Reactivity of the unsaturated hydride [Mo2(η5- C5H5)2(μ-H)(μ-PCy2)(CO) 2] toward 17- and 16-electron metal carbonyl fragments: Rational synthesis of electron-deficient heterometallic clusters

Article abstract of DOI:10.1021/om060826v

Reactions of the 30-electron hydride [Mo₂Cp₂(μ-H) (μ-PCy₂)(CO)₂] (Cp = η⁵-C ₅H₅) with the 17-electron-fragment precursors [M ₂Cp₂(CO)_n] (M = Mo, W, n = 6; M = Ru, n = 4) or [Mn₂(CO)₁₀] lead to the 46-electron clusters [Mo ₂MCp₃(μ-PCy₂)(μ₃-CO)(CO) ₄] (M = Mo, W), [Mo₂RuCp₃(μ-PCy ₂)(μ-CO)(CO)₃], and [MnMo₂Cp ₂(μ-PCy₂)(μ-CO)₂(CO)₅]. The structure of the trimolybdenum cluster was confirmed by an X-ray diffraction study and displays two long (ca. 3.1 A) and one short Mo-Mo distance (2.743(1) A). The title unsaturated hydride also proved to be highly reactive toward the appropriate precursors of 16-electron fragments such as M(CO) ₅ (M = Cr, Mo, W) and MnCp′(CO)₂ (Cp′ = η⁵-C₅H₄CH₃), then leading to the 46-electron hydride clusters [MMo₂Cp₂(μ₃-H) (μ-PCy₂)(CO)₇] (M = Cr, Mo, W) and [MnMo ₂Cp₂Cp′(μ₃-H)(μ-PCy ₂)(CO)₄]. The structures of the compounds having Mo ₂W and Mo₂Mn skeletons were also determined by X-ray diffraction methods, both of them displaying Mo-Mo distances (ca. 2.6 A) somewhat shorter than expected for double Mo=Mo bonds and Mo - M distances longer than the corresponding single-bond lengths. A similar reaction takes place with the 12-electron compound CuCl, to give the hydride [CuMo ₂ClCp₂(μ₃-H)(μ-PCy₂)(CO) ₂]. In contrast, the reaction of the title hydride with [Fe ₂(CO)₉], a precursor of the 16-electron fragment Fe(CO)₄, gives the heterodinuclear complex [FeMo(μ-PCy ₂)(CO)₆] (Fe - Mo = 2.931(1) A).

Full text of DOI:10.1021/om060826v

Organometallics 2007, 26, 321-331
321
Reactivity of the Unsaturated Hydride
[Mo2(η5-C5H5)2(µ-H)(µ-PCy2)(CO)2] toward 17- and 16-Electron
Metal Carbonyl Fragments: Rational Synthesis of
Electron-Deficient Heterometallic Clusters
Celedonio M. Alvarez,† M. Angeles Alvarez,† M. Esther Garc´ıa,† Alberto Ramos,†
Miguel A. Ruiz,*,† Claudia Graiff,‡ and Antonio Tiripicchio‡
Departamento de Qu´ımica Orga´nica e Inorga´nica/IUQOEM, UniVersidad de OViedo, E-33071 OViedo,
Spain, and Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica,
UniVersita` di Parma, Parco Area delle Science 17/A, I-43100 Parma, Italy
ReceiVed September 9, 2006
Reactions of the 30-electron hydride [Mo2Cp2(µ-H)(µ-PCy2)(CO)2] (Cp ) η5-C5H5) with the 17-electron-
fragment precursors [M2Cp2(CO)n] (M ) Mo, W, n ) 6; M ) Ru, n ) 4) or [Mn2(CO)10] lead to the
46-electron clusters [Mo2MCp3(µ-PCy2)(µ3-CO)(CO)4] (M ) Mo, W), [Mo2RuCp3(µ-PCy2)(µ-CO)(CO)3],
and [MnMo2Cp2(µ-PCy2)(µ-CO)2(CO)5]. The structure of the trimolybdenum cluster was confirmed by
an X-ray diffraction study and displays two long (ca. 3.1 Å) and one short Mo-Mo distance (2.743(1)
Å). The title unsaturated hydride also proved to be highly reactive toward the appropriate precursors of
16-electron fragments such as M(CO)5 (M ) Cr, Mo, W) and MnCp′(CO)2 (Cp′ ) η5-C5H4CH3), then
leading to the 46-electron hydride clusters [MMo2Cp2(µ3-H)(µ-PCy2)(CO)7] (M ) Cr, Mo, W) and
[MnMo2Cp2Cp′(µ3-H)(µ-PCy2)(CO)4]. The structures of the compounds having Mo2W and Mo2Mn
skeletons were also determined by X-ray diffraction methods, both of them displaying Mo-Mo distances
(ca. 2.6 Å) somewhat shorter than expected for double ModMo bonds and Mo-M distances longer than
the corresponding single-bond lengths. A similar reaction takes place with the 12-electron compound
CuCl, to give the hydride [CuMo2ClCp2(µ3-H)(µ-PCy2)(CO)2]. In contrast, the reaction of the title hydride
with [Fe2(CO)9], a precursor of the 16-electron fragment Fe(CO)4, gives the heterodinuclear complex
[FeMo(µ-PCy2)(CO)6] (Fe-Mo ) 2.931(1) Å).
+ 2
either CH2 or CH3
)
to obtain trinuclear clusters.3 These
Introduction
hydrides are also reactive toward [Au(PPh3)]+ 4 (a fragment
isolobal to H+)5 and other group 11 and 12 compounds, such
as CuX (X ) halogen),6 Zn(Hg),6 or [M(CtCPh)] (M ) Au,
Cu, Ag),7 thus allowing the synthesis of different trinuclear (M
) Au, Ag, Zn), pentanuclear (M ) Au), or hexanuclear (M )
Cu, Ag) Mn2Mx clusters. Extensive studies have also been
carried out with the isoelectronic dirhenium complex [Re2(µ-
H)2(CO)8], which reacts easily with different transition-metal
complexes such as the metal carbonyl anions [M(CO)x]- (M )
Mn, Re, Ir; x ) 4, 5)8 and [Re2H(CO)9]- 8a,9 or the neutral late
transition-metal compounds [Pt(PPh3)2(C2H4)],10 [Pt(COD)2],11
In our preliminary exploration of the reactivity of the triply
bonded hydride [Mo2Cp2(µ-H)(µ-PCy2)(CO)2] (1) we noticed
the ability of this unsaturated species to incorporate the 16-
electron fragment MnCp′(CO)2, as well as the 17-electron
fragment MoCp(CO)3, this suggesting the opportunity to develop
rational synthetic methods to prepare electron-deficient hetero-
metallic clusters that might be difficult or impossible to prepare
through more conventional preparative procedures.1 Several
rational methods for the synthesis of heterometallic clusters have
been developed during the last three decades, some of them
inspired by the isolobal relationships existing between metal
fragments and organic molecules.2 However, the high reactivity
of unsaturated hydride-bridged compounds has not been fully
exploited for this purpose. Among these substrates, only a few
complexes having doubly bonded M2(µ-H)2 cores (M ) Mn,
Re, Os) have been studied in detail. For example, we have
analyzed the reactions of the 32-electron dimanganese hydrides
[Mn2(µ-H)2(CO)6(µ-L2)] (L2 ) (EtO)2POP(OEt)2, Ph2PCH2-
PPh2) toward the appropriate precursors of 16-electron fragments
such as Fe(CO)4 and M(CO)5 (M ) Cr, Mo, W) (isolobal to
(3) Carren˜o, R.; Riera, V.; Ruiz, M. A.; Bois, C.; Jeannin, Y. Organo-
metallics 1992, 11, 4022.
(4) Carren˜o, R.; Riera, V.; Ruiz, M. A.; Bois, C.; Jeannin, Y. Organo-
metallics 1992, 11, 2923.
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171.
(6) Riera, V.; Ruiz, M. A.; Tiripicchio, A.; Tiripicchio-Camellini, M.
Organometallics 1993, 12, 2962.
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Tiripicchio-Camellini, M. Organometallics 1994, 13, 993.
(8) (a) D’Alfonso, G. Chem.-Eur. J. 2000, 6, 209. (b) Beringhelli, T.;
Ciani, G.; D’Alfonso, G.; Garlaschelli, L.; Moret, M.; Sironi, A. J. Chem.
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D’Alfonso, G.; Ciani, G.; Moret, M.; Sironi, A. Organometallics 1996, 15,
3876.
* Author to whom correspondence should be addressed: E-mail:
mara@uniovi.es.
† Universidad de Oviedo.
‡ Universita` di Parma.
(1) Alvarez, C. M.; Alvarez, M. A.; Garc´ıa, M. E.; Ramos, A.; Ruiz, M.
A.; Lanfranchi, M.; Tiripicchio, A. Organometallics 2005, 24, 7.
(2) (a) Hoffmann, R. Angew. Chem., Int. Ed. Engl. 1982, 21, 711. (b)
Stone, F. G. A. Angew. Chem., Int. Ed. Engl. 1984, 23, 89.
(9) Bergamo, M.; Beringhelli, T.; D’Alfonso, G.; Mercandelli, P.; Moret,
M.; Sironi, A. Organometallics 1997, 16, 4129.
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10.1021/om060826v CCC: $37.00 © 2007 American Chemical Society
Publication on Web 12/15/2006

322 Organometallics, Vol. 26, No. 2, 2007
AlVarez et al.
or [Ir(CO)(η5-C9H7)(η2-C8H14)],12 to give new tri- or tetranuclear
clusters. Finally, the reactivity of the triosmium dihydride [Os3-
(µ-H)2(CO)10] toward organometallic fragments has been also
widely studied, allowing the synthesis of heterometallic clusters
with higher nuclearity and incorporating transition-metal atoms
from groups 6,13,14 8,15-17 9,18-20 10,19a,21 11,19a,22 and 12.23
During the last decades, organometallic clusters have had an
important role in chemistry, not only because of their singular
bonding and structures but also because of their potential
application in homogeneous catalysis (as catalysts or precursors)
and heterogeneous catalysis (anchored to solid supports) or in
the synthesis of homo- and heterometallic nanoparticles.24 Yet,
the synthesis of these species is not a matter completely solved,
and the implementation of new rational synthetic procedures
remains a valuable target. In this sense, the high reactivity of
the 30-electron hydride 1 provided us with an excellent
opportunity to explore synthetic routes for new heterometallic
clusters having molybdenum and other transition or post-
transition metals. In this paper we report our full results on the
use of 1 as a precursor of such species. Two main synthetic
routes have been developed. In one of them, the hydride ligand
in 1 is replaced by a 17-electron metal fragment, which is
generated in situ through the homolytic cleavage of a metal-
metal bond. In the second one, a 16-electron metal fragment
just adds to the multiple bond present in 1 (a similar result is
obtained using 12-electron fragments such as CuCl or [Au-
(PPh3)]+). In all cases, electron-deficient trinuclear clusters are
formed.
Chart 1
the unsaturated hydride 1, such as the cyclopentadienyl dimers
[M2Cp2(CO)n] (M ) Mo, W, n ) 6; M ) Fe, Ru, n ) 4) or the
carbonyl dimers [M2(CO)n] (M ) Mn, Re, n ) 10; M ) Co, n
) 8). Except for the cobalt complex, no reaction occurred in
the absence of light, even in refluxing toluene (ca. 383 K).
However, rapid reactions took place under visible or UV
irradiation. It is well known that the dimers [M2Cp2(CO)6] (M
) Mo, W) undergo homolytic cleavage of the metal-metal bond
under photochemical conditions. This process competes with
decarbonylation and is favored, in relative terms, when irradiat-
ing with visible rather than UV light.25a,b A similar effect is
observed for the binary carbonyls [M2(CO)n].25a,c Therefore, it
seems that the homolytic cleavage of the metal-metal bond in
these substrates is the critical step for the reaction to proceed,
a matter that will be discussed later on.
Compound 1 reacts slowly at 288 K with [Mo2Cp2(CO)6]
upon exposure to visible light to give the trimolybdenum cluster
[Mo3Cp3(µ-PCy2)(µ3-CO)(CO)4] (2a) in good yield after 5 h.
Compound 1 reacts similarly with [W2Cp2(CO)6] to give a
mixture of the heterometallic clusters of formula [Mo2WCp3-
(µ-PCy2)(µ3-CO)(CO)4] (2b, 2c) (Chart 1 and Scheme 1).
Isomers 2b and 2c differ in the position of the dicyclohexyl-
phosphide bridge on the Mo2W metal skeleton and are obtained
in a equilibrium ratio showing only a modest dependence on
the solvent (see Experimental Section).
Compound 1 is also reactive toward metal-metal bonded
binary carbonyls, but most of the products obtained were rather
unstable and could not be properly purified and characterized.
The reaction with [Co2(CO)8] proceeds at room temperature in
the absence of light, but no heterometallic cluster could be
identified in the complex mixture of unstable products formed.
The reaction of 1 with [Re2(CO)10] required visible-UV
irradiation to proceed, but it was more selective. Unfortunately,
it led to a mixture of several Mo2Re clusters that could not be
properly characterized due to decomposition during attempts
of purification (chromatography, crystallization). In contrast, the
Results and Discussion
Incorporation of 17-Electron Metal Fragments. Several
precursors of 17-electron metal fragments were reacted with
(11) (a) Ciani, G.; Moret, M.; Sironi, A.; Antognazza, P.; Beringhelli,
T.; D’Alfonso, G.; Della Pergola, R.; Minoja, A. J. Chem. Soc., Chem.
Commun. 1991, 1255. (b) Antognazza, P. Beringhelli, T.; D’Alfonso, G.;
Minoja, A.; Ciani, G.; Moret, M.; Sironi, A. Organometallics 1992, 11,
1777.
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J. R. Inorg. Chem. 1997, 36, 4397.
(13) Park, J. T.; Cho, J. J.; Chun, K. M.; Yun, S. S. J. Organomet. Chem.
1992, 433, 295.
(14) Chi, Y.; Shapley, J. R.; Churchill, M. R.; Li, Y. J. Inorg. Chem.
1986, 25, 4165.
(15) Plotkin, J. S.; Alway, D. G.; Weisenberger, C. R.; Shore, S. G. J.
Am. Chem. Soc. 1980, 102, 6156.
(16) Pereira, L.; Leong, W. K.; Wong, S. Y. J. Organomet. Chem. 2000,
609, 104.
(17) Martin, L. R.; Einstein, F. W. B.; Pomeroy, R. K. Organometallics
1988, 7, 294.
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1989, 25, 195.
(19) (a) Farrugia, L. J.; Howard, J. A. K.; Mitrprachachon, P.; Spencer,
J. L.; Stone, F. G. A.; Woodward, P. J. Chem. Soc., Chem. Commun. 1978,
260. (b) Jan, D. Y.; Hsu, L. Y.; Hsu, W. L.; Shore, S. G. Organometallics
1987, 6, 274. (c) Colombie, A., McCarthy, D. A.; Krause, J.; Hsu, L. Y.;
Hsu, W. L.; Jan, D. Y.; Shore, S. G. J. Organomet. Chem. 1990, 383, 421.
(d) Yeuk-Wah, Hung, S.; Wong, W.-T. J. Organomet. Chem. 1998, 566,
237.
(20) (a) Hsu, L. Y.; Hsu, W. L.; McCarthy, D. A.; Krause, J. A.; Chung,
J. H.; Shore, S. G. J. Organomet. Chem. 1992, 426, 121. (b) Srinivasan,
P.; Leong, W. K. J. Organomet. Chem. 2006, 691, 403.
(21) (a) Farrugia, L. J.; Howard, J. A. K.; Mitrprachachon, P.; Stone, F.
G. A.; Woodward, P. J. Chem. Soc., Dalton Trans. 1981, 155. (b) Noren,
B.; Sundberg, P. J. Chem. Soc., Dalton Trans. 1987, 3103.
(22) Bruce, M. I.; Horn, E.; Matisons, J. G.; Snow, M. R. J. Organomet.
Chem. 1985, 286, 271.
(23) Au, Y.-K.; Wong, W.-T. J. Chem. Soc., Dalton Trans. 1996, 899.
(24) See for example: (a) Shriver, D. F.; Kaesz, H. D.; Adams, R. D.
The Chemistry of Metal Cluster Complexes; VCH: Weinheim, Germany,
1990. (b) Adams, R. D.; Cotton, F. A. Catalysis by Di- and Polynuclear
Metal Complexes; Wiley-VCH: New York, 1998. (c) Braunstein, P.; Oro,
L. A.; Raithby, P. R. Metal Clusters in Chemistry; Wiley-VCH: Weinheim,
Germany, 1999; Vols. 1 and 2.
(25) (a) Geoffroy, G. L.; Wrighton, M. S. Organometallic Photochem-
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Chem. Soc. 1993, 115, 107, and references therein.

ReactiVity of [Mo2(η5-C5H5)2(µ-H)(µ-PCy2)(CO)2]
Organometallics, Vol. 26, No. 2, 2007 323
Scheme 1. Reaction Pathway Proposed for the Formation
of Compounds 2
Figure 1. ORTEP diagram (30% probability) of compound 2a,1
with H atoms and Cy rings omitted for clarity, except the C1 atoms.
Selected bond lenghts (Å): Mo(1)-Mo(2) 2.743(1); Mo(1)-Mo-
(3) 3.085(1); Mo(2)-Mo(3) 3.094(1); Mo(1)-P(1) 2.399(2); Mo-
(2)-P(1) 2.398(2); Mo(1)-C(3) 2.275(6); Mo(2)-C(3) 2.197(6);
Mo(3)-C(3) 2.042(6).
reaction with [Mn2(CO)10] under the same conditions gave
almost quantitatively the manganese-molybdenum cluster
[MnMo2Cp2(µ-PCy2)(µ-CO)2(CO)5] (3) after 10 min. This
allowed the spectroscopic characterization of the product even
when it could not be isolated in a completely pure form nor
characterized through X-ray diffraction methods, due to its
progressive decomposition upon manipulation.
Mo3 plane, which implies a trans to cis rearrangement in the
hydride 1 upon reaction. The Mo(1)-Mo(3) and Mo(2)-Mo-
(3) distances, 3.085(1) and 3.094(1) Å, respectively, are in good
agreement with the presence of single Mo-Mo bonds, whereas
the Mo(1)-Mo(2) distance (2.743(1) Å) is significantly shorter
and close to the values found for double Mo-Mo bonds in
related systems (for example, 2.713(1) Å for the bis(diphe-
nylphosphide) complex [Mo2Cp2(µ-PPh2)2(CO)2]).27 So it seems
that the electronic unsaturation of the cluster is rather localized
on just a pair of metal atoms. Interestingly, a similar localization
effect occurs in the isolectronic cluster [Mo3Cp*3(µ2-H)(µ3-O)-
(CO)4],28 which appears to be the only other 46-electron Mo3
cluster structurally characterized so far, since it displays Mo-
Mo distances of 2.916(1), 2.917(1), and 2.660(1) Å. In the case
of 2a, the asymmetrically triply bridging carbonyl plays an
active role in defining the intermetallic separations. The
corresponding Mo-C distances are 2.275(6) [Mo(1)-C(3)],
2.197(6) [Mo(2)-C(3)], and 2.042(6) Å [Mo(3)-C(3)], so this
carbonyl can be viewed as involved in a normal (for a bridging
group) bond to the Mo(3) atom [the Mo(3)-C(3)-O(3) angle
is 139.9(5)°] and in weaker interactions (of semibridging type)
with the other two metal atoms. This implies an additional
electron transfer from the original MoCp(CO)3 moiety to the
unsaturated Mo2Cp2(µ-PCy2) fragment, in agreement with the
intermetallic separations. In the absence of such a bridging
carbonyl, the MoCp(CO)3 fragment would behave much as the
hydride ligand in 1 does, and then shorter Mo(1)-Mo(2) and
longer Mo-Mo(3) lengths would have been expected.
Iron and ruthenium cyclopentadienyl dimers [M2Cp2(CO)4]
also react with hydride 1 under photochemical conditions, but
with very different results. The reaction with the iron dimer
gave no detectable heterometallic cluster, but led instead to the
tetracarbonyl complex [Mo2Cp2(µ-H)(µ-PCy2)(CO)4]26 as the
only carbonyl-containing species. The latter compound is
obviously formed by reaction of the photogenerated CO with 1
(in fact, this electron-precise hydride is always obtained in
variable amounts as a side product in all photochemical reactions
here reported). In contrast, visible-UV irradiation of a toluene
solution of 1 and [Ru2Cp2(CO)4] for 10 min gives a mixture of
the heterometallic clusters of formula [Mo2RuCp3(µ-PCy2)(µ-
CO)(CO)3] (4a, 4b). As it was the case of the Mo2W clusters,
isomers 4a and 4b differ in the position of the dicyclohexy-
lphosphide bridge on the Mo2Ru metal skeleton (Chart 1). Even
though in this case two different brown fractions could be
separated upon chromatography in alumina (activity IV) at 253
Κ, the IR and NMR spectra of the resulting solutions at room
temperature (see below) proved them to have the same
composition, suggesting that fast isomerization occurs on the
laboratory time scale to reach an equilibrium ratio between
isomers, which is ca. 1:1 for these ruthenium clusters, with no
significant dependence on the solvent, as deduced from the
Spectroscopic data in solution for compounds 2a-c (Table
1 and Experimental Section) are essentially consistent with the
solid structure of 2a, but reveal the presence of dynamic
processes in solution. The IR spectra for 2a and that for the
mixture of 2b and 2c are similar and display five CO stretching
bands in CH2Cl2 in each case, as expected. The 31P spectra for
these clusters exhibit in each case singlet resonances with
1
integration of the H NMR spectra recorded in CDCl3, C6D6,
and (CD3)2CO solutions.
Solid State and Solution Structure of Compounds 2. The
structure of compound [Mo3Cp3(µ-PCy2)(µ3-CO)(CO)4] (2a)
was confirmed through a single-crystal X-ray diffraction study
and previously reported (Figure 1).1 The molecule displays two
MoCp(CO) groups and one MoCp(CO)2 moiety, all bound
together to form a Mo3 triangle, which is asymmetrically capped
by a carbonyl ligand. The MoCp(CO) fragments are bridged
by a dicyclohexylphosphide ligand and all three Cp ligands,
and the bridging carbonyls are placed on the same side of the
chemical shifts of 178.3 (2a), 170.9 (2b), and 143.5 (JPW
)
319 Hz) (2c). The relative shielding and the appearance of a
large 31P-183W coupling in the latter resonance is a clear
indication that the phosphide bridge in 2c is placed over the
(27) Adatia, T.; McPartlin, M.; Mays, M. J.; Morris, M. J.; Raithby, P.
R. J. Chem. Soc., Dalton Trans. 1989, 1555.
(26) Garc´ıa, M. E.; Riera, V.; Ruiz, M. A.; Rueda, M. T.; Sa´ez, D.
Organometallics 2002, 21, 5515.
(28) Gibson, C. P.; Rae, A. D.; Tomchick, D. R.; Dahl, L. F. J.
Organomet. Chem. 1988, 340, C23.

324 Organometallics, Vol. 26, No. 2, 2007
Table 1. Selected IRa and 31P{1H} NMRb Data for New Compounds
AlVarez et al.
compound
ν(CO)
δP
[Mo3Cp3(µ-PCy2)(µ3-CO)(CO)4] (2a)
1954 (vs), 1915 (m), 1890 (m),
1866 (m), 1814 (w)
1952 (vs), 1916 (m), 1885 (m),
1864 (m), 1808 (w)
2015 (m), 1946 (m, sh), 1926 (vs),
1842 (w), 1797 (w)
1956 (s), 1935 (s, sh), 1921 (s),
1891 (vs), 1812 (s), 1769 (vs)
2050 (m), 1931 (vs)g
178.3c (185.4, 150.2)d
[Mo2WCp3(µ-PCy2)(µ3-CO)(CO)4] (2b,c)
[MnMo2Cp2(µ-PCy2)(µ-CO)2(CO)5] (3)
[Mo2RuCp3(µ-PCy2)(µ-CO)(CO)3] (4a,b)
170.9e (2b) 143.5e [319],f (2c)
207.0c
224.1e (4a) 169.1e (4b)
[CrMo2Cp2(µ3-H)(µ-PCy2)(CO)7] (5a)
[Mo3Cp2(µ3-H)(µ-PCy2)(CO)7] (5b)
[Mo2WCp2(µ3-H)(µ-PCy2)(CO)7] (5c)
207.4e
208.4e
205.0
2062 (m), 1941 (vs), 1908 (m, sh)g
2058 (s), 1969 (w, sh), 1934 (vs),
1908 (m, sh), 1848 (w), 1832 (w, sh)
1915 (vs), 1875 (m, sh), 1851 (s),
1833 (m, sh)
2065 (s), 2009 (m), 1989 (vs),
1981 (s), 1934 (s), 1867 (s)i
1905 (m), 1850 (vs)
[MnMo2Cp2Cp′(µ3-H)(µ-PCy2)(CO)4] (6)
[FeMoCp(µ-PCy2)(CO)6] (7)
167.5h
199.1
230.8e
[CuMo2ClCp2(µ3-H)(µ-PCy2)(CO)2] (8)
b
a Recorded in dichloromethane solution, unless otherwise stated, ν in cm-1. Recorded in CD2Cl2 solutions at 290 K and 121.50 MHz, unless otherwise
c
d
e
f
stated, δ in ppm relative to external 85% aqueous H3PO4. In CDCl3 at 81.04 MHz. Isomer mixture at 193 K and 162.01 MHz (see text). In CDCl3. JPW
g
h
i
in Hz. The rest of the C-O stretching bands could not be assigned unambiguously. In C6D6. In petroleum ether.
Mo and W atoms. We note that the P-W coupling constant is
close to those found for the unsaturated compounds [W2Cp2-
(µ-PR2)2(CO)2],26 which exhibit similar coordination environ-
ments around the W and P atoms. The 1H NMR spectra for 2a
and 2b are in good agreement with the solid structure found
for 2a, both exhibiting two signals in a 2:1 ratio for the three
Cp ligands, consistent with the presence of a symmetry plane
making both MoCp(CO) fragments equivalent. In contrast, 2c
exhibits three different cyclopentadienyl resonances, since all
three metal fragments are now inequivalent. All the above data
are themselves consistent with the rigid structures based on the
crystal structure of 2a. However, the 13C{1H} NMR spectrum
of 2a recorded at room temperature is not consistent with that
structure, since it displays just one broad carbonyl resonance
at 256.3 ppm and four signals for the cyclohexyl carbon atoms,
while, according to the solid structure, there should be three
carbonyl and up to eight distinct cyclohexyl resonances present.
All this suggests the operation of dynamic processes in these
solutions, which proved to be due to the presence of two
interconverting isomers. Thus, on cooling a solution of 2a, its
31P{1H} NMR resonance at ca. 178 ppm first broadens and then
eventually splits into two different signals (185.4 ppm for isomer
A and 150.2 ppm for isomer B at 193 K, ratio A/B ) 1.7).
From the ill-defined coalescence point (Tc ca. 218 K) we can
estimate an average activation barrier of 36 ( 1 kJ mol-1, which
Scheme 2. Isomerization Equilibrium Proposed for
Compound 2a in Solution
also a generalized carbonyl scrambling results (not shown in
the scheme). Of course, in the absence of further data, we cannot
exclude other possibilities at present.
Reaction Pathways in the Formation of Compounds 2.
As stated above, no reaction between 1 and the cyclopentadienyl
dimers [M2Cp2(CO)6] occurs in the absence of light, even in
refluxing toluene. On the other hand, a separate experiment
proved that compound 1 does not experience any significant
change when irradiated with visible light. Thus, in light of the
known photochemistry of these dimers,25a,b it is reasonable to
propose that these reactions are initiated by the homolytic
cleavage of their single metal-metal bonds to yield the
corresponding 17-electron radicals [MCp(CO)3]•, which then
would rapidly add to the hydride 1 to yield a transient
paramagnetic cluster, which spontaneously would lose a hy-
drogen atom to afford the diamagnetic clusters 2a,b (Scheme
1). An NMR monitoring experiment carried out using C6D6 as
solvent revealed the essentially quantitative formation of [WH-
Cp(CO)3], identified by its characteristic proton resonances [δH
) -7.2 ppm, JHW ) 37 Hz; δCp ) 4.9 ppm]. This proves that
these reactions imply eventually the complete H atom transfer
from 1 to the photogenerated [MCp(CO)3]• radicals. The radical
attack on 1 would be facilitated by the presence of multiple
metal-metal bonding in this substrate, which provides it with
empty, low-lying antibonding orbitals not present in related
electron-precise complexes. Finally, in order to explain the
formation of 2c, we propose that, once formed, the dimolyb-
1
is a fairly low figure. Unfortunately, the H NMR spectra do
not exhibit informative changes over that temperature range,
apart from a general broadening of all resonances. In order to
explain the above spectroscopic observations, we propose the
operation in these solutions of a fast isomerization equilibrium
between two of the possible conformers for 2a. By considering
the large 31P chemical shift difference between these isomers
(ca. 35 ppm), we propose that only a cis/trans rearrangement at
the Mo2(µ-PCy2) center can account for such a large shift
difference (Scheme 2). Indeed, we have shown previously that
the unsaturated complex cis-[Mo2Cp2(µ-PPh2)(µ-PtBu2)(CO)2]26
displays a 31P shift some 40-50 ppm above that of its trans
isomer, thus allowing us to identify the major and more
deshielded isomer A as that one exhibiting a cis arrangement
around the Mo2(µ-PCy2) center, as found in the crystal. The
exchange between isomers A and B would possibly imply a
transition state whereby the µ3-CO ligand becomes edge-
bridging, then allowing the MoCp(CO)x fragments to rotate. In
this way, not only are the isomers A and B interconverted, but

ReactiVity of [Mo2(η5-C5H5)2(µ-H)(µ-PCy2)(CO)2]
Organometallics, Vol. 26, No. 2, 2007 325
Chart 2
denum-tungsten cluster 2b rearranges by exchanging CO and
PCy2 ligands between molybdenum and tungsten atoms to reach
a thermodynamic equilibrium between isomers 2b and 2c. Given
the almost identical atom sizes and covalent radii of the Mo
and W atoms, the relative amounts of these isomers are likely
to be governed by the relative strengths of the corresponding
M-C and W-P bonds.
Solution Structure of Compounds 3 and 4. Unfortunately,
no suitable crystals for X-ray diffraction could be grown for
either of these rather unstable compounds, so our structural
proposal for these species must be based on limited spectro-
scopic data recorded in solution. The IR spectrum of the MnMo2
cluster 3 displays five CO stretching bands, with the position
and high intensity of the band at highest frequency (2015 cm-1
)
being indicative of the presence of a facial Mn(CO)3 oscillator,29
then discarding the presence of a cis-Mn(CO)4 group, for which
the highest-frequency band appears typically in the range 2060-
2090 cm-1 29,30
On the other hand, the presence of low-
.
frequency bands (<1800 cm-1) suggests that there is at least
one bridging carbonyl in the molecule. In fact, we propose for
3 a structure with two bridging (or semibridging) CO ligands,
in order to fulfill the EAN formalism in an equilibrated way
(Chart 1). The proposal of the PCy2 ligand in 3 as bridging Mo
and Mn atoms is based on the fact that its 31P NMR resonance
appears at a relatively high chemical shift (207.0 ppm in C6D6)
and it is abnormally broad at room temperature. The latter is a
well-known effect caused by the quadrupolar 55Mn nucleus on
31P nuclei bonded to it, while there is also a general trend for
phosphide ligands to exhibit more deshielded 31P resonances
when bridging over lighter transition-metal atoms.31
previously, most of them are electron-precise species (48
electrons). In fact, we are only aware of another family of 46-
electron Mo2Ru species, these being the above-mentioned [Mo2-
RuCp2(µ3-CCH2R)(µ-PPh2)(CO)5] clusters (R ) H, Me).32
Incorporation of 16-Electron Metal Fragments. These
metal fragments can be generated in a number of ways, for
example, through either thermal or photochemical decarbony-
lation of suitable carbonyl complexes, by displacement of labile
ligands, etc. These well-established strategies have been used
to test the ability of the unsaturated hydride 1 to generate new
heterometallic clusters by addition of 16-electron fragments of
the groups 6, 7, and 8 metals to its multiple metal-metal bond,
in a process similar to the organic cyclopropanation reaction.2b
Compound 1 reacts rapidly with the group 6 hexacarbonyls
[M(CO)6] (M ) Cr, Mo, W) in toluene solution under visible-
UV irradiation to give the corresponding 46-electron clusters
[MMo2Cp2(µ3-H)(µ-PCy2)(CO)7] [M ) Cr (5a), Mo (5b), W
(5c)] (Chart 2), along with significant amounts of the tetracar-
bonyl complex [Mo2Cp2(µ-H)(µ-PCy2)(CO)4]26 as a side prod-
uct. Attempts to prepare these clusters by the thermal reaction
of 1 and the solvates [M(CO)5(THF)] gave no detectable
amounts of the trinuclear clusters, which suggests that the
hydride 1 has only a moderate electron-donor ability. Com-
pounds 5a and 5b were very unstable and decomposed progres-
sively upon manipulation to give mixtures of compound 1 and
its tetracarbonyl derivative. Fortunately, the Mo2W tungsten
cluster was more stable and could be completely characterized
both in solution and in the solid state (see below).
Group 7 metal cyclopentadienyl fragments could be intro-
duced using tetrahydrofuran adducts. Thus, a THF solution of
the adduct [MnCp′(CO)2(THF)] (Cp′ ) η5-C5H4CH3) reacts with
compound 1 at room temperature to give the trinuclear cluster
[MnMo2Cp2Cp′(µ3-H)(µ-PCy2)(CO)4] (6) with good yield, along
with variable amounts of the tetracarbonyl [Mo2Cp2(µ-H)(µ-
PCy2)(CO)4] as a side product. Compound 6, which could be
characterized through an X-ray diffraction study (see below),
is a rare example of a Mo2Mn cluster. In fact there appears to
be just another cluster (apart from 3) having a triangular Mo2-
Mn core, this being the electron-precise cluster [Mo2Mn2Cp2-
(µ3-Se)4(CO)7].33 For this reason, we examined also the reaction
of 1 with the rhenium adduct [ReCp(CO)2(THF)], but this turned
out to give a mixture of unstable compounds, which could be
neither isolated nor characterized properly.
The mixture of isomers 4a and 4b exhibits six stretching CO
bands ranging from 1769 to 1956 cm-1, this alone suggesting
that there is more than one compound in solution, since the
expected product would have only four CO ligands and therefore
no more than four stretching bands. Moreover, the positions of
the lowest bands in frequency (1812 and 1769 cm-1) suggest
the presence of bridging or semibridging CO ligands in both
isomers. These isomers are characterized by quite separated 31
P
NMR resonances, which appear at 224.1 (4a) and 169.1 (4b)
ppm, while the proton NMR spectrum reveals the lack of any
element of symmetry in both cases, since three distinct Cp
resonances are observed in each case, therefore excluding any
symmetrical structure similar to that found for 2b. Thus, the
large difference in the 31P chemical shifts of isomers 4a and 4b
is taken as an indication that the PCy2 ligand might be bridging
a Mo2 vector in one isomer (4b, by comparison with the shifts
for 2b) and a MoRu one in the other isomer (4a, this structure
being comparable to that of 3, after replacing the Mn(CO)3
fragment in the latter by the isoelectronic RuCp one). We can
compare the shift in 4a with those of the Mo2Ru clusters [Mo2-
RuCp2(µ3-CdCRH)(µ-PPh2)2(CO)4] and [Mo2RuCp2(µ3-CCH2R)-
(µ-PPh2)(CO)5] (R ) H, Me), ranging from 188 to 202 ppm.32
Taking into account that PCy2 shifts tend to be higher than those
of PPh2, the value of 224.1 ppm seems to be a reasonable figure
for compound 4a. Finally, we should note that while a number
of trinuclear clusters having Mo2Ru cores have been reported
(29) Braterman, P. S. Metal Carbonyl Spectra; Academic Press: London,
UK, 1975.
(30) See for example: (a) Iggo, J. A.; Mays, M. J.; Raithby, P. R.;
Henrick, K. J. Chem. Soc., Dalton Trans. 1983, 205. (b) Horton, A. D.;
Kemball, A. C.; Mays, M. J. J. Chem. Soc., Dalton Trans. 1988, 2953.
(31) Carty, A. J.; McLaughin, S. A.; Nucciarone, D. In Phosphorus-31
NMR Spectroscopy in Stereochemical Analysis; Verkade, J. G., Quin, L.
D., Eds.; VCH: New York, 1987; Chapter 16.
Compound 1 is also very reactive toward [Fe2(CO)9], which
is a classical precursor of the Fe(CO)4 fragment. However, this
(32) Adams, H.; Bailey, N. A.; Gill, L. J.; Morris, M. J.; Sadler, N. D.
J. Chem. Soc., Dalton Trans. 1997, 3041.
(33) Adams, R. D.; Kwon, O.-S. Inorg. Chem. 2003, 42, 6175.

326 Organometallics, Vol. 26, No. 2, 2007
AlVarez et al.
Scheme 3. Fluxional Process Proposed for Compounds 5, 6,
and 8 in Solution
Figure 2. ORTEP diagram (30% probability) of compound 5c,
with H atoms and Cy rings omitted for clarity, except the C1 atoms
and the hydride ligand.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
Compound 6
Mo(1)-Mo(2)
Mo(1)-Mn(1)
Mo(2)-Mn(1)
Mo(1)-P(1)
Mo(2)-P(1)
Mo(1)-H(1)
Mo(2)-H(1)
Mn(1)-H(1)
C(2)-Mo(2)
C(2)-Mo(1)
C(1)-Mo(1)
2.6448(8)
3.135(1)
3.122(1)
2.386(2)
2.368(2)
1.86(6)
1.85(6)
1.64(7)
1.929(8)
2.835(7)
1.952(7)
Mo(1)-Mo(2)-Mn(1)
Mo(2)-Mn(1)-Mo(1)
Mn(1)-Mo(1)-Mo(2)
C(1)-Mo(1)-Mo(2)
C(2)-Mo(2)-Mo(1)
Mo(1)-P(1)-Mo(2)
O(1)-C(1)-Mo(1)
O(2)-C(2)-Mo(2)
P(1)-Mo(1)-H(1)
P(1)-Mo(2)-H(1)
C(3)-Mn(1)-C(4)
65.25(2)
50.01(2)
64.74(3)
88.8(2)
74.8(2)
67.62(5)
176.5(6)
172.3(6)
97(2)
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
Compound 5c
Mo(1)-Mo(2)
Mo(1)-W(1)
Mo(2)-W(1)
Mo(1)-P(1)
Mo(2)-P(1)
Mo(1)-C(1)
Mo(2)-C(2)
Mo(2)-C(1)
Mo(1)-H(1)
Mo(2)-H(1)
W(1)-H(1)
2.6351(5)
3.3714(5)
3.3103(6)
2.380(1)
2.386(1)
1.924(4)
1.965(4)
2.755(4)
1.80(5)
Mo(1)-Mo(2)-W(1)
Mo(2)-W(1)-Mo(2)
W(1)-Mo(1)-Mo(2)
C(1)-Mo(1)-Mo(2)
C(2)-Mo(2)-Mo(1)
Mo(1)-P(1)-Mo(2)
O(1)-C(1)-Mo(1)
O(2)-C(2)-Mo(2)
P(1)-Mo(1)-H(1)
P(1)-Mo(2)-H(1)
68.00(2)
46.44(2)
65.56(3)
72.5(1)
95.6(1)
67.14(3)
170.7(3)
176.7(3)
96(2)
98(2)
86.4(6)
would be a better description for the binding in the Mo2W core,
whereby the electron donor (the multiple Mo-Mo bond) just
shares a bonding electron pair with the acceptor (the tungsten
atom). This description is consistent not only with the Mo-
Mo separation found in 5c but also with the rather long Mo-W
distances, 3.3714(5) and 3.3103(6) Å, significantly much longer
than the single-bond Mo-Mo distances in related compounds
(e.g., ca. 3.10 Å for 2a).
1.92(5)
2.02(5)
92(1)
reaction proceeds readily with 1 in toluene at room temperature
to give with good yield the heterodinuclear compound [FeMoCp-
(µ-PCy2)(CO)6] (7) along with the dimer [Mo2Cp2(CO)6], rather
than the expected trinuclear cluster. No intermediate species
could be reproducibly detected by IR or 31P NMR monitoring
of the corresponding reaction mixtures. In contrast, the reaction
of 1 with Ru3(CO)12 under visible-UV irradiation (this acting
as a precursor of the Ru(CO)4 fragment) led to complex mixtures
of products that could not be isolated.
Spectroscopic data in solution for compounds 5a-c are
essentially consistent with the structure found in the solid state
for 5c, although dynamic processes are present once more, and
only limited data are available for compounds 5a,b due to their
low stability. In fact, only for compound 5c could the C-O
stretching bands in the IR spectra be unambiguously assigned,
since for the other complexes some of these bands are
overlapping with those of compound 1 and its tetracarbonyl
derivative, these being formed upon manipulation of the new
clusters. Nevertheless, the IR spectra clearly display in all cases
a strong band in the range 2050-2060 cm-1, characteristic of
the presence of M(CO)5 fragments (M ) Cr, Mo, W).29 As for
the 31P NMR spectra, compounds 5a-c exhibit single reso-
nances ranging from 205 to 208 ppm. These chemical shifts
are significantly higher than those for other clusters having the
PCy2 ligand over formally double ModMo bonds discussed in
this paper (Table 1), but are lower than the chemical shift in
the triply bonded 1 (232.3 ppm).34 This is consistent with a
retention in solution of the same 3c-2e interaction at the Mo2W
metal skeleton that is found in the crystal. The 1H NMR
spectrum reflects the significant modification operating in the
hydride environment upon coordination (from the µ2- to the µ3-
mode), since the unusually deshielded resonance in 1 (-6.94
ppm) moves into a more shielded region upon coordination of
the new metal atom [δH ) -16.88 (5a), -13.34 (5b), -12.46
Solid State and Solution Structure of Compounds 5. The
crystal structure of [Mo2WCp2(µ3-H)(µ-PCy2)(CO)7] (5c) was
determined through a single-crystal X-ray diffraction study
(Figure 2 and Table 2). The molecule can indeed be viewed as
resulting from the addition of a W(CO)5 moiety to the dimetal
center in the hydride 1 with little distortion of the dimolybdenum
substrate. Thus, the Cp groups remain placed on opposite sides
of the Mo2P plane, as do the carbonyl ligands. However, the
hydride ligand is significantly perturbed upon binding of the
tungsten fragment, since it is now located as triply bridging the
metal triangle in an asymmetrical way (closer to the molybde-
num atoms). The intermetallic Mo-Mo distance, 2.6351(5) Å,
is slightly shorter (ca. 0.03 Å) than that measured for the 46-
electron cluster [Mo3Cp*3(µ2-H)(µ3-O)(CO)4]28 and much shorter
(ca. 0.11 Å) than the formally double Mo-Mo length measured
for 2a. On the other side, this distance is 0.06 to 0.1 Å longer
than those measured in the 30-electron compounds [Mo2Cp2-
(µ-PCy2)(µ-SnPh3)(CO)2] and 1, respectively, for which triple
Mo-Mo bonds can be proposed under the EAN formalism.1
In summary, the Mo-Mo interaction for compound 5c might
be viewed both as a short double bond and as a long triple bond.
This suggests that the W(CO)5 fragment might be acting
+
essentially as an acceptor group (isolobal to CH3 rather than
(34) Garc´ıa, M. E.; Melo´n, S.; Ramos. A.; Riera, V.; Ruiz, M. A.; Belletti,
D.; Graiff, C.; Tiripicchio, A. Organometallics 2003, 22, 1983.
to CH2).2 In this case, a 3c-2e interaction (rather than 3c-4e)

ReactiVity of [Mo2(η5-C5H5)2(µ-H)(µ-PCy2)(CO)2]
Organometallics, Vol. 26, No. 2, 2007 327
Figure 3. ORTEP diagram (30% probability) of one of the two
independent molecules in the unit cell of compound 6, with H atoms
and Cy rings omitted for clarity, except the C1 atoms and the hydride
ligand.
Figure 4. ORTEP diagram (30% probability) of one (B) of the
two independent molecules in the unit cell of compound 7, with H
atoms and Cy rings omitted for clarity, except the C1 atoms.
ppm (5c)], as expected. However, these spectra exhibit in each
case a single resonance for both cyclopentadienyl groups, itself
inconsistent with the solid state structure of 5c. The same is
concluded from the 13C NMR spectrum of 5c, which displays
a single resonance for each of the inequivalent pairs of MoCO
and cyclopentadienyl groups (but not for the diastereotopic C2
and C3 cyclohexyl carbon atoms). Therefore, a dynamic process
creating a false C2 symmetry axis bisecting the Mo2W triangle
must be operative in solution for these compounds, which we
propose to involve just a shift of the hydride ligand from one
side to the other of the metal triangle (Scheme 3). Although
we have not studied this process in detail, we note that it should
be of an intramolecular nature, since H-P and H-W couplings
are retained under fast exchange conditions. Besides we also
note the appearance of just one resonance at 197.6 ppm for the
five carbonyls attached to the tungsten atom, which suggests
the occurrence of a further exchange process inside the
pentacarbonyl fragment, which is also fast on the NMR time
scale at room temperature.
Solid State and Solution Structure of Compound 6. The
crystal structure of 6 was also confirmed through a single-crystal
X-ray diffraction study (Table 3 and Figure 3). The structure is
very similar to that found for 5c, if the W(CO)5 fragment is
replaced by the isoelectronic MnCp′(CO)2 group, with the
methylcyclopentadienyl ligand and the triply bridging hydride
on the same side of the Mo2Mn plane. The intermetallic
separations are also comparable to those of the Mo2W tungsten
cluster, suggesting that the binding within the metal triangle
might also be described in terms of a 3c-2e interaction (H+-
like behavior of the MnCp′(CO)2 fragment). However, the Mo-
Mo distance (2.6448(8) Å) is a bit longer than that in 5c,
whereas the Mo-Mn distances (3.135(1) and 3.122(1) Å) are
now closer to the reference single-bond lengths (cf. 3.11 Å in
[MnMoCp(CO)7{P(OMe)3}]35 or 3.09 Å in [MnMoCp(µ-H)-
(µ-PPh2)(CO)6]).36 This suggests that, compared to the W(CO)5
fragment, the MnCp′(CO)2 fragment binds more tightly to the
hydride 1, surely due to its higher electron density at the metal
center, derived from the presence of the methylcyclopentadienyl
ligand. This could make a Mn-based electron pair become more
available for cluster binding (CH2-like behavior of the metal
fragment).
Table 4. Selected Bond Lengths (Å) and Angles (deg) for
Compound 7 [molecule B]
Mo(1)-Fe(1)
Mo(1)-P(1)
Fe(1)-P(1)
Fe(1)-C(1)
Fe(1)-C(2)
Fe(1)-C(3)
Fe(1)-C(4)
Mo(1)-C(5)
Mo(1)-C(6)
2.929(1)
2.412(1)
2.283(1)
1.803(3)
1.806(3)
1.786(3)
1.810(3)
1.946(3)
1.938(3)
Mo(1)-P(1)-Fe(1)
C(1)-Fe(1)-C(3)
C(1)-Fe(1)-C(4)
C(1)-Fe(1)-C(2)
C(3)-Fe(1)-C(4)
C(3)-Fe(1)-C(2)
C(4)-Fe(1)-C(2)
C(5)-Mo(1)-C(6)
C(5)-Mo(1)-Fe(1)
C(6)-Mo(1)-Fe(1)
77.16(3)
90.5(1)
176.9(1)
90.8(1)
91.7(1)
109.8(1)
90.5(1)
78.7(1)
84.7(1)
119.5(1)
Spectroscopic data in solution for compound 6 are in quite
good agreement with the solid structure but again reveal the
presence of dynamic effects. The IR spectrum displays four CO
stretching bands, itself in accordance with the low symmetry
of this tetracarbonylic cluster, the 31P NMR spectrum exhibits
a resonance at 167.5 ppm, a shift similar to those found for
other Mo2(µ-PCy2) moieties discussed in this work (Table 1),
and the hydride resonance appears at -15.82 ppm, therefore
consistent with a triply bridging position. However, the Cp
1
ligands exhibit just one H or 13C NMR resonance at room
temperature, while the Mo-bound carbonyls (but not the Mn-
bound ones) and both cyclohexyl groups appear as equivalent
groups too (but not the diastereotopic pairs of C2 and C3 atoms
in each ring). Therefore, the dynamic process is generating a
false C2 axis, as found for compounds 5. Indeed, at 233 K that
process is slowed enough so as to yield separate 13C resonances
for the Cp ligands. In order to explain all these spectroscopic
features, we must assume for 6 the operation of a dynamic
process similar to that proposed for the heptacarbonyl clusters
5, that is, a shift of the hydride ligand between both sides of
the metal triangle. However, in the case of 6 this needs to be
accompanied by a simultaneous rotation of the manganese
fragment (Scheme 3), since otherwise the process would be an
isomerization (not observed).
Structure of Compound 7. In the crystals of 7 two
crystallographically independent molecules (A and B), even if
very similar, are present. The structure of one of them (molecule
B) is shown in Figure 4, while Table 4 collects some relevant
structural parameters of both molecules. The molecule displays
MoCp(CO)2 and Fe(CO)4 moieties bound through a dicylo-
hexylphosphide bridge, and a metal-metal bond, strictly
comparable to those found in the diphenylphosphide-bridged
(35) Ingham, W. L.; Billing, D. G.; Levendis, D. C.; Coville, N. J. Inorg.
Chim. Acta 1991, 187, 17.
(36) Horton, A. D.; Mays, M. J.; Raithby, P. R. J. Chem. Soc., Chem.
Commun. 1985, 247.

328 Organometallics, Vol. 26, No. 2, 2007
AlVarez et al.
compounds [FeMoCp(µ-PPh2)(CO)5L] (L ) CO,37 P(OMe)3).38
The iron fragment displays a pseudo-octahedral geometry, if
the Mo atom is considered as a coordination position. Under
the analogous assumption, the molybdenum atom displays then
the classical piano stool geometry. The Mo-Fe distance (2.934-
(1) and 2.929(1) Å for molecules A and B, respectively) is
consistent with the single Mo-Fe bond formulated for this
molecule under the EAN formalism and is similar to the bond
lengths measured in the mentioned MoFe complexes. Other
bond lengths and angles are also similar to those found in the
above diphenylphosphide compounds and thus deserve no
further comments.
Spectroscopic data in solution for 7 are fully consistent with
its solid structure. The IR spectrum in petroleum ether, for
instance, shows six CO stretching bands, with a pattern similar
to that measured in the solid state for [FeMoCp(µ-PPh2)(CO)6].37
The 31P NMR spectrum for 7 exhibits a singlet at 199.1 ppm,
a chemical shift ca. 40 ppm higher than that measured for the
above diphenylphosphide complex, as expected for PCy2 and
PPh2 chemical shifts in comparable structures.
Reaction with CuCl. Since the interaction of hydride 1 with
16-electron transition-metal fragments of the type M(CO)5 and
MCp(CO)2 seems to point to an essentially acceptor role of the
heterometal fragment and a donor role of the unsaturated
dimolybdenum center, we examined the possibility of synthesiz-
ing Mo2-group 11 clusters by reacting the hydride 1 with neat
electron acceptors such as the gold cations [Au(PR3)]+ or the
neutral copper(I) halides. Indeed, both reactions take place
readily at room temperature, but only that with CuCl gave a
reasonably stable and pure product, identified as the trinuclear
cluster [CuMo2ClCp2(µ3-H)(µ-PCy2)(CO)2] (8).
3). We note finally that compound 8 exhibits a relatively little
shielded resonance (δ -6.71 ppm, JPH ) 4 Hz), not very
different from that for the starting hydride 1 (δ -6.94 ppm,
JPH ) 11 Hz). It is tempting to conclude from this that the
hydride ligand in 8 might be edge-bridging the molybdenum
atoms, rather than triply bridging the Mo2Cu face. However,
we must consider that hydride ligands are themselves relatively
deshielded when bridging to copper atoms. For example, in the
cluster [CuMn2(µ-H)3(CO)6{µ-(EtO)2POP(OEt)2}(PPh3)] the
chemical shifts for the hydride ligands are -26.2 (Mn-Mn)
and -9.0 ppm (Mn-Cu).6 Therefore, in the absence of further
structural data, we must assume that the hydride ligand in 8 is
likely to be placed bridging (even if asymmetrically) the trimetal
skeleton of the cluster.
Concluding Remarks
The 30-electron dinuclear hydride 1 readily reacts with 17-
electron metal fragments of type MCp(CO)3 or M(CO)x to give
46-electron trinuclear clusters after formal replacement of the
hydride ligand by the isolobal metal fragment. On the other
hand, compound 1 adds easily to 16-electron metal fragments
of the type M(CO)x or MCp(CO)2 to give the corresponding
unsaturated trinuclear clusters in which the hydride ligand
bridges the three metal atoms. The structure and bonding
interaction in the hydride-bridged clusters can be essentially
described in terms of a 3c-2e donor-acceptor interaction
between the multiply metal-metal bonded hydride (donor) and
the heterometal fragment (acceptor). In any case, all the above
reactions proved to be efficient and rational synthetic routes
for electron-deficient trinuclear clusters, although some of them
were found to be quite unstable species.
Although no suitable crystals for a diffractometric study could
be grown for 8, the spectroscopic data suggest a structure related
to those of the hydride clusters 5 and 6 just discussed, perhaps
with a more pronounced donor-acceptor interaction to sustain
the heterometallic Mo2Cu framework (Chart 2). In the first place,
the IR spectrum for 8 shows two CO stretching bands with a
pattern (well-separated medium and strong bands, in order of
decreasing frequency) different from that in 1 and very similar
to that found for the molybdenum-tin derivative [Mo2Cp2(µ-
PCy2)(µ-SnPh3)(CO)2].1 This indicates that the carbonyl ligands
are still in a transoid arrangement, but a distorted one in order
to better accommodate the bridging group. Interestingly, the
average C-O stretching frequencies for 1 and 8 in tetrahydro-
furan solution are 1854 and 1878 cm-1, respectively, which
gives support to our idea that these hydride-bridged heterome-
tallic clusters derived from 1 are essentially supported by a
donor-acceptor interaction from the hydride substrate to the
heterometal fragment. This interaction is possibly the strongest
in the case of the Mo2Cu cluster 8. In fact, the chemical shift
of the phosphorus nucleus in 8 (230.8 ppm) is much higher
than those for clusters 5 or 6 (Table 1) and similar to the
chemical shifts found for PCy2 ligands bridging triple Mo-
Mo bonds.1,26,34 All this is consistent with a negligible electron
contribution of the CuCl group to the bonding in the cluster.
As observed for the hydride clusters 5 and 6, the 1H spectrum
of 8 at room temperature displays just one cyclopentadienyl
resonance, which is not consistent with the transoid arrangement
of the MoCp(CO) fragments clearly deduced from its IR
spectrum. Presumably, a fluxional process similar to those
already discussed is also operative for this compound (Scheme
Experimental Section
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.39 Compounds [Mo2Cp2(µ-H)(µ-PCy2)(CO)2]34 (1) and [Ru2-
Cp2(CO)4]40 were prepared according to literature procedures, and
all other reagents were obtained from the usual commercial suppliers
and used as received, unless otherwise stated. Petroleum ether refers
to that fraction distilling in the range 338-343 K. Photochemical
experiments were performed using jacketed Pyrex Schlenk tubes,
cooled by tap water (ca. 288 K). A 400 W mercury lamp (as source
of visible-UV light) or conventional 200 W lamp (as source of
visible light) both placed ca. 1 cm away from the Schlenk tube
were used for these experiments. Chromatographic separations were
carried out using jacketed columns cooled by tap water. 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 of CO ligands were measured in solution
and are referred to as ν(CO) (solvent). Nuclear magnetic resonance
(NMR) spectra were routinely recorded at 300.13 (1H), 121.50 (31P-
{1H}), or 75.47 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 H3-
PO4 solutions (31P). Coupling constants (J) are given in hertz.
Preparation of [Mo3Cp3(µ-PCy2)(µ3-CO)(CO)4] (2a). A toluene
solution (10 mL) of compound 1 (0.030 g, 0.05 mmol) and [Mo2-
(39) Armarego, W. L. F.; Chai, C. Purification of Laboratory Chemicals,
5th ed.; Butterworth-Heinemann: Oxford, UK, 2003.
(40) Humphries, A. P.; Knox, S. A. R. J. Chem. Soc., Dalton Trans.
1975, 1710.
(37) Lindner, E.; Sta¨ngle, M.; Hiller, W.; Fawzi, R. Chem. Ber. 1988,
121, 1421.
(38) Hsiao, S.-M.; Shyu, S.-G. Organometallics 1998, 17, 1151.

ReactiVity of [Mo2(η5-C5H5)2(µ-H)(µ-PCy2)(CO)2]
Organometallics, Vol. 26, No. 2, 2007 329
Cp2(CO)6] (0.050 g, 0.1 mmol) was irradiated with visible light
for 5 h at 288 K. Solvent was then removed from the solution under
vacuum, the residue was extracted with dichloromethane-petroleum
ether (1:4), and the extracts were chromatographed on an alumina
column (activity IV) at 253 K. Elution with dichloromethane-
petroleum ether (1:1) gave a brown fraction. Removal of solvents
from the latter under vacuum gave compound 2a (0.025 g, 61%)
as a dark brown solid. The crystals used in the X-ray study were
grown by slow diffusion of a layer of petroleum ether and diethyl
ether into a toluene solution of the complex at 253 K. Anal. Calcd
for C32H37Mo3O5P: C, 46.85; H, 4.55. Found: C, 47.13, H, 4.82.
31P{1H} NMR (81.04 MHz, CDCl3): δ 178.3 (s, µ-P). 31P{1H}
NMR (162.01 MHz, CD2Cl2, 193 K): δ 185.4 (s, br, µ-P, isomer
A), 150.2 (s, br, µ-P, isomer B), ratio A/B ) 1.7. 1H NMR (200.13
MHz, CDCl3): δ 5.31 (s, 5H, Cp), 5.07 (s, 10H, Cp), 2.50-1.00
(m, 22H, Cy) ppm. 1H NMR (400.13 MHz, 193 K): δ 5.36 (s, 5H,
Cp), 5.11 (s, 10H, Cp), 2.40-1.00 (m, 22H, Cy) ppm. 13C{1H}
NMR: δ 256.3 (s, br, CO), 93.0 (s, Cp), 90.0 (s, 2 × Cp), 47.3 (d,
JCP ) 18, C1-Cy), 32.7 (s, C2-Cy), 28.0 (d, JCP ) 12, C3-Cy), 26.6
(C4-Cy) ppm.
4.96 (d, JPH ) 1, 5H, Cp) ppm. Signals due to the cyclohexyl groups
are mixed with those of the other isomer, in the range 2.60-1.10
ppm.
Preparation of [CrMo2Cp2(µ3-H)(µ-PCy2)(CO)7] (5a). A tolu-
ene solution (10 mL) of compound 1 (0.030 g, 0.052 mmol) and
[Cr(CO)6] (0.016 g, 0.073 mmol) was irradiated with visible-UV
light for 10 min at 288 K to yield an orange solution containing
similar amounts of 5a and [Mo2Cp2(µ-H)(µ-PCy2)(CO)4].26 Solvents
were then removed under vacuum, the residue was extracted with
CH2Cl2-petroleum ether (1:9 mixture), and the extracts were
chromatographed on alumina (activity IV) at 253 K. Elution with
the latter mixture gave an orange fraction, which yielded, after
removal of solvents, compound 5a contaminated with small amounts
of 1 and [Mo2Cp2(µ-H)(µ-PCy2)(CO)4]. Compound 5a is an
unstable, air-sensitive compound, and further attempts to purify or
isolate it led to its progressive decomposition (to yield the above-
mentioned compounds). 31P{1H} NMR (CDCl3): δ 207.4 (s, µ-P)
ppm. 1H NMR (CDCl3): δ 5.25 (s, 10H, Cp), -16.88 (d, JPH ) 5,
1H, µ-H) ppm. Signals due to the cyclohexyl groups were mixed
with those of 1 and [Mo2Cp2(µ-H)(µ-PCy2)(CO)4].
Preparation of [Mo3Cp2(µ3-H)(µ-PCy2)(CO)7] (5b). A toluene
solution (10 mL) of compound 1 (0.030 g, 0.052 mmol) and [Mo-
(CO)6] (0.015 g, 0.057 mmol) was irradiated with visible-UV light
for 10 min at 288 K to yield an orange solution containing similar
amounts of 5b and [Mo2Cp2(µ-H)(µ-PCy2)(CO)4].26 Workup as
described above for 5a yielded 5b as an unstable, air-sensitive,
orange solid contaminated with small amounts of 1 and [Mo2Cp2-
(µ-H)(µ-PCy2)(CO)4]. 31P{1H} NMR (CDCl3): δ 208.4 (s, µ-P)
ppm. 1H NMR (CDCl3): δ 5.24 (s, 10H, Cp), -13.34 (d, JPH ) 4,
1H, µ-H) ppm. Signals due to the cyclohexyl groups were mixed
with those of 1 and [Mo2Cp2(µ-H)(µ-PCy2)(CO)4].
Reaction of 1 with [W2Cp2(CO)6]. The procedure is identical
to that above-described for 2a, but using [W2Cp2(CO)6] (0.055 g,
0.08 mmol) instead. Irradiation of the mixture for 2 h gave 0.025
g (59%) of the isomers [Mo2WCp3(µ-PCy2)(µ-CO)(CO)4] (2b,c).
The equilibrium ratio, measured by 1H NMR, was somewhat
dependent on the solvent, being 2b/2c ) 2.0 (CDCl3), 1.7 (C6D6),
or 1.3 [(CD3)2CO]. 31P{1H} NMR (81.04 MHz, CDCl3): δ 170.9
(s, µ-P, 2b), 143.5 (s, JPW ) 319, µ-P, 2c) ppm. 1H NMR (200.13
MHz, CDCl3, 2b): δ 5.38 (s, 5H, Cp), 5.05 (d, JPH ) 0.7, 10H,
Cp) ppm. Signals due to the cyclohexyl groups are mixed with
1
those of the other isomer, in the range 2.50-1.00 ppm. H NMR
Preparation of [Mo2WCp2(µ3-H)(µ-PCy2)(CO)7] (5c). A tolu-
ene solution (10 mL) of compound 1 (0.040 g, 0.070 mmol) and
[W(CO)6] (0.030 mg, 0.085 mmol) was irradiated with visible-
UV light for 8 min at 288 K to yield an orange solution containing
compound 5c as the major product. After removal of solvents under
vacuum, the orange residue was extracted with CH2Cl2-petroleum
ether (1:10 mixture) and the extracts were chromatographed on
alumina (activity IV) at 243 K. Elution with the same solvent
mixture gives an orange fraction, yielding, after removal of solvents,
compound 5c as an orange, microcrystalline solid (0.040 g, 63%).
The crystals used in the X-ray study were grown by slow diffusion
of a layer of petroleum ether into a toluene solution of the complex
at 253 K. Anal. Calcd for C29H33Mo2O7PW: C, 38.69; H, 3.69.
Found: C, 38.43, H, 3.77. 31P{1H} NMR: δ 205.0 (s, µ-P) ppm.
1H NMR: δ 5.27 (s, Cp, 10H), 2.50-1.20 (m, Cy, 22H), -12.46
(d, JPH ) 3, JWH ) 36, µ-H, 1H) ppm. 13C{1H} NMR: δ 245.2 (d,
JCP ) 13, MoCO), 197.6 (s, JCW ) 125, WCO), 90.7 (s, Cp), 51.9
(d, JCP ) 17, C1-Cy), 33.6 (d, JCP ) 5, C2,6-Cy), 32.5 (d, JCP ) 3,
C6,2-Cy), 28.3 (d, JCP ) 12, C3,5-Cy), 28.1 (d, JCP ) 10, C5,3-Cy),
26.5 (s, C4-Cy) ppm.
(200.13 MHz, CDCl3, 2c): δ 5.32 (s, 5H, Cp), 5.19 (d, JPH ) 1,
5H, Cp), 5.10 (d, JPH ) 1, 5H, Cp) ppm. Signals due to the
cyclohexyl groups are mixed with those of the other isomer, in the
range 2.50-1.00 ppm.
Preparation of [MnMo2Cp2(µ-PCy2)(µ-CO)2(CO)5] (3). A
toluene solution (10 mL) of compound 1 (0.040 g, 0.070 mmol)
and [Mn2(CO)10] (0.022 mg, 0.056 mmol) was irradiated at 288 K
with visible-UV light for 10 min to yield a brown-orange solution
containing similar amounts of 3 and [Mo2Cp2(µ-H)(µ-PCy2)-
(CO)4].26 Solvents were then removed under vacuum, and the
residue was extracted with CH2Cl2-petroleum ether (1:1 mixture)
and chromatographed on alumina (activity IV) at 253 K. Elution
with the latter mixture gave a brown fraction, which yielded, after
removal of solvents, compound 3 as a brown, highly air-sensitive
solid decomposing progressively upon manipulation. 31P{1H} NMR
(81.03 MHz, C6D6): δ 207.0 (s, µ-P) ppm. 1H NMR (200.13 MHz,
C6D6): δ 4.85, 4.80 (2 × s, 2 × 5H, Cp) ppm. Signals due to
cyclohexyl groups could not be assigned unambiguously because
of the presence of cyclohexyl-containing impurities in the NMR
sample.
Preparation of [MnMo2Cp2Cp′(µ3-H)(µ-PCy2)(CO)4] (6). A
THF solution of [MnCp′(CO)2(THF)] (Cp′ ) C5H4CH3) was
prepared from [MnCp′(CO)3] (50 µL, 0.3 mmol) according to
literature procedures.41 Compound 1 (0.030 g, 0.05 mmol) was then
added to this solution, and the mixture was stirred for 30 min at
room temperature. Solvent was then removed from the solution
under vacuum to yield a brown residue, which was extracted with
CH2Cl2-petroleum ether (1:4). The extracts were then chromato-
graphed on an alumina column (activity IV) at 253 K. Elution with
the same solvent mixture gave a green fraction, which yielded, after
removal of solvents under vacuum, compound 6 (0.023 g, 60%) as
a green solid. The crystals used in the X-ray study were grown by
slow diffusion of a layer of petroleum ether into a toluene solution
of the complex at 253 K. Anal. Calcd for C32H40MnMo2O4P: C,
50.15; H, 5.26. Found: C, 50.38; H, 5.40. 31P{1H} NMR (C6D6):
Reaction of 1 with [Ru2Cp2(CO)4]. A toluene solution (10 mL)
of compound 1 (0.060 g, 0.104 mmol) and [Ru2Cp2(CO)4] (0.049
mg, 0.110 mmol) was irradiated with visible-UV light for 5 min
at 288 K to obtain a brown solution containing the isomers [Mo2-
RuCp3(µ-PCy2)(µ-CO)(CO)3] (4a,b) (1:1 ratio). Solvents were then
removed under vacuum, the residue was extracted with CH2Cl2-
petroleum ether (1:4 mixture), and the extracts were chromato-
graphed on alumina (activity IV) at 253 K. Elution with CH2Cl2-
petroleum ether (1:1 mixture) gave two separated brown fractions
both containing, after removal of solvents, a 1:1 mixture of
compounds 4a and 4b, as a brown, highly air-sensitive solid (overall
yield 0.057 g, 69%). 31P{1H} NMR (CDCl3): δ 224.1 (s, µ-P, 4a),
169.1 (s, µ-P, 4b) ppm. 1H NMR (CDCl3, 4a): δ 5.31, 5.01, 4.99
(3 × s, 3 × 5H, Cp) ppm. Signals due to the cyclohexyl groups
are mixed with those of the other isomer, in the range 2.60-1.10
1
ppm. H NMR (CDCl3, 4b): δ 5.22, 5.08 (2 × s, 2 × 5H, Cp),
(41) Herrmann, W. A. Angew. Chem. 1974, 86, 345.

330 Organometallics, Vol. 26, No. 2, 2007
AlVarez et al.
Table 5. Crystal Data for Compounds 5c, 6, and 7
5c
6
7
mol formula
mol wt
C29H33Mo2O7PW
900.25
C32H40MnMo2O4P
766.43
C23H27FeMoO6P
582.21
cryst syst
monoclinic
P21/n
0.71073
12.047(2)
15.280(3)
16.888(3)
90
101.172(3)
90
monoclinic
P21
0.71073
9.9059(18)
22.193(4)
13.832(2)
90
100.521(3)
90
monoclinic
P21/c
0.71073
18.725(5)
16.262(5)
17.103(5)
90
107.51(5)
90
space group
radiation (λ, Å)
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
3049.8(10)
4
2989.7(9)
4
4967(2)
8
Z
calcd density, g cm-1
absorp coeff, mm-1
temperature, K
θ range, deg
index ranges (h, k, l)
no. of reflns collected
1.961
4.668
120(2)
1.81 to 28.28
-16, 15; 0, 20;0, 22
74 749
1.703
1.332
120(2)
1.50 to 28.33
-13, 12; -29, 28; 0, 18
37 847
1.557
1.188
293(2)
3.04 to 30.00
0, 26; 0, 22; -24, 22
14 865
no. of indep reflns (Rint
)
7797 (0.0492)
6083
14 379 (0.0658)
10 652
14 468
8385
no. of reflns with I > 2σ(I)
R indexes (data with I > 2σ(I))a
R1 ) 0.0235
wR2 ) 0.0433b
R1 ) 0.0452
wR2 ) 0.0526b
1.199
R1 ) 0.0444
wR2 ) 0.0644c
R1 ) 0.0886
wR2 ) 0.0776c
1.115
R1 ) 0.0356
wR2 ) 0.0780d
R1 ) 0.0790
wR2 ) 0.0898d
0.808
R indexes (all data)a
GOF
no. of restraints/params
0/449
1.362, -0.843
1/727
0.954, -1.140
126/577
0.665, -0.859
∆F(max., min.), e Å-3
2
2
2
2
2
2
a R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc| )2/∑w|Fo| ]1/2. w ) 1/[σ2(Fo ) + (aP)2 + bP] where P ) (Fo + 2Fc )/3. b a ) 0.0078, b ) 8.1989.
c a ) 0.0040, b ) 3.7660. a ) 0.0468, b ) 0.0000.
d
δ 167.5 (s, µ-P) ppm. 1H NMR (C6D6): δ 5.13 (s, 10H, Cp), 4.28
(s, 1H, C5H4), 4.19 (s, 2H, C5H4), 4.13 (s, 1H, C5H4), 3.00-0.80
(m, 22H, Cy), 1.93 (s, 3H, CH3), -15.82 (s, 1H, µ-H) ppm. 13C-
{1H} NMR (C6D6): δ 244.4 (d, JCP ) 12, 2 × MoCO), 235.0,
233.4 (2 × s, 2 × MnCO), 97.5 (s, C1-Cp′), 89.7 (s, 2 × Cp),
83.2, 82.1, 81.5, 81.3 (4 × s, C2-5-Cp′), 51.4 (s, br, C1-Cy), 33.9
X-ray Structure Determination of Compound 5c. The X-ray
intensity data were collected on a Smart-CCD-1000 Bruker dif-
fractometer using graphite-monochromated Mo KR radiation at 120
K. Cell dimensions and orientation matrixes were initially deter-
mined from least-squares refinements on reflections measured in 3
sets of 30 exposures collected in three different ω regions and
eventually refined against all reflections. The software SMART42
was used for collecting frames of data, indexing reflections, and
determining lattice parameters. The collected frames were then
processed for integration by the software SAINT,42 and a multiscan
absorption correction was applied with SADABS.43 Using the
program suite WinGX,44 the structures were solved by Patterson
interpretation and phase expansion and refined with full-matrix
least-squares on F2 with SHELXL97.45 All hydrogen atoms were
located in the Fourier map, except for those of C(24) to C(29) of
one of the cyclohexyl rings, which were geometrically located. All
of them were given an overall isotropic thermal parameter. The
final refinement on F2 proceeded by full-matrix least-squares
calculations using anisotropic thermal parameters for all the non-
hydrogen atoms.
X-ray Structure Determination of Compound 6. Collection
of data, structure solution, and refinements were done as described
for 5c. Two independent molecules are present in the asymmetric
unit, without significant differences. All non-hydrogen atoms were
refined anisotropically, except for C(44), which was persistently
nonpositive definite. Most of the hydrogen atoms were found in
the Fourier maps; however, because of the presence of two
molecules in the asymmetric unit, in order to reduce the number
of parameters to be refined, all hydrogen atoms were geometrically
(d, JCP ) 3, C2,6-Cy), 33.1 (s, C6,2-Cy), 28.5 (d, JCP ) 12, C3,5
-
Cy), 28.2 (d, JCP ) 10, C5,3-Cy), 26.6 (s, C4-Cy), 14.2 (s, Me) ppm.
13C{1H} NMR (100.63 MHz, tol-d8, 233 K, cyclopentadienyl
region): δ 98.5 (s, C1-Cp′), 91.1, 89.8 (2 × s, 2 × Cp), 84.0, 82.9,
81.9, 81.5 (4 × s, C2-5-Cp′) ppm.
Preparation of [FeMoCp(µ-PCy2)(CO)6] (7). A toluene solution
of compound 1 (0.040 g, 0.070 mmol) was stirred with [Fe2(CO)9]
(0.035 g, 0.096 mmol) for 1 h to give a brown solution containing
7 as the major product. Solvents were then removed under vacuum,
the residue was extracted with CH2Cl2-petroleum ether (1:4), and
the extracts were chromatographed on alumina (activity II). Elution
with the same mixture gave, after removal of solvents, compound
7 as an orange solid (0.026 g, 64%). The crystals used in the X-ray
study were grown by slow diffusion of a layer of petroleum ether
into a toluene solution of the complex at 253 K. Anal. Calcd for
C23H27FeMoO6P: C, 47.45; H, 4.67. Found: C, 47.36; H, 4.51.
1
31P{1H} NMR: δ 199.1 (s, µ-P) ppm. H NMR: δ 5.26 (s, 5H,
Cp), 2.80-0.80 (m, 22H, Cy) ppm.
Preparation of [CuMo2ClCp2(µ3-H)(µ-PCy2)(CO)2] (8). CuCl
(0.010 g, 0.101 mmol) was added to a toluene solution (10 mL) of
compound 1 (0.030 g, 0.052 mmol), and the mixture was stirred
for 1 h to give a brown solution. Solvent was then removed under
vacuum, and the residue was washed with petroleum ether (2 × 7
mL). Then, the brown solid was extracted with toluene (3 × 10
mL) and filtered through diatomaceous earth. Removal of solvent
from the filtrate yielded compound 8 (0.031 mg, 81%) as a brown,
microcrystalline solid. Anal. Calcd for C24H33ClCuMo2O2P: C,
42.68; H, 4.93. Found: C, 42.89; H, 5.37. 31P{1H} NMR (CDCl3):
(42) SMART & SAINT Software Reference Manuals, Version 5.051
(Windows NT Version); Bruker Analytical X-ray Instruments: Madison
WI, 1998.
(43) Sheldrick, G. M. SADABS, Program for Empirical Absorption
Correction; University of Go¨ttingen: Go¨ttingen, Germany, 1996.
(44) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.
(45) Sheldrick, G. M. SHELXL97: Program for the Refinement of Crystal
Structures; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
1
δ 230.8 (s, µ-P) ppm. H NMR (CDCl3): δ 5.29 (s, 10H, Cp),
2.60-1.00 (m, 22H, Cy), -6.71 (d, JPH ) 4, 1H, µ-H) ppm.

ReactiVity of [Mo2(η5-C5H5)2(µ-H)(µ-PCy2)(CO)2]
Organometallics, Vol. 26, No. 2, 2007 331
positioned, except the bridging hydride ligands, which were located
in the Fourier map and their positions refined. All of them were
given an overall isotropic thermal parameter.
were introduced into the geometrically calculated positions and
refined riding on the corresponding parent atoms. Two independent
but very similar molecules were present in the crystals.
X-ray Structure Determination of Compound 7. Data were
collected on a Philips PW1100 (Mo KR radiation) single-crystal
diffractometer. Details for the X-ray data collection are reported
in Table 5. A correction for absorption was made [maximum and
minimum value for the transmission coefficient was 1.000 and
0.821].46 The structure was solved by direct methods with SHELXS-
97 and refined against F2 with SHELXL-97,45 with anisotropic
thermal parameters for all non-hydrogen atoms. The hydrogen atoms
Acknowledgment. We thank the MEC of Spain for a Ph.D.
grant (to A.R.) and the MCYT for financial support (BQU2003-
05471).
Supporting Information Available: Crystallographic data for
the structural analysis of compounds 5c, 6, and 7 in CIF format.
This material is available free of charge via the Internet at
http://pubs.acs.org.
(46) (a) Walker N.; Stuart D. Acta Crystallogr. 1983, A39, 158. (b)
Ugozzoli F. Comput. Chem. 1987, 11, 109.
OM060826V