Reactions of New Osmium-Dihydride Complexes with Terminal Alkynes: Metallacyclopropene versus Metal-Carbyne. Influence of the Alkyne Substituent

Article abstract of DOI:10.1021/om990426q

Reaction of OsH₂(κ²-OCOCH₃){κ ¹-OC(O)CH₃}(PⁱPr₃)₂ (1) with 1/2HBF₄·OEt₂ leads to the dimer [{OsH₂(κ²-OCOCH₃)(PⁱPr ₃)₂}₂(μ-OCOCH₃)]BF₄ (2), while the reaction with HBF₄·OH₂ gives the aquo-derivative [OsH₂(κ²-OCOCH₃)(H₂O)(P ⁱPr₃)₂]BF₄ (3). The structure of 2 in the solid state has been determined by an X-ray diffraction study. The structure consists of two OsH₂(κ²-OCOCH₃)(PⁱPr ₃)₂ units connected through an acetate bridge. Complex 3 reacts with phenylacetylene and 1,1-diphenyl-2-propyn-1-ol to give the metallacyclopropene complexes [OsH(κ²OCOCH₃){C(Ph)CH₂}(P ⁱPr₃)₂]BF₄ (4) and OsH(κ²-OCOCH₃){C[C(OH)Ph₂]CH ₂}-(PⁱPr₃)₂]BF₄ (7), respectively. The structure of 4 in the solid state has been determined by an X-ray diffraction study. The geometry around the metal center can best be described as a pentagonal bipyramid with the two phosphorus atoms of the phosphines occupying apical positions. The equatorial plane is defined by the hydride, the acetate ligand, and the two carbon atoms of the metallacyclopropene. Reaction of 3 with tert-butylacetylene or trimethylsilylacetylene affords the carbyne complexes [OsH(κ²-OCOCH₃)(≡CCH₂R)(P ⁱPr₃)₂]BF₄ [R = CMe₃ (8), H (9)], respectively. Deprotonation of 8 and 9 with KOH gives the vinylidene derivatives OsH(κ²-OCOCH₃)(=C=CHR)(PⁱPr ₃)₂ [R = CMe₃ (10), H (11)]. The carbyne analogue of 8 and 9 bearing a phenyl group, [OsH(κ²-OCOCH₃)(≡CCH₂Ph)(P ⁱPr₃)₂]BF₄ (5), can be obtained upon protonation of OsH(κ²-OCOCH₃)(=C=CHPh)(PⁱPr ₃)₂ (6) with HBF₄· OEt₂. In agreement with the experimental results, DFT (B3PW91) calculations show that the cyclopropene product is thermodynamically preferred for phenylacetylene, while the carbyne isomer is preferred for tert-butylacetylene.

Full text of DOI:10.1021/om990426q

Organometallics 1999, 18, 4949-4959
4949
Rea ction s of New Osm iu m -Dih yd r id e Com p lexes w ith
Ter m in a l Alk yn es: Meta lla cyclop r op en e ver su s
Meta l-Ca r byn e. In flu en ce of th e Alk yn e Su bstitu en t
Mar´ıa L. Buil,† Odile Eisenstein,*,‡ Miguel A. Esteruelas,*,†
Cristina Garc´ıa-Yebra,† Enrique Gutie´rrez-Puebla,§ Montserrat Oliva´n,†
Enrique On˜ate,† Natividad Ruiz,† and Mar´ıa A. Tajada†
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza, CSIC, 50009 Zaragoza, Spain, LSDSMS (UMR5636)
Case Courrier 14, Universite´ de Montpellier 2, 34095 Montpellier Cedex 05, France, and
Instituto de Ciencia de Materiales de Madrid, CSIC, Campus de Cantoblanco,
28049 Madrid, Spain
Received J une 3, 1999
Reaction of OsH2(κ2-OCOCH3){κ1-OC(O)CH3}(PiPr3)2 (1) with 1/2HBF4‚OEt2 leads to the
dimer [{OsH2(κ2-OCOCH3)(PiPr3)2}2(µ-OCOCH3)]BF4 (2), while the reaction with HBF4‚OH2
gives the aquo-derivative [OsH2(κ2-OCOCH3)(H2O)(PiPr3)2]BF4 (3). The structure of 2 in the
solid state has been determined by an X-ray diffraction study. The structure consists of two
OsH2(κ2-OCOCH3)(PiPr3)2 units connected through an acetate bridge. Complex 3 reacts with
phenylacetylene and 1,1-diphenyl-2-propyn-1-ol to give the metallacyclopropene complexes
[OsH(κ2-OCOCH3){C(Ph)CH2}(PiPr3)2]BF4 (4) and OsH(κ2-OCOCH3){C[C(OH)Ph2]CH2}-
(PiPr3)2]BF4 (7), respectively. The structure of 4 in the solid state has been determined by
an X-ray diffraction study. The geometry around the metal center can best be described as
a pentagonal bipyramid with the two phosphorus atoms of the phosphines occupying apical
positions. The equatorial plane is defined by the hydride, the acetate ligand, and the two
carbon atoms of the metallacyclopropene. Reaction of 3 with tert-butylacetylene or trimeth-
ylsilylacetylene affords the carbyne complexes [OsH(κ2-OCOCH3)(tCCH2R)(PiPr3)2]BF4 [R
) CMe3 (8), H (9)], respectively. Deprotonation of 8 and 9 with KOH gives the vinylidene
derivatives OsH(κ2-OCOCH3)(dCdCHR)(PiPr3)2 [R ) CMe3 (10), H (11)]. The carbyne
analogue of 8 and 9 bearing a phenyl group, [OsH(κ2-OCOCH3)(tCCH2Ph)(PiPr3)2]BF4 (5),
can be obtained upon protonation of OsH(κ2-OCOCH3)(dCdCHPh)(PiPr3)2 (6) with HBF4‚
OEt2. In agreement with the experimental results, DFT (B3PW91) calculations show that
the cyclopropene product is thermodynamically preferred for phenylacetylene, while the
carbyne isomer is preferred for tert-butylacetylene.
In tr od u ction
drido-carbyne derivatives OsHCl2(tCCH2R)(PiPr3)2
(R ) Ph, Cy, CH2CtCSiMe3, H), according to eq 1.3
Reactions between transition metal hydride com-
plexes and alkynes are fundamental steps in many
catalytic cycles.1 These reactions generally result in the
formation of alkenyl derivatives as a result of the
insertion of the alkyne into the M-H bond.2
In contrast to the general trend, the six-coordinate
osmium(IV)-dihydride OsH2Cl2(PiPr3)2 reacts with phe-
nylacetylene, cyclohexylacetylene, 1-(trimethylsilyl)-1,4-
pentadiyne, or trimethylsilylacetylene to give the hy-
Osmium(II) dihydrogen-vinylidene species have been
proposed as the key intermediates in this process. Thus,
the reactions were rationalized as the electrophilic
attack of the acidic hydrogen atom of the dihydrogen
ligand at the Câ atom of the vinylidene group. In
agreement with this, the five-coordinate hydrido-vi-
nylidene complex OsHCl(dCdCHPh)(PiPr3)2 reacts with
HCl to give OsHCl2(tCCH2Ph)(PiPr3)2.4 Related five-
† Universidad de Zaragoza.
‡ Universite´ de Montpellier 2.
§ Instituto de Ciencia de Materiales de Madrid.
(1) (a) J ames, B. R. Homogeneous Hydrogenation; Wiley: New York,
1973. (b) Parshall, G. W. Homogeneous Catalysis; Wiley: New York,
1980. (c) Master, C. Homogeneous Transition-Metal Catalysis-A Gentle
Art; Chapman and Hall: New York, 1981. (d) Chaloner, P. A.;
Esteruelas, M. A.; J oo´, F.; Oro, L. A. Homogeneous Hydrogenation;
Kluwer Academic Publishers: Dordrecht, 1994.
(2) Collman, J . P.; Hegedus, L. S. Principles and Applications of
Organotransition Metal Chemistry; University Science Books: Mill
Valley, CA 1980. (b) Crabtree, R. H. The Organometallic Chemistry of
the Transition Metals; Wiley: New York, 1988. (c) Elschenbroich, C.;
Salzer, C. Organometallics; VCH Verlagsgesellshft: Weinheim, 1989.
(3) Espuelas, J .; Esteruelas, M. A.; Lahoz, F. J .; Oro, L. A.; Ruiz, N.
J . Am. Chem. Soc. 1993, 115, 4683.
(4) Bourgault, M.; Castillo, A.; Esteruelas, M. A.; On˜ate, E.; Ruiz,
N. Organometallics 1997, 16, 636.
10.1021/om990426q CCC: $18.00 © 1999 American Chemical Society
Publication on Web 11/02/1999

4950 Organometallics, Vol. 18, No. 24, 1999
Buil et al.
Sch em e 1
coordinate hydrido-vinylidene derivatives of osmium
and ruthenium have recently been prepared by reaction
of the trihydride compounds MH3Cl(PR3)2 (M ) Ru, Os;
PR3 ) PtBu2Me, PiPr3) with terminal alkynes.5
In contrast to OsH2Cl2(PiPr3)2, the dichloro-dihydro-
gen complex OsCl2(η2-H2)(CO)(PiPr3)2 reacts with phen-
ylacetylene to give the carbene complex OsCl2(dCHCH2-
Ph)(CO)(PiPr3)2 (eq 2).
complexes can afford not only alkenyl, but also carbyne,
carbene, vinylidene, and alkynyl derivatives, and that
new reaction patterns should be found during the study
of the reactivity of this type of compounds, if the
electronic properties of the metallic center are signifi-
cantly changed.
In the search for new reactions between transition
metal complexes and alkynes, we have prepared novel
seven-coordinate cationic dihydride compounds of os-
mium(IV) and have studied their reactivity toward
phenylacetylene, tert-butylacetylene, trimethylsilylacet-
ylene, or 1,1-diphenyl-2-propyn-1-ol. In this paper, we
show that the preparation of osmacyclopropene deriva-
tives, by reaction of osmium dihydride complexes with
terminal alkynes, is also possible if the substituent of
the alkyne is appropriately selected.
The formation of this carbene derivative proceeds by
elimination of HCl to afford, initially, a six-coordinate
hydride-π-alkyne intermediate, which evolves to the
insertion product. Subsequently, the alkenyl complex
undergoes an electrophilic attack by the HCl proton at
the Câ carbon atom.6
The seven-coordinate dihydride OsH2(κ2-OCOCH3){κ1-
OC(O)CH3}(PiPr3)2 neither follows the general trend nor
shows a behavior similar to OsH2Cl2(PiPr3)2 and OsCl2-
(η2-H2)(CO)(PiPr3)2. Thus, reaction of OsH2(κ2-OCOCH3)-
{κ1-OC(O)CH3}(PiPr3)2 with 2-methyl-1-buten-3-yne af-
fords the alkenylvinylidene complex OsH(κ2-OCOCH3){d
CdCHC(CH3)dCH2}(PiPr3)2 (eq 3).7
Resu lts a n d Discu ssion
1. Syn th esis a n d Ch a r a cter iza tion of [{OsH2(K2-
OCOCH3)(P iP r 3)2}2(µ-OCOCH3)]BF 4 a n d [OsH2(K2-
OCOCH3)(H2O)(P iP r 3)2]BF 4. Treatment of 7:1 diethyl
ether/dichloromethane solutions of OsH2(κ2-OCOCH3)-
{κ1-OC(O)CH3}(PiPr3)2 (1) with 0.5 equiv of HBF4‚OEt2
leads to the cationic tetrahydride compound [{OsH2(κ2-
OCOCH3)(PiPr3)2}2(µ-OCOCH3)]BF4 (2), which was iso-
lated as a pale yellow solid in 82% yield (Scheme 1).
The formation of this complex can be rationalized as a
result of the protonation of an acetate ligand of 0.5 equiv
of the starting material and the subsequent coordination
of the monodentate acetate ligand of the other 0.5 equiv
of 1 to the resulting fragment [OsH2(κ2-OCOCH3)-
(PiPr3)2]+. In agreement with this, we have observed
that the addition of 5 equiv of water to a chloroform-d
solution of 2 regenerates 0.5 equiv of 1 and gives 0.5
equiv of the mononuclear complex [OsH2(κ2-OCOCH3)-
(H2O)(PiPr3)2]BF4 (3), which can also be obtained, in
97% yield, by treatment of 7:1 diethyl ether/acetone
solutions of 1 with 1.5 equiv of HBF4‚H2O (Scheme 1).
Complexes 2 and 3 were characterized by elemental
The formation of this hydrido-alkenylvinylidene
complex involves, as in the other two cases, the initial
formation of an acid (acetic acid). However, in this case,
the proton of the acid is not capable of attacking the
vinylidene ligand.
The reactions shown in eqs 1-3, along with those
reported for the complexes OsHCl(CO)(PiPr3)2,8 [OsH-
(CO)2{η1-OC(CH3)2}(PiPr3)2]+,9
OsH3(κ2-OCOCH3)-
(PiPr3)2,10 and OsH2(η2-H2)(CO)(PiPr3)2,11 indicate that
the addition of terminal alkynes to osmium hydride
(5) (a) Oliva´n, M.; Clot, E.; Eisenstein, O.; Caulton, K. G. Organo-
metallics 1998, 17, 3091. (b) Huang, D.; Oliva´n, M.; Huffman, J . C.;
Eisenstein, O.; Caulton, K. G. Organometallics 1998, 17, 4700.
(6) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Valero, C.;
Zeier, B. J . Am. Chem. Soc. 1995, 117, 7935.
(7) Crochet, P.; Esteruelas, M. A.; Lo´pez, A. M.; Mart´ınez, M.-P.;
Oliva´n, M.; On˜ate, E.; Ruiz, N. Organometallics 1998, 17, 4500.
(8) (a) Werner H.; Esteruelas, M. A.; Otto, H. Organometallics 1986,
5, 2295. (b) Andriollo, A.; Esteruelas, M. A.; Meyer, U.; Oro, L. A.;
Sanchez-Delgado, R. A.; Sola, E.; Valero, C.; Werner, H. J . Am. Chem.
Soc. 1989, 111, 7431. (c) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.;
Oro, L. A.; Zeier, B. Organometallics 1994, 13, 1662. (d) Esteruelas,
M. A.; Oro, L. A.; Valero, C. Organometallics 1995, 14, 3596.
(9) Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, J . A.; Oro, L. A.;
Schlu¨nken, C.; Valero, C.; Werner, H. Organometallics 1992, 11, 2034.
(10) Esteruelas, M. A.; Oro, L. A.; Ruiz, N. Organometallics 1994,
13, 1507.
1
analysis, IR, and H, 13C{1H}, and 31P{1H} NMR spec-
troscopies. Complex 2 was further characterized by an
X-ray crystallographic study. A view of the cation of 2
is presented in Figure 1. Selected bond distances and
angles are listed in Table 1.
The cation is dinuclear and consists of two OsH2(κ2-
OCOCH3)(PiPr3)2 fragments connected through an ac-
etate bridge. Although the related structural parameters
of the two fragments are not strictly equal, they can be
considered equivalent due to the presence of a pseudo-
C2 axis, which contains the C(40)-C(39) bond of the
acetate bridge.
(11) Espuelas, J .; Esteruelas, M. A.; Lahoz, F. J .; Oro, L. A.; Valero,
C. Organometallics 1993, 12, 663.

Reactions of New Osmium-Dihydride Complexes
Organometallics, Vol. 18, No. 24, 1999 4951
F igu r e 1. Molecular diagram of the cation of 2, [{OsH2-
(κ2-OCOCH3)(PiPr3)2}2(µ-OCOCH3)]+.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for th e Com p lex
[{OsH2(K2-OCOCH3)(P iP r 3)2}2(µ-OCOCH3)]BF 4 (2)
Os(1)-O(1)
Os(1)-O(2)
Os(1)-O(3)
Os(1)-P(1)
Os(1)-P(2)
Os(1)-H(01)
Os(1)-H(02)
2.122(4)
2.197(4)
2.251(4)
2.3243(15)
2.2908(16)
1.50(3)
Os(2)-O(4)
Os(2)-O(5)
Os(2)-O(6)
Os(2)-P(3)
Os(2)-P(4)
Os(2)-H(03)
Os(2)-H(04)
2.113(4)
2.207(4)
2.232(4)
2.3142(16)
2.3006(16)
1.51(3)
F igu r e 2. HMQC (1H, 31P) NMR spectrum of 2 at 173 K.
Only the high-field region of the 1H NMR spectrum is
shown.
1.51(3)
1.51(3)
coupling constant of 37.2 Hz. Lowering the sample
temperature leads to broadening of this resonance.
Between 233 and 223 K decoalescence occurs, and at
173 K four triplets and a broad signal are observed. The
31P{1H} NMR spectrum shows a behavior similar to that
of the 1H NMR spectrum. At room temperature, the
spectrum contains a singlet at 31.7 ppm, while lowering
the sample temperature leads to a broadening of the
resonance. Between 223 and 213 K decoalescence oc-
curs, and at 173 K, in addition to a broad resonance,
five signals (two of them overlapping) are observed.
Figure 2 shows the HMQC (1H, 31P) NMR spectrum
at 173 K. According to this spectrum, at 173 K, four
environments around the osmium atoms, A, B, C, and
D, coexist in solution. Environment B involves chemi-
cally inequivalent hydrides and chemically inequivalent
phosphines and is the only distribution of ligands
around the osmium atoms that is consistent with the
one found in Figure 1. Environment A involves chemi-
cally equivalent hydrides and chemically inequivalent
phosphines, while environment C contains chemically
equivalent hydrides and phosphines. Environment D is
fluxional even at 173 K.
O(1)-Os(1)-O(2)
O(1)-Os(1)-O(3)
O(2)-Os(1)-O(3)
P(1)-Os(1)-P(2)
P(1)-Os(1)-O(1)
P(1)-Os(1)-O(2)
P(1)-Os(1)-O(3)
P(2)-Os(1)-O(1)
P(2)-Os(1)-O(2)
P(2)-Os(1)-O(3)
O(1)-Os(1)-H(01)
81.04(15) O(4)-Os(2)-O(5)
79.10(15) O(4)-Os(2)-O(6)
58.80(15) O(5)-Os(2)-O(6)
114.04(5) P(3)-Os(2)-P(4)
84.33(11) P(3)-Os(2)-O(4)
161.08(11) P(3)-Os(2)-O(5)
106.66(11) P(3)-Os(2)-O(6)
151.30(12) P(4)-Os(2)-O(4)
84.18(11) P(4)-Os(2)-O(5)
113.52(11) P(4)-Os(2)-O(6)
80.83(16)
78.99(15)
59.08(15)
112.84(6)
86.17(12)
162.42(11)
106.90(12)
149.94(12)
83.94(11)
114.55(12)
86(2)
86(2)
O(4)-Os(2)-H(03)
O(2)-Os(1)-H(01) 111(2)
O(3)-Os(1)-H(01) 163(2)
O(5)-Os(2)-H(03) 111(2)
O(6)-Os(2)-H(03) 163(2)
P(1)-Os(1)- H(01)
P(2)-Os(1)- H(01)
O(1)-Os(1)-H(02) 138(2)
O(2)-Os(1)-H(02) 106(2)
80(2)
76(2)
P(3)-Os(2)-H(03)
P(4)-Os(2)-H(03)
79(2)
76(2)
O(4)-Os(2)-H(04) 143(2)
O(5)-Os(2)-H(04) 110(2)
O(3)-Os(1)-H(02)
P(1)-Os(1)-H(02)
P(2)-Os(1)-H(02)
71(2)
78(2)
70(2)
O(6)-Os(2)-H(04)
P(3)-Os(2)-H(04)
P(4)-Os(2)-H(04)
78(2)
74(2)
66(2)
H(01)-Os(1)-H(02) 126(3)
H(03)-Os(2)-H(04) 119(3)
The two fragments have no symmetry elements other
than a C1 axis. At first glance, the coordination poly-
hedron around each osmium atom could be described
as a capped trigonal prism. The two trigonal faces are
made up by an oxygen atom of the bidentate acetate
ligand, a hydride ligand, and a phosphorus atom of the
triisopropylphosphine. The remaining vertex is occupied
by the oxygen atom of the bridging acetate.
Complex 3 is also fluxional in solution, and the
changes in the coordination polyhedron around the
osmium atom occur with lower energy barriers than in
the case of 2. At room temperature, the 1H NMR
spectrum of 3 shows a triplet, at -16.90 ppm, with a
H-P coupling constant of 35.5 Hz. Although decoales-
cence is not observed even at 173 K, lowering the sample
temperature leads to a broadening of the above-
mentioned triplet. The presence of a water ligand in this
At room temperature complex 2 is fluxional in solu-
tion, as can be seen from the 1H and 31P{1H} NMR
spectra. Although inspection of the structure shown in
Figure 1 predicts two different chemical shifts for the
hydride ligands and two different chemical shifts for the
phosphine ligands,13 both the H and the 31P{1H} NMR
1
1
complex is strongly supported by the H NMR spectrum
spectra show only one resonance for the corresponding
nucleus. In the 1H NMR spectrum the hydride reso-
nance appears at -16.92 ppm as a triplet with a H-P
at 193 K, which contains a broad resonance, centered
at 6.33 ppm, corresponding to the water hydrogen
atoms. The 31P{1H} NMR spectrum shows a behavior
similar to that of the 1H NMR spectrum. At room
temperature, the spectrum shows a singlet at 35.2 ppm.
Again, although decoalescence is not observed at 173
K, lowering the sample temperature leads to a broaden-
ing of the signal.
(12) The hydride ligands were located in the different Fourier maps
and refined as isotropic atoms along with the rest of the non-hydrogen
atoms of the structure.
(13) From a spectroscopic point of view, the fragments are chemically
equivalent. However, both hydrides and phosphines occupy chemically
inequivalent positions within each fragment.

4952 Organometallics, Vol. 18, No. 24, 1999
Buil et al.
The IR spectrum of 2 in Nujol shows the inequiva-
lence of the four hydrides in the solid state, displaying
four ν(Os-H) bands at 2233, 2207, 2181, and 2154 cm-1
,
while the IR spectrum in Nujol of complex 3 shows two
ν(Os-H) bands at 2225 and 2192 cm-1, characteristic
for this type of arrangement.7,14
2. Rea ction s of [OsH2(K2-OCOCH3)(H2O)(P iP r 3)2]-
BF 4 w ith P h en yla cetylen e a n d 1,1-Dip h en yl-2-
p r op yn -1-ol. Treatment of dichloromethane solutions
of 3 with 1 equiv of phenylacetylene leads to the
osmacyclopropene complex [OsH(κ2-OCOCH3){C(Ph)-
CH2}(PiPr3)2]BF4 (4), as a result of the displacement of
the water molecule of 3 by the alkyne, and the subse-
quent Markovnikov insertion of the C-C triple bond of
the alkyne into one of the two Os-H bonds of a π-alkyne
intermediate (eq 4).
F igu r e 3. Molecular diagram of one of the two indepen-
dent cations of 4, [OsH(κ2-OCOCH3){C(Ph)CH2}(PiPr3)2]+.
coordinated olefin in the complex [Os(η2-CH2dC(OMe)-
CH3}(NH3)5](OTf)2.
The osmacyclopropene complex 4 was isolated as a
purple solid in 55% yield and characterized by elemental
1
analysis, IR, and H, 13C{1H}, and 31P{1H} NMR spec-
troscopies, and by an X-ray crystallographic study. The
structure has two chemically equivalent, but crystallo-
graphically independent, molecules of complex 4 in the
asymmetric unit. A drawing of one of them is shown in
Figure 3. Selected bond distances and angles for both
molecules are listed in Table 2.
The coordination geometry around the osmium atom
can be rationalized as a distorted pentagonal bipyramid
with the two phosphorus atoms of the triisopropylphos-
phine ligands occupying trans positions [P(1)-Os(1)-
P(2) ) 161.37(9)° (molecule a) and 160.7(1)° (molecule
b)]. The osmium coordination sphere is completed by the
acetate ligand, which acts with a bite angle O(1)-Os-
(1)-O(2) of 59.3(3)° in molecule a and 59.6(3)° in
molecule b, the hydride ligand, and the atoms C(1) and
C(2) of the carbon donor ligand, which are coordined to
the osmium atom to form a three-membered ring [C(1)-
Os(1)-C(2) ) 40.2(4)° in both molecules].
Few metallacyclopropene complexes are known to
date. In general, they have been prepared by external
nucleophilic attack on coordinated alkyne ligands15 and
have been limited to early transition metals, mainly
Mo,16 W,17 and Re.18 As far as we know, the only
example of an osmacyclopropene is the complex [Os-
{C(CH3)CH2}(NH3)5](OTf)3, reported by Harman and co-
workers.19 In contrast to 4, this compound is obtained
by electrophilic extraction of the methoxy group of the
(14) (a) Aracama, M.; Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, J . A.;
Meyer, U.; Oro, L. A.; Werner, H. Inorg. Chem. 1991, 30, 288. (b)
Atencio, R.; Esteruelas, M. A.; Lahoz, F. J .; Oro, L. A.; Ruiz, N. Inorg.
Chem. 1995, 34, 1004.
(17) (a) Davidson, J . L.; Shiralian, M.; Manojlovic-Muir, L.; Muir,
K. W. J . Chem. Soc., Chem. Commun. 1979, 30. (b) Davidson, J . L.;
Vasapollo, G.; Manojlovic-Muir, L.; Muir, K. W. J . Chem. Soc., Chem.
Commun. 1982, 1025. (c) Carlton, L.; Davidson, J . L.; Miller, J . C.;
Muir, K. W. J . Chem. Soc., Chem. Commun. 1984, 11. (d) Davidson, J .
L.; Shiralian, M.; Manojlovic-Muir, L.; Muir, K. W. J . Chem. Soc.,
Dalton Trans. 1984, 2167. (e) Carlton, L.; Davidson, J . L.; Ewing, P.;
Monojlovic-Muir, L.; Muir, K. W. J . Chem. Soc., Chem. Commun. 1985,
1474. (f) Carlton, L.; Davidson, J . L. J . Chem Soc., Dalton Trans. 1987,
895. (g) Gamble, A. S.; Birdwhistell, K. R.; Templeton, J . L. J . Am.
Chem. Soc. 1990, 112, 1818. (h) Silva, C. J .; Giner, J . L.; Djerassi, C.
J . Am. Chem. Soc. 1992, 114, 295. (i) Feng, S. G.; Templeton, J . L.
Organometallics 1992, 11, 2168. (j) Kiplinger, J . L.; King, M. A.; Arif,
A. M.; Richmond, T. G. Organometallics 1993, 12, 3382. (k) Mayr, A.;
Asaro, M. F.; Glines, T. J .; Van Engen, D.; Tripp, G. M. J . Am. Chem.
Soc. 1993, 115, 8187. (l) Lee, T.-Y.; Mayr, A. J . Am. Chem. Soc. 1994,
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A. M.; Richmond, T. G. Organometallics 1996, 15, 5292. (n) Kiplinger,
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(15) Templeton, J . L. Adv. Organomet. Chem. 1989, 29, 1.
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1981, 1059. (b) Green, M.; Norman, N. C.; Orpen, A. G. J . Am. Chem.
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I. D. J . Chem. Soc., Chem. Commun. 1982, 826. (d) Allen, S. R.; Baker,
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D.; Welch, A. J . J . Am. Chem. Soc., Dalton Trans. 1983, 927. (e)
Davidson, J . L.; Wilson, W. F.; Manojlovic-Muir, L.; Muir, K. W. J .
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Preston, P. N.; Russo, M. V. J . Chem. Soc., Dalton Trans. 1983, 1783.
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Reactions of New Osmium-Dihydride Complexes
Organometallics, Vol. 18, No. 24, 1999 4953
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for th e Com p lex
Sch em e 2
[OsH(K2-OCOCH3){C(P h )CH2}(P iP r 3)2]BF 4
molecule a
molecule b
Os(1)-C(1)
2.141(11) Os(2)-C(51)
1.895(10) Os(2)-C(52)
2.146(12)
1.882(11)
2.219(7)
2.158(7)
2.433(3)
2.435(3)
1.56(9)
Os(1)-C(2)
Os(1)-O(1)
Os(1)-O(2)
Os(1)-P(1)
Os(1)-P(2)
Os(1)-H(01)
C(1)-C(2)
2.211(7)
2.162(7)
2.433(2)
2.434(3)
1.43(9)
Os(2)-O(51)
Os(2)-O(52)
Os(2)-P(51)
Os(2)-P(52)
Os(2)-H(02)
C(51)-C(52)
1.40(2)
1.41(2)
The different behavior of the complex OsH2Cl2(PiPr3)2
and that of the fragment [OsH2(κ2-OCOCH3)(PiPr3)2]+
should be noted (eqs 1 and 4). The reaction of the
complex OsH2Cl2(PiPr3)2 with phenylacetylene to afford
the hydrido-carbyne derivative OsHCl2(tCCH2Ph)-
(PiPr3)2 involves initial coordination of the alkyne to give
a dihydride-π-alkyne osmium(IV) intermediate, in
equilibrium with a dihydrogen-π-alkyne osmium(II)
species. Subsequently, a π-alkyne-vinylidene isomer-
ization occurs. Thus, the electrophilic attack of the acidic
hydrogen proton of the dihydrogen at the Câ atom of
the vinylidene leads to the carbyne3 (route b in Scheme
2). The formation of the osmacyclopropene complex 4
also involves initial coordination of the alkyne to give a
dihydride-π-alkyne osmium(IV) intermediate. How-
ever, this intermediate evolves by insertion of the C-C
triple bond into one of the two Os-H bonds to give an
alkenyl intermediate, which subsequently should afford
4 (route a in Scheme 2). So, the formation of a hydrido-
carbyne derivative or a hydride-osmacyclopropene
complex appears to depend on two factors: (i) the
tendency of the starting metallic fragment to promote
a dihydride-dihydrogen transformation and (ii) the
tendency of the coordinated alkyne to undergo isomer-
ization into vinylidene.
P(1)-Os(1)-P(2)
O(1)-Os(1)-O(2)
O(1)-Os(1)-C(1)
O(1)-Os(1)-C(2)
O(2)-Os(1)-C(1)
O(2)-Os(1)-C(2)
C(1)-Os(1)-C(2)
P(1)-Os(1)-O(1)
P(1)-Os(1)-O(2)
P(1)-Os(1)-C(1)
P(1)-Os(1)-C(2)
P(2)-Os(1)-O(1)
P(2)-Os(1)-O(2)
P(2)-Os(1)-C(1)
P(2)-Os(1)-C(2)
P(1)-Os(1)-H(01) 81(3)
P(2)-Os(1)-H(01) 84(3)
O(1)-Os(1)-H(01) 153(3)
O(2)-Os(1)-H(01) 93(3)
C(1)-Os(1)-H(01) 70(3)
C(2)-Os(1)-H(01) 110(3)
161.37(9) P(51)-Os(2)-P(52) 160.74(10)
59.3(3)
137.3(4)
97.2(4)
163.3(4)
156.4(4)
40.2(4)
95.1(2)
84.5(2)
92.6(3)
96.5(3)
92.4(2)
84.7(2)
93.5(3)
99.5(3)
O(51)-Os(2)-O(52) 59.6(3)
O(51)-Os(2)-C(51) 137.0(4)
O(51)-Os(2)-C(52) 96.8(4)
O(52)-Os(2)-C(51) 163.5(4)
O(52)-Os(2)-C(52) 156.3(4)
C(51)-Os(2)-C(52) 40.2(4)
P(51)-Os(2)-O(51) 96.0(2)
P(51)-Os(2)-O(52) 85.2(2)
P(51)-Os(2)-C(51) 92.2(4)
P(51)-Os(2)-C(52) 99.5(3)
P(52)-Os(2)-O(51) 91.9(2)
P(52)-Os(2)-O(52) 83.6(2)
P(52)-Os(2)-C(51) 94.0(4)
P(52)-Os(2)-C(52) 97.1(3)
P(51)-Os(2)-H(02) 78(4)
P(52)-Os(2)-H(02) 88(3)
O(51)-Os(2)-H(02) 153(4)
O(52)-Os(2)-H(02) 93(4)
C(51)-Os(2)-H(02) 70(4)
C(52)-Os(2)-H(02) 110(4)
The M-C bond to the monosubtituted carbon [C(2)]
is substantially shorter than the M-C bond to the
disubstituted carbon [C(1)]. Thus, the Os-C(2) bond
length [1.895(10) Å in molecule a and 1.882(11) Å in
molecule b] is statistically identical with the Os-C
double bond distance found in the carbene complex
OsCl2(CHCH2Ph)(CO)(PiPr3)2 [1.887(9) Å],6 while the
Os-C(1) bond length [2.141(1) Å in molecule a and
2.146(12) Å in molecule b] agrees well with the values
previously reported for Os-C(alkyl) distances [mean
value 2.16(5) Å].20 The C(1)-C(2) distance [1.405(15) Å
in molecule a and 1.407(16) Å in molecule b] is consis-
tent with a metallacyclopropene formulation. Similar
values have been reported for the related compounds
of Mo,16 W,17 and Re.18
The complex OsH2Cl2(PiPr3)2 shows a high tendency
to form elongated-dihydrogen compounds, as is revealed
by its chemistry in the presence of nucleophilic re-
agents.21 For example, simple addition of monodentate
ligands to OsH2Cl2(PiPr3)2 produces a dihydride-elon-
gated dihydrogen transformation.21 The fragment [OsH2-
(κ2-OCOCH3)(PiPr3)2]+ has a lower tendency to form
dihydrogen derivatives,7 and according with this, com-
plex 3 is a dihydride derivative. This behavior could
explain why this fragment reacts with phenylacetylene
to give the osmacyclopropene 4 instead of the hydrido-
carbyne [OsH(κ2-OCOCH3)(tCCH2Ph)(PiPr3)2]BF4 (5),
which can be obtained in 65% yield, by reaction of the
hydrido-vinylidene OsH(κ2-OCOCH3)(dCdCHPh)(PiPr3)2
(6) with HBF4‚Et2O in diethyl ether as solvent (eq 5).
In agreement with the M-C(2)-carbene and M-C(1)-
alkyl formulation the resonances of the C(2) and C(1)
carbon atoms appear in the 13C{1H} NMR spectrum at
263.2 and -0.7 ppm, respectively. In the 1H NMR
spectrum the most notable resonances are those corre-
sponding to the Os-CH2- and Os-H hydrogen atoms,
which are observed at 1.47 and -8.62 ppm, as triplets
with H-P coupling constants of 6.9 and 15.3 Hz,
respectively. The presence of a hydride ligand in 4 is
also supported by the IR spectrum in Nujol and the 31P
NMR spectrum. The IR spectrum shows a ν(Os-H)
band at 2236 cm-1, whereas the 31P{1H} NMR spectrum
contains a singlet at 25.5 ppm which, under off-
resonance conditions, is split into a doublet as a result
of coupling to the hydride ligand.
The presence of a hydride ligand in 5 is supported by
1
the IR, H, and 31P NMR spectra. The IR spectrum in
(20) Allen, F. H.; Kennard, O. 3D Search and Research Using the
Cambridge Structural Database. Chem. Des. Automation News. 1993,
8 (1), 1, 31-37.
(21) (a) Esteruelas, M. A.; Oro, L. A.; Ruiz, N. Inorg. Chem. 1993,
32, 3793. (b) Esteruelas, M. A.; Lahoz, F. J .; Oro, L. A.; On˜ate, E.;
Ruiz, N. Inorg. Chem. 1994, 33, 787.

4954 Organometallics, Vol. 18, No. 24, 1999
Buil et al.
Sch em e 3
Nujol shows a ν(Os-H) absorption at 2180 cm-1, while
resonance due to the disubstituted carbon atom is
observed at 9.6 ppm. The C(OH)Ph2 carbon atom gives
rise to a singlet at 95.0 ppm. The 31P{1H} NMR
spectrum contains a singlet at 28.2 ppm, which splits
into a doublet under off-resonance conditions, as a result
of the coupling with the hydride ligand.
1
the H NMR spectrum in dichloromethane-d2 contains
a triplet, with a H-P coupling constant of 15.6 Hz, at
-7.69 ppm. The 31P{1H} NMR spectrum shows a singlet
at 43.7 ppm, which is split into a doublet under
off-resonance conditions, as a result of the coupling with
the hydride ligand. In the 13C{1H} NMR spectrum the
most noticeable resonances are a triplet at 287.1 with
a C-P coupling constant of 8.3 Hz and a singlet at 60.3
ppm, which were assigned to the CR and Câ carbon
atoms of the carbyne ligand, respectively.
Complexes 4 and 7 can also be obtained, in about 50%
yield, by reaction of the dinuclear complex 2 with 1
equiv of the corresponding alkyne. In addition to the
cyclopropene derivatives, these reactions also give com-
pound 1. This indicates that the dinuclear complex 2 is
a result of the stabilization of the unsaturated fragment
[OsH2(κ2-OCOCH3)(PiPr3)2]+ by 1.
Similarly to the reaction of 3 with phenylacetylene,
treatment of dichloromethane solutions of 3 with 1.2
equiv of 1,1-diphenyl-2-propyn-1-ol, at 208 K, leads to
3. Rea ction of [OsH2(K2-OCOCH3)(H2O)(P iP r 3)2]-
BF 4 w ith ter t-Bu tyla cetylen e or Tr im eth ylsily-
la cetylen e. It has previously been mentioned that the
formation of a hydrido-osmacyclopropene derivative or
a hydrido-carbyne complex, by reaction of an unsatur-
ated osmium(IV) dihydride compound with a terminal
alkyne, appears to depend on two factors, one of them
characteristic of the starting metallic fragment and the
other one characteristic of the alkyne. In agreement
with the second factor, we have observed that the
reaction of 3 with tert-butylacetylene or trimethylsilyl-
aceylene does not lead to the corresponding osmacyclo-
propene compounds, related to 4 and 7, but instead
affords hydrido-carbyne complexes (Scheme 3). Treat-
ment of dichloromethane solutions of 3 with 1 equiv of
tert-butylacetylene leads to [OsH(κ2-OCOCH3)(tCCH2-
CMe3)(PiPr3)2]BF4 (8), which was isolated as a yellow
solid in 68% yield. Similarly, the addition of 2 equiv of
trimethylsilylacetylene to dichloromethane solutions of
3 affords [OsH(κ2-OCOCH3)(tCCH3)(PiPr3)2]BF4 (9), as
a yellowish solid in 60% yield. Alternatively, 9 can be
prepared in 97% yield starting from 2.
the hydrido-hydroxy-osmacyclopropene complex [OsH-
(κ2-OCOCH3){C[C(OH)Ph2]H2}(PiPr3)2]BF4 (7), which
was isolated as yellow solid in 87% yield, according to
eq 6.
In the IR spectrum of 7, the most noticeable absorp-
tions are those corresponding to the O-H and Os-H
bonds, which appear at 3540 and 2203 cm-1, respec-
tively. In the 1H NMR spectrum in chloroform-d, the
OH resonance is observed as a singlet at 6.13 ppm, while
the resonance corresponding to the -CH2- hydrogen
atoms of the carbon donor ligand appears as a triplet
at 2.17 with a H-P coupling constant of 8.1 Hz.
Furthermore, in the high-field region, the spectrum
contains a triplet at -8.14 ppm with a H-P coupling
constant of 16.2 Hz. The mutually cisoid disposition of
the hydride ligand and the -CH2- group of the three-
membered ring was confirmed by a NOE experiment.
Irradiation of the hydride resonance gave an increase
of 4.6% in the triplet at 2.17 ppm, whereas the reso-
nances of the phenyl groups were not affected.
The formation of 8 and 9, as shown in Scheme 3,
suggests that the π-alkyne-vinylidene isomerization
shown in Scheme 2 is more favored for tert-butylacety-
lene or trimethylsilylacetylene than for phenylacetylene
or 1,1-diphenyl-2-propyn-1-ol. Furthermore, the cleav-
age of the Si-C bond in the formation of 9 agrees well
with the participation of a vinylidene species as the key
intermediate. A similar desilylation has previously been
observed in the reaction of the dihydrido-dichloro OsH2-
Cl2(PiPr3)2 with trimethylsilylacetylene to give OsHCl2-
(tCCH3)(PiPr3)2. This desilylation has been attributed
to the presence in the reaction medium of slight traces
of water, which acts as an electrophilic reagent.3
The 13C{1H} NMR spectrum of 7 agrees well with that
of 4. The resonance corresponding to the monosubsti-
tuted carbon atom appears at 279.8 ppm, while the

Reactions of New Osmium-Dihydride Complexes
Organometallics, Vol. 18, No. 24, 1999 4955
The IR spectra of 8 and 9 in Nujol show the charac-
teristic ν(Os-H) band at 2178 (8) or 2170 cm-1 (9). In
the 1H NMR spectra the resonance corresponding to the
hydride ligand appears at -8.04 (8) or -8.36 ppm (9),
as triplets with H-P coupling constants of 16.2 (8) or
15.6 Hz (9). The presence of a carbyne ligand in these
compounds is mainly supported by the 13C{1H} NMR
spectra. In the 13C{1H} NMR spectrum of 8, the reso-
nance due to the CR atom of the carbyne appears as a
triplet at 292.5 ppm, with a C-P coupling constant of
6.9 Hz, while the resonance corresponding to the Câ
atom is observed as a singlet at 65.9 ppm. In the 13C-
{1H} NMR spectrum of 9, the CR atom of the carbyne
gives rise to a triplet at 286.3 ppm with a C-P coupling
constant of 8.4 Hz, whereas the -CH3 carbon atom
appears as a singlet at 40.1 ppm. The 31P{1H} NMR
spectra of both compounds contain singlets at 41.8 (8)
and 42.3 ppm (9). Under off-resonance conditions, these
singlets are split into doublets, as a result of coupling
to the hydride ligands.
F igu r e 4. Optimized (B3PW91) geometries of the metal-
lacyclopropene (CycR) and the carbyne (Ca r bR) for R )
Ph.
The hydrido-carbyne complexes 8 and 9 show a
behavior similar to the chloro derivatives OsHCl2-
(tCCH2R)(PiPr3)2.4 Thus, treatment of methanol solu-
tions of 8 or 9 with KOH leads to the corresponding
hydrido-vinylidene compounds OsH(κ2-OCOCH3)(dCd
CHCMe3)(PiPr3)2 (10) and OsH(κ2-OCOCH3)(dCdCH2)-
(PiPr3)2 (11), respectively, as a result of the deprotona-
tion of the Câ atom of the carbyne ligand of the starting
materials (Scheme 3). Complex 10 was isolated as an
orange-yellow solid in 40% yield and characterized by
We note that Allen et al.16i have previously observed
the rearrangement of the trimethylsilyl-metallacy-
clopropene complexes Mo(η5-C9H7){C(SiMe3)CHR}{P(O-
Me)3}2 (R ) H, Ph) to the corresponding carbyne
isomers, by an 1,2-shift of the silyl group from the
monosubstituted carbon atom into the disubstituted
carbon atom of the metallacyclopropene. The formation
of 8 and 9 by a similar procedure, involving metallacy-
clopropene intermediates related to 4 and 7, does not
seem to be a reasonable proposal since the formation of
8 should require the 1,2-shift of the tert-butyl group,
and the activation barrier for this migration should be
very high. Furthermore, in agreement with the partici-
pation of vinylidene intermediates during the formation
of 8 and 9, we have observed that addition of 1 equiv of
HBF4‚OEt2 to diethyl ether solutions of 10 and 11
rapidly regenerates 8 and 9, respectively.
4. Th eor etica l An a lysis. The two isomeric forms,
metallacyclopropene (CycR) and carbyne (Ca r bR),
were optimized with DFT(B3PW91)22 for R ) H, Me,
and Ph. The structures of CycR and Ca r bR (Figure 4)
show no remarkable features. The three ligands, ac-
etate, hydride, and metallacyclopropene or carbyne, are
situated in a plane that is perpendicular to the Os-P
direction. To compare the structure of CycP h with the
experimental structure of 4, we present only the geo-
metrical calculated parameters for R ) Ph. In CycP h ,
the Os-C(2) is shorter (1.932 Å) than Os-C(1) (2.163
Å), as expected from the partial Os-C(2) double bond.
The Os-C bond (1.736 Å) in Ca r bP h is the shortest.
1
IR, H, 31P{1H}, and 13C{1H} NMR spectroscopies. In
1
the H NMR spectrum in benzene-d6, the most notable
resonances are a triplet at 0.23 ppm with a H-P
coupling constant of 3.0 Hz, corresponding to the dCH
hydrogen atom of the vinylidene, and another triplet at
-12.82 ppm with a H-P coupling constant of 15.9 Hz,
due to the hydride ligand. In the 13C{1H} NMR spec-
trum, the resonance corresponding to the CR of the
vinylidene appears as a triplet at 288.8 ppm, with a
C-P coupling constant of 10.1 Hz, while the resonance
due to the Câ atom is observed as a singlet at 114.3 ppm.
The 31P{1H} NMR spectrum shows a singlet at 24.0
which, under off-resonance conditions, is split into a
doublet as a result of coupling to the hydride ligand.
Although the reaction is quantitative (by NMR spec-
troscopies), the isolated yield (23%) of complex 11 is
quite low, as its high solubility does not easily permit
us to precipitate it from solution. In the IR spectrum in
Nujol, the most noticeable feature is the presence of a
ν(Os-H) band at 2140 cm-1. The 1H NMR spectrum
shows the dCH2 resonance of the vinylidene as a triplet
at 0.45 ppm, with a H-P coupling constant of 2.7 Hz.
The hydride ligand gives rise to another triplet at
-12.87 ppm with a H-P coupling constant of 15.6 Hz.
In the 13C{1H} NMR spectrum the resonance due to the
CR atom of the vinylidene appears at 289.8 ppm as a
triplet with a C-P coupling constant of 10.7 Hz, and
the Câ atom also appears as a triplet at 84.1 ppm with
a C-P coupling constant of 1.8 Hz. As is seen in the
31P{1H} NMR spectrum of 10, the 31P{1H} NMR spec-
trum of 11 contains a singlet at 25.3 ppm which, under
off-resonance conditions, is split into a doublet as a
result of coupling to the hydride ligand.
(22) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J . R.; Zakrzewski, V. G.; Montgomery, J . A.,
J r.; Stratmann, R. E.; Burant, J . C.; Dapprich, S.; Millam, J . M.;
Daniels, A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J .;
Barone, V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo,
C.; Clifford, S.; Ochterski, J .; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J . B.; Cioslowski, J .; Ortiz, J . V.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R. L.;
Fox, D. J .; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Gonzalez, C.; Challacombe, M.; Gill, P. M. W.; J ohnson, B.; Chen, W.;
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burgh, PA, 1998.

4956 Organometallics, Vol. 18, No. 24, 1999
Buil et al.
In CycP h the Os-O bond pseudo-trans to H is slightly
longer (2.237 Å) than the Os-O bond (2.171 Å) trans to
C(1). In Ca r bP h the two Os-O bond lengths are more
equal (2.222 and 2.230 Å, respectively). As the rotation
of the C-C bond is essentially free, the conformation of
the phenyl group in Ca r bP h has no real significance.
The calculated structure of CycP h is close to the X-ray
structure of 4 (Figure 3)
chemistry but also because they have allowed us to find
a new reaction pattern between a transition metal
hydride complex and a terminal alkyne. Thus, the
reactions of these novel compounds with phenylacety-
lene or 1,1-diphenyl-2-propyn-1-ol afford the hydride
osmacyclopropene derivatives [OsH(κ2-OCOCH3){C(Ph)-
CH2} (PiPr3)2]BF4 and [OsH(κ2-OCOCH3){C[C(OH)Ph2]-
The dependence on R of the relative energies of CycR
and Ca r bR is remarkable. While for R ) H, CycH is
calculated to be 18 kcal‚mol-1 above Ca r bH. CycMe is
calculated to be only 8.7 kcal‚mol-1 above Ca r bMe.
There is a reversal in the relative energy of the isomers
for R ) Ph since CycP h is calculated to be 3.2
kcal‚mol-1 below Ca r bP h . Steric factors should not
modify the relative energies calculated for a model
deprived of steric effects (PH3 as model phosphine, Me
CH2}(PiPr3)2]BF4, respectively.
Although there is a marked difference in reactivity
toward phenylacetylene and 1,1-diphenyl-2-propyn-1-
ol between the metallic fragment [OsH(κ2-OCOCH3)(Pi-
Pr3)2]+ and the complex OsH2Cl2(PiPr3)2, in the presence
of tert-butylacetylene or trimethylsilylacetylene the
behavior of both species is the same. Thus it is also
observed that the reactions of [OsH2(κ2-OCOCH3)(H2O)-
(PiPr3)2]BF4 with the above-mentioned alkynes lead to
the hydride-carbyne derivatives [OsH(κ2-OCOCH3)-
(tCCH2CMe3)(PiPr3)2]BF4 and [OsH(κ2-OCOCH3)(tC-
CH3)(PiPr3)2]BF4, respectively. The related compound
[OsH(κ2-OCOCH3)(tCCH2Ph)(PiPr3)2]BF4, an isomer of
t
as a model for Bu). The Ph group has no large steric
effect. In addition, the phenyl group is calculated to be
lying on the Os-C(1)-C(2) in the metallacyclopropene
isomer, which minimizes the steric effects with the
phosphine ligands. CycP h should thus remain the
t
preferred isomer. In the case of R ) Bu, the carbyne
[OsH(κ2-OCOCH3){C(Ph)CH2} (PiPr3)2]BF4, is also ac-
cessible, and its preparation involves the protonation
of the hydride-vinylidene OsH(κ2-OCOCH3)(dCdCH-
Ph)(PiPr3)2.
isomer is the least sterically hindered, and the electronic
preference for Ca r bMe should also be found for R )
tBu.
While there is a strong energy preference for the
carbyne form for R ) H, any substitution stabilizes more
the metallacyclopropene form than the carbyne (9.3
kcal‚mol-1 for Me and 21.2 kcal‚mol-1 for Ph). The
stabilization already operative for alkyl substitution
through hyperconjugation of the alkyl group is magni-
fied for a phenyl group where conjugation with a true
π-system is possible. The conjugating effect of the phenyl
group has several structural consequences. The phenyl
ring lies on the Os-C(1)-C(2) plane. The Os-C(2) bond
is longer for R ) Ph (1.932 Å) than for R ) H (1.875 Å),
which indicates that the phenyl π-orbitals and one
occupied osmium d-orbital compete to conjugate with
the π-orbital of C(2). Finally, the conjugation of Ph with
C(2) is shown through the bond alternation, which is
more accentuated in CycP h sa difference of 0.03 Å
between short and long bondssthan in Ca r bP h (where
the difference is only 0.006 Å). As should be expected,
the geometries calculated for R ) H and Me are very
similar, which shows that there is little effect caused
by hyperconjugation of Me with C(2) in the metallacy-
clopropene isomer.
Theoretical calculations indicate that the relative
stability of the metallacyclopropene and carbyne struc-
tures depends on the substituent of the alkyne precur-
sors. The metallacyclopropene isomer is thermodynami-
cally more stable than the carbyne isomer when the
substituent is a phenyl group, while an inverse relation-
ship is observed for alkyl substituents.
In conclusion, the reactions of osmium compounds
containing two hydrogen atoms bonded to the metallic
center with terminal alkynes give not only carbyne,
carbene, and vinylidene but also osmacyclopropene
derivatives. The nature of the obtained products de-
pends on all the factors related to the electronic nature
of the starting material and also on the nature of the
substituent, R, of the alkyne.
In light of these results, it is clear that further work
needs to be done in order to be able to predict the result
of the addition of terminal alkynes to this type of
system, since the four dihydride compounds studied so
far lead to four different types of organometallic com-
pounds, all of them different from the usual alkenyl
derivatives.
Con clu d in g Rem a r k s
Exp er im en ta l Section
We have previously reported the synthesis of the
complexes OsH2Cl2(PiPr3)2,14a OsCl2(η2-H2)(CO)(PiPr3)2,6
and OsH2(κ2-OCOCH3){κ1-OC(O)CH3}(PiPr3)2,7 which
contain two hydrogen atoms bonded to the metallic
center. A study of their reactivities toward terminal
alkynes revealed new reaction patterns between transi-
tion metal hydride compounds and alkynes, giving
carbyne,3 carbene,6 and vinylidene7 derivatives. In this
paper we have described the synthesis of two new
compounds containing two hydrogen atoms bonded to
osmium, the tetrahydride [{OsH2(κ2-OCOCH3)(PiPr3)2}2-
(µ-OCOCH3)]BF4 and the dihydride [OsH2(κ2-OCOCH3)-
(H2O)(PiPr3)2]BF4, which are of interest not only because
they have no precendent in transition metal hydride
All reactions were carried out with rigorous exclusion of air
using standard Schlenk techniques. Solvents were dried by
known procedures and distilled under argon prior to use. OsH2-
(κ2-OCOCH3)(κ1-OCOCH3)(PiPr3)2 (1)7 and OsH(κ2-OCOCH3)-
(dCdCHPh)(PiPr3)2 (6)10 were prepared as previously reported.
Infrared spectra were run on a Nicolet 550 spectrometer as
solids (KBr pellet or Nujol mull). 1H, 31P, and 13C{1H} NMR
spectra were recorded either on a Varian Gemini 2000 or on a
Bruker AXR 300 instrument. Chemical shifts are referenced
to residual solvent peaks (1H, 13C{1H}) or external H3PO4 (31P).
Coupling constants, J and N (N ) J P-H + J P′-H for 1H and N
) J P-C + J P′-C for 13C{1H}), are given in hertz. C, H, and N
analyses were carried out either on a Perkin-Elmer 2400
CHNS/O or on a C.E. Instruments EA1108 analyzer. Mass
spectrum analysis was performed with a VG Auto Spec

Reactions of New Osmium-Dihydride Complexes
Organometallics, Vol. 18, No. 24, 1999 4957
instrument. The ions were produced, FAB+ mode, with the
stardard Cs+ gun at ca. 30 kV, and 3-nitrobenzyl alcohol (NBA)
was used as the matrix.
diethyl ether was treated with HBF4‚H2O (106 µL, 0.78 mmol).
A brown precipitate was immediately formed. After stirring
for 5 min at room temperature, the brown solid was separated
by filtration, washed with diethyl ether, and dried in vacuo.
Yield: 229.6 mg (65%). Anal. Calcd for C28H53BF4O2OsP2: C,
44.21; H, 7.02. Found: C, 43.90; H, 7.45. IR (Nujol, cm-1): ν-
(Os-H) 2180 (m), νasym(OCO) 1520 (m), νsym(OCO) 1395 (m),
ν(B-F) 1150-1000 (s). 1H NMR (300 MHz, CD2Cl2, 293 K): δ
7.40-7.20 (m, 5H, Ph), 2.79 (s, 2H, OstCCH2Ph), 2.41 (m, 6H,
PCH(CH3)2), 1.76 (s, 3H, OCOCH3), 1.36 (dvt, J H-H ) 7.5 Hz,
N ) 14.4 Hz, 18H, PCH(CH3)2), 1.30 (dvt, J H-H ) 7.2 Hz, N )
14.1 Hz, 18H, PCH(CH3)2), -7.69 (t, J P-H ) 15.6 Hz, 1H, Os-
H). 31P{1H} NMR (121.42 MHz, CD2Cl2, 293 K): δ 43.7 (s).
P r ep a r a tion of [{OsH2(K2-OCOCH3)(P iP r 3)2}2(µ-OCO-
CH3)]BF 4 (2). To a solution of 1 (100 mg, 0.16 mmol) in diethyl
ether/dichloromethane (7:1, 16 mL) was added HBF4‚Et2O (11
µL, 0.08 mmol). The resulting mixture was stirred for 45 min
at room temperature and then was evaporated to dryness.
Subsequent addition of diethyl ether (20 mL) caused the
precipitation of a pale yellow solid, which was washed with
further portions of diethyl ether and dried in vacuo. Yield: 84
mg (82%). Anal. Calcd for C42H97BF4O6Os2P4: C, 39.20; H, 7.50.
Found: C, 39.01; H, 7.51. IR (Nujol, cm-1): ν(Os-H) 2233 (m),
2207 (m), 2181 (s), 2154 (s), νasym(OCO) 1550 (s), ν(B-F) 1150-
1000 (s). 1H NMR (300 MHz, CD2Cl2, 293 K): δ 2.24 (s, 3H,
OCOCH3), 2.24 (m, 12H, PCH(CH3)2), 1.72 (s, 6H, OCOCH3),
1.25 (dd, J H-H ) 7.2 Hz, J P-H ) 13.8 Hz, 72H, PCH(CH3)2),
-16.92 (t, J P-H ) 37.2 Hz, 4H, Os-H). 31P{1H} NMR (121.42
MHz, CD2Cl2, 293 K): δ 30.5 (s). 13C{1H} NMR (75.47 MHz,
CD2Cl2, 293 K): δ 191.7 (s, OCOCH3), 181.2 (s, OCOCH3), 28.4
(s, OCOCH3), 28.0 (d, J P-C ) 32.8 Hz, PCH(CH3)2), 26.7 (s,
OCOCH3), 18.92 (s, PCH(CH3)2), 18.89 (s, PCH(CH3)2).
13C{1H} NMR (75.47 MHz, CD2Cl2, 293 K): δ 287.1 (t, J P-C
)
8.3 Hz, OstC), 189.9 (t, J P-C ) 1.9 Hz, OCOCH3), 131.7, 131.3,
131.0, 128.8 (each one s, Ph), 60.3 (s, OstCCH2Ph), 28.4 (vt,
N ) 27 Hz, PCH(CH3)2) 27.6 (s, OCOCH3), 21.2 (s, PCH(CH3)2),
20.9 (s, PCH(CH3)2).
P r ep a r a tion of [OsH(K2-OCOCH3){C[C(OH)P h 2]CH2}-
(P iP r 3)2]BF 4 (7). To a solution of 3 (258 mg, 0.38 mmol) in
dichloromethane (2 mL) at -65 °C was added 1,1-diphenyl-
2-propyn-1-ol (95.5 mg, 0.46 mmol). The resulting mixture was
stirred for 15 min at -65 °C, and then diethyl ether was added
to precipitate a yellow solid, which was washed three times
with diethyl ether at -65 °C and dried in vacuo. Yield: 288
mg (87%). Anal. Calcd for C35H59BF4O3OsP2: C, 48.49; H, 6.86.
Found: C, 48.23; H, 7.06. IR (KBr, cm-1): ν(OH) 3540, ν(Os-
P r ep a r a tion of [OsH 2(K2-OCOCH 3)(H2O)(P iP r 3)2]BF 4
(3). To a solution of 1 (222 mg, 0.35 mmol) in diethyl ether/
acetone (7:1, 16 mL) was added HBF4‚H2O (63 µL, 0.53 mmol).
The resulting mixture was stirred for 15 min at room tem-
perature and then was evaporated to dryness. Subsequent
addition of diethyl ether (20 mL) caused the precipitation of a
pale yellow solid, which was washed with diethyl ether and
1
H) 2203, ν(B-F) 1000-1100 (vs). H NMR (300 MHz, CDCl3,
253 K): δ 7.86 (d, J H-H ) 7.8 Hz, 4H, o-C6H5), 7.24 (t, J H-H
)
dried in vacuo. Yield: 231 mg (97%). Anal. Calcd for C20H49
-
7.8 Hz, 4H, m-C6H5), 7.11 (t, J H-H ) 7.8 Hz, 2H, p-C6H5), 6.13
(s, 1H, OH), 2.17 (t, 2H, J P-H ) 8.1 Hz, CH2, s in 1H{31P}
NMR), 2.10-1.92 (m, 6H, PCH(CH3)2), 2.00 (s, 3H, OCOCH3),
1.20 (dvt, J H-H ) 6.9 Hz, N ) 13.8 Hz, 18H, PCH(CH3)2), 0.84
(dvt, J H-H ) 7.05 Hz, N ) 14.5 Hz, 18H, PCH(CH3)2), -8.14
(t, J P-H ) 16.2 Hz, 1H, OsH). Irradiation of the signal at -8.14
ppm produces a NOE of 4.6% in the triplet at 2.17 ppm. 31P-
{1H} NMR (121.42 MHz, CDCl3, 253 K): δ 28.2 (s). 13C{1H}
NMR (75.47 MHz, CD2Cl2, 233K): δ 279.8 (s br, OsdC), 188.9
(s, OCOCH3), 140.6 (s, Cipso Ph), 128.7, 128.3 (both s, o-C6H5),
128.0, 127.6 (both s, p-C6H5), 124.6 (s, m-C6H5), 95.0 (s, C(OH)-
Ph2), 26.3 (s, OCOCH3), 23.0 (vt, N ) 25.6 Hz, PCH(CH3)2),
18.7 (s, PCH(CH3)2), 18.2 (s, PCH(CH3)2), 9.6 (s, Os-CH2-).
MS (FAB+): m/e (relative intesity) 781 (88) ([M]+), 780 (41)
([M]+ - H), 763 (23) ([M]+ - H - OH), 721 (66) ([M]+ - H -
OCOCH3).
BF4O3OsP2: C, 35.50; H, 7.20. Found: C, 35.25; H, 7.46. IR
(Nujol, cm-1): ν(H2O) 3350 (vs, br), ν(Os-H) 2225 (s), 2192
(s), ν(H2O) 1685 (s), νasym(OCO) 1555 (s), νsym(OCO) 1390, ν-
1
(B-F) 1150-1000 (s). H NMR (300 MHz, CD2Cl2, 293 K): δ
3.75 (br, 2H, H2O), 2.24 (m, 6H, PCH(CH3)2), 1.85 (s, 3H,
OCOCH3), 1.28 (dd, J H-H ) 7.5 Hz, J P-H ) 14.4 Hz, 36H, PCH-
(CH3)2), -16.90 (t, J P-H ) 35.5 Hz, 2H, Os-H). 31P{1H} NMR
(121.42 MHz, CD2Cl2, 293 K): δ 35.2 (s). 13C{1H} NMR (75.47
MHz, CD2Cl2, 293 K): δ 193.8 (s, OCOCH3), 28.2 (d, J P-C
33.2 Hz, PCH(CH3)2), 26.0 (s, OCOCH3), 18.9 (s, PCH(CH3)2).
)
P r ep a r a tion of [OsH(K2-OCOCH3){C(P h )CH2}(P iP r 3)2]-
BF 4 (4). A stoichiometric amount of phenylacetylene (16.2 µL,
0.15 mmol) was added, via syringe, to a solution of 3 (100 mg,
0.15 mmol) in dichloromethane (10 mL). An immediate color
change from pale yellow to purple was observed. The resulting
mixture was stirred for 15 min at room temperature and then
was evaporated to dryness. Subsequent addition of diethyl
ether caused the precipitation of a purple solid, which was
washed with diethyl ether and dried in vacuo. Yield: 62 mg
(55%). Anal. Calcd for C28H53BF4O2OsP2: C, 44.21; H, 7.02.
Found: C, 44.46; H, 6.36. IR (Nujol, cm-1): ν(Os-H) 2236 (w),
ν(CdC) 1590 (s), νasym(OCO) 1511 (m), ν(B-F) 1150-1000 (s).
1H NMR (300 MHz, CD2Cl2, 293 K): δ 9.40 (br, 1H, Ph), 8.06
(t, J H-H ) 7.5 Hz, 1H, Ph), 7.90 (br, 1H, Ph), 7.59 (br, 2H, Ph),
2.25 (m, 6H, PCH(CH3)2), 2.09 (s, 3H, OCOCH3), 1.47 (t, 2H,
J P-H ) 6.9 Hz, Os-CH2-), 1.37 (dvt, J H-H ) 7.2 Hz, N ) 14.1
Hz, 18H, PCH(CH3)2), 0.99 (dvt, J H-H ) 7.2 Hz, N ) 14.1 Hz,
18H, PCH(CH3)2), -8.62 (t, J P-H ) 15.3 Hz, 1H, Os-H). 1H
NMR (300 MHz, CD2Cl2, 213 K, aromatic region): δ 9.43 (d,
J H-H ) 7.5 Hz, 1H), 8.05 (t, J H-H ) 7.5 Hz, 1H), 7.90 (d, J H-H
) 7.2 Hz, 1H), 7.65 (t, J H-H ) 7.5 Hz, 1H), 7.53 (t, J H-H ) 7.5
Hz, 1H); there are no significant changes in the other signals.
31P{1H} NMR (121.42 MHz, CD2Cl2, 293 K): δ 25.5 (s, doublet
under off-resonance conditions). 13C{1H} NMR (75.47 MHz,
CD2Cl2, 213 K plus apt): δ 263.2 (s, OsdC), 188.5 (s, OCOCH3),
142.9 (s, Cipso Ph), 133.5, 132.2, 131.9, 131.3, 130.9 (each one
s, Ph), 26.8 (s, OCOCH3), 23.0 (br, PCH(CH3)2), 19.1 (s, PCH-
(CH3)2), 18.0 (s, PCH(CH3)2), -0.7 (s, Os-CH2).
Rea ction of [{OsH2(K2-OCOCH3)(P iP r 3)2}2(µ-OCOCH3)]-
BF 4 w ith P h CtCH. In a 5 mm NMR tube, 2 (11.6 mg, 9 ×
10-3 mmol) was disolved in CD2Cl2 (0.5 mL). To this solution
was added PhCtCH (1 µL, 9 × 10-3 mmol) via syringe. The
color of the resulting solution changed within time of mixing
from yellow to purple. 1H and 31P NMR spectra were im-
1
mediately recorded. Both H and 31P{1H} NMR spectra showed
peaks corresponding to OsH2(κ2-OCOCH3)(κ1-OCOCH3)(PiPr3)2
(50%)7 and [OsH(κ2-OCOCH3){C(Ph)CH2}(PiPr3)2]BF4 (50%),
by comparison with pure samples.
Rea ction of [{OsH2(K2-OCOCH3)(P iP r 3)2}2(µ-OCOCH3)]-
BF 4 w ith HCtCC(OH)P h 2. A 37 mg (2.9 × 10-2 mmol)
sample of 2 was reacted with 6 mg (2.9 × 10-2 mmol) of 1,1-
diphenyl-2-propyn-1-ol in 2 mL of dichloromethane at -40 °C.
The reaction mixture was stirred for 1 h and 30 min, while
warming to -10 °C. After this time, the solvent was evaporated
to dryness and diethyl ether added to precipitate a yellow solid,
which was extracted three times with the same solvent. The
diethyl ether solution was then evaporated to dryness and cold
pentane added to precipitate a yellow solid, which was dried
under vacuo and subsequently identified as OsH2(k2-OCOCH3)-
(k1-OCOCH3)(PiPr3)2 (10 mg, 1.58 × 10-2 mmol). The yellow
solid, originally precipitated from diethyl ether, was identified
as a mixture of compounds [{OsH2(k2-OCOCH3)(PiPr3)2}2(µ-
P r ep a r a tion of [OsH(K2-OCOCH3)(tCCH2P h )(P iP r 3)2]-
BF 4 (5). A solution of 6 (312.4 mg, 0.46 mmol) in 10 mL of

4958 Organometallics, Vol. 18, No. 24, 1999
Buil et al.
Ta ble 3. Cr ysta l Da ta a n d Da ta Collection a n d
OCOCH3)]BF4 (14%) and [OsH(κ2-OCOCH3){C[C(OH)Ph2]-
Refin em en t P a r a m eter s for
[{OsH2(K2-OCOCH3)(P iP r 3)2}2(µ-OCOCH3)]BF 4 (2)
CH2}(PiPr3)2]BF4 (86%).
P r epar ation of [OsH(K2-OCOCH3)(tCCH2CMe3)(P iP r 3)2]-
BF 4 (8). To a solution of 3 (100 mg, 0.15 mmol) in 10 mL of
dichloromethane was added HCtCtBu (18 µL, 0.15 mmol). The
resulting solution was stirred for 20 min at room temperature
and then evaporated to ca. 0.5 mL. Addition of diethyl ether
caused the precipitation of a pale yellow solid, which was
washed with diethyl ether and dried in vacuo. Yield: 75 mg
(68%). Anal. Calcd for C26H57BF4O2OsP2‚CH2Cl2: C, 39.28; H,
7.20. Found: C, 39.17; H, 7.19. IR (Nujol, cm-1): ν(Os-H)
2178, νasym(OCO) 1514, νsym(OCO) 1406, ν(BF4) 1100-1000. 1H
NMR (300 MHz, CDCl3, 293 K): δ 2.55 (m, 6H, PCH(CH3)2),
1.73 (s, 3H, OCOCH3), 1.56 (s, 2H, OstCCH2-), 1.38 (dvt, J H-H
a n d [OsH(K2-OCOCH3){C(P h )CH2}(P iP r 3)2]BF 4 (4)
2
4
formula
mol wt
color, habit
C
42H97BF4O6Os2P4
C28H53BF4O2OsP2
760.65
1289.29
pale yellow,
prismatic block
0.4 × 0.3 × 0.2
P21/c (14)
18.693(1)
18.190(1)
17.778(1)
90
114.737(10)
90
5490.3(5)
4
dark purple,
prismatic block
0.49 × 0.31 × 0.31
P21/n (14)
17.770(2)
12.928(2)
29.723(5)
90
102.22(3)
90
6673.6(17)
8
cryst size, mm
space group
a, Å
b, Å
c, Å
R, deg
) 6.6 Hz, N ) 13.5 Hz, 18H, PCH(CH3)2), 1.35 (dvt, J H-H
)
â, deg
γ, deg
7.2 Hz, N ) 14.7 Hz, 18H, PCH(CH3)2), 1.08 (s, 9H, CMe3),
-8.04 (t, J P-H ) 16.2 Hz, 1H, Os-H). 31P{1H} NMR (121.42
MHz, CD2Cl2, 293 K): δ 41.8 (s, doublet under off-resonance
conditions). 13C{1H} NMR (75.47 MHz, CD2Cl2, 293 K): δ 292.5
(t, J P-C ) 6.9 Hz, OstC), 187.2 (s, OCOCH3), 65.9 (s, -CH2-
), 32.3 (s, C(CH3)3), 30.6 (s, C(CH3)3), 27.0 (s, OOCCH3), 26.1
(vt, N ) 26.5 Hz, PCH(CH3)2), 19.5, 19.4 (both s, PCH(CH3)2).
P r ep a r a tion of [OsH(K2-OCOCH3)(tCCH3)(P iP r 3)2]BF 4
(9). This compound was prepared using two different proce-
dures. Method a: To a solution of 3 (100 mg, 0.15 mmol) in 10
mL of dichloromethane was added HCtCSiMe3 (21 µL, 0.15
mmol). The resulting solution was stirred for 10 min at room
temperature and then evaporated to ca. 0.5 mL. Addition of
diethyl ether caused the precipitation of a yellowish solid,
which was washed with diethyl ether and dried in vacuo.
Yield: 63 mg (60%). Method b: HCtCSiMe3 (76 µL, 0.53
mmol) was added to a solution of 2 (400 mg, 0.36 mmol) in 10
mL of dichloromethane. The resulting solution was stirred for
45 min at room temperature and then evaporated to ca. 0.5
mL. Addition of diethyl ether caused the precipitation of a light
yellow solid, which was washed with diethyl ether and dried
in vacuo. Yield: 242 mg (97%). Anal. Calcd for C22H49BF4O2-
OsP2: C, 38.60; H, 7.21. Found: C, 38.69; H, 6.73. IR (Nujol,
cm-1): ν(Os-H) 2170 (m), νasym(OCO) 1525 (m), νsym(OCO)
V, Å3
Z
D(calcd), g cm-3
µ, mm-1
scan type
1.560
4.793
1.514
3.97
ω scans at different ω/2θ
æ values
2θ range, deg
temp, K
no. of data collcd
no. of unique data
5 e 2θ e 46
153.0(2)
12757
3 e 2θ e 50
293.0(2)
13437
11729
706
7588
no. of params refined 574
R1a (Fo g 4.0σ(Fo))
wR2b (all data)
Sc (all data)
0.0313
0.0724
1.059
0.0443
0.1226
0.909
R1(F) ) ∑||Fo| - |Fc||/∑|Fo|. wR2(F2) ) [∑[w(Fo - Fc2)2]/
a
b
2
∑[w(Fo2)2]]1/2; w-1 ) [σ2(Fo2) + (aP)2 + bP], where P ) [max(Fo
,
2
0) + 2Fc2]/3 (2, a ) 0.0346, b ) 1.7805; 3, a )0.0326, b ) 1.4359).
2
c S ) [∑[w(Fo - Fc2)2]/(n - p)]1/2, where n is the number of
reflections and p the number of parameters.
OCOCH3), 114.3 (t, J P-C ) 3.2 Hz, OsdCdCHCMe3), 33.5 (s,
C(CH3)3), 25.4 (s, OOCCH3), 24.8 (vt, N ) 23.4 Hz, PCH(CH3)2),
24.5 (s, C(CH3)3), 19.9, 19.5 (both s, PCH(CH3)2).
P r epar ation of OsH(K2-OCOCH3)(dCdCH2)(P iP r 3)2 (11).
Compound 11 was prepared analogously as described for 10,
starting from 9 (100 mg, 0.146 mmol) and a solution (0.195
N) of KOH in methanol (766 µL, 0.146 mmol). Compound 11
was isolated as a yellow-greenish solid. Yield: 20 mg (23%).
Anal. Calcd for C22H48O2OsP2: C, 44.28; H, 8.11. Found: C,
43.96; H, 8.10. IR (Nujol, cm-1): ν(Os-H) 2140 (s), ν(CdC)
1613 (s), νasym(OCO) 1541(s), νsym(OCO) 1430 (s). 1H NMR (300
MHz, C6D6, 293 K): δ 2.72 (m, 6H, PCH(CH3)2), 1.62 (s, 3H,
OOCCH3), 1.35 (dvt, J H-H ) 6.9 Hz, N ) 13.2 Hz, 36H, PCH-
(CH3)2), 0.45 (t, 2H, J P-H ) 2.7 Hz OsdCdCH2), -12.87 (t,
1H, J P-H ) 15.6 Hz, Os-H). 31P{1H} NMR (121.42 MHz, C6D6,
293 K): δ 25.3 (s, doublet under off-resonance conditions). 13C-
{1H} NMR (75.47 MHz, C6D6, 293 K): δ 289.8 (t, J P-C ) 10.7
Hz, OsdCdCH2), 182.5 (br s, OCOCH3), 84.1 (br t, J P-C ) 1.8
Hz, OsdCdCH2), 24.9 (s, OCOCH3), 23.9 (vt, N ) 24.4 Hz,
PCH(CH3)2), 19.4 (s, PCH(CH3)2), 19.1 (s, PCH(CH3)2).
Rea ction of [{OsH2(K2-OCOCH3)(P iP r 3)2}2(µ-OCOCH3)]-
BF 4 w ith Me3SiCtCH. In a 5 mm NMR tube, 2 (9.25 mg, 7
× 10-3 mmol) was dissolved in CD2Cl2 (0.5 mL). To this
solution was added HCtCSiMe3 (1 µL, 7 × 10-3 mmol) via
syringe. After 15 min, the 1H and 31P{1H} NMR spectra showed
peaks corresponding to [OsH(κ2-OCOCH3)(tCCH3)(PiPr3)2]BF4
(45%), OsH2(κ2-OCOCH3)(κ1-OCOCH3)(PiPr3)2 (45%), and [{OsH2-
(κ2-OCOCH3)(PiPr3)2}2(µ-OCOCH3)]BF4 (10%).
1
1396 (m), ν(B-F) 1150-1000 (s). H NMR (300 MHz, CD2Cl2,
293 K): δ 2.54 (m, 6H, PCH(CH3)2), 1.75 (s, 3H, OCOCH3) 1.39
(dvt, 36H, J H-H ) 7.5 Hz, N ) 14.7 Hz, PCH(CH3)2), 1.30 (s,
3H, OstCCH3), -8.36 (t, 1H, J P-H ) 15.6 Hz). 31P{1H} NMR
(121.42 MHz, CD2Cl2, 293 K): δ 42.3 (s, doublet under off-
resonance conditions). 13C{1H} NMR (75.47 MHz, CD2Cl2, 293
K): δ 286.3 (t, J P-C ) 8.4 Hz, OstC CH3), 187.8 (br s,
OCOCH3), 40.1 (s, OstCCH3), 26.5 (vt, N ) 27.5 Hz, PCH-
(CH3)2), 25.9 (s, OOCCH3), 19.9 (s, PCH(CH3)2), 19.4 (s, PCH-
(CH3)2).
P r epar ation of OsH(K2-OCOCH3)(dCdCHCMe3)(P iP r 3)2
(10). A solution of 8 (100 mg, 0.13 mmol) in methanol (10 mL)
was treated with a solution (0.189 N) of KOH in methanol (0.7
mL, 0.13 mmol). The resulting mixture was stirred for 5 min
at room temperature and then evaporated to dryness. KBF4
was filtered away by adding toluene and filtering the resulting
suspension through Celite. The resulting toluene solution was
evaporated to dryness, and further addition of methanol
caused the precipitation of an orange-yellow solid, which was
washed with methanol and dried in vacuo. Yield: 35 mg (40%).
Anal. Calcd for C26H56O2OsP2: C, 47.83; H, 8.64. Found: C,
47.84; H, 8.60. IR (Nujol, cm-1): ν(Os-H) 2125 (m), ν(CdC)
1640 (m), νasym(OCO) 1544 (s), νsym(OCO) 1383 (s). 1H NMR
(300 MHz, C6D6, 293 K): δ 2.72 (m, 6H, PCH(CH3)2), 1.64 (s,
3H, OOCCH3), 1.37 (dvt, J H-H ) 6.9 Hz, N ) 13.5 Hz, 18H,
PCH(CH3)2), 1.28 (dvt, J H-H ) 6.6 Hz, N ) 12.6 Hz, 18H, PCH-
Rea ction of OsH(K2-OCOCH 3)(dCdCHCMe3)(P iP r 3)2
w ith HBF 4‚OEt2. In a 5 mm NMR tube, complex 10 (16.5 mg,
2.5 × 10-2 mmol) was dissolved in CDCl3 (0.5 mL). To this
solution was added HBF4‚OEt2 (3 µL, 2.5 × 10-2 mmol) via
syringe. 1H and 31P NMR spectra recorded immediately showed
quantitative formation of 8.
t
(CH3)2), 1.19 (s, 9H, Bu), 0.23 (t, J P-H ) 3.0 Hz, 1H, OsdCd
CHtBu), -12.81 (t, J P-H ) 15.9 Hz, 1H, Os-H). 31P{1H} NMR
(121.42 MHz, C6D6, 293 K): δ 24.0 (s, doublet under off-
resonance conditions). 13C{1H} NMR (75.47 MHz, C6D6, 293
K): δ 288.8 (t, J P-C ) 10.1 Hz, OsdCdCHtBu), 181.9 (s,
R ea ct ion of OsH(K2-OCOCH 3)(dCdCH 2)(P iP r 3)2 w it h
HBF 4‚OEt2. In a 5 mm NMR tube, complex 11 (5.4 mg, 9 ×

Reactions of New Osmium-Dihydride Complexes
Organometallics, Vol. 18, No. 24, 1999 4959
10-3 mmol) was disolved in CD2Cl2 (0.5 mL). To this solution
techniques and refined by full-matrix least-squares on F2
(SHELX97). Anisotropic parameters were used in the last
cycles of refinement for all nondisordered atoms (excluding the
hydrogen atoms). This hydrogen atoms (included in nondis-
ordered groups) were observed or calculated in idealized
positions and, most of them, refined riding on carbon atoms
using a common isotropic thermal parameter. The hydrogen
atoms H(01), H(02), H(03), and H(04) of 2 were refined as
isotropic atoms with the same Os-H distance and thermal
parameter, while the H(01), H(1A), H(1B), H(02), H(51A), and
H(51B) atoms of 4 were refined with all free variables. One of
the four phosphine ligands of the cation of 4 and both BF4
anions of the same molecule were found to be disordered and
were refined using geometry restraints and complementary
occupancy factors. Atomic scattering factors were implemented
by the program. The refinement converged to R1[F, F2 > 2σ-
(F2)] 0.0313 (2) or 0.0443 (4) and ωR2 (F2, all data) 0.0724 (2)
or 0.1293 (4).
1
was added HBF4‚OEt2 (1 µL, 9 × 10-3 mmol) via syringe. H
and 31P NMR spectra recorded after 5 min showed quantitative
formation of 9.
Com p u ta tion a l Deta ils. The calculations were carried out
with the Gaussian 98 suite of programs.22 Os was represented
with the Hay-Wadt relativistic core potential (ECP) for the
46 innermost electrons and its associated double-ú basis set.23
P
is also described with the Los Alamos ECPs and its
associated double-ú basis set augmented by a d polarization
function.24,25 A 6-31G(d,p) basis set26 was used for all other
atoms. The phenyl group was represented with a 6-31G for
the geometry optimization process, and the energies of the
resulting geometries were recalculated with a 6-31G(d,p) on
the phenyl group. Full optimizations without symmetry con-
straint have been carried out at the B3PW91 level.27,28
Cr ysta l Da ta for 2 a n d 4. Crystals suitable for the X-ray
diffraction study were obtained by slow diffusion of diethyl
ether into concentrated solutions of 2 and 4 in acetone at room
temperature. A summary of crystal data and refinement
parameters is reported in Table 3. The yellow (2) and deep
purple (4) crystals were glued on a glass fiber and mounted
on Siemens CCD (2) and Siemens-STOE (4) diffractometers
with graphite-monochromated Mo KR radiation. All data were
corrected for absorption using the SADABS program (2)29 or
a semiempirical method (4).30 The structures were solved by
Patterson (Os atoms, SHELX97)31 and conventional Fourier
Ack n ow led gm en t. We acknowledge financial sup-
port from the DGES of Spain (Project PB95-0806). C.G.-
Y. thanks C.S.I.C.-Repsol S.A. for a postdoctoral grant.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and equivalent isotropic displacement coefficients,
anisotropic thermal parameters, experimental details of the
X-ray studies, and bond distances and angles for 2 and 4. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(23) Hay, P. J .; Wadt, W. R. J . Chem. Phys. 1985, 82, 299.
(24) Wadt, W. R.; Hay, P. J . J . Chem. Phys. 1985, 82, 284.
(25) Holwarth, A.; Bohme, M.; Dapprich, S.; Ehlers, A. W.; Gobbi,
A.; J onas, V.; Kohler, K.; Stegmann, R.; Veldkamp, A.; Frenking, G.
Chem. Phys. Lett. 1993, 208, 237
OM990426Q
(26) Hariharan, P. C.; Pople, J . A. Theor. Chim. Acta 1973, 28, 213.
(27) Becke, A. D. J . Chem. Phys. 1993, 98, 5648.
(28) Perdew, J . P.; Wang, Y. Phys. Rev. B 1992, 45, 13244.
(29) SADABS. Sheldrick, G. Sadabs Userguide; Institut fu¨r Anor-
ganische Chemie der Universita¨t Go¨ttingen: Go¨ttingen, Germany.
(30) North, A. C. T.; Phillips, D. C.; Matthews, F. S. Acta Crystallogr.
1968, A24, 351.
(31) Sheldrick, G. SHELX97, Programs for Crystal Structure Solu-
tion and Refinement; Institut fu¨r Anorganische Chemie der Universita¨t
Go¨ttingen: Go¨ttingen, Germany, 1997.