Synthesis, spectroscopic characterization, and reactivity of the unusual five-coordinate hydrido-vinylidene complex OsHCl(C=CHPh)(PiPr3)2: Precursor for dioxygen activation

Article abstract of DOI:10.1021/om960525t

The hydrido-carbyne complex OsHCl₂(CCH₂Ph)(PiPr₃)₂ (1) reacts with sodium methoxide in 1:1 molar ratio to give the five-coordinate hydrido-vinylidene OsHCl(C=CHPh)(PiPr₃)₂ (2), which affords [OsHCl(CCH₂Ph)(H₂O)(PiPr₃)₂]BF ₄ (3) by reaction with HBF₄·H₂O. The spectroscopic data obtained for 2 indicate that in solution, it is a mixture of two conformers in equilibrium. The thermodynamic magnitudes involved in the equilibrium as well as the activation parameters for the conversion between them were determined by ¹H NMR spectroscopy in toluene-d₈. The values obtained were ΔH° = -0.7 (±0.1) kcal mol^-1, ΔS° = -2.3 (±0.6) cal K^-1 mol^-1, ΔH^? = 11.0 (±0.2) kcal mol^-1 and ΔS^? = 3.2 (±0.6) cal K^-1 mol^-1. At room temperature under argon, complex 2 is stable in the solid state and in solution. However in the presence of air, it activates molecular oxygen to give the dioxo-styryl compound OsCl{(E)-CH=CHPh}(O)₂(PiPr₃)₂ (4), which has been characterized by X-ray diffraction analysis. The geometry around of the osmium atom can be described as a distorted octahedron with the two oxygen atoms occupying two relative trans positions (O(1)-Os-O(2)= 179.5(5)°). Complex 2 also reacts with trimethylphosphite, sodium acetylacetonato (acetylacetonato = acac), and sodium acetato to give the six-coordinate hydrido-vinylidene derivatives OsHCl(C=CHPh){(P(OMe)₃}(PiPr₃)₂ (8), OsH(acac)(C=CHPh)(PiPr₃)₂ (9), and OsH(η²-O₂CCH₃)(C=CHPh)(PiPr ₃)₂ (10), respectively. Complex 10 can also be prepared by treatment of OsH₃(η²-O₂CCH₃)(PiPr ₃)₂ (11) with phenylacetylene. Similarly, the reactions of 11 with 1,1-diphenyl-2-propyn-1-ol and 1-ethynyl-1-cyclohexanol lead to OsH (η²-O₂CCH₃){C=CHC(OH)Ph ₂}(PiPr₃)₂ (12) and OsH(η²-O₂CCH₃){C=CHC=CH(CH ₂)₃CH₂}(PiPr₃)₂ (13), respectively.

Full text of DOI:10.1021/om960525t

636
Organometallics 1997, 16, 636-645
Syn th esis, Sp ectr oscop ic Ch a r a cter iza tion , a n d
Rea ctivity of th e Un u su a l F ive-Coor d in a te
Hyd r id o-Vin ylid en e Com p lex OsHCl(CdCHP h )(P iP r 3)2:
P r ecu r sor for Dioxygen Activa tion
Manuel Bourgault, Amaya Castillo, Miguel A. Esteruelas,* Enrique On˜ate, and
Natividad Ruiz
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-Consejo Superior de Investigaciones Cient´ıficas,
50009 Zaragoza, Spain
Received J uly 1, 1996X
The hydrido-carbyne complex OsHCl2(CCH2Ph)(PiPr3)2 (1) reacts with sodium methoxide
in 1:1 molar ratio to give the five-coordinate hydrido-vinylidene OsHCl(CdCHPh)(PiPr3)2
(2), which affords [OsHCl(CCH2Ph)(H2O)(PiPr3)2]BF4 (3) by reaction with HBF4‚H2O. The
spectroscopic data obtained for 2 indicate that in solution, it is a mixture of two conformers
in equilibrium. The thermodynamic magnitudes involved in the equilibrium as well as the
activation parameters for the conversion between them were determined by 1H NMR
spectroscopy in toluene-d8. The values obtained were ∆H° ) -0.7 ((0.1) kcal mol-1, ∆S° )
-2.3 ((0.6) cal K-1 mol-1 , ∆Hq ) 11.0 ((0.2) kcal mol-1 and ∆Sq ) 3.2 ((0.6) cal K-1 mol-1
.
At room temperature under argon, complex 2 is stable in the solid state and in solution.
However in the presence of air, it activates molecular oxygen to give the dioxo-styryl
compound OsCl{(E)-CHdCHPh}(O)2(PiPr3)2 (4), which has been characterized by X-ray
diffraction analysis. The geometry around of the osmium atom can be described as a distorted
octahedron with the two oxygen atoms occupying two relative trans positions (O(1)-Os-
O(2) ) 179.5(5)°). Complex 2 also reacts with trimethylphosphite, sodium acetylacetonato
(acetylacetonato ) acac), and sodium acetato to give the six-coordinate hydrido-vinylidene
derivatives OsHCl(CdCHPh){(P(OMe)3}(PiPr3)2 (8), OsH(acac)(CdCHPh)(PiPr3)2 (9), and
OsH(η2-O2CCH3)(CdCHPh)(PiPr3)2 (10), respectively. Complex 10 can also be prepared by
treatment of OsH3(η2-O2CCH3)(PiPr3)2 (11) with phenylacetylene. Similarly, the reactions
of 11 with 1,1-diphenyl-2-propyn-1-ol and 1-ethynyl-1-cyclohexanol lead to OsH (η2-O2CCH3)-
{CdCHC(OH)Ph2}(PiPr3)2 (12) and OsH(η2-O2CCH3){CdCHCdCH (CH2)3CH2}(PiPr3)2 (13),
respectively.
In tr od u ction
nometallic chemistry, including dihydrogen,3,4 mono and
binuclear tetrahydridoborato,4b,5 alkenyl,6 alkynyl,4c,7
vinylacetato,8 carbene,4e,9 aryl,10 π-butadiene,11 π-al-
kyne,12 and cyclopentadienyl13 compounds.
Our previous osmium chemistry has its starting point
in the five-coordinate complex OsHCl(CO)(PiPr3)2, which
is prepared in nearly quantitative yield by treatment
of OsCl3‚xH2O with triisopropylphosphine in refluxing
methanol (eq 1). During the reaction, the alcohol is de-
(2) (a) Esteruelas, M. A.; Sola, E.; Oro, L. A.; Werner, H.; Meyer, U.
J . Mol. Catal. 1988, 45, 1. (b) Andriollo, A.; Esteruelas, M. A.; Meyer,
U.; Oro, L. A.; Sa´nchez-Delgado, R. A.; Sola, E.; Valero, C.; Werner,
H. J . Am. Chem. Soc. 1989, 111, 7431. (c) Esteruelas, M. A.; Sola, E.;
Oro, L. A.; Werner, H.; Meyer, U. J . Mol. Catal. 1989, 53, 43. (d)
Esteruelas, M. A.; Valero, C.; Oro, L. A.; Meyer, U.; Werner, H. Inorg.
Chem. 1991, 30, 1159. (e) Esteruelas, M. A.; Oro, L. A.; Valero, C.
Organometallics 1992, 11, 3362.
(3) Esteruelas, M. A.; Oro, L. A.; Valero, C. Organometallics 1991,
10, 462.
(4) (a) Esteruelas, M. A.; Sola, E.; Oro, L. A.; Meyer, U.; Werner, H.
Angew. Chem., Int. Ed. Engl. 1988, 27, 1563. (b) Esteruelas, M. A.;
Garc´ıa, M. P.; Lo´pez, A. M.; Oro, L. A.; Ruiz, N.; Schlu¨nken, C.; Valero,
C.; Werner, H. Inorg. Chem. 1992, 31, 5580. (c) Espuelas, J .; Esteru-
elas, M. A.; Lahoz, F. J .; Oro, L. A.; Valero, C. Organometallics 1993,
12, 663. (d) Albe´niz, M. J .; Buil, M. L.; Esteruelas, M. A.; Lo´pez, A.
M.; Oro, L. A.; Zeier, B. Organometallics 1994, 13, 3746. (e) Esteruelas,
M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Valero, C.; Zeier, B. J . Am.
Chem. Soc. 1995, 117, 7935.
hydrogenated by the metal trichloride to give methanal,
which is probably the source of the carbonyl ligand.1 The
complex OsHCl(CO)(PiPr3)2 is an active and highly
selective catalyst for the reduction of unsaturated
organic substrates2 and for the addition of HSiEt3 to
phenylacetylene.3 In addition, it has been found to be
the master key for the development of extensive orga-
(5) Werner, H.; Esteruelas, M. A.; Meyer, U.; Wrackmeyer, B. Chem.
Ber. 1987, 120, 11.
(6) (a) Werner, H.; Esteruelas, M. A.; Otto, H. Organometallics 1986,
5, 2295. (b) Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, J . A.; Oro, L. A.;
Schlu¨nken, C.; Valero, C.; Werner, H. Organometalllics 1992, 11, 2034.
(7) (a) Werner, H.; Meyer, U.; Esteruelas, M. A.; Sola, E.; Oro, L. A.
J . Organomet. Chem. 1989, 366, 187. (b) Esteruelas, M. A.; Lahoz, F.
J .; Lo´pez, A. M.; On˜ate, E.; Oro, L. A. Organometallics 1995, 14, 2496.
X Abstract published in Advance ACS Abstracts, February 1, 1997.
(1) Esteruelas, M. A.; Werner, H. J . Organomet. Chem. 1986, 303,
221.
S0276-7333(96)00525-0 CCC: $14.00 © 1997 American Chemical Society

Synthesis of OsHCl(CdCHPh)(PiPr3)2
Organometallics, Vol. 16, No. 4, 1997 637
Sch em e 1
and heterogeneous catalytic reactions, including alkene
oligomerization, polymerization, metathesis of olefins,16
and Fischer-Tropsch synthesis,17 the isolated com-
pounds of this type are very rare. Werner has reported
that the treatment of IrCl(CdCHR)(PiPr3)2 with HBF4
in ether results in the formation of [IrHCl(CdCHR)-
(PiPr3)2]+ (R ) H, Me, Ph), which, in solution, smoothly
rearranges by a 1,3-hydrido shift to afford the isomers
[IrCl(CCH2R)(PiPr3)2]+ (R ) H, Me).18 Bercaw has
*
described that the reaction of Cp2 TaCl2 with vinylmag-
nesium bromide gives the neutral hydrido-vinylidene
*
*
Cp2 TaH(CdCH2), which leads to Cp2 Ta(CHdCH2)(CO)
by reaction with carbon monoxide.19 Bianchini has
observed that the 16-electron fragment [(PP3)OsH]+
(PP3 ) P(CH2CH2PPh2)3) is capable of promoting the
terminal alkyne to vinylidene tautomerism.20 We have
shown that the reaction of OsHCl(CO)(PiPr3)2 with
cyclohexylacetylene leads to OsHCl(CdCHCy) (CO)-
(PiPr3)2, which evolves to Os{(E)-CHdCHCy}Cl(CO)-
(PiPr3)2 in solution.21
With the notable exception of Werner’s complexes, the
above mentioned hydrido-vinylidene derivatives are
species of 18 valence electrons. The interest and the
novelty of the unsaturated hydrido-vinylidene com-
pounds prompted us to carry out the reaction of
OsHCl2(CCH2Ph)(PiPr3)2 with sodium methoxide in
order to prepare OsHCl(CdCHPh)(PiPr3)2. In this
paper, we report the synthesis and spectroscopic char-
acterization of this unusual complex, which is capable
of activating molecular oxygen, and the synthesis and
characterization of new six-coordinate hydrido-vi-
nylidene derivatives.
In agreement with the proposal that the carbonyl
ligand of OsHCl(CO)(PiPr3)2 is generated from methanol
through methanal, Meyer has found that the treatment
of OsCl3‚xH2O with triisopropylphosphine in refluxing
2-propanol leads to OsH2Cl2(PiPr3)2 in ca. 80% yield.14
This complex reacts with terminal alkynes H-CtC-R
to give the hydrido-carbyne compounds OsHCl2(CCH2R)-
(PiPr3)2. The mechanistic proposal for this transforma-
tion (Scheme 1) involves the initial coordination of the
alkyne to the osmium atom of OsH2Cl2(PiPr3)2 to give
dihydrido-π-alkyne-osmium(IV) intermediates, in equi-
librium with dihydrogen-π-alkyne-osmium(II) species.
The formal d4 f d6 reduction should favor the isomer-
ization of the π-alkyne complexes into vinylidene inter-
mediates. In this way, the subsequent electrophilic
attack of the acidic hydrogen of the dihydrogen ligand
to the Câ carbon atom of the vinylidene groups could
give the hydrido-carbyne complexes.15
According to Scheme 1, the key intermediates in the
formation of the hydrido-carbyne complexes are the
species OsCl2(η2-H2)(CdCHR)(PiPr3)2. Complexes of
this type have not been previously isolated. However,
the related carbonyl compound OsCl2(η2-H2)(CO)(PiPr3)2
has been recently reported. In solution, this complex
is highly activated toward HCl elimination, as a result
of the heterolytic cleavage of the dihydrogen ligand.4e
If the mechanistic proposal shown in Scheme 1 is
correct, in solution, one should expect an equilibrium
between the hydrido-carbyne complexes and no detect-
able concentrations of OsCl2(η2-H2)(CdCHR)(PiPr3)2. As
the related carbonyl complex, the dihydrogen-vi-
nylidene species should be activated toward HCl elimi-
nation. So, the treatment of the hydrido-carbyne
complexes with stronger bases than the Câ carbon atom
of a vinylidene group may afford five-coordinate hy-
drido-vinylidene complexes OsHCl(CdCHR)(PiPr3)2,
related to OsHCl(CO)(PiPr3)2.
Resu lts a n d Discu ssion
1. Syn th esis a n d Ch a r a cter iza tion of OsHCl-
(CdCHP h )(P iP r 3)2. Treatment at room temperature
of a tetrahydrofuran solution of the hydrido-carbyne
complex OsHCl2(CCH2Ph)(PiPr3)2 (1) with sodium meth-
oxide in a 1:1 molar ratio for 15 min gives, after solvent
removal, a sticky residue. Pentane extraction of the
residue and filtration to remove NaCl affords a green
solution, from which the five-coordinate hydrido-vi-
Although hydrido-vinylidene complexes are consid-
ered important intermediates in several homogeneous
nylidene complex OsHCl(CdCHPh)(PiPr3)2 (2) was iso-
lated as a green solid in 82% yield (eq 2).
(8) Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, A. M.; On˜ate, E.; Oro, L.
A. Organometallics 1994, 13, 1669.
(9) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Zeier, B.
Organometallics 1994, 13, 1662.
(16) (a) Turner, H. W.; Schrock, R. R.; Fellman, J . D.; Holmes, S. J .
J . Am. Chem. Soc. 1983, 105, 4942. (b) Green, J . C.; Green, M. L. H.;
Morley, C. P. Organometallics 1985, 4, 1302.
(10) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Sola, E.
J . Am. Chem. Soc. 1996, 118, 89.
(11) Bohanna, C.; Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro,
L. A.; Sola, E. Organometallics 1995, 14, 4825.
(12) Espuelas, J .; Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, A. M.; Oro,
L. A.; Valero, C. J . Organomet. Chem. 1994, 468, 223.
(13) Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A. M.; Oro, L. A.
Organometallics 1996, 15, 878.
(14) (a) Meyer, U. Ph.D. Thesis, University of Wu¨rzburg, 1988. (b)
Aracama, M.; Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, J . A.; Meyer, U.;
Oro, L. A.; Werner, H. Inorg. Chem. 1991, 30, 288.
(15) Espuelas, J .; Esteruelas, M. A.; Lahoz, F. J .; Oro, L. A.; Ruiz,
N. J . Am. Chem. Soc. 1993, 115, 4683.
(17) (a) McCandlish, L. E. J . Catal. 1983, 83, 362. (b) Erley, W.;
McBreen, P. H.; Ibach, H. J . Catal. 1983, 84, 229. (c) Hoel, E. L.; Ansell,
G. B.; Leta, S. Organometallics 1986, 5, 585. (d) Hoel, E. L. Organo-
metallics 1986, 5, 587. (e) Zheng, C.; Apeloig, V.; Hoffmann, R. J . Am.
Chem. Soc. 1988, 110, 749.
(18) Ho¨hn, A.; Werner, H. Angew. Chem., Int. Ed. Engl. 1986, 25,
737.
(19) Van Asselt, A.; Burger, B. J .; Gibson, V. C.; Bercaw, J . E. J .
Am. Chem. Soc. 1986, 108, 5347.
(20) Barbaro, P.; Bianchini, C.; Peruzzini, M.; Polo, A.; Zanobini,
F.; Frediani, P. Inorg. Chim. Acta 1994, 220, 5.
(21) Esteruelas, M. A.; Oro, L. A.; Valero, C. Organometallics 1995,
14, 3596.

638 Organometallics, Vol. 16, No. 4, 1997
Bourgault et al.
Ta ble 1. Equ ilibr iu m Con sta n ts a n d Ra tes for
Con ver sion of 2a in to 2b in Tolu en e-d 8
temp (°C)
K
k1 (s-1
)
-70
-60
-50
-40
-30
-20
-10
0
10
24
30
40
1.653
1.538
1.439
7 × 101
1 × 102
3 × 102
8 × 102
25 × 102
80 × 102
18 × 103
55 × 103
10 × 104
30 × 104
50 × 104
70 × 104
12 × 105
1.146
1.088
1.030
0.976
0.953
0.934
0.912
0.885
50
60
phosphine ligands are equivalent. This indicates that
CR, Câ, and the substituents of the vinylidene group lie
in a plane, which is perpendicular to the P-Os-P plane,
in agreement with that observed by X-ray diffraction
analysis in substituted vinylidene compounds contain-
ing two bulky phosphine ligands.22 The structure of 2,
therefore, is as that of the five-coordinate carbonyl
complex OsHCl(CO)(PiPr3)2,1 with the vinylidene ligand
in the position of the carbonyl group. Previous results
obtained by Caulton and co-workers on the related
system RuHX(CO)(PtBu2Me)2 suggest that the high
stability of the T shape with X disposed trans to the
π-acceptor ligand is a result of a push-pull mechanism
between the π-donor and the π-acceptor groups.23 Al-
though the vinylidene is a less efficient π-acceptor ligand
than the carbonyl group, complex 2 also shows a
disposition of this type, most probably because the
methyl groups of the phosphine ligands have an impor-
tant contribution to the stabilization of the T shape. In
this context, it should be noted that all five-coordinate
ruthenium(II) and osmium(II) complexes, containing
two triisopropylphosphine ligands and characterized by
X-ray diffraction analysis, show a square-pyramidal
arrangement of ligands around of the metallic center,
with the phosphine ligands mutually trans disposed.
The sixth (formally unoccupied) position of the octahe-
dron is well-shielded by 4 of the 12 methyl groups of
the phosphines, which surround the metal like an
umbrella.6a,24ab
F igu r e 1. Hydrido region of the 1H NMR spectrum of 2
at different temperatures: experimental in toluene-d8 (left)
and calculated (right).
In the IR spectrum of 2 in Nujol, the most noticiable
absorption is that corresponding to the vibration ν(Os-
H), which appears at 2019 cm-1. At room temperature,
1
the H NMR spectrum shows the expected resonances
for the triisopropylphosphine ligands and the phenyl
group of the vinylidene, along with a triplet at 2.03 ppm
(J P-H ) 2.6 Hz) assigned to the dCHPh proton, and a
broad triplet at -15.82 ppm (J P-H ) 19 Hz) correspond-
ing to the hydrido ligand. At the same temperature,
the CR and Câ carbon atoms of the vinylidene group
appear in the 13C{1H} NMR spectrum as triplets at
283.9 and 109.0 ppm with P-C coupling constants of 10.2
and 3.3 Hz, respectively. The 31P{1H} NMR spectrum
shows a singlet a 37.0 ppm.
1
The H, 13C{1H}, and 31P{1H} NMR spectra of 2 are
temperature-dependent. Figure 1 shows the hydrido
region of the 1H NMR spectra in toluene-d8 between -60
and 50 °C. At -60 °C, the spectrum contains two broad
hydrido resonances at -13.5 and -18.7 ppm. On
raising the temperature, they coalesce, and the resulting
averaged signal finally sharpens to give a triplet, the
chemical shift of this triplet being temperature-depend-
ent. This behavior can be understood as the result of
the equilibrium between the two possible conformers of
2 (eq 3). The lower field hydrido resonance at -13.5
The constants for the equilibrium between 2a and 2b
were measured in the range from -70 to 50 °C (Table
1). The temperature dependence of the equilibrium
(Figure 2) provides values for ∆H° and ∆S° of -0.7
((0.1) kcal mol-1 and -2.3 ((0.6) cal K-1 mol-1
,
respectively. The obtained values for ∆H° and ∆S°
suggest that both conformers have a similar thermody-
(22) (a) Alonso, F. J . G.; Ho¨hn, A.; Wolf, J .; Otto, H.; Werner, H.
Angew. Chem., Int. Ed. Engl. 1985, 24, 406. (b) Ho¨hn, A.; Otto, H.;
Dziallas, M.; Werner, H. J . Chem. Soc., Chem. Commun. 1987, 852.
(c) Rappert, T.; Nurnberg, O.; Mahr, N.; Wolf, J .; Werner, H. Organo-
metallics 1992, 11, 4156. (d) Werner, H.; Stark, A.; Schulz, M.; Wolf,
J . Organometallics 1992, 11, 1126. (e) Weber, B.; Steiner, P.; Wind-
muller, B.; Wolf, J .; Werner, H. J . Chem. Soc., Chem. Commun. 1994,
2595.
(23) (a) Poulton, J . T.; Folting, K.; Streib, W. E.; Caulton, K. G. Inorg.
Chem. 1992, 31, 3190. (b) Poulton, J . T.; Sigalas, M. P.; Eisenstein,
O.; Caulton, K. G. Inorg. Chem. 1993, 32, 5490. (c) Hegn, R. H.;
Huffman, J . C.; Caulton, K. G. New J . Chem. 1993, 17, 797. (d) Poulton,
J . T.; Sigalas, M. P.; Folting, K.; Streib, W. E.; Eisenstein, O.; Caulton,
K. G. Inorg. Chem. 1994, 33, 1476.
ppm is assignable to the conformer 2a , because we
assume that the ring current effects of the aromatic ring
of the vinylidene group on the hydrido ligand should be
greater in 2a than that in 2b. At -60 °C, the 13C{1H}
and 31P{1H} NMR spectra also support the presence of
2a and 2b in solution. Thus, the 13C{1H} NMR shows
four broad resonances for the CR and Câ carbon atoms
of the vinylidene ligand at 283.5 and 282.7 (CR) and
104.1 and 103.2 (Câ) ppm, and the 31P{1H} NMR
spectrum contains two singlets at 38.6 and 36.9 ppm.
The presence of two singlets in this spectrum suggests
that for both 2a and 2b, the mutualy trans disposed
(24) (a) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Zeier,
B. Organometallics 1994, 13, 4258. (b) Bohanna, C.; Esteruelas, M.
A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A. Organometallics 1995, 14, 4685.
(c) Atencio, R.; Bohanna, C.; Esteruelas, M. A.; Lahoz, F. J .; Oro, L. A.
J . Chem. Soc., Dalton Trans. 1995, 2171.

Synthesis of OsHCl(CdCHPh)(PiPr3)2
Organometallics, Vol. 16, No. 4, 1997 639
the carbyne ligand could explain the low value of the
activation enthalpy.
The five-coordinate carbonyl complex OsHCl(CO)-
(PiPr3)2 reacts with HCl to give the dihydrogen deriva-
tive OsCl2(η2-H2)(CO)(PiPr3)2.4e The related five-coor-
dinate vinylidene complex 2 also reacts with HCl.
However, the isolated product from the reaction is not
OsCl2(η2-H2)(CdCHPh)(PiPr3)2 but the hydrido-car-
byne 1 (eq 4).
F igu r e 2. Arrhenius plot of the equilibrium constants for
conversion of conformer 2a into conformer 2b.
The formation of 1, according to eq 4, is in agreement
with the participation of the vinylidene intermediates
during the last step of the reaction of the dihydrido-
dichloro OsH2Cl2(PiPr3)2 with terminal alkynes (Scheme
1) and suggests that the most basic center of 2 is the
Câ carbon atom of the vinylidene ligand. In agreement
with this, we have also observed that the addition of
the stoichiometric amount of a water solution of HBF4
to a toluene solution of 2 produces a beige solid in 65%
yield, which was characterized as the cationic hydrido-
carbyne complex [OsHCl(CCH2Ph)(H2O)(PiPr3)2]BF4 (3,
eq 5).
F igu r e 3. Eyring plot of the rate constants for conversion
of conformer 2a into conformer 2b.
The IR spectrum of 3 in Nujol shows the characteristic
ν(Os-H) band at 2156 cm-1, along with absorptions due
to [BF4]- at 1071, 1061, and 1036 cm-1. The splitting
of the Td symmetry of the anion suggests that in the
solid state, it interacts with the water molecule.24c At
room temperature, the 1H NMR spectrum in dichlo-
romethane-d2 contains the expected resonances for the
phosphine ligands and the phenyl group of the carbyne
ligand, a singlet at 2.86 ppm, corresponding to the
-CH2Ph protons, and two broad resonances, one of them
due to the water molecule at about 3.0 ppm and the
other corresponding to the hydrido ligand between -7
and -8 ppm. At -60 °C, the resonace of the water
molecule appears as a broad singlet located at 4.39 ppm,
while the hydrido resonance is observed at -6.36 ppm
as a triplet with a P-H coupling constant of 15.8 Hz.
At room temperature, the 31P{1H} NMR spectrum shows
a broad signal centered at 37.5 ppm. At -60 °C, this
signal is converted into a singlet at 30.1 ppm. At -60
°C, the 3C{1H} NMR spectrum contains a triplet at
278.9 ppm with a P-C coupling constant of 9 Hz and a
singlet at 57.3 ppm, which were assigned to the CR and
Câ carbon atoms of the carbyne ligand, respectively. The
above mentioned spectroscopic data suggest that in
solution, the cation of 3 is in equilibrium with a five-
coordinate hydrido-carbyne cation 3a , which is formed
as a result of the disociation of the water molecule from
3 (eq 6).
namic stability, as, at first glance, could be expected
from the proposed structures. At low temperatures, the
concentration of 2b is slightly higher than the concen-
tration of 2a . However at high temperatures, the latter
conformer is slightly more stable than the first one.
Line shape analysis of the spectra of Figure 1 allows
the calculation of the rate constants for the exchange
process between the relative positions of the vinylidene
substituents (Table 1). The activation parameters
obtained from the Eyring analysis (Figure 3) are ∆Hq
) 11.0 ((0.2) kcal mol-1 and ∆Sq ) 3.2 ((0.6) cal K-1
mol-1 . The activation entropy is nearly zero, suggest-
ing that the exchange process is intramolecular. The
value of the activation enthalpy is significantly lower
than those found for the related process in the vi-
nylidene complexes [(η5-C5H5)Re(NO)(PPh3)(dCdCHR)]+
(about 20 kcal mol-1), where it has been proposed that
the RedCdC isomerization occurs predominantly by
simple rotation around the Re-CR bond.25 In addition,
it should be noted that complex 2 is isoelectronic and
contains the same ligands as the [IrHCl(CdCHR)-
(PiPr3)2]+ complexes, which in solution are in equilib-
rium with the carbyne isomers [IrCl(CCH2R)(PiPr3)2]+.18
So, it appears reasonable to think that in solution,
complex 2 affords the short-lived species OsCl(CCH2-
Ph)(PiPr3)2 by a 1,3-hydrido shift. Thus, the rotation
of the -CH2Ph group around the single C-C bond of
Activa tion of Molecu la r Oxygen by 2. Transition
metal oxo complexes offer application in homogeneous
catalysis, including the oxidation of organic substrates
(25) Senn, D. R.; Wong, A.; Patton, A. T.; Marsi, M.; Strouse, C. E.;
Gladysz, J . A. J . Am. Chem. Soc. 1988, 110, 6096.

640 Organometallics, Vol. 16, No. 4, 1997
Bourgault et al.
with molecular oxygen. From a mechanistic point of
view, the reduction of the oxo complexes by the organic
substrates could directly occur. However, in general,
the reduced species of the oxo complex reagents cannot
be reoxidized by air but require stronger oxidants.26 In
this context, the formation of dioxo complexes by dioxy-
gen activation is a reaction of general interest.
In the solid state and in solution, complex 2 is stable
if kept under argon. However, at room temperature
under air, it is capable of activating the oxygen-oxygen
double bond of the molecular oxygen from the air to give
the dioxo compound OsCl{(E)-CHdCHPh}(O)2(PiPr3)2
(4)27 as an air-stable dark brown solid. The formation
of 4 further involves the migration of the hydrido ligand
at the CR carbon atom of the vinylidene group (eq 7).
F igu r e 4. Molecular diagram of the complex OsCl{(E)-
CHdCHPh}(O)2(PiPr3)2 (4).
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for th e Com p lex
OsCl{(E)-CHdCHP h }(O)2(P iP r 3)2 (4)
Bond Lengths
Os-P(1)
Os-P(2)
Os-Cl
Os-O(1)
Os-O(2)
Os-C(1a)
2.476(6)
2.496(6)
2.519(5)
1.701(11)
1.718(12)
1.985(14)
Os-C(1b)
1.979(30)
1.297(28)
1.502(31)
1.292(45)
1.500(82)
C(1a)-C(2a)
C(2a)-C(3a)
C(1b)-C(2b)
C(2b)-C(3b)
Complex 4 was characterized by elemental analysis,
1
IR and H, 31P{1H}, and 13C{1H} NMR spectroscopies,
and X-ray diffraction. Figure 4 shows the molecular
diagram of the structure of 4. Selected bond distances
and angles are listed in Table 2.
Bond Angles
P(1)-Os-P(2)
P(1)-Os-Cl
P(1)-Os-O(1)
P(1)-Os-O(2)
P(1)-Os-C(1a)
P(1)-Os-C(1b)
P(2)-Os-Cl
P(2)-Os-O(1)
P(2)-Os-O(2)
P(2)-Os-C(1a)
P(2)-Os-C(1b)
Cl-Os-O(1)
Cl-Os-O(2)
Cl-Os-C(1a)
178.2(2)
88.7(2)
88.9(4)
91.5(5)
91.2(5)
93(1)
89.5(2)
90.9(4)
88.8(5)
90.7(5)
89(1)
Cl-Os-C(1b)
170(1)
179.5(5)
82.4(6)
100(1)
97.2(7)
80(1)
124(2)
127(2)
121(3)
125(3)
131(3)
125(4)
122(6)
124(6)
O(1)-Os-O(2)
The geometry of the complex can be rationalized as a
distorted octahedron with the two phosphorus atoms of
the triisopropylphosphine ligands occupying the apical
positions (P(1)-Os-P(2) ) 178.2(2)°). The equatorial
plane is formed by the two oxygen atoms mutually trans
disposed (O(1)-Os-O(2) ) 179.5(5)°) and the chlorine
atom and the styryl ligand also in relative trans posi-
tions (Cl-Os-C(1a) ) 172.2(5)°, Cl-Os-C(1b) ) 170-
(1)°).
The osmium oxygen distances (Os-O(1) ) 1.701(11)
Å and Os-O(2) ) 1.718(12) Å) are statistically identical
and very similar to those previously reported for the
complexes Os(mes)2(O)2 (1.700(7) and 1.690(7) Å),28
[Me4N]2 [Os(O)2(COOMe)2(µ-OMe)]2 (1.728(5) and 1.722-
(5) Å),29 Os(CH3)2(O)2(py)2 (1.723(3) and 1.648(2) Å),
Os{CH2Si(CH3)3}2(O)2(py)2 (1.716(4) and 1.724(3) Å),30
Os(C6F5)2(O)2(py)2 (1.706(5) and 1.737(5) Å),31 and [(mes)-
O(1)-Os-C(1a)
O(1)-Os-C(1b)
O(2)-Os-C(1a)
O(2)-Os-C(1b)
Os-C(1a)-C(2a)
C(1a)-C(2a)-C(3a)
C(2a)-C(3a)-C(4a)
C(2a)-C(3a)-C(8a)
Os-C(1b)-C(2b)
C(1b)-C(2b)-C(3b)
C(2b)-C(3b)-C(4b)
C(2b)-C(3b)-C(8b)
89.8(4)
90.6(5)
172.2(5)
N2][Os(mes)(O)2(ONO2)2] (1.718(10) and 1.710(9) Å).32
In agreement with the relative trans position of the
oxygen atoms, the IR spectrum of 4 in Nujol contains a
single Os-O stretch at 841 cm-1
.
It has been previously proposed that the formation
of oxo compounds involves the participation of µ-peroxo
intermediates.26a The relative trans position of the oxo
ligands in 4 is in agreement with this proposal. In this
case, the µ-peroxo intermediates could be formed ac-
cording to Scheme 2. The five-coordinate carbonyl
complex OsHCl(CO)(PiPr3)2 reacts with molecular oxy-
gen to give the peroxo compound OsHCl(η2-O2)(CO)-
(PiPr3)2, which is stable.4a Similarly, the hydrido-
vinylidene complex 2 could coordinate dioxygen to afford
the peroxo-vinylidene complex 5. The six-coordinate
hydrido-carbonyl compounds show a low tendency to
give formyl derivatives by migratory CO insertion in the
hydrido ligand. In contrast, the six-coordinate hydrido-
(26) (a) Mimoun, H. In Comprehensive Coordination Chemistry;
Wilkinson, G., Gillard, R. D., McCleverty, J . A., Eds.; Pergamon:
Oxford, 1987; Vol. 6, Chapter 61.3. (b) J acobsen, E. N. In Comprehen-
sive Organometallic Chemistry II; Abel, E. W., Stone, F. G., Wilkinson,
G., Eds.; Pergamon: Oxford, 1995; Vol. 12, Chapter 11.1.
(27) This complex can also be prepared with pure dioxygen with
pentane as the solvent.
(28) Stravropoulos, P.; Edwards, P. G.; Behling, T.; Wilkinson, G.;
Motevalli, M.; Hursthouse, M. B. J . Chem. Soc., Dalton Trans. 1987,
169.
(29) Arnold, J .; Wilkinson, G.; Hussain, B.; Hursthouse, M. B.
Polyhedron 1989, 8, 597.
(30) (a) Herrmann, W. A.; Eder, S. J .; Kiprof, P.; Rypdal, K.;
Watzlowik, P. Angew. Chem., Int. Ed. Engl. 1990, 29, 1445. (b)
Herrmann, W. A.; Eder, S. J .; Kiprof, P. J . Organomet. Chem. 1991,
413, 27.
(31) Herrmann, W. A.; Eder, S. J .; Kiprof, P. J . Organomet. Chem.
1991, 412, 407.
(32) McGilligan, B. S.; Arnold, J .; Wilkinson, G.; Hussain-Bates, B.;
Hursthouse, M. B. J . Chem. Soc., Dalton Trans. 1990, 2465.

Synthesis of OsHCl(CdCHPh)(PiPr3)2
Organometallics, Vol. 16, No. 4, 1997 641
Sch em e 2
Sch em e 3
vinylidene complexes generally evolve to alkenyl deriva-
tives by migratory insertion of the CR carbon atom of
the vinylidene ligand into the metal-hydrido bond.21,33
So, the insertion of the CR carbon atom of the vinylidene
ligand of 5 into the osmium-hydrido bond could afford
unsaturated peroxo-styryl species (6). The coupling of
several units of 6 by one oxygen atom of the peroxo
ligand could give 7, which finally should lead to 4.
In the X-ray experiment, the styryl group of 4 was
found to be disordered. So, it was modeled using two
different moieties and refined with a complementary
occupancy factor (see Experimental Section). Despite
this, we can without a doubt say that the styryl group
has an E-stereochemistry. Thus, the 1H NMR spectrum
of 4 shows, for the HR and Hâ protons of the styryl
ligand, two doublets at 9.69 and 7.03 ppm, with a H-H
coupling constant of 16 Hz, a value which is character-
istic for this arrangement.6a In the 13C{1H} NMR
spectrum, the olefinic carbon atoms of the alkenyl group
display two triplets at 135.6 and 77.6 ppm with P-C
coupling constants of 6.2 and 16.2 Hz, respectively. The
-CH groups of the phosphines give a virtual triplet at
23.8 ppm (N ) 22.1 Hz), which is characteristic of two
equivalent triisopropylphosphine ligands in a relative
trans position. This is in agreement with the singlet
at 2.1 ppm found in the 31P{1H} NMR spectrum.
Syn th esis of Six-Coor din ate Hydr ido-Vin yliden e
Com p lexes. In pentane at -78 °C, the five-coordinate
hydrido-vinylidene complex 2 adds trimethylphosphite
to form the six-coordinate hydrido-vinylidene com-
pound OsHCl(CdCHPh){P(OMe)3}(PiPr3)2 (8), which
was isolated at -78 °C as a pink solid in 74% yield
(Scheme 3). Under argon in the solid state, the complex
is stable at 0 °C. However, in solution, it decomposes
to a mixture from which was isolated an ill-defined
straw-colored solid.
The spectroscopic data obtained for 8 at -30 °C
(33) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Rodriguez,
L.; Steinert, P.; Werner, H. Organometallics, in press.
support the structure proposed in Scheme 3. The 31P-

642 Organometallics, Vol. 16, No. 4, 1997
Bourgault et al.
Sch em e 4
{1H} NMR spectrum consists of a triplet at 98.0 ppm
and a doublet at 9.8 ppm (J P-P′ ) 18.6 Hz), in agreement
with a phosphite ligand cis to two equivalent triisopro-
pylphosphine ligands. The proposed trans disposition
of the hydrido and phosphite ligands is supported by
Complex 12, which is the first known hydrido-
hydroxyvinylidene compound, was isolated as an orange
solid in 60% yield. In the IR spectrum of 12 in Nujol,
the most noticiable absorptions are those corresponding
to the ν(O-H) and ν(Os-H) vibrations, which appear
1
1
the H NMR spectrum, which contains, at -4.5 ppm, a
at 3500 and 2104 cm-1. In the H NMR spectrum, the
doublet (J P-H ) 139.5 Hz) of triplets (J P′-H ) 22.8 Hz).
In the low-field region, the spectrum exhibits the
expected resonances for the phosphorus donor ligands
and the aromatic protons of the phenyl ring of the
vinylidene ligand, along with a broad signal at 1.58 ppm
corresponding to the dCHPh proton. In the 13C{1H}
NMR spectrum, the CR and Câ carbon atoms appear at
296.4 and 106.8 ppm as two broad signals.
hydrido ligand gives a triplet at -11.51 ppm with a P-H
coupling constant of 14.7 Hz. The low-field region
contains the expected resonances for the triisopropy-
lphosphine ligands and the phenyl protons of the
hydroxyvinylidene group, along with a singlet at 3.01
ppm corresponding to the -OH proton, and a triplet
(J P-H ) 3.0 Hz) at 1.74 ppm due to the dCH proton. In
the 13C{1H} NMR spectrum, the CR and Câ carbon atoms
of the hydroxyvinylidene ligand appear at 282.9 and
113.3 ppm as triplets, with P-C coupling constants of
10.5 and 3.1 Hz, respectively, while the COH carbon
atom is observed at 66.0 ppm as a singlet. The 31P{1H}
NMR spectrum shows a singlet at 24.1 ppm.
Complex 13, which is also the first known hydrido-
vinylvinylidene compound, was isolated as an orange
solid in 45% yield. The presence of a hydrido ligand in
13 was inferred from its 1H NMR spectrum, which
contains a triplet at -12.22 ppm with a P-H coupling
constant of 15.7 Hz. In the 13C{1H} NMR spectrum, the
CR and Câ carbon atoms of the vinylidene group appear
at 292.7 and 110.5 ppm as triplets with P-C coupling
constants of 10.5 and 3.2 Hz, respectively, while the
vinylic carbon atoms give rise to a triplet at 126.0 ppm
(J P-C ) 2.3 Hz) and a singlet at 110.7 ppm. The 31P-
{1H} NMR spectrum shows a singlet at 25.2 ppm.
Using complex 2 as the starting material, octahedral
six-coordinate hydrido-vinylidene complexes cannot
only be obtained by addition of ligands L, such as
trimethylphosphite, but also by displacement of the
chloride by acetylacetonato (acac) and acetato anions
(Scheme 3). The acetylacetonato complex OsH(acac)
(CdCHPh)(PiPr3)2 (9), was isolated as a brown solid in
42% yield. The IR spectrum of 9 in Nujol shows a ν-
1
(Os-H) band at 2093 cm-1. In the H NMR spectrum,
the hydrido signal appears as a triplet at -10.36 ppm,
with a P-H coupling constant of 16.5 Hz, and the
dCHPh proton gives a triplet at 2.32 ppm with a P-H
coupling constant of 2.5 Hz. In the 13C{1H} NMR
spectrum, the CR carbon atom of the vinylidene ligand
gives rise to a triplet at 289.7 ppm with a P-C coupling
constant of 10.2 Hz. The 31P{1H} NMR spectrum shows
a singlet at 24.9 ppm.
The acetato complex OsH(η2-O2CCH3)(CdCHPh)-
(PiPr3)2 (10) can also be obtained from the reaction of
the trihydrido-acetato compound OsH3(η2-O2CCH3)-
(PiPr3)2 (11) with the stoichiometric amount of pheny-
lacetylene.34 Hydroxyvinylidene and vinylvinylidene
complexes can be similarly prepared by reaction of 11
with alkynols. Thus, the complexes OsH(η2-O2CCH3)
{CdCHC(OH)Ph2}(PiPr3)2 (12) and OsH(η2-O2CCH3)-
The formation of 13 most probably involves the
participation of an hydroxyvinylidene intermediate,
which dehydrates under the reaction conditions. The
dehydration of hydroxyvinylidenes containing hydrogen
atoms adjacent to the hydroxy group can occur in two
different directions to give either vinylvinylidene or
allenylidene derivatives, depending on the electronic
and steric properties of the metal.35 Vinylvinylidene
products are obtained exclusively from reactions of the
rich electron fragment [Ru(η5-C5H5)(PMe3)2]+ with alkyn-
1-ols containing hydrogen atoms adjacent to the hydroxy
{CdCHCdCH(CH2)3CH2}(PiPr3)2 (13) were synthesized
starting from 1,1-diphenyl-2-propyn-1-ol and 1-ethynyl-
1-cyclohexanol, respectively (Scheme 4).
(34) Esteruelas, M. A.; Oro, L. A.; Ruiz, N. Organometallics 1994,
13, 1507.
(35) (a) Selegue, J . P. Organometallics 1982, 1, 217. (b) Selegue, J .
P. J . Am. Chem. Soc. 1983, 105, 5921.

Synthesis of OsHCl(CdCHPh)(PiPr3)2
Organometallics, Vol. 16, No. 4, 1997 643
group.36 A similar behavior has been observed for the
fragment [Os(η5-C5H5)(CO)(PiPr3)]+, which reacts with
1-ethynyl-1-cyclohexanol to afford the vinylvinylidene
The five-coordinate complex OsHCl(CdCHPh)(PiPr3)2
is also an useful starting material for the preparation
of new six-coordinate hydrido-vinylidene-osmium(II)
derivatives by addition of ligands, such as trimeth-
ylphosphite, and by replacement of the chloride by the
acetato and acetylacetonato anions.
In conclusion, we report the synthesis and spectro-
scopic characterization of the unusual hydrido-vi-
nylidene complex OsHCl(CdCHPh)(PiPr3)2, which ac-
tivates the oxygen-oxygen double bond of the molecular
oxygen from the air and is an useful starting material
to prepare new and unusual vinylidene complexes.
[Os(η5-C5H5){CdCHCdCH(CH2)3CH2}(CO)(PiPr3)]+ in
78% yield.13 The behavior of this electron rich fragment
is in contrast with that observed for [Ru(η5-C5H5) (CO)-
(PiPr3)]+ 37 and the arene system [RuCl2(η6-C6H6)-
(PMe3)] studied by Dixneuf,38 which give hydroxycar-
bene and alkoxycarbene derivatives via allenylidene
intermediates.
Con clu d in g Rem a r k s
Exp er im en ta l Section
This study has revealed that the hydrido-carbyne
complex OsHCl2(CCH2Ph)(PiPr3)2 reacts with sodium
methoxide to give the five-coordinate hydrido-vi-
nylidene derivative OsHCl(CdCHPh)(PiPr3)2, which has
a square-pyramidal structure like that of the well-
known carbonyl complex OsHCl(CO)(PiPr3)2,1 with the
vinylidene ligand in the position of the carbonyl group.
However, there is a marked difference in the behavior
of these complexes toward HCl. Whereas the dihydro-
gen compound OsCl2(η2-H2)(CO)(PiPr3)2 is obtained from
OsHCl(CO)(PiPr3)2 and HCl,4e the reaction of OsHCl-
(CdCHPh)(PiPr3)2 with HCl regenerates OsHCl2(CCH2-
Ph)(PiPr3)2. The formation of this complex is in agree-
ment with the participation of vinylidene intermediates
during the last step of the reaction of OsH2Cl2(PiPr3)2
with terminal alkynes to afford hydrido-carbyne de-
rivatives15 and suggests that the most basic center of
OsHCl(CdCHPh)(PiPr3)2 is the Câ carbon atom of the
vinylidene ligand. In agreement with this, we also
report that the reaction of the vinylidene complex with
a water solution of HBF4 leads to [OsHCl(CCH2Ph)-
(H2O)(PiPr3)2] BF4.
In solution, the compound OsHCl(CdCHPh)(PiPr3)2
has been characterized as a mixture of two conformers
of similar thermodynamic stability (∆H° ) -0.7 ((0.1)
kcal mol-1 and ∆S° ) -2.3 ((0.6) cal K-1 mol-1), which
is a result of the intramolecular exchange between the
relative positions of the vinylidene substituents. The
activation parameters for the exchange process (∆Hq )
11.0 ((0.2) kcal mol-1 and ∆Sq ) 3.2 ((0.6) cal K-1
mol-1) are in agreement with the participation of a
OsCl(CCH2Ph)(PiPr3)2 intermediate, which is formed by
a 1,3-hydrido shift.
All reactions were carried out under an argon atmosphere
using standard Schlenk techniques. Solvents were dried using
the appropiate drying agents and were freshly distilled under
argon before use. 1H, 31P{1H}, and 13C{1H} NMR spectra were
recorded on either a Varian UNITY 300 or on a Bruker 300
AXR spectrometer. Chemical shifts are expressed in ppm
upfield from Me4Si (1H and 13C) and 85% H3PO4 (31P).
Coupling constants (J and N [N ) J P-H + J P′-H or J P-C + J P′-C])
are given in hertz. IR data were recorded on a Perkin-Elmer
783 or on a Nicolet 550 spectrophotometer. Elemental analy-
ses were carried out with a Perkin-Elmer 240C microanalyser.
Mass spectra analyses were performed with a VG Autospec
instrument. In FAB+ mode (used for complexes 2 and 4), ions
were produced with the standard Cs+ gun at ca. 30 kV, and
2-nitrophenyl octyl ether (N-POE) for 2 and 3-nitrobenzyl
alcohol (NBA) for 4 were used as the matrix. The reagents
1,1-diphenyl-2-propyn-1-ol (ABCR) and 1-ethynyl-1-cyclohex-
anol (Fluka) were obtained from commercial sources as
indicated and used without further purification. The starting
complexes OsH2Cl2(PiPr3)2, OsH6(PiPr3)2, and OsHCl2(CCH2-
Ph)(PiPr3)2 (1) were prepared by published methods.14b,15
Kin etic An a lysis. The equilibrium constants K ) k1/k-1
) [2b]/[2a ] were calculated by 1H NMR spectroscopy in
toluene-d8. At temperatures below the coalescence point, the
ratio was calculated by integration of the hydrido signals
corresponding to 2a and 2b and above the coalescence tem-
perature by measuring the chemical shift of the exchange-
averaged hydrido resonance. A least-squares fit of the values
of ln K vs 1/T gave the thermodynamic magnitudes ∆H° and
∆S° involved in this equilibrium. Error analysis assumed a
10% error in the value of the equilibrium constant, whereas
the error in temperature was estimated at 1 K. Errors were
computed by standard error propagation formulas for least-
squares fitting.39
The two parameters K and k1 are sufficient to characterize
and simulate the hydrido regions of the variable-temperature
1H NMR spectra. Complete line shape analysis of the 1H NMR
spectra was achieved using the program DNMR6 (QCPE,
Indiana University). The rate constants (k1) for various
temperatures were obtained by visually matching observed
and calculated spectra. Due to the broadness of the signals
obtained at the lowest temperature reached, the individual
coupling constants J P-H for the two hydrides could not be
evaluated; thus, the averaged value of J P-H was used for both
hydrides. The transverse relaxation time T2 used was common
for the two signals for all temperatures recorded and was
obtained from the line width of the exchange-averaged reso-
nance above the fast-exchange limit. To avoid the influence
of these mentioned simplifications in the calculation of the
activation parameters, only data for the spectra that exhibited
significant line broadening were included. The activaction
parameters ∆Hq and ∆Sq were calculated by least-squares fit
of ln(k1/T) vs 1/T (Eyring equation). Error analysis assumed
Complex OsHCl(CdCHPh)(PiPr3)2 is capable of acti-
vating the oxygen-oxygen double bond of the molecular
oxygen contained in the air, to give the dioxo compound
OsCl{(E)-CHdCHPh}(O)2(PiPr3)2, which has been char-
acterized by X-ray diffraction analysis. From a struc-
tural point of view, it should be mentioned that the
oxygen atoms occupy relative trans positions in an
octahedral enviroment.
(36) Selegue, J . P.; Young, B. A.; Logan, S. L. Organometallics 1991,
10, 1972.
(37) Esteruelas, M. A.; Gomez, A. V.; Lahoz, F. J .; Lo´pez, A. M.;
On˜ate, E.; Oro, L. A. Organometallics, 1996, 15, 3423.
(38) (a) Le Bozec, H.; Touchard, D.; Dixneuf, P. H. Adv. Organomet.
Chem. 1989, 29, 163. (b) Le Bozec, H.; Ouzzine, K.; Dixneuf, P. H. J .
Chem. Soc., Chem. Commun. 1989, 219. (c) Romero, A.; Vegas, A.;
Dixneuf, P. H. Angew. Chem., Int. Ed. Engl. 1990, 29, 215. (d) Le Bozec,
H.; Ouzzine, K.; Dixneuf, P. H. Organometallics 1991, 10, 2768. (e)
Pilette, D.; Ouzzine, K.; Le Bozec, H.; Dixneuf, P. H.; Rickard, C. E.
F.; Roper, W. R. Organometallics 1992, 11, 809. (f) Lavastre, O.;
Dixneuf, P. H.; Pacreau, A.; Vairon, J . P. Organometallics 1994, 13,
2500. (g) Pilette, D.; Moreau, S.; Le Bozec, H.; Dixneuf, P. H.; Corrigan,
J . F.; Carty, A. J . J . Chem. Soc., Chem. Commun. 1994, 409. (h) Peron,
D.; Romero, A.; Dixneuf, P. H. Organometallics 1995, 14, 3319.
(39) Bevington, P. R. Data Reduction and Error Analysis for the
Physical Sciences; McGraw-Hill, New York, 1969; Chapter 4.

644 Organometallics, Vol. 16, No. 4, 1997
Bourgault et al.
a 10% error in the rate constant and 1 K in the temperature.
Errors were computed by published methods.40
green to pink. After 5 min of stirring at -78 °C, the pink solid
formed was decanted, washed twice with 2 mL of pentane at
-78 °C, and dried in vacuo Yield: 101 mg (74%). Anal. Calcd
for C29H58ClO3OsP3: C, 45.05; H, 8.27. Found: C, 45.64; H,
8.27. 1H NMR (300 MHz, CD2Cl2, -30 °C): δ 7.05 (m, 2 H,
m-C6H5), 6.84 (d, J H-H ) 7.0 Hz, 2 H, o-C6H5), 6.66 (m, 1H,
p-C6H5), 3.81 (d, J P-H ) 10.0 Hz, 9 H, P(OCH3)3), 2.71 (m, 6
H, PCHCH3), 1.58 (br, 1 H, dCH), 1.29 (dvt, N ) 12.9 Hz,
J H-H ) 6.6 Hz, 18 H, PCHCH3), 1.24 (dvt, N ) 13.5 Hz, J H-H
P r ep a r a tion of OsHCl(CdCHP h )(P iP r 3)2 (2). A solution
of OsHCl2(CCH2Ph)(PiPr3)2 (1) (110 mg, 0.16 mmol) in 20 mL
of THF was treated with sodium methoxide (9 mg, 0.16 mmol).
After 15 min of stirring, the solution became green. The
solvent was evaporated to dryness, and the residue was
dissolved in 20 mL of pentane. After filtration and concentra-
tion to 1 mL, the solution was left 15 h at -20 °C. The
resulting green solid was decanted, washed with 1 mL of cold
pentane, and dried in vacuo. Yield: 86 mg (82%). Anal. Calcd
for C26H49ClOsP2: C, 48.10; H, 7.61. Found: C, 47.94; H, 8.07.
IR (Nujol, cm-1): ν(Os-H) 2019. 1H NMR (300 MHz, C6D6,
20 °C): δ 7.19 (m, 2 H, m-C6H5), 7.07 (d, J H-H ) 7.0 Hz, 2 H,
o-C6H5), 6.76 (m, 1H, p-C6H5), 2.63 (m, 6 H, PCHCH3), 2.03 (t,
J P-H ) 2.6 Hz, 1 H, dCH), 1.22 (dvt, N ) 13.2 Hz, J H-H ) 7.1
Hz, 18 H, PCHCH3), 1.19 (dvt, N ) 13.7 Hz, J H-H ) 7.1 Hz,
18 H, PCHCH3), -15.82 (t, J P-H ) 19 Hz, 1 H, OsH). 31P{1H}
NMR (121.42 MHz, C6D6, 20 °C): δ 37.0 (s, PiPr3). 13C{1H}
NMR (75.43 MHz, C6D6, 20 °C): δ 283.9 (t, J P-C ) 10.2 Hz,
OsdCdC), 130.4, 123.3, 122.9 (3 s, C6H5), 109.0 (t, J P-C ) 3.3
Hz, OsdCdC), 25.5 (vt, N ) 24.5 Hz, PCHCH3), 20.3, 20.2 (2
s, PCHCH3). 31P{1H} NMR (121.42 MHz, C7D8, -80 °C): δ
38.6, 36.9 (2 s, PiPr3). 13C{1H} NMR (75.43 MHz, C7D8, -60
°C): δ 283.5, 282.7 (2 br, OsdCdC), 124.6-118.0 (C6H5), 104.1,
103.2 (2 br, OsdCdC), 21.3, 19.6 (2 br, PCHCH3), 16.7-15.4
(m, PCHCH3). MS (FAB): m/e 650 (M+).
P r ep a r a tion of [OsHCl(CCH2P h )(H2O)(P iP r 3)2] BF 4 (3).
HBF4 in water (21 µL, 0.154 mmol) was added to a solution of
OsHCl(CdCHPh)(PiPr3)2 (2) (100 mg, 0.154 mmol) in 20 mL
of toluene. The solution changed from green to yellow, and a
white precipitate was formed. After 1 h, the solvent was re-
moved and the residual solid was washed with 3 mL of toluene
and subsequently dried in vacuo, giving a beige powder.
Yield: 76 mg (65%). Anal. Calcd for C26H52BClF4OOsP2: C,
41.34; H, 6.89. Found: C, 40.77; H, 6.92. IR (Nujol, cm-1):
ν(Os-H) 2156, ν(BF4) 1071, 1061, 1036. 1H NMR (300 MHz,
CD2Cl2, 20 °C): δ 7.43-7.15 (m, 5 H, C6H5), 2.95 (br, 2 H, H2O),
2.86 (s, 2 H, CH2), 2.47 (m, 6 H, PCHCH3), 1.38 (dvt, N ) 14.3
Hz, J H-H ) 7.1 Hz, 18 H, PCHCH3), 1.34 (dvt, N ) 14.4 Hz,
J H-H ) 7.2 Hz, 18 H, PCHCH3), -7.5 (br, 1 H, OsH). 31P{1H}
NMR (121.42 MHz, CD2Cl2, 20 °C): δ 37.5 (br, PiPr3). 1H NMR
(300 MHz, CD2Cl2, -60 °C): δ 7.39-7.19 (m, 5 H, C6H5), 4.39
(s, 2 H, H2O), 2.71 (s, 2 H, CH2), 2.26 (br, 6 H, PCHCH3), 1.29
(br, 36 H, PCHCH3), -6.36 (t, J P-H ) 15.8 Hz, 1 H, OsH).
31P{1H} NMR (121.42 MHz, CD2Cl2, 20 °C): δ 30.1 (s, PiPr3).
13C{1H} NMR (75.43 MHz, CD2Cl2, -60 °C) : δ 278.9 (t, J P-C
) 9 Hz, OsC), 129.1, 128.8, 128.2, 126.9 (4 s, C6H5), 57.3 (s,
CH2), 26.0 (br, PCHCH3), 18.8 (s, PCHCH3).
) 6.9 Hz, 18 H, PCHCH3), -4.5 (dt, J P-H ) 139.5 Hz, J P′-H
)
22.8 Hz, 1 H, OsH). 31P{1H} NMR (121.42 MHz, CD2Cl2,-30
°C): δ 98.0 (t, J P-P′ ) 18.6 Hz, P(OMe)3), 9.8 (d, J P-P′ ) 18.6
Hz, PiPr3). 13C{1H} NMR (75.43 MHz, C7D8, -30 °C): δ 296.4
(br, OsdCdC), 131.4, 127.4, 123.3, 121.5 (4 s, C6H5), 106.8 (br,
OsdCdC), 53.8 (dt, J P-C ) 54.5 Hz, J P′-C ) 27.2 Hz, P(OCH3)3),
24.5 (vt, N ) 24.9 Hz, PCHCH3), 19.8, 19.4 (2 s, PCHCH3).
P r ep a r a tion of OsH(a ca c)(CdCHP h )(P iP r 3)2 (9). So-
dium acetylacetonato (29 mg, 0.23 mmol) was added to a
solution of OsHCl(CdCHPh)(PiPr3)2 (2) (151 mg, 0.23 mmol)
in 20 mL of dichloromethane. After the mixture was stirred
for 30 min at room temperature, the mixture was filtered
through kieselguhr and the solvent was evaporated in vacuo.
The residual brown oil was dissolved in 2 mL of ether, and
after 14 h at -20 °C, a pale brown solid precipitated. After
decantation, the solid was washed twice with 2 mL of pen-
tane and dried in vacuo. Yield: 75 mg (42%). Anal. Calcd
for C31H56O2OsP2: C, 52.22; H, 7.92. Found: C, 51.78; H, 7.47.
IR (Nujol, cm-1): ν(Os-H) 2093. 1H NMR (300 MHz, C6D6,
20 °C): δ 7.3-6.8 (m, 5 H, C6H5), 5.06 (t, J P-H ) 2.4 Hz, 1 H,
CH of acac), 2.48 (m, 6 H, PCHCH3), 2.32 (t, J P-H ) 2.5 Hz, 1
H, dCH), 1.75, 1.58 (2 s, 6 H, O-C-CH3), 1.34 (dvt, N ) 13.0
Hz, J H-H ) 6.9 Hz, 18 H, PCHCH3), 1.19 (dvt, N ) 12.6 Hz,
J H-H ) 7.0 Hz, 18 H, PCHCH3), -10.36 (t, J P-H ) 16.5 Hz, 1
H, OsH). 31P{1H} NMR (121.42 MHz, C6D6, 20 °C): δ 24.9 (s,
PiPr3). 13C{1H} NMR (75.43 MHz, C6D6, 20 °C): δ 289.7 (t,
J P-C ) 10.2 Hz, OsdCdC), 185.0, 182.8 (2 s, O-C-CH3), 133.7,
128.9, 123.6, 121.7, 109.6, 101.2 (6 s, C6H5, CH of acac and
Os-CdC), 28.2, 27.3 (2 s, O-C-CH3), 24.4 (vt, N ) 23.0 Hz,
PCHCH3), 19.8, 19.5 (2 s, PCHCH3).
P r ep a r a tion of OsH(η2-O2CCH3)(CdCHP h )(P iP r 3)2(10).
This complex was prepared analogously to 9, starting from 2
(151 mg, 0.23 mmol) and sodium acetato (20 mg, 0.24 mmol).
After the mixture was stirred for 40 min, the mixture was
filtered through kieselguhr. The filtrate was evaporated in
vacuo, and the residual oil was dissolved in 2 mL of pen-
tane. After 15 h at -20 °C, a brown solid precipitated. The
resulting brown solid was decanted, washed with cold pentane,
and dried in vacuo. Yield: 52 mg (33%). Anal. Calcd for
C
28H52O2OsP2: C, 49.97; H, 7.80. Found: C, 49.62; H, 8.30.
P r ep a r a tion of OsCl{(E)-CHdCHP h }(O)2(P iP r 3)2(4). A
solution of OsHCl(CdCHPh)(PiPr3)2 (2) (142 mg, 0.22 mmol)
in 20 mL of pentane was left 1 h in air atm, causing the
precipitation of a dark brown solid. After decantion, the
precipitate was washed twice with 2 mL of pentane and
then dried in vacuo. Yield: 120 mg (80%). Anal. Calcd for
IR (Nujol, cm-1): ν(Os-H) 2130, ν(OCO) 1555, 1460. 1H NMR
(300 MHz, C6D6, 20 °C): δ 7.25-6.83 (m, 5H, C6H5), 2.59 (m,
6H, PCHCH3), 2.25 (t, 2 H, J P-H ) 2.5 Hz, 1 H, dCH), 1.67 (s,
3 H, CH3), 1.33 (dvt, N ) 13.3 Hz, J H-H ) 7.1 Hz, 18 H,
PCHCH3), 1.30 (dvt, N ) 12.8 Hz, J H-H ) 6.9 Hz, 18 H,
PCHCH3), -11.51 (t, J P-H ) 15.6 Hz, 1 H, OsH). 31P{1H} NMR
(121.42 MHz, C6D6, 20 °C): δ 26.8 (s, PiPr3). 13C{1H} NMR
(75.43 MHz, C6D6, 20 °C): δ 291.5 (t, J P-C ) 10.5 Hz, OsdC),
182.6 (s, OCO), 132.1, 123.3, 122.0 (3 s, C6H5), 107.5 (t, J P-C
) 2.8 Hz, dCH), 25.3 (s, CH3), 25.0 (vt, N ) 23.9 Hz, PCHCH3),
19.9, 19.5 (2 s, PCHCH3).
P r ep a r a t ion of OsH (η2-O2CCH 3){CdCH C(OH )P h 2}-
(P iP r 3)2 (12). A solution of OsH6(PiPr3)2 (187 mg, 0.36 mmol)
in 12 mL of toluene was treated with acetic acid (22.5 µL, 0.36
mmol) and heated under reflux for 30 min. After the mixture
was cooled at room temperature, the solution was filtered
through kieselguhr and the filtrate (OsH3(η2-O2CCH3)(PiPr3)2)
treated with 1,1-diphenyl-2-propyn-1-ol (97.56 mg, 0.47 mmol).
After it was stirred for 17 h at room temperature, the solution
was filtered through kieselguhr and concentrated until an
orange-colored solid precipitated. This solid was stored at -78
°C, decanted, washed with acetone, and dried in vacuo.
Yield: 160 mg (60%). Anal. Calcd. for C35H52O3OsP2: C,
53.84; H, 6.66. Found: C, 53.57; H, 6.97. IR (Nujol, cm-1): ν
C
26H49ClO2OsP2: C, 45.79; H, 7.19. Found: C, 45.68; H, 7.04.
IR (Nujol, cm-1): ν(Os-O) 841. 1H NMR (300 MHz, CD2Cl2,
20 °C): δ 9.69 (d, J H-H ) 16.0 Hz, 1 H, HCdCH(C6H5)), 7.26-
6.84 (m, 5 H, C6H5), 7.03 (d, J H-H ) 16.0 Hz, 1 H, HCdCH-
(C6H5)), 2.99 (m, 6 H, PCHCH3), 1.17 (dvt, N ) 13.8 Hz, J H-H
) 6.9 Hz, 36 H, PCHCH3). 31P{1H} NMR (121.42 MHz, CD2-
Cl2, 20 °C): δ 2.1 (s, PiPr3). 13C{1H} NMR (75.43 MHz, CD2-
Cl2, 20 °C): δ 135.6 (t, J P-C ) 6.2 Hz, Os-CdC), 141.7, 134.7,
126.5, 126.1 (4 s, C6H5), 77.6 (t, J P-C ) 16.2 Hz, Os-CdC),
23.8 (vt, N ) 22.1 Hz, PCHCH3), 18.3 (s, PCHCH3). MS
(FAB): m/e 647 (M+ - Cl).
P r ep a r a tion of OsHCl(CdCHP h ){P (OMe)3}(P iP r 3)2 (8).
P(OMe)3 (26 µL, 0.175 mmol) was added to a solution of OsHCl-
(CdCHPh)(PiPr3)2 (2) (114 mg, 0.175 mmol) in 10 mL of
pentane at -78 °C. The solution changed inmediately from
(40) Morse, P. M.; Spencer, M. O.; Wilson, S. R.; Girolami, G. S.
Organometallics 1994, 13, 1646 and references therein.

Synthesis of OsHCl(CdCHPh)(PiPr3)2
Organometallics, Vol. 16, No. 4, 1997 645
(OH) 3500, ν (Os-H) 2104. 1H NMR (300 MHz, C6D6, 20 °C):
δ 7.7 (d, J H-H ) 7.5 Hz, 4 H, o-C6H5), 7.20 (m, 4 H, m-C6H5),
7.00 (m, 2 H, p-C6H5), 3.01 (s, 1 H, OH), 2.58 (m, 6 H,
PCHCH3), 1.74 (t, J P-H ) 3.0 Hz, dCH), 1.63 (s, 3 H, CH3),
1.31 (dvt, N ) 13.8 Hz, J H-H ) 7.2 Hz, 18 H, PCHCH3), 1.26
(dvt, N ) 13.5 Hz, J H-H ) 6.9 Hz, 18 H, PCHCH3), -11.51 (t,
J P-H ) 14.7 Hz, 1 H, OsH). 31P{1H} NMR (121.42 MHz, C6D6,
20 °C): δ 24.1 (s, PiPr3). 13C{1H} NMR (75.43 MHz, C6D6, 20
°C): δ 282.9 (t, J P-C ) 10.5 Hz, OsdC), 182.3 (s, OCO), 152.3
(s, Cipso), 127.9, 126.1, 126.0 (3 s, C6H5), 113.3 (t, J P-C ) 3.1
Hz, dCH), 66.0 (s, COH), 25.1 (s, CH3), 25.0 (vt, N ) 23.8 Hz,
PCHCH3), 19.6, 19.2 (2 s, PCHCH3).
Ta ble 3. Cr ysta l Da ta a n d Da ta Collection a n d
Refin em en t for OsCl{(E)-CHdCHP h }(O)2(P iP r 3)2
(4)
Crystal Data
formula
mw
C26H49ClO2OsP2
681.27
color and habit
cryst size, mm
symmetry
space group
a, Å
dark brown, irregular prism
0.21 × 0.14 × 0.24
triclinic
P1h (No. 2)
9.759(3)
b, Å
c, Å
10.419(3)
15.363(5)
70.81(2)
89.24(2)
83.26(2)
1464.6(8)
2
1.545
R, deg
P r ep a r a t ion
of
OsH (η2-O2CCH 3){CdCH CdCH -
â, deg
γ, deg
(CH2)3CH2}(P iP r 3)2 (13). This complex was prepared analo-
gously to 12, starting from OsH6(PiPr3)2 (295 mg, 0.57 mmol),
acetic acid (33.53 µL, 0.57 mmol), and 1-ethynyl-1-cyclohexanol
(92 mg, 0.74 mmol). After the mixture was stirred for 30 min
at room temperature, the solution was concentrated to dry-
ness. Addition of acetone caused the precipitation of an orange
solid after storing at -78 °C for 2 days. The resulting orange
solid was decanted, washed with acetone, stored at -70 °C,
and dried in vacuo. Yield 202 mg (45%). Anal. Calcd. for
V, Å3
Z
D
calcd, g cm-3
Data Collection and Refinement
diffractometer
λ(Mo KR), Å; technique
monochromator
µ, mm-1
four-circle Siemens-P4
0.710 73; bisecting geometry
graphite oriented
4.57
scan type
θ/2θ
C
23H56O2OsP2: C; 49.73; H, 8.28. Found: C, 49.70; H, 8.18.
2θ range, deg
temp, K
2 e 2θ e 50
IR (Nujol, cm-1): ν(Os-H) 2160, 2138. 1H NMR (300 MHz,
293
no. of data collcd
no. of unique data
no. of params refined
R1a [F2 > 2σ(F2)]
wR2b [all data (Fo g 0)]
Sc
5690
C6D6, 20 °C): δ 5.07 (unresolved t, 1 H, -CdCH(CH2)3CH2),
2.61 (m, 6 H, PCHCH3), 2.53 (br m, 2 H, allylic CH2), 2.24 (br,
3 H, OsCdCH and allylic CH2), 1.72 (br m, 4 H, alkyl CH2),
1.62 (s, 3 H, CH3), 1.33 (dvt, N ) 13.2 Hz, J H-H ) 7.0 Hz, 18
H, PCHCH 3), 1.27 (dvt, N ) 12.6 Hz, J H-H ) 7.0 Hz, 18 H,
PCHCH3), -12.22 (t, J P-H ) 15.7 Hz, 1 H, OsH). 31P{1H} NMR
(121.42 MHz, C6D6, 20 °C): δ 25.2 (s, PiPr3). 13C{1H} NMR
(75.43 MHz, C6D6, 20 °C): δ 292.7 (t, J P-C ) 10.5 Hz, OsdC),
4845 (Rint ) 0.0503)
286
0.0731
0.1840
0.983
a
b
2
R1(F) ) Σ||Fo| - |Fc||Σ|Fo|. wR2(F2) ) {Σ[w(Fo - Fc2)2]/
Σ[w(Fo2)2]}1/2
.
c Goodness of fit ) S ) {Σ[w(Fo - Fc2)2]/(n - p)}1/2
,
2
where n is the number of observed reflections and p is the number
182.2 (t, J P-C ) 1.5 Hz, OC|O), 126.0 (t, J P-C ) 2.3 Hz, dCHs
of refined parameters.
|
CdCH), 110.7 (s, dCHsCdCH), 110.5 (t, J P-C ) 3.2 Hz,
|
a-labeled atoms and 0.29(2) for the b ones. The styryl groups
were refined including geometrical restrictions, the distances
C(1)-C(2) and C(2)-C(3) were fixed to 1.29(1) and 1.49(1) Å
(medium values observed in the CSD44 for related styryl
complexes of osmium: DFIX43 facility), and both groups were
refined with the identical geometry (SAME43 facility). Aniso-
tropic parameters were used in the last cycles of refinement
for all non-hydrogen atoms, except those involved in disorder.
The hydrogen atoms for the nondisordered carbon atoms were
calculated (C-H ) 0.96 Å) and refined riding on carbon atoms
with a common isotropic thermal parameter. Atomic scatter-
ing factors, corrected for anomalous dispersion for Os and P
were implemented by the program.43 The refinement converge
to R1 ) 0.073 [F2 > 2σ(F2)] and wR2 ) 0.184 (all data, F2 > 0),
with weighting parameters x ) 0.1004 and y ) 0.
dCHsCdCH), 29.4, 25.5 (2 s, allylic CH2), 25.3 (s, CH3), 24.9
(vt, N ) 23.9 Hz, PCHCH3), 23.9, 23.7 (2 s, alkyl CH2), 19.9,
19.5 (2 s, PCHCH3).
X-r a y St r u ct u r e An a lysis of Com p lex OsCl{(E)-
CHdCHP h }(O2) (P iP r 3)2 (4). All attempts at preparing
crystals of 4 from solutions of 4 in toluene or pentane were
unsuccessful. The only suitable crystal was grown in a
solution of complex 2 in toluene left under an air atmosphere
for 3 weeks. A summary of the crystal data and refinement
parameters is reported in Table 3. The dark brown irregular
crystal, of approximate dimensions 0.21 × 0.14 × 0.24 mm,
was glued on a glass fiber and mounted on a Siemens P4
diffractometer. A group of 50 reflections in the range 20° e
2θ e 25° were carefully centered and used to obtain, by least-
squares methods, the unit cell dimensions. Three standard
reflections were monitored at periodic intervals thoughout data
collection: no significant variations were observed. All data
were corrected for absorption using a semiempirical method.41
The structure was solved by Patterson (Os atom, SHELXTL-
PLUS42 ) and conventional Fourier techniques and was refined
by full-matrix least-squares on F2 (SHELXL93).43 The styryl
group of 4 was found to be disordered. This disorder could
result from a rotation of approximately 180° around the Os-
C(1) bond and was modeled by including two different moieties
(C(1a) to C(8a) and C(1b) to C(8b)) with complementary
occupancy factors, initially assigned on the basis of thermal
parameters and refined to a final value of 0.71(2) for the
Ack n ow led gm en t. We thank the D. G. I. C. Y. T.
(Project PB95-0806, Programa de Promocio´n General del
Conocimiento) and E. U. (Project: Selective Precesses
and Catalysis Involving Small Molecules) for financial
support. M.B. thanks the E. U. for a postdoctoral grant.
Su p p or tin g In for m a tion Ava ila ble: Tables of anisotro-
pic thermal parameters, atomic coordinates and thermal
parameters for hydrogen atoms, experimental details of the
X-ray study, bond distances and angles, and selected least-
squares planes and interatomic distances (15 pages). Ordering
information is given on any current masthead page.
(41) North, A. C. T.; Phillips, D. C.; Mathews, F. S. Acta Crystallogr.
1968, A24, 351.
(42) Sheldrick, G. SHELXTL-PLUS; Siemens Analitical X-Ray
Instruments, Inc., Madison, WI, 1990.
OM960525T
(43) Sheldrick, G. SHELXL-93. Program for Crystal Structure
Refinement; Institu¨t fu¨r Anorganische Chemie der Universita¨t, Go¨t-
tingen, Germany, 1993.
(44) Allen, F. H.; Kennard, O. 3D Search and Research Using the
Cambridge Structural Database.Chem. Des. Automation News, 1993,
8 (1), 1, 31-37.