4)
Fe(1)-C(5)-O(5)
62.3(1)
71.4(1)
95.4(1)
79.1(2)
160.8(4)
176.4(4)
83.9(1)
84.7(2)
129.3(4)
114.2(3)
112.0(4)
93.0(1)
86.1(1)
76.6(1)
62.1(2)
177.2(5)
177.9(5)
178.7(5)
C(2)-O(2)
Fe(1)-C(3)
Fe(1)-C(4)
Fe(1)-C(5)
Fe(1)-C(1)
C(6)-O(6)
178(1)
179(1)
comparable to those measured for other clusters having
μ3-OMe groups.33 However, the Mo-O lengths are ca.
C(6)-C(7)
˚
˚
0.35 A longer than the Fe-O separation of 1.88(1) A,
edges and the O atom bridges the molybdenum atoms.
This coordination mode of the acetyl ligand is comparable
to that found in other acyl-bridged clusters such as
[Fe2WCp{μ3-C(O)CH2(p-tol)}(μ-PPh2)2(CO)5],35 [Os3W{μ3-
C(O)CH2(p-tol)}(CO)11],36 [NEt4][Fe3{μ3-C(O)Me}(CO)9],37
and [Fe3(μ-H){μ3-C(O)Me}(CO)9].38 The large C(6)-O(6)
˚
exceeding the ca. 0.2 A difference in the covalent radii of
these metal atoms.34 This is suggestive of a stronger binding
of the methoxy ligand to the iron atom, surely to balance the
relative deficiency of that metal center.
Spectroscopic data for compounds 8d,e are consistent with
the structure found for 8e in the solid state and are also very
similar to those of either 7 or the mentioned methoxycarbyne
clusters [MMo2Cp2(μ3-COMe)(μ-PCy2)(CO)5] (M=Fe, Ru);25
therefore a detailed discussion is not needed. We just note that
the 1H resonances for the methoxy ligands appear at 3.32 and
3.65 ppm, respectively, these being values comparable to those
reported for other clusters displaying triply bridging methoxy
ligands.33
Solid-State and Solution Structure of Compound 9. The
molecular structure of this compound in the crystal (Figure 5
and Table 6) can be derived from that of 8 after replacing the
bridging methoxy group by an acetyl ligand bridging the
Mo2Fe triangle, so that the C atom spans one of the Mo-Fe
˚
length of 1.386(6) A in 9, almost identical to the single C-O
˚
bondlengthof the methoxy group in 8e(1.40(2) A), along with
the short C(6)-M and O(6)-Mo lengths, in the range of
the corresponding single-bond figures, indicates a strong
binding of the acetyl ligand over the metal triangle, therefore
to be considered essentially as a five-electron donor group.
This renders a saturated (48-electron) cluster, as opposed
to the unsaturated nature of its methoxycarbyne-bridged
isomer [FeMo2Cp2(μ3-COMe)(μ-PCy2)(CO)5],25 or the com-
plexes 7 and 8. In agreement with this, the Mo-Mo length of
(35) (a) Jeffery, J. C.; Lawrence-Smith, J. G. J. Chem. Soc., Chem.
Commun. 1985, 275. (b) Jeffery, J. C.; Lawrence-Smith, J. G. J. Chem. Soc.,
Dalton Trans. 1990, 1063.
(33) (a) Litos, C.; Terzis, A.; Raptopoulou, C.; Rontoyianni, A.;
Karaliota, A. Polyhedron 2006, 25, 1337. (b) Adrian, R. A.; Yaklin, M. M.;
Klausmeyer, K. K. Organometallics 2004, 23, 1252. (c) Villanneau, R.;
Delmont, R.; Proust, A.; Gouzerh, P. Chem.;Eur. J. 2000, 6, 1184.
(34) Cordero, B.; Gomez, V.; Platero-Prats, A. E.; Reves, M;
ꢀ
Echeverrıa, J.; Cremades, E.; Barragan, F.; Alvarez, S. Dalton Trans.
(36) Park, J. T.; Shapley, J. R.; Churchill, M. R.; Bueno, C. Inorg.
Chem. 1983, 22, 1579.
(37) Wong, W. K.; Wilkinson, G.; Galas, A. M.; Hursthouse, M. B.;
Thornton-Pett, M. J. Chem. Soc., Dalton Trans. 1981, 2496.
(38) Wong, W. K.; Chiu, K. W.; Wilkinson, G.; Galas, A. M. R.;
Thornton-Pett, M.; Hursthouse, M. B. J. Chem. Soc., Dalton Trans.
1983, 1557.
ꢀ
ꢀ
2008, 2832.

Article
Organometallics, Vol. 29, No. 4, 2010 911
Scheme 2. Fluxional Process Proposed for Compound 9 in
Solutiona
a Mo = MoCp(CO); Fe = Fe(CO)3; P = PCy2.
˚
2.8474(5) A in 9 is substantially higher than the values found
˚
for the mentioned unsaturated clusters (ca. 2.68 A), although
still somewhat shorter than those in the electron-precise
˚
clusters 3a,b and 6 (ca. 2.94 A). We finally note the presence
of a very incipient semibridging interaction between one of
the Mo-bound carbonyls and the iron atom (C(1) Fe ca.
3 3 3
˚
2.52 A), surely to balance the electron densities at the Mo and
Fe atoms.
Figure 6. ORTEP diagram (30% probability) of compound 10,
with Cy rings (except the C1 atoms) and H atoms omitted for
clarity.
The spectroscopic data for 9 in solution are essentially
consistent with the structure found in the crystal, but reveal
the presence of dynamic effects. The IR spectrum exhibits
just three strong C-O stretching bands corresponding to the
Fe(CO)3 moiety, as observed for the isomeric methoxycar-
byne clusters [MMo2Cp2(μ-COMe)(μ-PCy2)(CO)5] (M=Fe,
Ru),25 although the very weak bands arising from the Mo2-
(CO)2 unit can be appreciated when the spectrum is recorded
in a Nujol mull (see Experimental Section). In addition, the
spectrum also displays a weak band at 1600 cm-1 (1575 cm-1
in Nujol mull) corresponding to the C-O stretch of the
acetyl ligand. This suggests that the corresponding C-O
bond might retain substantial multiplicity, not revealed by
the geometric parameters discussed above. In contrast, the
31P{1H} NMR spectrum of 9 exhibits a resonance at 154.1
ppm, a shift close to those measured for the 48-electron
clusters 6 and [MnMo2Cp3(μ3-COMe)(μ-PCy2)(CO)4],25
therefore consistent with a five-electron contribution of the
acetyl ligand to cluster binding.
˚
Table 7. Selected Bond Lengths (A) and Angles (deg) for
Compound 10
Mo(1)-Mo(2)
Mo(1)-Fe(1)
Mo(2)-Fe(1)
Mo(1)-C(5)
Mo(2)-C(5)
Fe(1)-C(5)
Mo(2)-O(5)
Mo(1)-P(1)
Mo(2)-P(1)
Mo(1)-C(1)
Fe(1)-C(1)
Fe(1)-C(2)
Fe(1)-C(3)
Fe(1)-C(4)
C(5)-C(6)
2.8469(4)
2.7560(5)
2.6609(5)
1.972(3)
2.478(3)
1.865(3)
1.702(2)
2.369(1)
2.463(1)
1.965(3)
2.650(4)
1.788(4)
1.766(4)
1.781(3)
1.509(4)
Mo(1)-Fe(1)-Μο(2)
Mo(1)-P(1)-Mo(2)
Mo(1)-Μο(2)-O(5)
Mo(2)-Mo(1)-C(1)
P(1)-Mo(1)-C(5)
P(1)-Mo(2)-C(5)
P(1)-Mo(1)-C(1)
Mo(1)-C(1)-O(1)
Fe(1)-Mo(1)-C(1)
Mo(1)-C(5)-Mo(2)
Mo(1)-C(5)-Fe(1)
Mo(2)-C(5)-Fe(1)
Fe(1)-C(2)-O(2)
Fe(1)-C(3)-O(3)
Fe(1)-C(4)-O(4)
63.4(1)
72.2(2)
108.8(1)
78.7(1)
102.0(1)
86.4(1)
95.6(1)
166.6(3)
65.8(1)
78.6(1)
91.8(1)
74.1(1)
177.7(3)
177.0(3)
179.5(3)
acetyl carbon atom gives rise to a relatively shielded reso-
nance at 199.9 ppm, not far from the figure reported for the
cluster [Fe2WCp{μ3-C(O)(p-tol)}(μ-PPh2)(CO)5] (ca. 197
ppm).35,36 These are values considerably lower than those
measured recently for several binuclear derivatives of 1
having μ2-acetyl ligands (δC ca. 275 ppm).40
The 1H NMR and 13C{1H} NMR spectra of 9 reveal the
occurrence of two fluxional processes in solution. In the first
place, there is a single cyclopentadienyl resonance at room
temperature, which is inconsistent with the absence of any
symmetry elements in the static structure. On lowering the
temperature, this resonance broadens and eventually splits
into two resonances of the same intensity, as expected. From
the coalescence temperature of the proton resonances (Tc =
263 ( 1 K) we can estimate39 a free energy of activation of
55.5 ( 0.5 kJ mol-1 for the corresponding process, proposed
to involve the migration of the bridgehead carbon atom of
the acetyl ligand between both Fe-Mo edges (Scheme 2).
This also implies the averaging of the Mo-bound carbonyl
sites, in agreement with the presence of a single and broad
resonance at 251.2 ppm for these ligands in the room-
temperature 13C NMR spectrum, which splits into separated
resonances below 243 K (see Experimental Section). At room
temperature, however, the ligands of the Fe(CO)3 fragments
give rise also to just a single 13C resonance, with this
requiring the existence of an additional exchange process
within this pyramidal fragment analogous to that proposed
for compound 7. Both dynamic processes are slowed down
enough at 208 K to allow the observation of three separated
Fe-CO resonances. Finally we note that the bridgehead
Solid-State and Solution Structure of Compound 10.
The molecular structure of this oxo complex (Figure 6 and
Table 7) can be viewed as resulting from the removal of a
Mo-bound carbonyl ligand from 9 and cleavage of the acetyl
C-O bond, thus yielding a bridging ethylidyne and an oxo
ligand, the latter being coordinated to the decarbonylated
metal atom in a terminal fashion, on the same side of the
intermetallic plane as the carbyne group. This oxygen atom
is strongly bound to the Mo(2) atom, as usually found in
organomalybdenum oxo complexes,41 with the correspond-
˚
ing Mo-O length of 1.702(2) A being comparable to those
measured in the binuclear complexes [Mo2Cp2(μ-PPh2)-
(μ-CHCHPh)(O)(CO)], [Mo2Cp2(μ-PPh2)2(O)(CO)], and
[W2Cp2(μ-PPh2)(μ-CH2PPh2)(O)(CO)].42 We have shown
recently that the oxo ligand can be thus described as a
(40) Alvarez, M. A.; Garcıa, M. E.; Martınez, M. E.; Ramos, A.;
Ruiz, M. A. Organometallics 2009, 28, 6293.
(41) Bottomley, F.; Sutin, L. Adv. Organomet. Chem. 1988, 28, 339.
(42) (a) Endrich, K.; Korswagen, R.; Zhan, T.; Ziegler, M. L. Angew.
Chem., Int. Ed. Engl. 1982, 21, 919. (b) Adatia, T.; McPartlin, M.; Mays,
M. J.; Morris, M. J.; Raithby, P. R. J. Chem. Soc., Dalton Trans. 1989, 1555.
(c) Alvarez, M. A.; García, M. E.; Riera, V.; Ruiz, M. A.; Falvello, L. R.; Bois,
C. Organometallics 1997, 16, 354.
(39) Calculated using the modified Eyring equation ΔG#
=
19.14Tc[9.97 þ log(Tc/Δν)] (J mol-1). See: Gunter, H. NMR Spectros-
copy; John Wiley: Chichester, U.K., 1980; p 243.
€

912 Organometallics, Vol. 29, No. 4, 2010
Alvarez et al.
four-electron donor in this sort of complexes,43 and this
would lead to the formulation of compound 10 as an
electron-precise molecule. In any case, this oxo ligand has
a significant labilizing effect on the remaining ligands there
˚
present, such as the phosphide ligand (ca. 0.1 A closer to
Mo(1)) and the carbyne ligand, essentially edge-bridging the
˚
opposite Mo(1)-Fe bond (C(5) Mo(2)=2.478(3) A). The
3 3 3
latter ligand seems to be more strongly bound to the Mo(1)
˚
atom, since the Mo(1)-C(5) length of 1.972(3) A is shorter
than the corresponding distances in compounds 3a,b (almost
˚
edge-bridging the Mo atoms, Mo-C ca. 2.05 A), while the
˚
C(5)-Fe length of 1.865(3) A is slightly longer than that
measured in the triply bridged methoxycarbyne complex
25
˚
[FeMo2Cp2(μ3-COMe)(μ-PCy2)(CO)5] (1.82(3) A). The
intermetallic distances, however, are somewhat shorter
than the single-bond lengths expected for an electron-precise
cluster, a circumstance alsofoundfor the acetylprecursor9, as
discussed above. Yet, the more striking feature inthe structure
of 10 is perhaps the fact that the shorter intermetallic length
Figure 7. ORTEP diagram (30% probability) of compound 11
(reproduced from ref 1b), with Cy rings (except the C1 atoms) and
H atoms (except H9) omitted for clarity. Selected bond lengths
˚
(A): Mo(1)-Mo(2) = 2.835(1), Mo(1)-Fe(1) = 2.725(1), Mo-
˚
(1)-Fe(2) = 2.707(1), Mo(2)-Fe(1) = 2.770(1), Fe(1)-Fe(2) =
2.537(1), Mo(1)-C(9) = 2.144(6), Mo(2)-C(9) = 2.113(6), Fe-
(1)-C(9) = 1.906(6), Fe(2)-C(9) = 2.001(6), Mo(1)-P(1) =
2.476(2), Mo(2)-P(1) = 2.392(1).
(Fe-Mo(2) = 2.6609(5) A) corresponds to the metal edge
lacking any bridging ligand and involving the metal atom
bearing the oxygen ligand. Currently we cannot offer a
satisfactory explanation for this structural feature.
The IR spectrum of 10 in CH2Cl2 solution exhibits two
strong C-O stretching bands corresponding to the Fe(CO)3
fragment and a weak band at 1818 cm-1 arising from the
Mo(CO) moiety. The 13C NMR spectrum displays a strongly
deshielded carbyne resonance at 401.5 ppm, a chemical shift
significantly higher than those measured in the triply bridged
clusters [Mo2Ru(μ3-CR)(μ-PPh2)(CO)5] (R=Me, Et; δC ca.
350 ppm),44 this being suggestive that the carbyne ligand
retains in solution the almost edge-bridging coordination
found in the crystal. Besides, the Fe-bound carbonyls give
rise to a single resonance at room temperature, with this
indicating the operation of a fast fluxional process within the
Fe(CO)3 fragment, as found for the clusters 7 and 9.
yielding electron-precise (62-electron) “butterfly” structures. In
contrast, the methylidyne ligand in 11 is not involved in agostic
interactions, as indicated by the large values of the closest
˚
M
H approaches (ca. 2.6 A) and the normal value (not
3 3 3
˚
elongated) of the C-H distance (0.84(9) A).
The IR spectrum of cluster 11 is consistent with the
structure just described, since it exhibits five strong- to
medium-intensity C-O stretching bands, which can be as-
signed as arising from an asymmetric Fe2(CO)6 oscillator,
and a weak band at 1870 cm-1 probably originating from the
Mo2(CO)2 oscillator. In agreement with this, the 13C NMR
spectra display independent resonances for the inequivalent
pairs of Cp ligands and Mo-bound carbonyls, as expected.
However, the six carbonyl ligands bound to iron atoms give a
single resonance at 215.1 ppm at room temperature, thus
suggesting the occurrence of a fast exchange process invol-
ving the six Fe-CO ligands. This process is slowed down
enough at 213 K to yield independent resonances for all these
ligands, in agreement with the static structure. Although we
have not studied this rearrangement in detail, we note that
these exchange processes are common in trinuclear iron
carbonyl clusters.47
The coordination mode of the methylidyne ligand of
compound 11 in solution might be slightly different from
that found in the crystal. For instance, its proton shift (4.24
ppm) is substantially higher than those measured for the
mentioned agostic methylidyne clusters (δH in the range þ2
to -2 ppm),45,46 but still much lower than all other methy-
lidyne complexes reported in this work (δH in the range 10 to
15 ppm, Table 2). Therefore it can be proposed that, in
solution, the methylidyne ligand in compound 11 might be
involved in weak agostic interactions with the iron atoms.
In line with this, the methylidyne carbon (δC = 243.8 ppm)
exhibits a reduced C-H coupling of 143 Hz. Although this
value is certainly higher than those measured for the men-
tioned agostic clusters (JCH ≈ 105 Hz), it is significantly lower
than a “normal” coupling in a methylidyne-bridged cluster
(i.e., JCH = 162 Hz for 3a).
Solid-State and Solution Structure of Compound 11. The
molecular structure of this tetranuclear cluster (Figure 7)10
can be viewed as derived from the addition of two Fe(CO)3
moieties to a dehydrogenated molecule of 1, which still holds
the bridging dicyclohexylphosphide ligand and a transoid
arrangement of the Cp and CO ligands. Unexpectedly, this
60-electron cluster does not display a tetrahedral structure,
but a “butterfly” one with the CH ligand bridging the four
metal atoms in a rather symmetrical way; therefore the
molecule must be considered electronically unsaturated. In
˚
agreement with this, the intermetallic lengths are 0.1-0.2 A
shorter than the corresponding single-bond lengths of refer-
ence, this indicating a delocalization of such an unsaturation.
It is interesting noting that only a few similar “butterfly”
methylidyne clusters, [Fe4(μ-CH)(μ-H)(CO)12]45 and [MFe3-
(μ-CH)(CO)x]n (M=Cr, W, Mn, Rh;x= 12, 13; n=0, -1),46
have been reported previously. These, however, display CH
ligands involved in agostic C-H-M interactions, therefore
ꢀ
ꢀ
(43) (a) Garcıa, M. E.; Garcıa-Vivo, D.; Melon, S.; Ruiz, M. A.;
Graiff, C.; Tiripicchio, A. Inorg. Chem. 2009, 48, 9282. (b) García, M. E.;
ꢀ
Melon, S.; Ramos, A.; Ruiz, M. A. Dalton Trans. 2009, 8171.
(44) Adams, H.; Bailey, N. A.; Gill, L. J.; Morris, M. J.; Sadler, N. D.
J. Chem. Soc., Dalton Trans. 1997, 3041.
(45) (a) Tachikawa, M.; Muetterties, E. L. J. Am. Chem. Soc. 1980,
102, 4541. (b) Beno, M. A.; Williams, J. A.; Tachikawa, M.; Muetterties, E. L.
J. Am. Chem. Soc. 1980, 102, 4542. (c) Wadepohl, H.; Braga, D.; Grepioni,
F. Organometallics 1995, 14, 24.
(46) Hriljac, J. A.; Harris, S.; Shriver, D. F. Inorg. Chem. 1988, 27,
816.
(47) Mann, B. E. J. Chem. Soc., Dalton Trans. 1997, 1457.

Article
Organometallics, Vol. 29, No. 4, 2010 913
Scheme 3. Reaction Pathways in the Formation of Compounds
3-12a
Mo-CH3 bond (or CH3 migration to CO) to give an acetyl
ligand, this allowing the electronic saturation of the cluster
after rearrangement of the latter ligand into a face-bridging
position. The resulting cluster 9 may afterward experience
thermally or photochemically induced decarbonylation, this
triggering the cleavage of the C-O bond of the acetyl ligand
to yield oxo and carbyne ligands, thus preserving the electron
count of the molecule.
Under photochemical activation, however, the intermedi-
ate A would preferentially undergo dehydrogenation. This
reaction cannot occur at an earlier stage (i.e., directly from 1)
since separate experiments indicate that 1 does not experi-
ence any dehydrogenation under photolytic conditions, but
just decarbonylation to give the methyl-bridged agostic
complex 2.10 In addition, our results suggest that dehydro-
genation of A might occur in two different ways. First, the
simple dehydrogenation (surely involving several elemental
steps in turn) would be the dominant reaction path for the
group 6 and 7 metal fragments, this leading to the electron-
precise clusters 3 and 6, after rearrangement of the so-formed
methylidyne ligand into a face-bridging position. The ob-
served equilibrium relating the methyl, hydride-methylidene,
and dihydride-methylidyne tautomers in the iron cluster
[Fe3(CO)9CH4]4b is an attractive model of the elementary
steps that might connect the intermediate A with our methy-
lidyne derivatives, thus explaining the need to incorporate at
least one more metal atom to the unsaturated compound 1,
to achieve the dehydrogenation of the methyl ligand. Inci-
dentally, under this scheme the minor chromium product 3c
would thus be the kinetic product in the corresponding
reaction, although further rearrangement of the phosphide
and methylidyne ligands would then rapidly occur so as to
reach an equilibrium mixture of isomers 3c-5.
When the heterometal in the intermediate A is ruthenium
or iron, however, the dehydrogenation process is accompa-
nied by further decarbonylation (we do not know which of
these elementary steps would take place first), this leading to
a 46-electron cluster that would be stable only for ruthenium
(compound 7). The corresponding iron species would be an
unstable intermediate B that might evolve either through
rearrangement of the bridging ligands, to give a more stable
isomer 12, or by the addition of a second Fe(CO)4 fragment
and further decarbonylation to give the tetranuclear cluster
11. Separate experiments revealed that compound 12 does
not react further with [Fe2(CO)9] under photolytic condi-
tions. Moreover, an electron-precise cluster [FeMo2Cp2(μ-
CH)(μ-PCy2)(CO)6] also seems an unlikely intermediate in
the formation of 11, since the isoelectronic cluster 3a failed to
react under photolytic conditions with [Fe2(CO)9] to yield a
hypothetical Mo3Fe analogue of 11, according to indepen-
dent experiments. All this gives indirect support to the
hypothesis that the precursor of the tetranuclear cluster 11
must be a 46-electron isomer of compound 12.
a Mo = MoCp; P = PCy2.
Solution Structure of Compound 12. The IR spectrum of
this trinuclear cluster in CH2Cl2 solution exhibits just two
strong C-O bands, corresponding to the Fe(CO)3 moiety, as
found for 10, and a weaker band at 1858 cm-1 probably
arising from the Mo2(CO)2 oscillator. The number of carbo-
nyls and lack of symmetry of the molecule is denoted by the
appearance, in the room-temperature 13C NMR spectrum,
of two Mo-CO and three Fe-CO resonances (see Experi-
mental Section). This asymmetry is attributed to the presence
of the bridging phosphide ligand over a Fe-Mo edge, rather
than the original positioning between the Mo atoms. This is
also suggested by the strong deshielding of the corresponding
phosphorus resonance (δP = 244.8 ppm), comparable to
that of the isomer 4 and much higher than those of all other
compounds here reported with PCy2 bridges over Mo2 edges
(Table 2). As for the methylidyne ligand, it gives rise to very
deshielded NMR resonances (δH =15.47 ppm; δC =330.1
ppm), with the high chemical shift of the 13C resonance being
taken as an indication of its positioning over a Mo-Fe edge,
rather than over the Mo2Fe face. All this would substantially
increase the crowding around the iron atom, thus explaining
the unusual rigid behavior of the Fe(CO)3 fragment on the
NMR time scale.
Reaction Pathways in the Formation of the Heterometallic
Clusters 3-12. Leaving apart the formation of the methoxy-
bridged compounds 8, obviously derived from the presence
of trace amounts of oxygen in the reaction media, the
formation of all other heterometallic clusters 3-12 reported
in the present work can be rationalized by assuming a
common initial step, the addition of a thermally (Fe) or
photochemically generated 16-electron metal fragment ML-
(CO)n (M = Cr, Mo, W, Mn, Ru, Fe; L = CO, Cp0; n =
2-4) to the unsaturated dimolybdenum center in 1 to give a
heterometallic intermediate A possibly having a terminal
methyl ligand (Scheme 3). This intermediate then might
evolve in three likely ways. First, in the absence of photo-
chemical activation (thermal reaction with [Fe2(CO)9]), the
intermediate A might evolve by CO insertion into the
Concluding Remarks
The methyl complex 1 reacts with different metal carbonyl
complexes under conditions in which the corresponding
16-electron metal fragments ML(CO)n (M = Cr, Mo, W,
Mn, Ru, Fe; L = CO, Cp0; n = 2-4) can be generated to a
significant extent. The reaction seems to involve in all cases
the addition of the corresponding fragment to the unsatu-
rated dimetal center in 1 to give a trinuclear intermediate that
can evolve in different ways, depending on the nature of the

914 Organometallics, Vol. 29, No. 4, 2010
Alvarez et al.
metal and the reaction conditions. Under thermal condi-
tions, no dehydrogenation of the methyl ligand can take
place, only CO insertion into the Mo-CH3 bond to give an
acetyl-bridged cluster. Under photolytic conditions, dehy-
drogenation of the methyl ligand to give a methylidyne-
bridged cluster occurs in all cases at the corresponding
trinuclear intermediate. When M is a metal of the group 6
or 7, this leads directly to stable 48-electron clusters. When M
is a metal of the group 8, the dehydrogenation process is
accompanied by further decarbonylation to yield unsatu-
rated 46-electron clusters that are stable only for ruthenium,
but are able to add a further metal fragment in the case of
iron, now to yield a 60-electron tetranuclear cluster with a
butterfly Mo2Fe2 metal core.
Preparation of [Mo2WCp2(μ3-CH)(μ-PCy2)(CO)7] (3b). A
toluene solution (4 mL) of compound 1 (0.025 g, 0.042 mmol)
and [W(CO)6] (0.027 g, 0.076 mmol) was irradiated in a quartz
Schlenktubewithvisible-UVlightunder a gentleN2 (99.9995%)
purge for 10 h to give a greenish-brown solution. The solvent
was then removed under vacuum, and the residue was dissolved
in a minimum of dichloromethane and chromatographed
through an alumina column (activity IV) at 288 K. Elution with
dichloromethane-petroleum ether (1:9) yielded a yellowish-
green fraction. Removal of solvents under vacuum from this
fraction gave compound 3b as a brown microcrystalline solid
(0.025 g, 64%). The crystals used in the X-ray study were grown
by slow diffusion of petroleum ether into a dichloromethane
solution of the complex at 253 K. Anal. Calcd for C30H33-
Mo2O7PW: C, 39.50; H, 3.65. Found: C, 39.55; H, 3.70. 1H
NMR (300.13 MHz): δ 12.05 (d, JPH = 5, JWH = 4, 1H, CH),
5.26 (d, JPH = 1, 10H, Cp), 2.04-1.16 (m, 22H, Cy).
Experimental Section
Reaction of 1 with [Cr(CO)6]. A toluene solution (4 mL) of
compound 1 (0.020 g, 0.034 mmol) and [Cr(CO)6] (0.018 g, 0.034
mmol) was irradiated in a Pyrex Schlenk tube with visible-UV
light under a gentle N2 (99.9995%) purge for 4.5 h togive a brown
solution. The solvent was then removed under vacuum, and the
residue was dissolved in a minimum of dichloromethane and
chromatographed through an alumina column (activity IV) at
288 K. Elution with dichloromethane-petroleum ether (1:9)
yielded a yellowish-brown fraction. Removal of solvents under
vacuum from the latter fraction gave 0.020 g (75%) of a mixture
of the isomers 3c, 4, and 5 in a ratio 1:15:5. The 4/5 equilibrium
ratio, as measured by 1H NMR, was somewhat dependent on the
solvent, it being 3 in CD2Cl2 and 4 in C6D6; however, when
acetone-d6 was used as solvent, only signals attributable to the
isomer 4 were observed. Anal. Calcd for C30H33CrMo2O7P: C,
46.17; H, 4.26. Found: C, 45.85; H, 4.05. Spectroscopic data for
3c: 1H NMR: δ 11.67 (d, JPH =14, 1H, CH), 5.25 (d, JPH =1,
10H, Cp), 2.98-1.00 (m, 22H, Cy). Spectroscopic data for 4: 1H
NMR: δ 13.47 (s, JCH =161, 1H, CH), 5.48, 5.16 (2s, 2 ꢀ 5H,
General Procedures and Starting Materials. All manipulations
and reactions were carried out under a nitrogen (99.995%)
atmosphere using standard Schlenk techniques. Solvents were
purified according to literature procedures and distilled prior to
use.48 Petroleum ether refers to that fraction distilling in the
range 338-343 K. The compounds [Mo2Cp2(μ-CH3)(μ-PCy2)-
(CO)2] (1) and [Mo2Cp2(μ-κ1:η2-CH3)(μ-PCy2)(μ-CO)] (2) were
prepared as described previously.1,10 All other reagents were
obtained from the usual commercial suppliers and used as
received. Photochemical experiments were performed using
jacketed quartz or Pyrex Schlenk tubes, cooled by tap water
(ca. 288 K). A 400 W mercury lamp placed ca. 1 cm away from
the Schlenk tube was used for all the experiments. Chromato-
graphic separations were carried out using jacketed columns
cooled by tap water (ca. 288 K). Commercial aluminum oxide
(Aldrich, activity I, 150 mesh) was degassed under vacuum prior
to use. The latter was mixed under nitrogen with the appropriate
amount of water to reach the activity desired. IR stretching
frequencies were measured in solution or Nujol mulls and are
referred as ν (solvent) or ν (Nujol), respectively. Nuclear mag-
netic resonance (NMR) spectra were routinely recorded at
400.13 (1H), 121.50 (31P{1H}), or 100.63 MHz (13C{1H}) at
290 K in CD2Cl2 solutions unless otherwise stated. Chemical
shifts (δ) are given in ppm, relative to internal tetramethylsilane
(1H, 13C) or external 85% aqueous H3PO4 (31P). Coupling
constants (J) are given in Hz.
Preparation of [Mo3Cp2(μ3-CH)(μ-PCy2)(CO)7] (3a). A to-
luene solution (4 mL) of compound 1 (0.025 g, 0.042 mmol) and
[Mo(CO)6] (0.018 g, 0.068 mmol) was irradiated in a Pyrex
Schlenk tube with visible-UV light under a gentle N2
(99.9995%) purge for 5 h to give a greenish-brown solution.
The solvent was then removed under vacuum, and the residue
was dissolved in a minimum of dichloromethane and chroma-
tographed through an alumina column (activity IV) at 288 K.
Elution with dichloromethane-petroleum ether (1:8) yielded a
brown fraction. Removal of solvents under vacuum from this
fraction gave compound 3a as a brown microcrystalline solid
(0.028 g, 80%). The crystals used in the X-ray study were grown
by slow diffusion of petroleum ether into a dichloromethane
solution of the complex at 253 K. Anal. Calcd for C30H33-
Mo3O7P: C, 43.71; H, 4.03. Found: C, 43.55; H, 3.85. 1H NMR
(300.13 MHz): δ 12.26 (d, JPH = 5, JCH = 162, 1H, CH), 5.25
(d, JPH = 1, 10H, Cp), 2.34-1.13 (m, 22H, Cy). 13C{1H} NMR
(75.49 MHz): δ 244.7 (d, JCP = 21, CH), 244.1 (d, JCP = 9, 2CO),
222.0 (s, 2CO), 213.8 (s, 2CO), 201.6 (s, CO), 90.6 (s, Cp), 52.5
[d, JCP = 18, C1(Cy)], 44.8 [d, JCP = 7, C1(Cy)], 32.5 [d, JCP = 4,
C2(Cy)], 31.0 [s, C2(Cy)], 28.0, 27.7 [2d, JCP = 10, C3(Cy)], 26.7,
26.4 [2s, C4(Cy)].
Cp), 2.98-1.00 (m, 22H, Cy). 13C{1H} NMR: δ 273.5 (d, JCP
=
3, CH), 242.3 (d, JCP = 14, MoCO), 232.9 (d, JCP = 15, CrCO),
230.4 (s, MoCO), 229.2 (d, JCP = 5, CrCO), 228.4 (s, MoCO),
225.8 (d, JCP = 8, CrCO), 220.7 (d, JCP = 6, CrCO), 94.1, 92.9
(2s, Cp), 55.5 [d, JCP = 14, C1(Cy)], 55.1 [d, JCP = 9, C1(Cy)],
36.4 [d, JCP = 6, C2(Cy)], 36.4 [d, JCP = 5, C2(Cy)], 34.8 [s,
2C2(Cy)], 29.0 [d, JCP = 11, C3(Cy)], 28.7 [d, JCP = 9, C3(Cy)],
28.6, 28.5 [2d, JCP = 11, C3(Cy)], 26.8, 26.5 [2s, C4(Cy)]. Spectro-
scopic data for 5: 1H NMR: δ 9.47 (d, JPH =14, 1H, CH), 5.37,
5.15 (2s, 2 ꢀ 5H, Cp), 2.98-1.00 (m, 22H, Cy). 13C{1H} NMR: δ
94.3, 93.0 (2s, Cp), 50.2 [d, JCP = 11, C1(Cy)], 45.2 [d, JCP = 5,
C1(Cy)], 35.6 [s, C2(Cy)], 33.9, 33.7 [2d, JCP = 5, C2(Cy)], 33.1 [s,
C2(Cy)], 26.7 [s, C4(Cy)] ppm. Other resonances of this isomer
were obscured by those from the major isomer.
Preparation of [MnMo2Cp2Cp0(μ3-CH)(μ-PCy2)(CO)4] (6). A
toluene solution (4 mL) of compound 1 (0.025 g, 0.042 mmol)
and [MnCp0(CO)3] (20 μL, 0.127 mmol) was irradiated in a
quartz Schlenk tube with visible-UV light under a gentle N2
(99.9995%) purge for 3.5 h to give an orange solution, which was
filtered using a canula. The solvent was then removed under
vacuum, and the residue was dissolved in a minimum of
dichloromethane and chromatographed through an alumina
column (activity IV) at 288 K. Elution with dichloromethane-
petroleum ether (1:1) yielded a pink fraction. Removal of
solvents under vacuum from this fraction gave compound 6 as
a pink microcrystalline solid (0.015 g, 45%). The crystals used in
the X-ray study were grown by slow diffusion of petroleum ether
into a dichloromethane solution of the complex at 253 K and
were found to contain two dichloromethane molecules per
molecule of complex. Anal. Calcd for C33H40MnMo2O4P: C,
50.92; H, 5.18. Found: C, 50.74; H, 5.21. 1H NMR: δ 12.79 (d,
J
PH = 7, 1H, CH), 5.00 (d, JPH = 1, 10H, Cp), 4.32, 4.11 (2 false
t, apparent JPH = 2, 2 ꢀ 2H, C5H4), 2.16 (s, 3H, Me), 2.32-1.09
(48) Armarego, W. L. F.; Chai, C. Purification of Laboratory Che-
micals, 5th ed.; Butterworth-Heinemann: Oxford, U.K., 2003.
(m, 22H, Cy).

Article
Preparation of [Mo2RuCp2(μ3-CH)(μ-PCy2)(CO)5] (7). A
Organometallics, Vol. 29, No. 4, 2010 915
C2(Cy)], 28.2 [d, JCP = 13, C3(Cy)], 28.0 [d, JCP = 8, C3(Cy)],
27.6 [d, JCP = 10, 2C3(Cy)], 26.4, 26.3 [2s, C4(Cy)]. 13C{1H}
NMR (208 K): δ 254.0, 251.1 (2s, MoCO), 221.0, 217.8, 211.7
(3s, FeCO), 199.7 [s, C(O)Me], 93.2, 89.0 (2s, Cp), 44.8, 39.8 [2s,
br, C1(Cy)], 40.2 (s, CH3); other resonances in this spectrum
were too broad to be unambiguously assigned.
toluene solution (4 mL) of compound 1 (0.025 g, 0.042 mmol)
and [Ru3(CO)12] (0.031 g, 0.048 mmol) was irradiated in a Pyrex
Schlenk tube with visible-UV light under a gentle N2 (99.9995%)
purge for 2 h 30 min to give a greenish-brown solution, which was
filtered using a canula. The solvent was then removed under
vacuum, and the residue was dissolved in a minimum of dichlor-
omethane and chromatographed through an alumina column
(activity IV) at 288 K. Elution with dichloromethane-petroleum
ether (1:8) yielded a brown fraction. Removal of solvents under
vacuum from this fraction gave 0.028 g of compound 7 containing
variable amounts of [Mo2RuCp2(μ3-OCH3)(μ-PCy2)(CO)5] (8d).
Further purification was achieved by the slow diffusion of petro-
leum ether into a toluene solution of the impure product at 253 K,
this yielding compound 7 as black crystals suitable for X-ray
diffraction (0.020 g, 69%). Spectroscopic data for 7: Anal. Calcd
for C28H33Mo2O5PRu: C, 43.48; H, 4.30. Found: C, 43.30; H,
4.19. 1H NMR (300.13 MHz): δ 13.59 (s, 1H, CH), 5.15 (s, 10H,
Cp), 2.77-0.86 (m, 22H, Cy). 13C{1H} NMR (75.48 MHz): δ
270.6 (d, JCP = 2, CH), 256.8 (d, JCP = 7, 2MoCO), 201.9 (s,
Preparation of [FeMo2Cp2(μ-CCH3)(μ-PCy2)(O)(CO)4] (10).
A toluene solution (3 mL) of compound 9 (0.020 g, 0.026 mmol)
was irradiated in a Pyrex Schlenk tube with visible-UV light
under a gentle N2 (99.9995%) purge for 30 min to give an orange
solution. The solvent was then removed under vacuum, and the
residue was dissolved in a minimum of dichloromethane and
chromatographed through an alumina column (activity IV) at
288 K. Elution with dichloromethane-petroleum ether (1:5)
yielded a pink fraction. Removal of solvents under vacuum from
the latter fraction gave compound 10 as a pink microcrystalline
solid (0.015 g, 84%). The crystals used in the X-ray study were
grown by the slow evaporation of a concentrated petroleum
ether solution of the complex at room temperature. Anal. Calcd
for C28H35FeMo2O5P: C, 46.05; H, 4.83. Found: C, 46.25; H,
5.15. 1H NMR (300.13 MHz): δ 5.91 (s, 5H, Cp), 5.54 (d, JPH
=
3RuCO), 89.4 (s, Cp), 48.0 [d, JCP = 23, C1(Cy)], 43.8 [d, JCP
=
15, C1(Cy)], 34.2, 32.7 [2s, C2(Cy)], 28.2 [d, JCP = 12, 2C3(Cy)],
26.8, 26.6 [2s, C4(Cy)]. Spectroscopicdata for 8d: 1H NMR (300.13
MHz): δ 5.19 (s, 10H, Cp), 3.56 (s, 3H, OCH3), 2.77-0.86
1, 5H, Cp), 2.86 (d, JPH = 1, 3H, Me), 2.57-0.45 (m, 22H, Cy).
13C{1H} NMR (75.48 MHz): δ 401.5 (d, JCP = 5, CMe), 241.4
(d, JCP = 8, MoCO), 218.1 (s, 3FeCO), 102.5, 91.0 (2s, Cp), 46.8
[d, JCP = 20, C1(Cy)], 46.7 (s, CH3), 39.8 [d, JCP = 13, C1(Cy)],
34.5 [s, C2(Cy)], 34.1 [d, JCP = 3, C2(Cy)], 32.6 [d, JCP = 5,
C2(Cy)], 29.5 [d, JCP = 3, C2(Cy)], 28.2 [d, JCP = 10, C3(Cy)],
28.1 [d, JCP = 14, C3(Cy)], 27.7 [d, JCP = 10, C3(Cy)], 27.4 [d,
JCP = 14, C3(Cy)], 26.5, 26.1 [2s, C4(Cy)].
(m, 22H, Cy). 13C{1H} NMR (75.48 MHz): δ 255.6 (d, JCP
=
7, 2MoCO), 202.4 (s, 3RuCO), 90.8 (s, Cp), 47.3 [d, JCP = 23,
C1(Cy)], 42.5 [d, JCP = 16, C1(Cy)], 32.5, 32.0 [2s, C2(Cy)]; other
resonances were obscured by those of the major reaction
product.
Preparation of [FeMo2Cp2(μ3-OCH3)(μ-PCy2)(CO)5] (8e).
Solid [Fe2(CO)9] (0.031 g, 0.085 mmol) was added to a toluene
solution (4 mL) of compound 2, prepared in situ from compound
1 (0.025 g, 0.042 mmol), and the mixture was stirred for 1 h to give
a brown solution. The solvent was then removed under vacuum,
and the residue was dissolved in a minimum of dichloromethane
and chromatographed through an alumina column (activity IV) at
288 K. Elution with dichloromethane-petroleum ether (1:6)
yielded an orange fraction. Removal of solvents under vacuum
from this fraction gave compound 8e as a brown microcrystalline
solid (0.015 g, 48%). The crystals used in the X-ray study were
grown by slow diffusion of petroleum ether into a dichloro-
methane solution of the complex at 253 K. Anal. Calcd for
C28H35FeMo2O6P: C, 45.06; H, 4.72. Found: C, 45.13; H, 4.67.
1H NMR (300.13 MHz): δ 5.16 (d, JPH = 1, 10H, Cp), 3.65 (s, 3H,
OMe), 2.72-0.78 (m, 22H, Cy).
Preparation of [Fe2Mo2Cp2(μ4-CH)(μ-PCy2)(CO)8] (11). A
toluene solution (4 mL) of compound 1 (0.025 g, 0.042 mmol) and
[Fe2(CO)9] (0.020 g, 0.127 mmol) was irradiated in a Pyrex Schlenk
tube with visible-UV light under a gentle N2 (99.9995%) purge
for 3.5 h to give a greenish-brown solution, which was filtered
using a canula. The solvent was then removed under vacuum, and
the residue was dissolved in a minimum of dichloromethane and
chromatographed through an alumina column (activity IV) at
288 K. Elution with dichloromethane-petroleum ether (1:5)
yielded a greenish-brown fraction. Removal of solvents under
vacuum from this fraction gave compound 11 as a greenish-
brown microcrystalline solid (0.025 g, 68%). Elution with dichlor-
omethane-petroleum ether (1:5) yielded an orange fraction.
Removal of solvents under vacuum from the latter fraction gave
ca. 0.008 g of a mixture of compound 10 and [FeMo2Cp2(μ3-
CH)(μ-PCy2)(CO)5] (12) in variable amounts. The crystals used
in the X-ray study of compound 11 were grown by the slow
diffusion of petroleum ether into a toluene solution of the
complex at 253 K. Spectroscopic data for 11: Anal. Calcd for
C31H33Fe2Mo2O8P: C, 42.89; H, 3.83. Found: C, 42.51; H, 3.97.
1H NMR: δ 5.46, 5.00 (2s, 2 ꢀ 5H, Cp), 4.24 (d, JPH = 2, 1H,
Preparation of [FeMo2Cp2{μ3-K1:η2:K1-C(O)CH3}(μ-PCy2)-
(CO)5] (9). A toluene solution (8 mL) of compound 1 (0.050 g,
0.085 mmol) was stirred at room temperature for 16 h while
adding solid [Fe2(CO)9] (0.031 g, 0.085 mmol) every two hours
to give an orange solution. The solvent was then removed under
vacuum, and the residue was dissolved in a minimum of
dichloromethane and chromatographed through an alumina
column (activity IV) at 288 K. Elution with dichloromethane-
petroleum ether (1:5) yielded an orange fraction. Removal of
solvents under vacuum from this fraction gave compound 9 as
an orange microcrystalline solid (0.054 g, 84%). The crystals
used in the X-ray study were grown by slow diffusion of
petroleum ether into a toluene solution of the complex at 253
K. Anal. Calcd for C29H35FeMo2O6: C, 45.93; H, 4.65. Found:
C, 45.77; H, 4.57. ν(CO) (Nujol): 1990 (vs), 1934 (s), 1889 (s),
1800 (w), 1575 (w). 1H NMR: δ 5.17 (d, JPH = 1, 10H, Cp), 2.39
(s, 3H, Me), 2.34-0.98 (m, 22H, Cy). 1H NMR (248 K): δ 5.26,
5.16 (2s, 2 ꢀ 5H, Cp), 3.38 (s, 3H, Me), 2.34-0.98 (m, 22H, Cy).
13C{1H} NMR: δ 251.2 (s, br, 2MoCO), 216.5 (s, br, 3FeCO),
199.9 [s, C(O)Me], 91.0 (s, Cp), 45.9 [d, JCP = 21, C1(Cy)], 40.8
[s, C1(Cy)], 40.0 (s, CH3), 33.4, 31.9 [2s, C2(Cy)], 28.3, 27.8 [2d,
JCP = 11, C3(Cy)], 26.6, 26.4 [2s, C4(Cy)]. 13C{1H} NMR (248
K): δ 253.2 (s, MoCO), 251.0 (d, JCP = 10, MoCO), 199.7 [s,
C(O)Me], 93.2, 89.0 (2s, Cp), 45.3 [d, JCP = 21, C1(Cy)], 40.2 [d,
JCP = 6, C1(Cy)], 40.1 (s, CH3), 33.8, 32.5, 32.4, 30.5 [4s,
CH), 2.18-0.83 (m, 22H, Cy). 13C{1H} NMR: δ 243.8 (d, JCP
=
14, MoCO), 239.4 (d, JCP = 12, MoCO), 234.3 (d, JCP = 11,
CH), 215.1 (s, 6FeCO), 92.4, 91.1 (2s, Cp), 50.0 [d, JCP = 17,
C1(Cy)], 44.6 [d, JCP = 10, C1(Cy)], 34.4 [d, JCP = 4, C2(Cy)],
32.9 [d, JCP = 3, C2(Cy)], 32.4 [d, JCP = 4, C2(Cy)], 31.6 [s,
C2(Cy)], 28.8 [d, JCP = 11, C3(Cy)], 28.2 [d, JCP = 10, C3(Cy)],
28.0 [d, JCP = 12, C3(Cy)], 27.1 [d, JCP = 11, C3(Cy)], 26.5 [s,
2C4(Cy)]. 13C{1H} NMR (213 K): δ 243.9 (d, JCP = 19, MoCO),
240.0 (d, JCP = 14, MoCO) 232.6 (d, JCP = 13, CH), 225.2, 224.0,
217.3 (3s, FeCO), 215.5 (s, 2FeCO), 213.8 (s, FeCO), 92.3, 90.8
(2s, Cp), 48.8[d, JCP =17, C1(Cy)], 43.0[s, br, C1(Cy)], 33.8, 33.4,
31.3, 30.7 [4s, C2(Cy)], 28.5 [d, JCP = 11, C3(Cy)], 27.7 [d, JCP
=
15, C3(Cy)], 27.6 [d, JCP = 16, C3(Cy)], 26.5 [d, JCP = 13,
C3(Cy)], 26.2, 26.1 [2s, C4(Cy)]. 13C NMR: δ 234.3 (d, JCH = 143,
CH). Spectroscopic data for 12: 1H NMR (300.13 MHz, CDCl3):
δ 15.47 (s, 1H, CH), 5.73, 5.52 (2s, 2 ꢀ 5H, Cp), 2.55-0.52 (m,
22H, Cy). 13C{1H} NMR: δ 330.1 (d, JCP = 7, CH), 241.1 (s,
MoCO), 232.0 (s, MoCO), 229.2 (s, FeCO), 223.8, 213.4 (2s, br,
2FeCO), 93.4, 92.7 (2s, Cp), 46.1 [d, JCP = 18, C1(Cy)], 45.8 [d,
J
CP = 11, C1(Cy)], 33.5 [d, JCP = 2, C2(Cy)], 32.9, 32.6, 31.9 [3s,

916 Organometallics, Vol. 29, No. 4, 2010
Alvarez et al.
Table 8. Crystal Data for New Compounds
3b
6 2CH2Cl2
3
7
8e
9
10
mol formula
C
30H33Mo2-
O7PW
C
35H44Cl4-
MnMo2O4P
C
28H33Mo2-
O5PRu
C
28H35-
FeMo2O6P
C29H35-
FeMo2O6P
C
28H35-
FeMo2O5P
mol wt
cryst syst
space group
912.26
monoclinic
P21/c
0.71073
10.0848(3)
15.5653(3)
19.2321(6)
90
95.862(1)
90
3003.13(14)
4
2.018
4.742
100(2)
2.13-25.24
-11, 11; 0,
18; 0, 23
27 503
948.29
773.46
triclinic
P1
0.71073
9.8055(2)
10.1325(3)
15.6350(4)
92.550(2)
90.460(2)
116.682(1)
1385.93(6)
2
1.853
1.523
100(2)
1.3-25.24
-11, 11; -12,
12; 0, 18
19 070
746.26
758.27
730.26
monoclinic
P21/c
1.54184
14.1100(2)
15.5049(1)
17.9623(2)
90
111.979(1)
90
3644.08(7)
4
1.728
11.749
100(2)
3.38-73.87
-17, 16; -18,
16; -19, 21
19 519
monoclinic
P21/c
0.71073
9.7313(3)
20.2819(7)
16.6023(6)
90
118.749(1)
90
2872.87(17)
4
1.725
1.453
100(2)
2.33-25.24
-11, 11; -24,
0; -19, 10
5629
monoclinic
P21/c
0.71073
10.2670(2)
18.5240(4)
15.1115(4)
90
91.566(1)
90
2872.92(11)
4
1.753
1.455
100(2)
2.27-25.24
-12, 12; 0,
22; 0, 18
22 464
monoclinic
P21/c
0.71073
8.4495(2)
16.7274(2)
20.1560(4)
90
100.350(1)
90
2802.46(9)
4
1.731
1.485
100(2)
1.59-25.24
-10, 9; 0,
20; 0, 24
20 196
˚
radiation (λ, A)
˚
a, A
˚
b, A
˚
c, A
R, deg
β, deg
γ, deg
3
˚
V, A
Z
calcd density, g cm-3
absorp coeff, mm-1
temperature, K
θ range (deg)
index ranges (h, k, l)
no. of reflns collected
no. of indep reflns (Rint
reflns with I > 2σ(I)
)
5267(0.0575)
4371
6984(0.0347)
5871
4980(0.0248)
4189
5061(0.0581)
3533
5181(0.0493)
3860
5061(0.0320)
4416
R indexes [data with I > 2σ(I)]a
R indexes (all data)a
R1 = 0.0522
wR2 = 0.1416b
R1 = 0.0666
wR2 = 0.1637b
1.217
R1 = 0.044
wR2 = 0.117c
R1 = 0.0559
wR2 = 0.1283c
1.076
1/429
0.948, -1.181
P
R1 = 0.0471
wR2 = 0.1316d
R1 = 0.0581
wR2 = 0.1537d
1.236
1/338
2.412, -2.082
R1 = 0.0735
wR2 = 0.1902e
R1 = 0.1064
wR2 = 0.2239e
1.121
0/344
1.622, -1.649
R1 = 0.0393
wR2 = 0.0967f
R1 = 0.0621
wR2 = 0.1115f
1.134
0/353
0.843, -0.856
R1 = 0.0317
wR2 = 0.0884g
R1 = 0.0386
wR2 = 0.1068g
1.276
0/335
1.068, -1.483
GOF
no. of restraints/params
ΔF(max., min.), e A
0/374
2.792, -2.674
P
-3
˚
P
P
aR =
Fo| - |Fc /
|Fo|. wR = [ w(|Fo|2 - |Fc|2)2/ w|Fo|2]1/2. w = 1/[σ2(Fo2) þ (aP)2 þ bP] where P = (Fo þ 2Fc2)/3. b a = 0.0741, b = 46.0162.
2
c a = 0.0512, b = 26.8266. d a = 0.0843, b = 4.6921. e a = 0.0993, b = 28.3430. f a = 0.0561, b = 1.7199. g a = 0.0607, b = 1.6420.
C2(Cy)], 28.3 [d, JCP = 12, C3(Cy)], 28.1 [d, JCP = 11, C3(Cy)],
X-ray Structure Determination of Compound 6. Data collec-
tion was performed on an Oxford Diffraction Xcalibur Nova
single-crystal diffractometer, using Cu KR radiation. Images
were collected at a 65 mm fixed crystal-detector distance, using
the oscillation method, with 1° oscillation and variable exposure
time per image (2-8 s). Data collection strategy was calculated
with the program CrysAlis Pro CCD.54 Data reduction and cell
refinement were performed with the program CrysAlis Pro
RED.54 An empirical absorption correction was applied using
the SCALE3 ABSPACK algorithm as implemented in the pro-
gram CrysAlis Pro RED.54 Using the program suite WinGX,52
the structure was solved by Patterson interpretation and phase
expansion and refined with full-matrix least-squares on F2 using
SHELXL97.53 This compound was found to crystallize with two
molecules of dichloromethane. All non-hydrogen atoms were
refined anisotropically. All hydrogen atoms were geometrically
placed, except the methylidyne hydrogen H(5), which was located
in the Fourier maps andrefinedwitha restraint on the C-H bond
27.5 [d, JCP = 10, 2C3(Cy)], 26.5, 26.4 [2s, C4(Cy)].
X-ray Structure Determination of Compounds 3b, 7, 8e, 9, and
10. Data collection for these compounds was performed on a
Nonius Kappa CCD single diffractometer, using graphite-
monochromated Mo KR radiation. Images were collected at
29 to 65 mm fixed crystal-detector distance, using the oscil-
lation method, with 1° to 1.7° oscillation and 2 to 120 s
exposure time per image, depending on the particular com-
pound. Data collection strategy was calculated with the
program Collect.49 Data reduction and cell refinements were
performed with the programs HKL Denzo and Scalepack.50
Semiempirical absorption corrections were applied using the
program SORTAV.51 Using the program suite WinGX,52 the
structures were solved by Patterson interpretation and phase
expansion and refined with full-matrix least-squares on F2
with SHELXL97.53 All non-hydrogen atoms were refined
anisotropically. All hydrogen atoms were geometrically
placed, except the methylidyne hydrogen in compounds 3b
and 7, which were located in the Fourier maps and refined.
They all were given an overall isotropic thermal parameter. A
˚
length (0.95(2) A). All hydrogen atoms were given an overall
isotropic thermal parameter. Further details of the datacollection
and refinements are given in Table 8.
˚
restraint on the methylidyne C-H bond length (0.95(2) A)
had to be applied for 7; in that case, the largest residual
electron density was located around the ruthenium atom.
Further details of the data collection and refinements are
given in Table 8.
Acknowledgment. We thank the DGI of Spain for
financial support (project CTQ2006-01207/BQU).
Supporting Information Available: A CIF file giving the
crystallographic data for the structural analysis of compounds
3b, 6, 7, 8e, 9, and 10. This material is available free of charge via
the Internet at http://pubs.acs.org.
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