μ-alkylidyne and μ-alkylidene complexes from a bridging side-on vinylidene sulfur-rich dimolybdenum precursor

Article abstract of DOI:10.1021/om010853f

The reaction of the μ-vinylidene sulfur-rich dimolybdenum complexes with μ-alkyldyne derivatives was investigated. The reaction resulted in good yield, and when treated with a HBF₄·Et₂O based complex it readily converted into μ-alkyldene species. The α-agostic interactions in the μ-alkyldene complexes were revealed through NMR spectroscopy.

Full text of DOI:10.1021/om010853f

448
Organometallics 2002, 21, 448-450
µ-Alk ylid yn e a n d µ-Alk ylid en e Com p lexes fr om a
Br id gin g Sid e-on Vin ylid en e Su lfu r -Rich Dim olybd en u m
P r ecu r sor
Nolwenn Cabon, Philippe Schollhammer, Franc¸ois Y. Pe´tillon,* and
J ean Talarmin
UMR CNRS 6521, Chimie, Electrochimie Mole´culaires et Chimie Analytique,
Faculte´ des Sciences, Universite´ de Bretagne Occidentale, BP 809, 29285 Brest-Ce´dex, France
Kenneth W. Muir*
Department of Chemistry, University of Glasgow, Glasgow G12 8QQ, Great Britain
Received September 26, 2001
Summary: Reaction of the µ-vinylidene complexes [Mo2(η5-
C5H5)2(µ-SMe)3(µ-η1:η2-CdCHR)](BF4) (1; R ) Tol (1a ),
n-Pr (1b)) with NaBH4 produced the µ-alkylidyne de-
rivatives [Mo2(η5-C5H5)2(µ-SMe)3(µ-CCH2R)] (2; R ) Tol
(2a ), n-Pr (2b)) in good yields. Upon treatment with
HBF4‚Et2O 2a and 2b were readily converted into the
µ-alkylidene species [Mo2(η5-C5H5)2(µ-SMe)3(µ-η1:η2-
CHCH2R)](BF4) (R ) Tol (3a ), n-Pr (3b)). NMR studies
on these µ-alkylidene complexes revealed R-agostic in-
teractions.
accessible vinylidene derivatives [Mo2Cp2(µ-SMe)3(µ-η1:
η2-CdCHR)](BF4) (1) to see if η1:η2 coordination induces
original reactivity in the vinylidene moiety or is instead
a dead end in its transformation pathway. Accordingly,
we are currently studying reactions of 1 with various
electrophilic or nucleophilic reagents. We describe here
our preliminary results concerning the formation of
µ-alkylidyne derivatives [Mo2Cp2(µ-SMe)3(µ-CCH2R)] (2;
R ) Tol (2a ), n-Pr (2b)) through formal addition of
hydride to the outer carbon atom of the vinylidene
bridge in 1 (R ) Tol (1a ), n-Pr (1b)). Furthermore, face
protonation5 of the alkylidyne bridge in 2 results in the
formation of µ-alkylidene derivatives [Mo2Cp2(µ-SMe)3-
(µ-η1:η2-CHCH2R)](BF4) (3; R ) Tol (3a ), n-Pr (3b)).
The reaction of [Mo2Cp2(µ-SMe)3(µ-η1:η2-CdCHR)]-
(BF4) (R ) Tol (1a ), n-Pr (1b)) with NaBH4 (excess) in
acetonitrile at room temperature readily afforded deep
blue solutions from which the compounds [Mo2Cp2(µ-
SMe)3(µ-CCH2R)] (2; R ) Tol (2a ), n-Pr (2b)) were
isolated in good yields as blue powders (Scheme 1).6
Compounds 2 were characterized by elemental analyses
The bis(cyclopentadienyl) bimetallic auxiliary frag-
ment {M2Cp′2} (Cp′ ) η5-C5R5) continues to attract
interest.1 For example, we have recently shown that
terminal alkynes HCtCR can be activated by the
{MoIII2Cp2} compound [Mo2Cp2(µ-SMe)3(MeCN)2](BF4)
(Cp ) η5-C5H5) and that the key isomerization process
is the conversion of the terminal alkyne into a CdCHR
vinylidene ligand. This process is recognized as an
important mode of activation of terminal alkynes by
metallic species.2,3 Moreover, we reported that this
tris(thiolato)-bridged compound induced C-C and C-S
couplings in the presence of excess alkyne and that a
thio-alkenyl species, namely {[Mo2Cp2(µ-SMe)2(µ-CR′d
CRSMe)]+}, was the most probable intermediate in
these transformations, rather than the well-defined
η1:η2-vinylidene derivative [Mo2Cp2(µ-SMe)3(µ-η1:η2-
CdCHR)](BF4) (1), which appears to be a more stable
species than its alkyne adduct precursor [Mo2Cp2(µ-
SMe)3(µ-HCtCR)](BF4).3 The relative scarcity of com-
plexes featuring {M2(µ-η1:η2-CdCHR)} groups4 and the
small number of systematic studies of their behavior
prompted us to investigate the reactivity of the readily
1
and NMR spectroscopy. Their H NMR (CDCl3) spectra
were typical for complexes with a {Mo2Cp2(µ-SMe)3}
core; they exhibited a single resonance for the two
cyclopentadienyl ligands and three peaks for the three
(5) Torraca, K. E.; Ghiviriga, I.; McElwee-White, L. Organometallics
1999, 18, 2262 and references therein.
(6) Preparation of 2: a solution of complex 1 (0.2 g; 0.30 mmol of
1a , 0.32 mmol of 1b) in acetonitrile (10 mL) was stirred in the presence
of an excess of NaBH4 (3 equiv: 0.034 g (2a ), 0.037 g (2b)) for a few
minutes at room temperature. The solution turned readily from blue
to deep blue. The solvent was then removed, and the residue was
extracted with diethyl ether (40 mL). The extracts were evaporated to
dryness, and the residue was chromatographed on a silica gel column.
Elution with hexane-CH2Cl2 (4:1) afforded a blue solution of 2, which
was evaporated under vacuum. After they were washed with cold
pentane, 2a and 2b were obtained as blue powders (2a , 0.148 g, 85%
yield; 2b, 0.111 g, 65% yield). 2a (R ) Tol): 1H NMR (CDCl3, 25 °C; δ)
7.10, 6.90 (2 × d, J HH ) 7.8 Hz, 2 × 2H, CH3C6H4), 5.33 (s, 10H, C5H5),
5.00 (s, 2H, CCH2R), 2.36 (s, 3H, CH3C6H4), 1.78 (s, 3H, SCH3), 1.70
(s, 3H, SCH3), 1.41 (s, 3H, SCH3); 13C{1H} NMR (CDCl3, 25 °C; δ) 445.1
(CCH2R), 129.1, 129.3, 135.8, 140.4 (CH3C6H4), 95.5 (C5H5), 65.4
(CCH2R), 31.9 (SCH3), 21.6 (CH3C6H4), 8.3 (SCH3), 7.2 (SCH3). Anal.
Calcd for C22H26Mo2S3: C, 45.5; H, 4.8. Found: C, 45.2; H, 4.6. 2b (R
) n-Pr): 1H NMR (CDCl3, 25 °C; δ) 5.49 (s, 10H, C5H5), 3.92 (m, 2H,
CCH2R), 1.78 (s, 3H, SCH3), 1.59 (s, 3H, SCH3), 1.35-1.45 (m, 4H,
(CH2)2), 1.39 (s, 3H, SCH3), 0.95 (t, J HH ) 7.1 Hz, 3H, (CH2)2CH3);
13C{1H} NMR (CDCl3, 25 °C; δ) 449.0 (CCH2R), 93.2 (C5H5), 60.0
(CCH2R), 30.7 (CH2), 22.5 (CH2), 30.6 (SCH3), 14.1 ((CH2)2CH3), 7.9
(SCH3), 6.7 (SCH3). Anal. Calcd for C18H28Mo2S3: C, 40.6; H, 5.2.
Found: C, 40.9; H, 5.4.
(1) For recent examples and reviews: (a) Bridgeman, A. J .; Mays,
M. J .; Woods, A. D. Organometallics 2001, 20, 2076. (b) Hobert, S. E.;
Bruce, C.; Noll, B. C.; Rakowski DuBois, M. Organometallics 2001,
20, 1370. (c) Takagi, Y.; Matsuzaka, H.; Ishii, Y.; Hidai, M. Organo-
metallics 1997, 16, 4445. (d) Alvarez, M. A.; Garcia, G.; Garcia, M. E.;
Riera, V.; Ruiz, M. A.; Lanfranchi, M.; Tiripicchio, A. Organometallics
1999, 18, 4509. (e) Adams, H.; Allott, C.; Bancroft, M. N.; Morris, M.
J . J . Chem. Soc., Dalton Trans. 2000, 4145. (f) Curtis, M. D. Polyhedron
1987, 6, 759. (g) Winter, M. J . Adv. Organomet. Chem. 1989, 29, 101.
(h) Rakowski DuBois, M. Polyhedron 1997, 16, 3089. (i) Hidai, M.;
Mizobe, Y.; Matsuzaka, H. J . Organomet. Chem. 1994, 473, 1.
(2) Modern Acetylene Chemistry; Stang, P. J ., Diederich, F., Eds.;
Wiley-VCH: Weinheim, Germany, 1995.
(3) Schollhammer, P.; Cabon, N.; Capon, J . F.; Pe´tillon, F. Y.;
Talarmin, J .; Muir, K. W. Organometallics 2001, 20, 1230.
(4) (a) Bruce, M. I. Chem. Rev. 1991, 91, 197. (b) El Amouri, H.;
Gruselle, M. Chem. Rev. 1996, 96, 1077.
10.1021/om010853f CCC: $22.00 © 2002 American Chemical Society
Publication on Web 01/05/2002

Communications
Organometallics, Vol. 21, No. 3, 2002 449
Sch em e 1
SMe bridges.7 Instead of the characteristic 1H NMR
signal of the dCâHR group in 1, between 6 and 8 ppm,3
two protons were detected as a singlet (2a ) or a
multiplet (2b) between 4 and 5 ppm, suggesting that a
hydride anion had been added to the outer carbon atom
(Câ) of the vinylidene group (dCRdCâHR) to give a new
hydrocarbyl bridge. The 13C NMR spectra of 2 displayed
a resonance at extreme low field, ca. 445-450 ppm,
which was assigned to the carbon atom bonded to the
two molybdenum atoms.8 Two-dimensional hetero-
1
nuclear inverse-correlation H-13C experiments (HMQC,
HMBC) allowed further characterization of 2. Correla-
tion peaks between the CH2 protons at 5.00 ppm and
both the carbon atom at 445.1 ppm (2J CH) and the
F igu r e 1. View of a molecule of [Mo2Cp2(µ-SMe)3(µ-CCH2-
n-Pr)] (2b) showing 20% probability ellipsoids. Hydrogen
atoms are drawn as spheres of arbitrary radius. Selected
bond lengths (Å) and angles (deg): Mo(1)-C(4) ) 1.9940(17),
Mo(2)-C(4) ) 1.9958(17), Mo(1)-C(14) ) 2.277(2), Mo(1)-
C(13) ) 2.284(2), Mo(1)-C(15) ) 2.343(2), Mo(1)-C(12) )
2.345(2), Mo(1)-C(11) ) 2.398(2), Mo(2)-C(23) ) 2.278(2),
Mo(2)-C(24) ) 2.279(2), Mo(2)-C(22) ) 2.337(2), Mo(2)-
C(25) ) 2.345(2), Mo(2)-C(21) ) 2.383(2), C(4)-C(5) )
1.492(5), C(5)-C(6) ) 1.535(3), C(6)-C(7) ) 1.516(3), C(7)-
C(8) ) 1.518(3), Mo(1)-Mo(2) ) 2.5846(2); Mo(1)-C(4)-
Mo(2) ) 80.75(6), C(4)-Mo(1)-C(14) ) 92.9(1), C(4)-
Mo(1)-C(13) ) 91.9(1), C(4)-Mo(1)-C(15) ) 124.8(1),
C(4)-Mo(1)-C(12) ) 123.2(1), C(4)-Mo(1)-C(11) ) 148.8(1),
C(4)-Mo(2)-C(23) ) 93.3(1), C(4)-Mo(2)-C(24) ) 91.1(1),
C(4)-Mo(2)-C(22) ) 125.7(1), C(4)-Mo(2)-C(25) ) 121.6(1),
C(4)-Mo(2)-C(21))148.4(1),C(5)-C(4)-Mo(1))138.57(14),
C(5)-C(4)-Mo(2))140.45(14),C(4)-C(5)-C(6))113.51(15),
C(7)-C(6)-C(5) ) 112.06(17), C(8)-C(7)-C(6) ) 113.1(2),
C(4)-C(5)-C(6)-C(7) ) 174.6(2), C(5)-C(6)-C(7)-C(8) )
176.9(2)°.
carbon atoms at 140.4 ppm (2J CH) and 129.1 ppm (3J CH
)
of the tolyl group were detected for 2a , in agreement
with a CCH2R backbone. The equivalence of Cp groups
suggested that the alkylidyne bridge is symmetrically
bonded to the two molybdenum atoms and that the
π-Mo-C overlap, required by electron-counting rules,
is delocalized through the Mo-C-Mo bridge. These
conclusions were confirmed by X-ray analysis of a single
crystal of 2b, obtained by cooling a pentane solution to
-15 °C (Figure 1).9 This showed that 2b contains a
µ-CCH2-n-Pr group which is bonded through one carbon
atom, C(4), to the two molybdenum atoms of a {Mo2-
Cp2(µ-SMe)3} core. The Mo-C(4) distances (1.994(2) and
1.996(2) Å) are equal to within experimental error. They
lie between the value of 1.894(5) Å for the formally
double ModC in the vinylidene compound [Mo2Cp2(µ-
SMe)3(µ-η1:η2-CdCHTol)](BF4) (1a ) and that of 2.068(3)
Å for the single Mo-C bond in the acetylide derivative
[Mo2Cp2(µ-SMe)3(µ-η1:η2-CtCPh)].3 The Mo-C(4) lengths
therefore are in accord with a symmetrical coordination
of the alkylidyne group through Mo-C bonds of order
1.5. The C(4)-C(5) bond length (1.492(2) Å) is close to
[Mo2Cp2(µ-SMe)3(µ-η1:η2-CtCPh)] (1.238(4) Å, CtC)
and [Mo2Cp2(µ-SMe)3(µ-η1:η2-CdCHTol)](BF4) (1.356(6)
Å, CdC).3 2b appears to be the first structurally
characterized alkylidyne-molybdenum complex; how-
ever, the geometry of the W2(µ2-CCR3) unit is well-
established10a and the coordination of C(4) in 2b closely
resembles that of the corresponding atoms in, for
example, [(C5Me5)WMe(µ2-CCH3)]2 (µ-W-C, 1.95(1) and
1.97(1) Å; C-CH3, 1.54 Å).10b The angles at C(4) (C(5)-
C(4)-Mo, 138.6(1) and 140.5(1)°; Mo-C(4)-Mo, 80.8(1)°)
show the deviations from sp2 hybridization implied by
the Mo-C and Mo-Mo bond lengths and broadly agree
with those found in [(C5Me5)WMe(µ2-CCH3)]2. Addition
of H- to the Câ atom of the CRdCâHR bridge in 1 gives
a product where C(4) carries a staggered n-butyl chain
of unexceptional geometry (Figure 1). It is striking that
the Cp ligands bend away from S(3) to adopt a cis
disposition relative to the Mo-Mo axis (Cp-Mo-Mo,
168.7(1) and 168.1(1)°, where Cp is the ring centroid)
2
3
that expected for a Csp -Csp single bond and is sub-
stantially longer than corresponding distances in
(7) Pe´tillon, F. Y.; Schollhammer, P.; Talarmin, J .; Muir, K. W.
Coord. Chem. Rev. 1998, 178-180, 203.
(8) For examples of µ-alkylidyne 13C NMR chemical shifts: (a) Casey,
C. P.; Meszaros, M. W.; Fagan, P. J .; Bly, R. K.; Marder, S. R.; Austin,
E. A. J . Am. Chem. Soc. 1986, 108, 4043. (b) Casey, C. P.; Gohdes, M.
A.; Meszaros, M. W. Organometallics 1986, 5, 196. (c) J effery, J . C.;
Ruiz, M. A.; Stone, F. G. A. J . Chem. Soc., Dalton Trans. 1988, 1131.
(d) Chi, Y.; Shapley, J . R. Organometallics 1985, 4, 1900. (e) Farrugia,
L. J .; J effery, J . C.; Marsden, C.; Sherwood, P.; Stone, F. G. A. J . Chem.
Soc., Dalton Trans. 1987, 51. (f) Green, M.; Howard, J . A. K.; J ames,
A. P.; J elfs, A. N. de M.; Nunn, C. M.; Stone, F. G. A. J . Chem. Soc.,
Dalton Trans. 1987, 81. (g) Byrne, P. G.; Garcia, M. E.; Tran-Huy, N.
H.; J effery, J . C.; Stone, F. G. A. J . Chem. Soc., Dalton Trans. 1987,
1243. (h) Delgado, E.; Hein, J .; J effery, J . C.; Ratermann, A. L.; Stone,
F. G. A.; Farrugia, L. J . J . Chem. Soc., Dalton Trans. 1987, 1191. (i)
Holton, J .; Lappert, M. F.; Pearce, R.; Yarrow, P. I. W. Chem. Rev.
1983, 83, 135.
(9) Crystallographic data for [Mo2Cp2(µ-SMe)3(µ-CCH2-n-Pr)] (2b):
C18H28Mo2S3, Mr ) 532.46, triclinic, space group P1h, a ) 7.9604(4) Å,
b ) 10.7934(6) Å, c ) 12.1014(7) Å, R ) 91.874(5)°, â ) 102.708(4)°, γ
) 90.914(5)°, V ) 1013.5(1) Å3, Z ) 2, Dc ) 1.745 g cm-3, µ(Mo KR) )
1.543 mm-1. For all 6148 unique, absorption-corrected intensities with
θ(Mo KR) < 30.4°, R(F) ) 0.025 and Rw(F2) ) 0.067 after refinement
(10) (a) A search of the Cambridge Structural Database (version 521,
3
233 218 entries) revealed 13 entries for W2(µ2-CCsp ) complexes. (b) Liu,
A. H.; Murray, R. C.; Dewan, J . C.; Santarsiero, B. D.; Schrock, R. R.
of 213 parameters. |∆F| < 1.16 e Å-3
.
J . Am. Chem. Soc. 1987, 109, 4282.

450 Organometallics, Vol. 21, No. 3, 2002
Communications
Sch em e 2
Finally, expected correlation peaks between the protons
of the CH2 group at 4.51 ppm and carbon atoms at 338.0
ppm (CH) and at 137.8 and 128.3 ppm (tolyl) were
observed in the HMBC 13C-1H spectrum of 3a , in
accordance with the proposed structure [Mo2Cp2(µ-
SMe)3(µ-η1:η2-CHCH2R)]+. It must be emphasized here
that the more commonly observed â-agostic structure13
is not adopted by 3, probably because the crowded
thiomethyl environments would prevent such an inter-
action. Observation of a single resonance for the Cp
groups in the 1H NMR spectra of 3, down to 213 K,
suggested that compounds 3 are fluxional on the NMR
time scale.
The â-addition of electrophiles to vinylidene ligands
is a well-established synthetic path to alkylidyne
groups.14 In contrast, there are very few reports of the
formation of alkylidyne ligands by formal addition of a
nucleophile to the outer carbon atom of a vinylidene
moiety. This is in keeping with the nucleophilic char-
acter of the â-carbon atom of vinylidene ligands.15 As
far as we know, the closest parallel to such an addition
is the reaction of the monometallic complex [Mo(Cd
CHPh)Br{P(OMe)3}2Cp] with Li[CuPh2] or K[BH(s-
Bu)3] to give the carbyne species [Mo(tCCHRPh)-
{P(OMe)3}2Cp] (R ) H, Ph) through a proposed SN2′
substitution of the bromide ligand.16 A second example
which may involve hydride addition at the â-carbon of
a vinylidene involves the solution equilibrium between
hydrido-vinylidene [IrHCl(CdCHR)(P-i-Pr3)2]+ and alkyl-
idyne [IrCl(C-CH2R)(P-i-Pr3)2]+ isomers, which has
been rationalized in terms of a 1,3-hydride shift.17 The
versatile behavior which can be exhibited by binuclear
complexes containing side-on vinylidene bridges is il-
lustrated by the charge-controlled protonation and
frontier-orbital-controlled addition of nucleophiles to the
R-carbon atom of the neutral vinylidene species
[Mo2Cp2(CO)4(µ-η1:η2-CdCR′R)].18 No evidence for the
formation of an intermediate arising from the addition
of H- to sites in 1 other than Câ (e.g. metal or CR) has
been found. Further experiments are now planned to
extend the scope of the reactivity of these side-on
vinylidene species and to understand better the factors
which govern their behavior.
in preference to the usual linear Cp-Mo-Mo-Cp
disposition.7 This feature does not appear to have a
steric origin. It may indicate that the alkylidyne ligand
exerts a weak trans influence which requires Mo(1)-
C(11) and Mo(2)-C(21) to be the longest π-Mo-C(Cp)
bonds. Finally, the length of the Mo-Mo single bond in
2b (2.585(1) Å) is typical of values for other [Mo2Cp2-
(µ-SMe)3(µ-X)] complexes7 and the methyl groups of the
thiolate bridges have an anti orientation.
Addition of HBF4‚Et2O to a solution of 2 in dichloro-
methane readily afforded brownish red solutions of the
complexes [Mo2Cp2(µ-SMe)3(µ-η1:η2-CHCH2R)](BF4) (3;
R ) Tol (3a ), n-Pr (3b)) (Scheme 2).11 The structure of
3 could not be established by X-ray analysis since, even
when the counterion was varied (BF4-, BPh4-), single
crystals of diffraction quality were not obtained. Never-
theless, the NMR data clearly indicated that 3 results
from a face-addition5 of a proton to a Mo-C bond in 2.
The 1H NMR spectra displayed, apart from features
expected for a {Mo2Cp2(µ-SMe)3} core, a signal attribut-
able to a methylene group (observed between 3.0 and
5.0 ppm as a doublet with a coupling constant (J HH) of
4.0 Hz) and a strongly shielded, high-field resonance
(appearing as a broad, unresolved triplet at ca. -5.5
ppm) ascribed to a single proton. Two-dimensional 1H-
1H experiments showed correlation peaks between these
resonances. This coupling and the high-field shift strongly
suggest the presence of a {RCH2C(µ-H)Mo} backbone
featuring an R-agostic interaction.5,12 13C NMR and
HMQC and HMBC 1H-13C experiments yielded ad-
ditional information which supports this suggestion. The
HMQC 1H-13C spectrum of 3a indicated that the
additional proton at -5.71 ppm was attached to a
deshielded carbene-like carbon atom which resonates
1
at 338 ppm. The value of the coupling constant J CH
(66.0 Hz), determined by recording the 13C NMR spec-
Ack n ow led gm en t. We are grateful to N. Kervarec
and Dr. R. Pichon for recording of the two-dimensional
NMR spectra on a Bruker DRX 500 spectrometer.
1
trum of 3b without H decoupling, lies in the range of
J CH values typical of agostic alkylidene complexes.5,12
Su p p or tin g In for m a tion Ava ila ble: For 2b, tables giv-
ing details of the structure determination, non-hydrogen
atomic positional parameters, all bond distances and angles,
anisotropic displacement parameters, and hydrogen atomic
coordinates. This material is avalaible free of charge via the
Internet at http://pubs.acs.org.
(11) Preparation of 3: to a solution of 2 (0.1 g; 0.17 mmol of 2a ,
0.19 mmol of 2b) in CH2Cl2 (10 mL) was added 1 equiv of H[BF4]‚
Et2O. The blue solution readily turned brownish red. The volume was
then reduced under vacuum and diethyl ether was added to precipitate
a brownish red powder of 3 (3a , 0.965 g, 85% yield; 3b, 0.101 g, 86%
yield). 3a (R ) Tol): 1H NMR (CD2Cl2, -10 °C; δ) 7.08, 6.76 (2 × d,
J HH ) 7.7 Hz, 2 × 2H, CH3C6H4), 5.98 (s, 10H, C5H5), 4.51 (d, J HH
)
4.0 Hz, 2H, CHCH2R), 2.30 (s, 3H, CH3C6H4), 2.02 (s, 3H, SCH3), 1.90
(s, 3H, SCH3), 1.84 (s, 3H, SCH3), -5.71 (t, br, 1H, CHCH2R); 13C{1H}
NMR (CD2Cl2, -10 °C; δ) 338.0 (CHCH2R), 137.8, 137.5, 129.9, 128.3
(CH3C6H4), 98.7 (C5H5), 61.0 (CCH2R), 37.9 (SCH3), 21.1 (CH3C6H4),
13.1 (SCH3), 10.5 (SCH3). Elemental analyses for 3a were obtained
under argon on four independently prepared samples (NMR grade)
and allowed to obtain reproducible values, showing the presence of
dichloromethane in the microcrystalline powder of 3a . Anal. Calcd for
OM010853F
(13) J affart, J .; Etienne, M.; Maseras, F.; McGrady, J . E.; Eisenstein,
O. J . Am. Chem. Soc. 2001, 123, 6000.
(14) (a) Mayr, A.; Hoffmeister, H. Adv. Organomet. Chem. 1991, 32,
227. (b) Espuelas, J .; Esteruelas, M. A.; Lahoz, F. J .; Oro, L. A.; Ruiz,
N. J . Am. Chem. Soc. 1993, 115, 4683.
C
22H29BF4Mo2S3‚0.75CH2Cl2: C, 37.3; H, 4.2. Found: C, 37.4; H, 4.2.
(15) Kostic, N. M.; Fenske, R. F. Organometallics 1982, 1, 974.
(16) Beevor, R. G.; Green, M.; Orpen, A. G.; Williams, I. D. J . Chem.
Soc., Dalton Trans. 1987, 1319.
(17) Ho¨hn, A.; Werner, H. Angew. Chem., Int. Ed. Engl. 1986, 25,
737.
(18) (a) Bamber, M.; Conole, G. C.; Deeth, R. J .; Froom, S. F. T.;
Green, M. J . Chem. Soc., Dalton Trans. 1994, 3569. (b) Bamber, M.;
Froom, S. F. T.; Green, M.; Schulz, M.; Werner, H. J . Organomet. Chem.
1992, 434, C19.
3b (R ) n-Pr): 1H NMR (CDCl3, 25 °C; δ) 6.16 (s, 10H, C5H5), 3.45 (m,
2H, CHCH2R), 2.01 (s, 3H, SCH3), 1.89 (s, 3H, SCH3), 1.47 (s, 3H,
SCH3), 1.5-1.0 (m, 2 × 2H, (CH2)2CH3), 0.86 (t, J HH) 7.2 Hz, 3H,
(CH2)2CH3), -5.41 (1H, m, CHCH2R); 13C{1H} NMR (CDCl3, 25 °C; δ)
340.1 (CHCH2R), 99.5 (C5H5), 56.9 (CHCH2R), 37.1 (SCH3), 33.4 (CH2),
22.2 (CH2), 9.9, 12.5, 13.7 (SCH3, (CH2)2CH3, SCH3).
(12) Brookhart, M.; Green, M. L. H.; Wong, L. L. Prog. Inorg. Chem.
1988, 36, 1.