Hydride-alkenylcarbyne to alkenylcarbene transformation in bisphosphine-osmium complexes

Article abstract of DOI:10.1021/ja053186g

The elongated dihydrogen complex [Os{C₆H₄C(O)CH ₃}(η²-H₂)(H₂O)(P ⁱPr₃)₂]BF₄ (1) reacts with 1,1-diphenyl-2-propyn-1-ol and 2-methyl-3-butyn-2-ol to give the hydride-hydroxyvinylidene-π-r-alkynol derivatives [OsH{=C=CHC(OH)R ₂}{η²-HC≡CC(OH)R₂}(P ⁱPr₃)₂]BF₄ (R = Ph (2), Me (3)), where the π-alkynols act as four-electron donor ligands. Treatment of 2 and 3 with HBF₄ and coordinating solvents leads to the dicationic hydride-alkenylcarbyne compounds [OsH(≡CCH=CR₂)S ₂(PⁱPr₃)₂][BF₄] ₂ (R = Ph, S = H₂O (4), CH₃CN (5); R = Me, S = CH₃CN (6)), which in acetonitrile evolve into the alkenylcarbene complexes [Os(=CHCH=CR₂)(CH₃CN)₃(P ⁱPr₃)₂][BF₄]₂ (R = Ph (7), Me (8)) by means of a concerted 1,2-hydrogen shift from the osmium to the carbyne carbon atom. Treatment of 2-propanol solutions of 5 with NaCl affords OsHCl₂(≡CCH=CPh₂)(PⁱPr₃) ₂ (10), which reacts with AgBF₄ and acetonitrile to give [OsHCl-(≡CCH=CPh₂)(Ch₃CN)(PⁱPr ₃)₂]BF₄ (11). In this solvent complex 11 is converted to [OsCl(=CHCH= CPh₂)(CH₃CN)₂(P ⁱPr₃)₂]BF₄ (12). Complex 5 reacts with CO to give [Os(=CHCH=CPh₂)(CO)(CH₃CN) ₂-(PⁱPr₃)₂][BF₄] ₂ (15). DFT calculations and kinetic studies for the hydride-alkenylcarbyne to alkenylcarbene transformation show that the difference of energy between the starting compounds and the transition states, which can be described as η²-carbene species (Os=C(R)H), increases with the basicity of the metallic center. The X-ray structures of 4 and 7 and the rotational barriers for the carbene ligands of 7, 8, and 12 are also reported.

Full text of DOI:10.1021/ja053186g

Published on Web 07/15/2005
Hydride-Alkenylcarbyne to Alkenylcarbene Transformation in
Bisphosphine-Osmium Complexes
Tamara Bolan˜o, Ricardo Castarlenas, Miguel A. Esteruelas,*
F. Javier Modrego, and Enrique On˜ate
Contribution from the Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales
de Arago´n, UniVersidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received May 16, 2005; E-mail: maester@posta.unizar.es
Abstract: The elongated dihydrogen complex [Os{C6H4C(O)CH3}(η2-H2)(H2O)(PiPr3)2]BF4 (1) reacts with
1,1-diphenyl-2-propyn-1-ol and 2-methyl-3-butyn-2-ol to give the hydride-hydroxyvinylidene-π-alkynol
derivatives [OsH{dCdCHC(OH)R2}{η2-HCtCC(OH)R2}(PiPr3)2]BF4 (R ) Ph (2), Me (3)), where the
π-alkynols act as four-electron donor ligands. Treatment of 2 and 3 with HBF4 and coordinating solvents
leads to the dicationic hydride-alkenylcarbyne compounds [OsH(tCCHdCR2)S2(PiPr3)2][BF4]2 (R ) Ph, S
) H2O (4), CH3CN (5); R ) Me, S ) CH3CN (6)), which in acetonitrile evolve into the alkenylcarbene
complexes [Os(dCHCHdCR2)(CH3CN)3(PiPr3)2][BF4]2 (R ) Ph (7), Me (8)) by means of a concerted 1,2-
hydrogen shift from the osmium to the carbyne carbon atom. Treatment of 2-propanol solutions of 5 with
NaCl affords OsHCl2(tCCHdCPh2)(PiPr3)2 (10), which reacts with AgBF4 and acetonitrile to give [OsHCl-
(tCCHdCPh2)(CH3CN)(PiPr3)2]BF4 (11). In this solvent complex 11 is converted to [OsCl(dCHCHd
CPh2)(CH3CN)2(PiPr3)2]BF4 (12). Complex 5 reacts with CO to give [Os(dCHCHdCPh2)(CO)(CH3CN)2-
(PiPr3)2][BF4]2 (15). DFT calculations and kinetic studies for the hydride-alkenylcarbyne to alkenylcarbene
transformation show that the difference of energy between the starting compounds and the transition states,
which can be described as η2-carbene species (OsdC(R)H), increases with the basicity of the metallic
center. The X-ray structures of 4 and 7 and the rotational barriers for the carbene ligands of 7, 8, and 12
are also reported.
Introduction
carbon atom have been found in the tungsten complex WH(tCs
Mes)(CO){P(OMe)3}3, which affords W(dCHsMes)(CO)L-
Complexes containing MdC and MtC bonds are attracting
much attention, due to their use as tools in organic synthesis
and homogeneous catalysis.1 Among the transformations involv-
ing both types of compounds, the equilibrium between hydride-
carbyne and carbene species (eq 1) is one of the most fascinating
processes.2
{P(OMe)3}3 (L ) CO, P(OMe)3, PMe3) via a five-coordinate
carbene intermediate.4 The 1,2-hydrogen shift has been mainly
observed in the opposite sense. The extraction of the chloride
ligand from the cyclopentadienyl-osmium-carbene complexes
Os(η5-C5H5)Cl(dCHPh)(PR3) gives rise to the hydride-carbyne
derivatives [OsH(η5-C5H5)(tCPh)(PR3)]PF6 (R ) PiPr3,5
PiPr2[C(CH3)dCH2]6). The related compounds [OsH(η5-C5H5)-
(tCCH2Ph)(PiPr3)]BF4 and [OsH(η5-C5H4SiPh3){tCCH-
7
(3) For example, see: (a) Clark, G. R.; Marsden, K.; Roper, W. R.; Wright,
L. J. J. Am. Chem. Soc. 1980, 102, 6570. (b) Holmes, S. J.; Schrock, R. R.
J. Am. Chem. Soc. 1981, 103, 4599. (c) Wengrovius, J. H.; Schrock, R. R.;
Churchill, M. R.; Wasserman, H. J. J. Am. Chem. Soc. 1982, 104, 1739.
(d) Holmes, S. J.; Clark, D. N.; Turner, H. W.; Schrock, R. R. J. Am. Chem.
Soc. 1982, 104, 6322. (e) Freudenberger, J. H.; Schrock, R. R. Organo-
metallics 1985, 4, 1937. (f) Mayr, A.; Asaro, M. F.; Kjelsberg, M. A.;
Lee, K. S.; Van Engen, D. Organometallics 1987, 6, 432. (g) Garret, K.
E.; Sheridan, J. B.; Pourreau, D. B.; Feng, W. C.; Geoffroy, G. L.; Staley,
D. L.; Rheingold, A. L. J. Am. Chem. Soc. 1989, 111, 8383. (h) Doyle, R.
A.; Angelici, R. J. Organometallics 1989, 8, 2207. (i) Blasch, L. L.; Abboud,
K.; Boncella, J. M. J. Am. Chem. Soc. 1991, 113, 7066. (j) Etienne, M.;
White, P. S.; Templeton, J. L. J. Am. Chem. Soc. 1991, 113, 2324. (k)
Bastos, C. M.; Daubenspeck, N.; Mayr, A. Angew. Chem., Int. Ed. Engl.
1993, 32, 743. (l) Giannini, L.; Solari, E.; Floriani, C.; Chiesi-Villa, A.;
Rizzoli, C. J. Am. Chem. Soc. 1998, 120, 823.
A large number of carbene complexes have been prepared
by protonating carbyne compounds.3 However, not in all cases
it has been clear the participation of the metallic center.
Evidences for 1,2-hydrogen shift from the metal to the carbyne
(1) For example, see: (a) Schrock, R. R. J. Chem. Soc., Dalton Trans. 2001,
2541. (b) Bunz, U. H. F. Acc. Chem. Res. 2001, 34, 998. (c) Hoveyda A.
H.; Schrock, R. R. Chem.sEur. J. 2001, 7, 945. (d) Guerchais, V. Eur. J.
Inorg. Chem. 2002, 783. (e) Schrock, R. R. Chem. ReV. 2002, 102, 145.
(f) Connon, S. J.; Blechert, S. Angew. Chem., Int. Ed. 2003, 42, 1900. (g)
Mass, G. Chem. Soc. ReV. 2004, 33, 183. (h) Cadierno, V.; Gamasa, M.
P.; Gimeno, J. Coord. Chem. ReV. 2004, 248, 1627. (i) Grubbs, R. H.
Tetrahedron 2004, 60, 7117. (j) Jia, G. Acc. Chem. Res. 2004, 37, 479. (k)
Barluenga, J.; Santamar´ıa, J.; Toma´s, M. Chem. ReV. 2004, 104, 2259.
(2) For example, see: (a) Caulton, K. G. J. Organomet. Chem. 2001, 617-
618, 56. (b) Jacobsen, H. J. Organomet. Chem. 2003, 674, 50.
(4) Bannwart, E.; Jacobsen, H.; Furno, F.; Berke, H. Organometallics 2000,
19, 3605.
(5) Esteruelas, M. A.; Gonza´lez, A. I.; Lo´pez, A. M.; On˜ate, E. Organometallics
2003, 22, 414.
(6) Esteruelas, M. A.; Gonza´lez, A. I.; Lo´pez, A. M.; On˜ate, E. Organometallics
2004, 23, 4858.
9
11184
J. AM. CHEM. SOC. 2005, 127, 11184-11195
10.1021/ja053186g CCC: $30.25 © 2005 American Chemical Society

Hydride-Alkenylcarbyne to Alkenylcarbene
A R T I C L E S
(Ph)R}(PiPr3)]BF4 (R ) H, CH3)8 are also known. Similarly,
the rhenium-hydride-carbyne complexes ReH(tCCH3)-
(η2-CH2dCH2)(PNP) (PNP ) N(SiMe2CH2PCy2)2),9 [ReH2-
(tCCH2R)(mq)(PPh3)2]PF6, and ReH(tCCH2R)(mq)(PPh3)2
(mq ) the anion of 2-mercaptoquinoline)10 are stable, and the
migratory insertion of the carbyne ligands into the ResH bond
is not observed. On the other hand, analogous ruthenium
compounds prefer the carbene form.11
which affords the cationic elongated dihydrogen derivate
[Os{C6H4C(O)CH3}(η2-H2)(H2O)(PiPr3)2]BF4 by reaction with
HBF4‚OH2.21 This complex reacts with terminal alkynes,
RCtCH, to give in a competitive manner hydride-vinylidene-
π-alkyne compounds [OsH(dCdCHR)(η2-HCtCR)(PiPr3)2]-
BF4 and hydride-osmacyclopropene species [OsH{C6H4C(O)-
CH3}{dC(R)CH2}(PiPr3)2]BF4. The preferred formation of one
The formation of [OsH(η5-C5H5)(tCPh)(PR3)]+ by means
of the creation of a coordination vacancy in Os(η5-C5H5)Cl-
(dCHPh)(PR3)2 agrees well with the existence of [OsH{κ-N,κ-
O[ONdC(CH3)2]}(tCCH2R)(PiPr3)2]BF4,12 [OsH(κ2-O2CCH3)-
(tCCH2R)(PiPr3)2]BF4,13 [OsHX(tCCH2Ph)(Hpz)(PiPr3)2]BF4
(X ) F, Cl),14 and OsHCl2(tCR)(PR′3)2.15 The latter are
isomers of the unknown compounds OsCl2(dCHR)(PR′3)2,
which should be the osmium counterparts to the Grubbs-type
carbene ruthenium derivatives RuCl2(dCHR)(PR′3)2.16 DFT
calculations indicate that although the energies of hydride-
carbyne and carbene isomers are similar, the energy for the
hydride migration is too large. Thus, the formation of
of the two types of compounds depends on the substituent R of
the alkyne.22 Hydrogen and alkyl groups exclusively afford
hydride-vinylidene-π-alkyne complexes, while phenyl gives rise
to a mixture of both types of derivates. The reaction with 4.5
equiv of phenylacetylene and 2.0 equiv of HBF4 leads to
[Os{(E)-CHdCHPh}(CtCPh)(tCCH2Ph)(PiPr3)2]BF4, which
coordinates chloride to form the isometallabenzene with struc-
ture of 1,2,4-cyclohexatriene Os{dCdC(Ph)CH(Ph)CHdC-
(CH2Ph)}Cl(PiPr3)2.23 Now, we have observed that the reactions
of [Os{C6H4C(O)CH3}(η2-H2)(H2O)(PiPr3)2]BF4 with alkynols
lead to hydride-hydroxyvinylidene-π-alkynol complexes, which
generate dicationic hydride-alkenylcarbyne derivatives.
OsCl2(dCHEt)(CO)(PiPr3)2 from OsHCl2(tCEt)(PiPr3)2 is
17
associative in CO.18
As a part of our work on the capacity of high valent metal
complexes to activate CsH bonds,19 we have recently shown
that the d2 hexahydride OsH6(PiPr3)2 activates an ortho-CH
In this paper we report the following: (i) the preparation and
characterization of novel hydride-hydroxyvinylidene-π-alkynol
and dicationic hydride-alkenylcarbyne complexes, (ii) the
transformation of the latter into dicationic alkenylcarbene
derivatives, (iii) the mechanism of the transformation, and (iv)
the influence of the co-ligands on the activation parameters of
the 1,2-hydrogen shift.
bond of acetophenone to yield OsH3{C6H4C(O)CH3}(PiPr3)2,20
(7) (a) Baya, M.; Esteruelas, M. A. Organometallics 2002, 21, 2332. (b) Baya,
M.; Esteruelas, M. A.; On˜ate, E. Organometallics 2002, 21, 5681.
(8) Baya, M.; Esteruelas, M. A.; On˜ate, E. Organometallics 2001, 20, 4875.
(9) Ozerov, O. V.; Huffman, J. C.; Watson, L. A.; Caulton, K. G. Organo-
metallics 2003, 22, 2539. (b) Ozerov, O. V.; Watson, L. A.; Pink, M.;
Caulton, K. G. J. Am. Chem. Soc. 2004, 126, 6363.
Results and Discussion
(10) Leeaphon, M.; Ondracek, A. L.; Thomas, R. J.; Fanwick, P. E.; Walton,
R. A. J. Am. Chem. Soc. 1995, 117, 9715.
1. Preparation and Characterization of [OsH{dCdCHC-
(OH)R2}{η2-HCtCC(OH)R2}(PiPr3)2]BF4 and [OsH(tCCHd
CR2)S2(PiPr3)2][BF4]2 (R ) Ph, Me; S ) H2O, CH3CN). The
chemical bonding in transition-metal alkyne complexes is
described in a way similar to that for transition-metal alkene
compounds. The bonding is considered to arise from donor-
acceptor interactions between the alkyne and the metal. A major
difference between alkene and alkyne is that the latter has a
second occupied π orbital orthogonal to the MC2 plane (M )
which, in some cases, engages in the transition-metal-alkyne
bonding. In that case, the alkyne is a four-electron-donor ligand
by means of its M| and M orbitals.
(11) For example, see: (a) Esteruelas, M. A.; Lahoz, F. J.; On˜ate, E.; Oro, L.
A.; Zeier, B. Organometallics 1994, 13, 4258. (b) Albeniz, M. J.; Esteruelas,
M. A.; Lledo´s, A.; Maseras, F.; On˜ate, E.; Oro, L. A.; Sola, E.; Zeier, B.
J. Chem. Soc., Dalton Trans. 1997, 181. (c) Esteruelas, M. A.; Liu, F.;
On˜ate, E.; Sola, E.; Zeier, B. Organometallics 1997, 16, 2919. (d) Trnka,
T. M.; Morgan, J. P.; Sanford, M. S.; Wilhelm, T. E.; Scholl, M. S.; Choi,
T.-L.; Ding, S.; Day, M. W.; Grubbs, R. H. J. Am. Chem. Soc. 2003, 125,
2546. (e) Dinger, M. B.; Nieczypor, P.; Mol, J. C. Organometallics 2003,
22, 5291. (f) Volland, M. A. O.; Hansen, S. M.; Rominger, F.; Hofmann,
P. Organometallics 2004, 23, 800. (g) Pru¨hs, S.; Lehmann, C. W.; Fu¨rstner,
A. Organometallics 2004, 23, 280. (h) Forman, G. S.; McConnell, A. E.;
Hanton, M. J.; Slawin, A. M. Z.; Tooze, R. P.; van Rensburg, W. J.; Meyer,
W. H.; Dwyer, C.; Kirk, M. M.; Serfontein, D. W. Organometallics 2004,
23, 4824. (i) Mishal, T. K.; Mondal, B.; Puranik, V. G.; Wadgaonkar, P.
P.; Lahiri, G. K.; Sarkar, A. J. Organomet. Chem. 2005, 690, 1018.
(12) Barrio, P.; Esteruelas, M. A.; On˜ate, E. Organometallics, 2002, 21, 2491.
(13) (a) 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. (b) Buil, M. L.;
Eisenstein, O.; Esteruelas, M. A.; Garc´ıa-Yebra, C.; Gutierrez-Puebla, E.;
Oliva´n, M.; On˜ate, E.; Ruiz, N.; Tajada, M. A. Organometallics 1999, 18,
4949. (c) Buil, M. L.; Esteruelas, M. A.; Garc´ıa-Yebra, C.; Gutie´rrez-Puebla,
E.; Oliva´n, M. Organometallics 2000, 19, 2184. (d) Esteruelas, M. A.;
Garc´ıa-Yebra, C.; Oliva´n, M.; On˜ate, E.; Tajada, M. A. Organometallics
2000, 19, 5098.
In dichloromethane, the elongated dihydrogen complex
[Os{C6H4C(O)CH3}(η2-H2)(H2O)(PiPr3)2]BF4 (1) releases aceto-
phenone to afford the highly unsaturated monohydride [OsH-
(H2O)(PiPr3)2]+,22 which rapidly coordinates two alkynol mol-
(14) Esteruelas, M. A.; Oliva´n, M.; On˜ate, E.; Ruiz, N.; Tajada M. A.
Organometallics 1999, 18, 2953.
(15) (a) Espuelas, J.; Esteruelas, M. A.; Lahoz, F. J.; Oro, L. A.; Ruiz, N. J.
Am. Chem. Soc. 1993, 115, 4683. (b) Spivak, G. J.; Coalter, J. N.; Oliva´n,
M.; Eisenstein, O.; Caulton, K. G. Organometallics 1998, 17, 999. (c)
Werner, H.; Jung, S.; Weberndo¨rfer, B.; Wolf, J. Eur. J. Inorg. Chem. 1999,
951.
(16) (a) Ferrando, G.; Gerard, H.; Spivak, G. J.; Coalter, J. N., III; Huffman, J.
C.; Eisenstein, O.; Caulton, K. G. Inorg. Chem. 2001, 40, 6610. (b)
Ferrando-Miguel, G.; Ge´rard, H.; Eisenstein, O.; Caulton, K. G. Inorg.
Chem. 2002, 41, 6440. (c) Ferrando, G.; Coalter, J. N., III; Ge´rard, H.;
Huang, D.; Eisenstein, O.; Caulton, K. G. New. J. Chem. 2003, 27, 1451.
(17) This complex is another member of the OsCl2(dCHCH2R)(CO)(PiPr3)2
series. See: Esteruelas, M. A.; Lahoz, F. J.; On˜ate, E.; Oro, L. A.; Valero,
C.; Zeier, B. J. Am. Chem. Soc. 1995, 117, 7935.
(19) (a) Barea, G.; Esteruelas, M. A.; Lledo´s, A.; Lo´pez, A. M.; On˜ate, E.;
Tolosa, J. I. Organometallics 1998, 17, 4065. (b) Barrio, P.; Castarlenas,
R.; Esteruelas, M. A.; On˜ate, E. Organometallics 2001, 20, 2635. (c)
Esteruelas, M. A.; Lledo´s, A.; Maseras, F.; Oliva´n, M.; On˜ate, E.; Tajada,
M. A.; Toma´s, J. Organometallics 2003, 22, 2087. (d) Esteruelas, M. A.;
Lledo´s, A.; Oliva´n, M.; On˜ate, E.; Tajada, M. A.; Ujaque, G. Organo-
metallics 2003, 22, 3753. (e) Barrio, P.; Esteruelas, M. A.; On˜ate, E.
Organometallics 2004, 23, 3627. (g) Eguillor, B.; Esteruelas, M. A.; Oliva´n,
M.; On˜ate, E. Organometallics 2004, 23, 6015. (h) Eguillor, B.; Esteruelas,
M. A.; Oliva´n M.; On˜ate, E. Organometallics 2005, 24, 1428.
(20) Barrio, P.; Castarlenas, R.; Esteruelas, M. A.; Lledo´s, A.; Maseras, F.; On˜ate,
E.; Toma´s, J. Organometallics 2001, 20, 442.
(21) Barrio, P.; Esteruelas, M. A.; Lledo´s, A.; On˜ate, E.; Toma´s, J. Organo-
metallics 2004, 23, 3008.
(22) Barrio, P.; Esteruelas, M. A.; On˜ate, E. Organometallics 2003, 22, 2472.
(23) Barrio, P.; Esteruelas, M. A.; On˜ate, E. J. Am. Chem. Soc. 2004, 126, 1946.
(18) (a) Spivak, G. J.; Coalter, J. N.; Oliva´n, M.; Eisenstein, O.; Caulton, K. G.
Organometallics 1998, 17, 999. (b) Spivak, G. J.; Caulton, K. G.
Organometallics 1998, 17, 5260.
9
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A R T I C L E S
Bolan˜o et al.
ecules. Thus, the treatment of dichloromethane solutions of 1
with 2.5 equiv of 1,1-diphenyl-2-propyn-1-ol and 2-methyl-3-
butyn-2-ol, at 243 K, leads to [OsH{dCdCHC(OH)R2}{η2-
HCtCC(OH)R2}(PiPr3)2]BF4 (R ) Ph (2), Me (3)), containing
a hydroxyvinylidene group and a four-electron donor π-alkynol
ligand (eq 2).
In the 1H NMR spectra in dichloromethane-d2, the resonances
corresponding to the H-C(sp)-proton of the alkynols appear at
9.91 (2) and 10.09 (3) ppm. These chemical shifts agree well
with those found for the cyclopentadienyl complexes [Os(η5-
C5H5){η2-HCtCC(OH)R2}(PiPr3)]PF6 (δ, 9.43 (R ) Ph) and
9.17 (R ) Me)). On the other hand, they are strongly shifted
toward lower field with regard to the HsC(sp) resonances
observed for the two-electron-donor alkynols of the compounds
Os(η5-C5H5)Cl{η2-HCtCC(OH)R2}(PiPr3) (δ, 4.32 (R ) Ph)
and 3.72 (R ) Me)).29 A similar relationship is observed
between the 13C{1H} NMR spectra of these compounds. The
C(sp) resonances are observed at 158.6 and 142.3 (2) and 163.0
and 138.0 (3) ppm, in agreement with the chemical shifts found
for the cationic cyclopentadienyl complexes (δ, 179.0 and 146.0
(R ) Ph) and 182.8 and 143.3 (R ) Me)). However, they appear
strongly shifted toward lower field with regard to those observed
for Os(η5-C5H5)Cl{η2-HCtCC(OH)R2}(PiPr3) (δ, 82.2 and 57.5
(R ) Ph) and 69.1 and 49.6 (R ) Me)).30
In agreement with a parallel disposition of the carbon-carbon
triple bond of the alkynols with regard to the P-P direction,
the 31P{1H} NMR spectra show AB spin systems centered at
32.9 (2) and 31.5 (3) ppm and defined by ∆ν ) 664 Hz and
JA-B ) 117.9 Hz (2) and ∆ν ) 956 Hz and JA-B ) 120.5 Hz
(3). This disposition imposes a high steric hindrance between
the C(OH)R2 substituents and one of the phosphines. As a result,
the stability of 2 and 3 is very low. In solution at room
temperature, both compounds decompose to give a complex
mixture of unidentified species.
Complexes 2 and 3 are notable because they are rare examples
of five-coordinate cationic hydride-hydroxyvinylidene deriva-
tives. With the exception of the neutral six-coordinate compound
OsH(κ2-O2CCH3){dCdCHC(OH)Ph2}(PiPr3)2,24 as far as we
know, species of this type have not been previously reported in
the osmium chemistry, in particular those containing at the same
time hydride, hydroxyvinylidene, and π-alkynol ligands.
The chemistry of four-electron-donating alkynes has been
centered at early transition metals, mainly molybdenum and
tungsten. A wide variety of six-coordinate Mo(II) and W(II)
complexes have been synthesized.25 Four-coordinate d6 com-
plexes of the types ML(alkyne)326 and ML2(alkyne)227 have been
also reported. However, five-coordinate d6 monoalkyne com-
plexes with the general formula ML4(alkyne) are very scarce.28
In addition to [OsH{dCdCHR}{η2-HCtCR}(PiPr3)2]BF4 (R
) H, Cy, Ph),22 we have reported the cyclopentadienyl-osmium
derivatives [Os(η5-C5H5){η2-HCtCC(OH)R2}(PiPr3)]PF6 (R )
Ph, Me).29
Complexes 2 and 3 were isolated as orange and brown solids,
respectively, in almost quantitative yield and characterized by
elemental analysis, MS, IR, and 1H, 31P{H}, and 13C{1H} NMR
spectroscopy. The NMR spectra strongly support the presence
in these compounds of π-alkynol groups acting as four-electron
donor ligands. Furthermore, they indicate that the structure of
2 and 3 is like that of [OsH{dCdCHR}{η2-HCtCR}(PiPr3)2]-
BF4 which, on the basis of an X-ray diffraction study on the
acetylene derivative, has been described as a trigonal bipyramid
with apical phosphines and inequivalent angles within the
equatorial plane.22
The hydride ligands display doublet of doublets at -3.89 (2)
and -4.09 (3) ppm with H-P coupling constants of 29.7 and
1
22.2 (2) and 30.7 and 23.8 (3) Hz, in the H NMR spectra,
whereas the resonances corresponding to the Câ-H hydrogens
of the hydroxyvinylidene ligands appear at 3.63 (2) and 2.64
(3) ppm as triplets with H-P coupling constants of about 4.5
Hz. In the 13C{1H} NMR spectra, the Os-CR resonances of
the η1-carbon donor ligands are observed at 279.9 (2) and 282.4
(3) ppm, as triplets with C-P coupling constants of 14.4 and
15.1 Hz, respectively.
The hydroxy groups of the hydroxyvinylidene ligands of 2
and 3 are easily extracted from the organic skeletons by reaction
with H+. The hydroxyvinylidene-alkenylcarbyne transformation
is accompanied by the release of the π-alkynol ligand from the
osmium atom. The resulting highly unsaturated hydride-
alkenylcarbyne species are stabilized by action of coordinating
solvents. Thus, the treatment of dichloromethane solutions of
2 and 3 with 2 equiv of HBF4 at 243 K, and the subsequent
addition of water or acetonitrile, at room temperature, leads to
[OsH(tCCHdCR2)S2(PiPr3)2][BF4]2 (R ) Ph, S ) H2O (4),
CH3CN (5); R ) Me, S ) CH3CN (6)), which are isolated in
high yield according to eq 3.
(24) Bourgault, M.; Castillo, A.; Esteruelas, M. A.; On˜ate, E.; Ruiz, N.
Organometallics 1997, 16, 636.
(25) For example, see: (a) Templeton, J. L. AdV. Organomet. Chem. 1989, 29,
1. (b) Baker, P. K. AdV. Organomet. Chem. 1996, 40, 45. (c) Frohnapfel,
D. S.; Reinartz, S.; White, P. S.; Templeton, J. L. Organometallics 1998,
17, 3759. (d) Frohnapfel, D. S.; Enriquez, A. E.; Templeton, J. L.
Organometallics 2000, 19, 221.
(26) For example, see: (a) Tate, D. P.; Augl, J. M. J. Am. Chem. Soc. 1963,
85, 2174. (b) Wink, D. J.; Creagan, B. T. Organometallics 1990, 9, 328.
(c) Szyma´nska-Buzar, T.; Glowiak, T. J. Organomet. Chem. 1994, 467,
223. (d) Yeh, W.-Y.; Ting, C.-S. Organometallics 1995, 14, 1417. (e)
Mealli, C.; Masi, D.; Galindo, A.; Pastor, A. J. Organomet. Chem. 1998,
569, 21.
(27) For example, see: (a) Do¨tz, K. H.; Mu¨hlemeier, J. Angew. Chem., Int. Ed.
Engl. 1982, 21, 929. (b) Salt, J. E.; Girolami, G. S.; Wilkinso G.; Motevalli,
M.; Thornton-Pett, M.; Hursthouse, M. B. J. Chem. Soc., Dalton Trans.
1985, 685. (c) Wink, D. J.; Fox, J. R.; Cooper, N. J. J. Am. Chem. Soc.
1985, 107, 5012.
(28) For example, see: (a) Wink, D. J.; Creagan, B. T. J. Am. Chem. Soc. 1990,
112, 8585. (b) Pearson, J.; Cooke J.; Takats, J.; Jordan, R. B. J. Am. Chem.
Soc. 1998, 120, 1434. (c) Mao, T.; Zhang, Z.; Washington, J.; Takats, J.;
Jordan, R. B. Organometallics 1999, 18, 2331. (d) Ishino, H.; Kuwata, S.;
Ishii, Y.; Hidai, M. Organometallics 2001, 20, 13.
(29) Carbo´, J. J.; Crochet, P.; Esteruelas, M. A.; Jean, Y.; Lledo´s, A.; Lo´pez,
A. M.; On˜ate, E. Organometallics 2002, 21, 305.
Figure 1 shows a view of the geometry of the cation of 4.
Selected bond distances and angles are listed in Table 1. The
9
11186 J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005

Hydride-Alkenylcarbyne to Alkenylcarbene
A R T I C L E S
In agreement with the presence of a hydride ligand in 4-6,
1
their H NMR spectra in the high field region show triplets at
-9.86 (4), -6.44 (5), and -6.66 (6) ppm, with H-P coupling
constants of about 16 Hz. In the low field region the most
noticeable signal is a singlet between 4.8 and 5.5 ppm
corresponding to the C(sp2)-H proton of the alkenyl group of
the carbyne ligands. In the 13C{1H} spectra the Os-CR
resonances appear between 260 and 281 ppm, as triplets with
C-P coupling constants of about 8 Hz. The 31P{1H} NMR
spectra contain singlets between 25 and 50 ppm.
2. Formation and Characterization of [Os(dCHCHd
CR2)(CH3CN)3(PiPr3)2][BF4]2 (R ) Ph, Me). Dicationic
alkenylcarbyne complexes are rare.33 In the osmium chemistry,
they have been previously isolated as half-sandwich deriva-
tives.34 As far as we know dicationic osmium-hydride-alkenyl-
carbyne complexes were unknown until now. In contrast to the
neutral and monocationic derivatives previously reported, they
show a high tendency to evolve into alkenylcarbene compounds.
Thus, in acetonitrile under reflux, complexes 5 and 6 give rise
to the dicationic alkenylcarbene derivatives [Os(dCHCHd
CR2)(CH3CN)3(PiPr3)2][BF4]2 (R ) Ph (7), Me (8)), which are
isolated as green (7) and gray (8) solids in almost quantitative
yield, according to eq 4.
Figure 1. Molecular diagram of the cation of complex [OsH{tCCHd
CPh2}(H2O)2(PiPr3)2][BF4]2 (4).
Table 1. Selected Bond Lengths (Å) and Angles (deg) for
[OsH(tCCHdCPh2)(H2O)2(PiPr3)2][BF4]2 (4)
Os-P(1)
Os-P(2)
Os-O(1)
Os-O(2)
2.4197(17)
2.4410(17)
2.198(4)
Os-C(1)
C(1)-C(2)
C(2)-C(3)
1.733(6)
1.406(8)
1.352(8)
2.272(5)
P(1)-Os-P(2)
P(1)-Os-O(1)
P(1)-Os-O(2)
P(1)-Os-C(1)
P(1)-Os-H(01)
P(2)-Os-O(1)
P(2)-Os-O(2)
P(2)-Os-C(1)
P(2)-Os-H(01)
170.16(6)
88.30(13)
94.50(15)
90.5(2)
O(1)-Os-O(2)
O(1)-Os-C(1)
O(1)-Os-H(01)
O(2)-Os-C(1)
O(2)-Os-H(01)
C(1)-Os-H(01)
Os-C(1)-C(2)
C(1)-C(2)-C(3)
77.12(18)
176.5(2)
78(3)
99.7(2)
155(3)
105(3)
168.0(5)
128.6(6)
82(3)
85.86(13)
91.91(15)
95.7(2)
89(3)
Complexes 7 and 8 are also rare examples of dicationic
species containing an Os-C double bond, in the osmium
chemistry.35 They were characterized by elemental analysis, IR,
and 1H, 13C{1H}, and 31P{1H} NMR spectroscopy. Complex 7
was further characterized by an X-ray crystallographic study.
A view of the structure of the cation of this species is shown in
Figure 2. Selected bond distances and angles are listed in Table
2.
The geometry around the osmium atom can be described as
a distorted octahedron with the phosphorus atoms of the
phosphine ligands occupying trans positions (P(1)-Os-P(2) )
173.95(4)°). The perpendicular plane is formed by the aceto-
nitrile molecules mer disposed (N(1)-Os-N(3) ) 174.97(14)°)
and the carbene group trans disposed to N(2) (N(2)-Os-C(1)
) 172.05(16)°).
In this case, the most noticeable feature of the structure is
the Os-C(1) bond length of 1.890(5) Å, which supports the
Os-C double bond formulation.36 In agreement with the sp2
hybridization at C(1), the angles around this atom are between
112(3)° and 132.0(3)°. The parameters of the alkenyl moiety
agree well with those of 4. The C(1)-C(2) distance is 1.428(6)
coordination around the osmium atom can be rationalized as a
distorted octahedron with the phosphorus atoms of the phosphine
ligands occupying trans positions (P(1)-Os-P(2) ) 170.16(6)°).
The perpendicular plane is formed by the water molecules cis
disposed (O(1)-Os-O(2) ) 77.12(18)°), the hydride ligand
trans disposed to O(2), and the carbyne group trans disposed to
O(1) (O(1)-Os-C(1) ) 176.5(2)°).
The most conspicuous feature of the structure is the very short
Os-C(1) bond length of 1.733(6) Å, which is fully consistent
with an Os-C(1) triple bond formulation.31 Similarly to other
carbyne-metal compounds,32 a slight bending in the Os-C(1)-
C(2) moiety is also present (Os-C(1)-C(2) ) 168.0(5)°). The
alkenyl carbyne proposal is supported by the bond lengths and
angles within the η1-carbon donor ligand; e.g., C(1) and C(2)
are separated by 1.406(8) Å and C(2) and C(3), by 1.352(8) Å,
and the angles around C(2) and C(3) are in the range 111°-
128°.
(30) Esteruelas, M. A.; Lo´pez, A. M.; Ruiz, N.; Tolosa, J. I. Organometallics
1997, 16, 4657.
(33) (a) Jung, S.; Brandt, C. D.; Werner, H. New J. Chem. 2001, 25, 1101. (b)
Bustelo, E.; Jimenez-Tenorio, M.; Mereiter, K.; Puerta, M. C.; Valerga, P.
Organometallics 2002, 21, 1903. (c) Rigaut, S.; Touchard, D.; Dixneuf, P.
H. Organometallics 2003, 22, 3980. (d) Castarlenas, R.; Dixneuf, P. H.
Angew. Chem., Int. Ed. 2003, 42, 4524.
(31) For example, see: (a) Weber, B.; Steinert, P.; Windmu¨ller, B.; Wolf, J.;
Werner, H. J. Chem. Soc., Chem. Commun. 1994, 2595. (b) Bin, T. B.;
Yang, S.-Y.; Zhou, Z. Y.; Lin, Z.; Lau, C.-P.; Jia, G. Organometallics 2000,
19, 3757. (c) Castarlenas, R.; Esteruelas, M. A.; On˜ate, E. Organometallics
2001, 20, 3283. (d) Wen, T. B.; Zhou, Z. Y.; Lo, M. F.; Williams, I. D.;
Jia, G. Organometallics 2003, 22, 5217.
(34) (a) Baya, M.; Crochet, P.; Esteruelas, M. A., Gutierrez-Puebla, E.; Lo´pez,
A. M.; Modrego, J.; On˜ate, E.; Vela, N. Organometallics 2000, 19, 2585.
(b) Esteruelas, M. A.; Lo´pez, A. M.; On˜ate, E.; Royo, E. Organometallics
2004, 23, 3021. (c) Asensio, A.; Buil, M. L.; Esteruelas, M. A.; On˜ate, E.
Organometallics 2004, 23, 5787.
(32) Schubert, U. Solid-state Structures of Carbyne Complexes. In Carbyne
Complexes; Fischer, H., Hofmann, P., Kreissl, F. R., Schrock, R. R.,
Schubert, U., Weiss, K., Eds; VCH Verlagsgesellschaft mbH: Weinheim,
Germany, 1988; p 53.
(35) Esteruelas, M. A.; Oro, L. A. AdV. Organomet. Chem. 2001, 47, 1.
9
J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005 11187

A R T I C L E S
Bolan˜o et al.
Figure 2. Molecular diagram of the cation of complex [Os(dCHCHd
CPh2)(CH3CN)3(PiPr3)2][BF4]2 (7).
1
Figure 3. Variable-temperature H{31P} NMR spectra in the acetonitrile
region of [Os(dCHCHdCPh2)(CH3CN)3(PiPr3)2][BF4]2 (7): experimental
in CD2Cl2 (left) and calculated (right).
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
[Os(dCHCHdCPh2)(CH3CN)3(PiPr3)2][BF4]2 (7)
Os-P(1)
Os-P(2)
Os-N(1)
Os-N(2)
Os-N(3)
2.4575(12)
2.4638(12)
2.003(3)
2.129(3)
2.011(3)
Os-C(1)
1.890(5)
1.428(6)
1.355(6)
Line shape analysis of the cis acetonitrile methyl resonances
of 7 and 8 allows the calculation of the rate constants for the
rotation processes. The activation parameters obtained from the
corresponding Eyring analysis are ∆Hq ) 12.8 ( 0.4 kcal mol-1
and ∆Sq ) -0.6 ( 1.0 cal mol-1 K-1 for 7 and ∆Hq ) 13.7 (
0.5 kcal mol-1 and ∆Sq ) 1.4 ( 1.0 cal mol-1 K-1 for 8. The
values of the activation entropy, near zero, are consistent with
a rotational process, whereas the values of the activation
enthalpy lie within the range reported for other transition-metal-
carbene complexes37 and indicate that the substituents of the
alkenyl moiety have not any significant influence in the rotation.
C(1)-C(2)
C(2)-C(3)
P(1)-Os-P(2)
P(1)-Os-N(1)
P(1)-Os-N(2)
P(1)-Os-N(3)
P(1)-Os-C(1)
P(2)-Os-N(1)
P(2)-Os-N(2)
P(2)-Os-N(3)
P(2)-Os-C(1)
173.95(4)
93.56(9)
82.23(9)
90.60(10)
89.93(14)
87.90(9)
91.89(9)
87.68(10)
95.91(13)
N(1)-Os-N(2)
N(1)-Os-N(3)
N(1)-Os-C(1)
N(2)-Os-N(3)
N(2)-Os-C(1)
N(3)-Os-C(1)
Os-C(1)-C(2)
C(1)-C(2)-C(3)
90.22(12)
174.97(14)
91.59(15)
87.55(13)
172.05(16)
91.23(15)
132.0(3)
127.1(4)
1
In the H NMR spectra the most noticeable resonances of
the alkenylcarbene ligands are those corresponding to the CR-H
and Câ-H protons, which appear at 19.13 and 8.24 (7) and
19.04 and 7.57 (8) ppm, respectively, as doublets with H-H
coupling constants of about 14 Hz. In the 13C{1H} NMR spectra
the Os-CR resonances are observed at 267.9 (7) and 265.3 (8)
ppm, as triplets with C-P coupling constants of about 7 Hz.
The 31P{1H} NMR spectra shows singlets at 3.1 (7) and 2.5 (8)
ppm.
3. Mechanism of the Hydride-Alkenylcarbyne to Alkenyl-
carbene Transformation. The reactions shown in eq 4 were
followed by 1H NMR spectroscopy by measuring the appearance
of the CR-H resonance of the alkenylcarbene ligands of 7 and
8 as a function of time. As shown in Figure 4 for the
transformation from 5 to 7, in acetonitrile as solvent, the
increases of 7 and 8 (with the corresponding decreases of 5
and 6) are exponential functions of time, in agreement with
pseudo first-order processes.
Å, whereas the C(2)-C(3) bond length is 1.355(6) Å, and the
angles around C(2) and C(3) are in the range 116°-128°.
The 1H and 13C{1H} NMR spectra of 7 and 8 are temperature
dependent. Figure 3 shows the acetonitrile region of the 1H{31P}
NMR spectrum of 7 in dichloromethane-d2, as a function of
the temperature. The spectrum of 8 is similar. According to
Figure 2, the hydrogen and alkenyl substituents of the carbene
carbon atom lie in the plane containing the nitrogen atoms. As
a result, the acetonitrile molecules cis disposed to the alkenyl-
carbene ligand are chemically inequivalent. In agreement with
this, the spectrum at 223 K contains three resonances for the
acetonitrile methyl groups at 3.2 (cis to carbene), 2.95 (trans to
carbene), and 2.88 (cis to carbene) ppm. On raising the
temperature, the cis acetonitrile methyl resonances coalesce, until
finally only one resonance is observed. This behavior can be
understood as the result of the rotation of the alkenylcarbene
ligand around the Os-C double bond.
To determine the role of acetonitrile during these reactions,
we have also followed the transformation from 5 to 7 in
chloroform-d as solvent and in the presence of acetonitrile
concentrations between 0.83 and 3.34 M. Interestingly, at 363
(36) For example, see: (a) Esteruelas, M. A.; Lahoz, F. J.; On˜ate, E.; Oro, L.
A.; Zeier, B. Organometallics 1994, 13, 1662. (b) Brumaghim, J. L.;
Girolami, G. S. Chem. Commun. 1999, 953. (c) Werner, H.; Stu¨er, W.;
Wolf, J.; Laubender, M.; Weberndo¨rfer, B.; Herbst-Irmer, R.; Lehmann,
C. Eur. J. Inorg. Chem. 1999, 1889. (d) Castarlenas, R.; Esteruelas, M.
A.; On˜ate, E. Organometallics 2001, 20, 2294. (e) Gusev, D. G.; Lough,
A. J. Organometallics 2002, 21, 2601. (f) Weberndo¨rfer, B.; Henig, G.;
Hockless, D. C. R.; Bennett, M. A.; Werner, H. Organometallics 2003,
22, 744.
(37) For example, see: (a) Kegley, S. E.; Brookhart, M.; Husk, G. R.
Organometallics 1982, 1, 760. (b) Gunnoe, T. B.; White, P. S.; Templeton,
J. L. Organometallics 1997, 16, 370.
9
11188 J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005

Hydride-Alkenylcarbyne to Alkenylcarbene
A R T I C L E S
Figure 4. Stacked 1H NMR spectra illustrating the transformation from 5
to 7 in CD3CN at 323 K.
Table 3. Rate Constants for the Hydride-Alkenylcarbyne to
Alkenylcarbene Transformations
1
k
obs (105 s-
)
Figure 5. Eyring plot of kobs for the formation of 7 (b), 8 (4), and 12 (9).
T (K)
solvent
[CH3CN]
7
8
12
313
323
333
333
333
333
338
343
348
353
CD3CN
CD3CN
CD3CN
CDCl3
CDCl3
CDCl3
CD3CN
CD3CN
CD3CN
CD3CN
3.5 ( 0.03
11.6 ( 0.1
44.2 ( 0.5
53.1 ( 0.4
42.9 ( 0.4
33.5 ( 1.3
1.0 ( 0.03
3.4 ( 0.2
9.6 ( 0.3
0.6 ( 0.01
3.3
2.1
0.8
1.1 ( 0.1
1.8 ( 0.1
4.1 ( 0.2
6.4 ( 0.3
137.0 ( 1.4
264.5 ( 2.3
30.5 ( 0.4
89.7 ( 0.5
K, the value of kobs for the reaction carried out in acetonitrile
as solvent (4.4 × 10-4 s-1) lies within the range of values found
for the reactions carried out in chloroform-d and in the presence
of acetonitrile, between 3.3 × 10-4 and 5.3 × 10-4 s-1. This
result clearly shows that the formation rates of the alkenylcar-
bene ligands of 7 and 8 are independent of the acetonitrile
amount in the reaction medium. So, acetonitrile does not play
any role in the formation of the alkenylcarbene ligands. Its role
in the reactions is to trap the five-coordinate intermediates
[Os(dCHCHdCR2)(CH3CN)2(PiPr3)2]2+ (9), which are gener-
ated as a result of the 1,2-hydrogen shift from the osmium atom
to the carbon atom of the carbyne ligands of 5 and 6.
The values obtained for kobs in the temperature range studied
are collected in Table 3. The activation parameters for the
formation of both 7 and 8 have been obtained from the
corresponding Eyring analysis (Figure 5). The values found for
the formation of 7, ∆Hq ) 23.8 ( 1.6 kcal mol-1 and ∆Sq )
-2.8 ( 2.3 cal mol-1 K-1, are similar to those obtained for the
formation of 8, ∆Hq ) 23.9 ( 1.3 kcal mol-1 and ∆Sq ) -5.3
( 2.3 cal mol-1 K-1. This indicates that the substituents of the
alkenyl moiety of the alkenylcarbyne ligands have not any
significant influence in the reaction shown in eq 4.
The slightly negative values of the activation entropy suggest
that the insertion of the alkenylcarbyne ligands into the Os-H
bond of 5 and 6 is an intramolecular process, which occurs by
a concerted mechanism with a geometrically highly oriented
transition state. To obtain information about the nature of this
transition state, we have performed DFT calculations on the
process shown in eq 4, using PH3 and CCHdCH2 as models of
the triisopropylphosphine and alkenylcarbyne ligands, respec-
tively (Figure 6).
Figure 6. Optimized structures and relative energies (kcal mol-1) of [OsH-
(tCCHdCH2)(CH3CN)2(PH3)2]2+ (5t), [Os(dCHCHdCH2)(CH3CN)2-
(PH3)2]2+ (9t), [Os(dCHCHdCH2)(CH3CN)3(PH3)2]2+ (7t), and the tran-
sition state TS1.
alkenylcarbyne starting compound [OsH(tCCHdCH2)(CH3-
CN)2(PH3)2]2+ (5t) takes place via the five-coordinate interme-
diate [Os(dCHCHdCH2)(CH3CN)2(PH3)2]+ (9t), which lies 2.5
kcal mol-1 above 5t. The coordination of an acetonitrile
molecule to 9t is exothermic by 36.7 kcal mol-1
.
The geometry around the osmium atom of 9t can be
rationalized as a square pyramid with the alkenylcarbene ligand
located at the apex, trans phosphines (169.0°) and trans
acetonitriles (173.4°). The Os-C distance of 1.908 Å agrees
well with that found by X-ray diffraction analysis for 7.
The transition state TS1 connecting 5t with the intermediate
9t was located. It results from the approach of the hydride ligand
to the carbyne carbon atom in 5t. As a consequence of the
approach process the osmium-hydride-carbyne unit forms an
(OsdC(R)H) system. The OssC distance of 1.859 Å is 0.1 Å
longer than that found in 5t (1.759 Å) and 0.049 Å shorter than
the calculated one in 9t. The OssH and CsH distances are
The formation of the six-coordinate alkenylcarbene complex
[Os(dCHCHdCH2)(CH3CN)3(PH3)2]2+ (7t) from the hydride-
9
J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005 11189

A R T I C L E S
Scheme 1
Bolan˜o et al.
2.144 and 1.165 Å, respectively, whereas the CsOssH angle
is 32.9°. This distorted η2-coordination mode has been observed
in alkylidene complexes of electron-deficient transition metals.38
In agreement with the values obtained by 1H NMR spectroscopy
for the activation enthalpy of the reactions shown in eq 4, the
energy of TS1 is 19.4 kcal mol-1 above 5t.
1
Figure 7. Variable-temperature H{31P} NMR spectra in the acetonitrile
region of [OsCl(dCHCHdCPh2)(CH3CN)2(PiPr3)2]BF4 (12): experimental
in CD2Cl2 (left) and calculated (right).
As a consequence of the inequivalence of the acetonitrile
molecules and the rotation of the alkenylcarbene ligand around
the Os-C double bond, the acetonitrile resonances of 12 are
4. Influence of the Co-ligands on the Activation Param-
eters of the 1,2-Hydrogen Shift. Treatment of 2-propanol
solutions of 5 with 5.0 equiv of NaCl produces the replacement
of the acetonitrile molecules by chloride ligands. The substitu-
tion leads to OsHCl2(tCCHdCPh2)(PiPr3) (10), which is
isolated as a green solid in 69%, according to Scheme 1.
The 1H NMR spectrum of 10 in dichloromethane-d2 shows a
singlet at 4.91 ppm, due to the Câ-H proton of the alkenyl-
carbyne group. The hydride ligand gives rise to a triplet at -7.28
ppm, with a H-P coupling constant of 17.1 Hz. In the 13C{1H}
NMR spectrum the Os-CR resonance of the η1-carbon donor
ligand appears at 254.1 ppm, as a triplet with a C-P coupling
constant of 10.8 Hz. The 31P{1H} NMR spectrum shows a
singlet at 18.3 ppm.
temperature dependent in the H and 13C{1H} NMR spectra.
1
Line shape analysis of the observed ones in the 1H{31P} NMR
spectrum (Figure 7) allows the calculation of the rate constants
for the rotation process. The activation parameters obtained from
the corresponding Eyring analysis are ∆Hq ) 13.3 ( 0.6 kcal
mol-1 and ∆Sq ) -3.2 ( 1.3 cal mol-1 K-1. These values agree
well with those obtained for 7 and 8.
1
In the H NMR spectrum of 12 in dichloromethane-d2, the
most noticeable resonances of the alkenylcarbene ligand are
those due to the CR-H and Câ-H protons, which appear at 20.29
and 7.98 ppm, respectively, as doublets with a H-H coupling
constant of 13.2 Hz. In the 13C{1H} NMR spectrum, the Os-
CR resonance is observed at 252.0 ppm, as a triplet with a C-P
coupling constant of 8.3 Hz. The 31P{1H} NMR spectrum
contains a singlet at -6.3 ppm.
In acetonitrile as solvent, complex 10 reacts with 1.0 equiv
of AgBF4 to give the monocationic derivative [OsHCl(tCCHd
CPh2)(CH3CN)(PiPr3)2]BF4 (11) as a result of the extraction of
one of the chloride ligands and the coordination of an acetonitrile
molecule. Complex 11 is isolated as an orange solid in 89%
yield.
The formation of 12 was followed by 1H NMR spectroscopy
(Table 3) by measuring the appearance of the CR-H resonance
of the alkenylcarbene ligand as a function of time. The reaction
is a first-order process, with activation parameters of ∆Hq )
27.6 ( 3.7 kcal mol-1 and ∆Sq ) -0.4 ( 4.8 cal mol-1 K-1
(Figure 5). The value of the activation enthalpy, which is slightly
higher than that obtained for the formation of 7, suggests that,
in 5, the substitution of an acetonitrile molecule by a chloride
ligand produces an increase of the activation barrier for the 1,2-
hydrogen shift from the osmium to the carbyne carbon atom.
This is also supported by DFT calculations (Figure 8).
The insertion of the alkenylcarbyne ligand into the OssH
bond of the model compound [OsHCl(tCCHdCH2)(CH3CN)-
(PH3)2]+ (11t) leads to the five-coordinate complex [OsCl-
(dCHCHdCH2)(CH3CN)(PH3)2]+ (13t), which lies 1.9 kcal
mol-1 above 11t. The process takes place via the transition state
TS2, which is 22.8 kcal mol-1 above 11t. In agreement with
the spectroscopic results, this value is slightly higher (3.2 kcal
mol-1) than the energy difference between TS1 and 5t.
The structure of the five-coordinate intermediate 13t is similar
to that of 9t with P-Os-P and Cl-Os-N angles of 173.3°
1
The H NMR spectrum of 11 in dichloromethane-d2 shows
the Câ-H resonance corresponding to the alkenylcarbyne ligand
at 5.14 ppm, as a singlet, whereas the hydride resonance appears
at -6.51 ppm as a triplet with a H-P coupling constant of 16.8
Hz. In the 13C{1H} NMR spectrum the Os-CR resonance is
observed at 256.9 ppm, as a triplet with a C-P coupling of
13.2 Hz. The 31P{1H} NMR spectrum contains a singlet at 25.5
ppm.
Like 5 and 6, in acetonitrile under reflux, complex 11 evolves
into an alkenylcarbene species, [OsCl(dCHCHdCPh2)(CH3-
CN)2(PiPr3)2]BF4 (12), as a result of the 1,2-hydrogen shift of
the hydride ligand from the osmium to the carbyne carbon atom.
Complex 12 is isolated as a yellow solid in 91% yield.
(38) (a) Schultz, A. J.; Williams, J. M.; Schrock, R. R.; Rupprecht, G. A.;
Fellmann, J. D. J. Am. Chem. Soc. 1979, 101, 1593. (b) Goddard, R. J.;
Hoffmann, R.; Jemmis, E. D. J. Am. Chem. Soc. 1980, 102, 7667.
9
11190 J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005

Hydride-Alkenylcarbyne to Alkenylcarbene
A R T I C L E S
hydride carbyne to carbene transformation from an experimental
point of view, since the activation barrier for the substitution
of one of the chloride ligands by an acetonitrile molecule is
lower than that for the 1,2-hydrogen shift. In fact, in acetonitrile
at 353 K complex 10 evolves into [OsCl(dCHCHdCPh2)(CH3-
CN)2(PiPr3)2]Cl via [OsHCl(tCCHdCPh2)(CH3CN)(PiPr3)2]Cl.
The increase of the activation barrier is certainly a conse-
quence of the increase of electron density on the metallic center.
The substitution of an acetonitrile molecule in 5 by carbon
monoxide, which in contrast to chloride is a π-acceptor ligand,
produces a rapid hydride-carbyne to carbene transformation.
Thus, at room temperature under carbon monoxide atmosphere,
complex 5 affords [Os(dCHCHdCPh2)(CO)(CH3CN)2(PiPr3)2]-
[BF4]2 (15), which is isolated as an orange solid in 90% yield
according to eq 5.
Figure 8. Optimized structures and relative energies (kcal mol-1) of
[OsHCl(tCCHdCH2)(CH3CN)(PH3)2]+ (11t), [OsCl(dCHCHdCH2)(CH3-
CN)(PH3)2]+ (13t), and the transition state TS2.
The presence of a carbonyl ligand in 15 is strongly supported
by its IR and 13C{1H} NMR spectrum. The IR spectrum in Nujol
shows a ν(CO) band at 1970 cm-1, whereas the 13C{1H} NMR
spectrum in dichloromethane-d2 contains a triplet at 179.8 ppm,
with a CsP coupling constant of 8.3 Hz. The resonance due to
the OssCR carbon atom of the alkenylcarbene appears at 270.5
ppm, also as a triplet but with a CsP coupling constant of 4.7
Hz. In agreement with the mutually cis disposition of the
acetonitrile molecules, the spectrum also contains four reso-
nances for these ligands at 134.8 and 128.1 (CtN) and 4.3 and
1
4.0 (CH3) ppm. The H NMR spectrum is consistent with the
13C{1H} NMR spectrum. Thus it shows two acetonitrile methyl
singlets at 2.81 and 2.74 ppm. The CRsH and CâsH resonances
of the alkenylcarbene ligand are observed at 16.27 and 8.48
ppm, respectively, as doublets with a HsH coupling constant
of 13.9 Hz. The 31P{1H} NMR spectrum contains a singlet at
21.1 ppm. These spectra are temperature invariant between 183
and 333 K. This is in agreement with theoretical calculations
on d6 carbene-metal complexes, suggesting that a carbonyl
ligand cis disposed to the carbene gives rise to high activation
energy for the carbene rotation.39
Figure 9. Optimized structures and relative energies (kcal mol-1) of
OsHCl2(tCCHdCH2)(PH3)2 (10t), OsCl2(dCHCHdCH2)(PH3)2 (14t), and
the transition state TS3.
The transformation from 5 to 15 has been also analyzed by
means of DFT calculations (Figure 10). Initially, the reaction
appears to involve the substitution of an acetonitrile molecule
by the carbonyl group. From a thermodynamic point of view,
the substitution of the acetonitrile ligand disposed trans to the
hydride is favored with regard to the replacement of the
acetonitrile molecule disposed trans to the OssC triple bond.
Thus, the cis-hydride-carbonyl isomer of the model compound
[OsH(tCCHdCH2)(CO)(CH3CN)(PH3)2]2+ (16t) lies 7.6 kcal
mol-1 above the trans isomer. The 1,2-hydrogen shift in the
latter affords the five-coordinate derivative [Os(dCHCHd
CH2)(CO)(CH3CN)(PH3)2]2+ (17t). This species is 9.5 kcal
mol-1 more stable than 16t-trans. The migration takes place
via the transition state TS4. Accordingly with the experimental
observations the difference in energy between TS4 and
and 159.4°, respectively, and an Os-C bond length of 1.895
Å. The geometry around the osmium atom of TS2 also agrees
well with that of TS1. As in the latter, the osmium-hydride-
carbyne unit form an (OsdC(R)H) system with OssC, OssH,
and CsH distances of 1.837, 2.062, and 1.185 Å, respectively,
and a CsOssH angle of 34.8°.
The replacement of the acetonitrile molecule of 11 by a
chloride ligand (the substitution of the second acetonitrile
molecule of 5 by a chloride ligand) produces a new increase of
the activation barrier for the 1,2-hydrogen shift from the osmium
to the carbyne carbon atom. Thus, DFT calculations show that
the transformation of the model compound OsHCl2(tCCHd
CH2)(PH3)2 (10t) into the five-coordinate species OsCl2-
(dCHCHdCH2)(PH3)2 (14t) occurs via TS3, related to TS1
and TS2, which lies 26.3 kcal mol-1 above 10t (Figure 9). The
height of the activation barrier in 10 makes impossible the
(39) Maouche, B.; Volatron, F.; Jean, Y. New J. Chem. 1993, 17, 449.
9
J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005 11191

A R T I C L E S
Bolan˜o et al.
Experimental Section
All reactions were carried out with rigorous exclusion of air using
Schlenk-tube techniques. Solvents were dried according to the usual
procedures and distilled under argon prior to use. The starting material
[Os{C6H4C(O)CH3}(η2-H2O)(PiPr3)2]BF4 (1) was prepared according
to the published method.12 1H, 31P{1H}, and 13C{1H} NMR spectra were
recorded on a Varian Gemini 2000, a Bruker AXR 300, or a Bruker
Avance 400 MHz instrument. Chemical shifts (expressed in parts per
million) are referenced to residual solvent peaks (1H, 13C{1H}) or
external H3PO4 (31P{1H}). Coupling constants, J and N, are given in
hertz. Infrared spectra were run on a Perkin-Elmer 1730 spectrometer
(Nujol mulls on polyethylene sheets). C, H, and N analyses were carried
out in a Perkin-Elmer 2400 CHNS/O analyzer. Mass spectra analyses
were performed with a VG Austospec instrument in LSIMS+ mode,
ions were produced with the standard Cs+ gun at ca. 30 kV, and
3-nitrobenzyl alcohol (NBA) was used in the matrix.
Figure 10. Optimized structures and relative energies (kcal mol-1) of [OsH-
(tCCHdCH2)(CO)(CH3CN)(PH3)2]2+ (16t), [Os(dCHCHdCH2)(CO)(CH3-
CN)(PH3)2]2+ (17t), and the transition state TS4.
Preparation of [OsH{dCdCHC(OH)Ph2}{η2-HCtCC(OH)-
Ph2}(PiPr3)2]BF4 (2). An orange solution of 1 (568 mg, 0.77 mmol)
in 7 mL of dichloromethane was treated with 1,1-diphenyl-2-propyn-
1-ol (401 mg, 1.92 mmol) and stirred for 1 min at room temperature.
The resulting mixture was cooled to 243 K and concentrated to dryness.
Subsequent addition of diethyl ether (5 mL) at 243 K caused the
precipitation of an orange solid, which was washed with diethyl ether
and dried in vacuo. Yield: 727 mg (93%). Anal. Calcd for C48H67-
BF4O2OsP2: C, 56.80; H, 6.65. Found: C, 56.85; H, 6.67. IR (Nujol,
cm-1): ν(OH) 3461 (br); ν(OsH) 2119 (w); ν(BF) 1059 (vs). MS: m/z
928 [M + H]+. 1H NMR (300 MHz, CD2Cl2, 293 K): δ 9.91 (d, JH-P
) 28.8, 1H, tCH), 7.70-7.07 (m, 20H, Ph), 4.22 (s, 1H, OH), 3.63
(t, JH-P ) 4.5, 1H, dCHs), 3.27 and 2.79 (both m, 6H, PCH), 1.16
(dvt, N ) 13.6, JH-H ) 7.0, 18H, PCHCH3), 1.12 (s, 1H, OH),40 1.07
(dvt, N ) 15.9, JH-H ) 6.9, 18H, PCHCH3), -3.89 (dd, JH-P ) 29.7
and 22.2, 1H, OsH). 31P{1H} NMR (121.4 MHz, CD2Cl2, 293 K): δ
32.9 (AB spin system, ∆ν ) 664, JA-B ) 117.9, PiPr3). 19F NMR (282.3
MHz, CD2Cl2, 293 K): δ -152.8 (br). 13C{1H}-APT NMR plus HMBC
and HSQC (75.4 MHz, CD2Cl2, 243 K): δ 279.9 (t, JC-P ) 14.4,
OsdC), 158.6 (t, JC-P ) 2.3, tCR), 148.2 and 146.7 (both s, Cipsos
Ph), 147.4 and 141.1 (both s, CipsosPh), 134.6-123.5 (all s, CHPh),
142.3 (s, tCH), 114.5 (t, JC-P ) 5.5, dCHs), 81.9 (d, JC-P ) 7.4,
C(OH)), 68.9 (s, C(OH)), 25.2 (br, PCH), 17.5 (br, PCHCH3).
16t-trans (10.2 kcal mol-1) is significantly smaller than that
between TS1 and 5t (19.4 kcal mol-1).
Concluding Remarks
This study reveals that the elongated dihydrogen complex
[Os{C6H4C(O)CH3}{η2-H2)(H2O)(PiPr3)2BF4 is a synthon for
the 12-valence electron monohydride [OsH(PiPr3)2]+, which
coordinates two alkynol molecules to afford the novel hydride-
hydroxyvinyliedene-π-alkynol derivatives [OsH{dCdCHC-
(OH)R2}{η2-HCtCC(OH)R2}(PiPr3)2]BF4 (R ) Ph, Me), where
the π-alkynol acts as a four-electron donor ligand.
These species are the entry to the dicationic hydride-
alkenylcarbyne complexes [OsH(tCCHdCR2)S2(PiPr3)2][BF4]2
(R ) Ph, Me; S ) H2O, CH3CN) which, in contrast to the
previously reported neutral hydride-carbyne compounds
OsHCl2(tC-alkyl)(PiPr3)2, undergo 1,2-hydrogen shift from the
osmium to carbyne carbon atom. Thus, in acetonitrile, they
evolve into the corresponding dicationic alkenylcarbene deriva-
tives [Os(dCHCHdCR2)(CH3CN)3(PiPr3)2][BF4]2.
Kinetic studies suggest that the formation of these six-
coordinate alkenycarbene complexes takes place via the five-
coordinate intermediates [Os(dCHCHdCR2)(CH3CN)2(PiPr3)2]2+,
which coordinate an acetonitrile molecule. In agreement with
the kinetic results, DFT calculations on the model system
[OsH(tCCHdCH2)(CH3CN)2(PH3)2]2+ have located the transi-
tion state connecting the hydride-alkenylcarbyne and five-
coordinate alkenylcarbene intermediate [Os(dCHCHdCH2)(CH3-
CN)2(PH3)2]2+ at 19.4 kcal mol-1 above the starting compound.
Preparation of [OsH{dCdCHC(OH)Me2}{η2-HCtCC(OH)-
Me2}(PiPr3)2]BF4 (3). This complex was prepared as described for 2
starting from 305 mg (0.41 mmol) of 1 and 2-methyl-3-butyn-2-ol (101
µL, 1.03 mmol). A light brown solid was obtained. Yield: 300 mg
(95%). Anal. Calcd for C28H59BF4O2OsP2: C, 43.86; H, 7.76. Found:
C, 43.91; H, 7.74. IR (Nujol, cm-1): ν(OH) 3512 (br); ν(OsH) 2118
1
(w); ν(BF) 1056 (vs). MS: m/z 680 [M + H]+. H NMR (300 MHz,
CD2Cl2, 293 K): δ 10.09 (dd, JH-H ) 1.8, JH-P ) 29.4, 1H, tCH),
3.34 and 3.09 (both m, 6H, PCH), 2.94 (s, 1H, OH), 2.64 (t, JH-P
)
It can be described as an η2-carbene species (OsdC(R)H).
4.6, 1H, dCHs), 1.78 and 1.60 (both s, 6H, CH3), 1.36 (dvt, N )
13.6, JH-H ) 7.0, 18H, PCHCH3), 1.65 (s, 1H, OH),40 1.18 (dvt, N )
15.4, JH-H ) 7.0, 18H, PCHCH3), 1.08 and 1.04 (both s, 6H, CH3),
-4.09 (dd, JH-P ) 30.7 and 23.8, 1H, OsH). 31P{1H} NMR (121.4
The sequential substitution of acetonitrile molecules by
chloride ligands in the dicationic hydride-alkenylcarbyne com-
pounds produces a sequential increase of the activation energy
for the hydride migration. This is a consequence of the gradual
increase of the electron richness of the metal center. While two
chloride ligands inhibit the hydride-alkenylcarbyne to carbene
transformation, the latter is favored by a carbonyl group.
MHz, CD2Cl2, 293 K): δ 31.5 (AB spin system, ∆ν ) 956, JA-B
)
120.5, PiPr3). 19F NMR (282.3 MHz, CD2Cl2, 293 K): δ -152.6 (br).
13C{1H}-APT NMR plus HMBC and HSQC (100.5 MHz, CD2Cl2, 243
K): δ 282.4 (t, JC-P ) 15.1, OsdC), 163.0 (t, JC-P ) 10.5, tCR),
138.0 (br, tCH), 116.0 (t, JC-P ) 6.0, dCHs), 75.2 (d, JC-P ) 7.0,
C(OH)), 65.8 (s, C(OH)), 34.0, 32.5, 31.1 and 30.0 (all s, CH3), 23.6
(d, JC-P ) 29.1, PCH), 19.9 (s, PCHCH3), 18.8 (d, JC-P ) 2.0,
PCHCH3).
In conclusion, we show an easy access to novel dicationic
hydride-alkenylcarbyne and alkenylcarbene complexes, study
the mechanism of the transformation between both types of
species, and analyze the influence of the coligands on the
activation energy of the hydride-alkenylcarbyne to carbene
transformation.
(40) Masked by the triisopropylphosphine methyl resonances. Assigned on the
basis of a correlated 1H-13C{1H} HMBC experiment.
9
11192 J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005

Hydride-Alkenylcarbyne to Alkenylcarbene
A R T I C L E S
Preparation of [OsH(tCCHdCPh2)(H2O)2(PiPr3)2][BF4]2 (4).41
An orange solution of 2 (150 mg, 0.15 mmol) in 5 mL of dichloro-
methane at 243 K was treated with HBF4‚OH2 (22 µL, 0.30 mmol).
Immediately, the reaction mixture became green. After 30 min at 243
K, the solvent was removed and the green residue was washed with
diethyl ether and dried in vacuo. The crude product was recrystallized
from a mixture CH2Cl2/Et2O at 243 K to afford orange crystals of 4.
Yield: 65 mg (48%). IR (Nujol, cm-1): ν(OH) 3423 (br); ν(OsH) 2166
(m); ν(CdC) 1541 (m); ν(BF) 1060 (vs). MS: m/z 723 [M - 2H2O +
F]+, 563 [M - PiPr3 - 2H2O]+. 1H NMR (300 MHz, CD2Cl2, 233 K):
δ 7.69-7.14 (m, 10H, Ph), 5.40 (s, 1H, dCHs), 4.23 (br, 4H, H2O),
2.38 (m, 6H, PCH), 1.25 (m, 36H, PCHCH3), -9.86 (t, JH-P ) 15.7,
1H, OsH). 31P{1H} NMR (121.4 MHz, CD2Cl2, 293 K): δ 46.1 (s).
19F NMR (282.3 MHz, CD2Cl2, 293 K): δ -151.6 (br). 13C{1H}-APT
NMR plus HMBC and HSQC (75.4 MHz, CD2Cl2, 293 K): δ 264.1
(br, OstC), 158.6 (s, dCPh2), 137.7 and 138.8 (both s, CipsosPh),
130.7, 130.5, 129.7, 128.7, 128.6 and 128.2 (all s, CHPh), 130.2 (s,
sCHd), 24.9 (vt, N ) 12.2, PCH), 18.5 and 18.3 (both s, PCHCH3).
Preparation of [Os(dCHCHdCPh2)(CH3CN)3(PiPr3)2][BF4]2 (7).
A red solution of 5 (600 mg, 0.63 mmol) in 12 mL of acetonitrile
were heated under reflux for 2 h. The solution was filtered through
Celite, and the solvent was removed in vacuo. The addition of diethyl
ether to the resulting residue led to a green solid, which was washed
with diethyl ether and dried in vacuo. Yield: 594 mg (95%). Anal.
Calcd for C39H63B2F8N3OsP2: C, 46.86; H, 6.35; N, 4.20. Found: C,
46.64; H, 6.19; N, 4.20. IR (Nujol, cm-1): ν(CtN) 2323 (w), 2271
(w); ν(CdC) 1528 (m); ν(BF) 1055 (vs). MS: m/z 413 (M2+). 1H NMR
(300 MHz, CD2Cl2, 233 K): δ 19.13 (d, JH-H ) 13.6, 1H, OsdCH),
8.24 (d, JH-H ) 13.6, 1H, sCHd), 7.71-7.18 (m, 10H, Ph), 3.20,
2.95 and 2.88 (all s, 9H, CH3CN), 2.39 (m, 6H, PCH), 1.23 (br, 36H,
PCHCH3). 31P{1H} NMR (121.4 MHz, CD2Cl2, 293 K): δ 3.1 (s). 19
F
NMR (282.3 MHz, CD2Cl2, 293 K): δ -151.6 (br). 13C{1H}-APT
NMR plus HMBC and HSQC (75.4 MHz, CD2Cl2, 233 K): δ 267.9
(t, JC-P ) 7.0, OsdCH), 149.2 (s, dCPh2), 147.5 (s, sCHd), 140.9
and 139.6 (both s, CipsosPh), 137.4, 125.4 and 124.4 (s, CN), 131.2,
130.0, 129.5, 128.8, 128.6 and 127.9 (all s, CHPh), 25.4 (br, PCH),
18.9 and 18.5 (both s, PCHCH3), 4.8, 4.3 and 4.0 (all s, CH3CN).
Preparation of [OsH(tCCHdCPh2)(CH3CN)2(PiPr3)2][BF4]2 (5).
An orange solution of 2 (316 mg, 0.31 mmol) in 5 mL of dichloro-
methane at 243 K was treated with HBF4‚OEt2 (85 µL, 0.62 mmol).
Immediately, the reaction mixture became green. After 30 min at 243
K, the solvent was removed and the residue was washed with diethyl
ether and dried in vacuo. The crude product was treated with 10 mL
of acetonitrile and stirred for 4 h at room temperature. The brown
solution was filtered through Celite and evaporated to dryness.
Subsequent addition of diethyl ether caused the precipitation of a red
solid, which was washed with diethyl ether and dried in vacuo. Yield:
250 mg (84%). Anal. Calcd for C37H60B2F8N2OsP2: C, 46.36; H, 6.31;
N, 2.92. Found: C, 46.29; H, 6.67; N, 2.79. IR (Nujol, cm-1): ν(CtN)
2316 (w), 2286 (w); ν(OsH) 2151 (m); ν(CdC) 1531 (m); ν(BF) 1056
Preparation of [Os(dCHCHdCMe2)(CH3CN)3(PiPr3)2][BF4]2 (8).
This complex was prepared as described for 7 starting from 200 mg
(0.24 mmol) of 6. A gray solid was obtained. Yield: 206 mg (98%).
Anal. Calcd for C29H59B2F8N3OsP2: C, 39.78; H, 6.79; N, 4.80.
Found: C, 39.97; H, 6.69; N, 4.31. IR (Nujol, cm-1): ν(CtN) 2320
1
(w), 2276 (w); ν(CdC) 1577 (m); ν(BF) 1059 (vs). H NMR (300
MHz, CD2Cl2, 233 K): δ 19.04 (d, JH-H ) 13.9, 1H, OsdCH), 7.57
(d, JH-H ) 13.9, 1H, sCHd), 3.02, 2.96 and 2.90 (all s, 9H, CH3CN),
2.41 (br, 6H, PCH), 1.54 and 1.32 (both s, 6H, Me), 1.19 (m, 36H,
PCHCH3). 31P{1H} NMR (121.4 MHz, CD2Cl2, 293 K): δ 2.5 (s). 19
F
NMR (282.3 MHz, CD2Cl2, 293 K): δ -151.8 (br). 13C{1H}-APT
NMR plus HMBC and HSQC (75.4 MHz, CD2Cl2, 233 K): δ 265.3
(d, JC-P ) 7, OsdCH), 154.8 (s, dCMe2), 149.8 (s, sCHd), 135.8,
124.0 and 123.9 (all s, CN), 29.0 and 22.4 (both s, Me), 24.6 (vt, N )
12.4, PCH), 18.8 and 18.7 (both s, PCHCH3), 4.9, 4.6 and 4.0 (all s,
CH3CN).
1
(vs). MS: m/z 960 [M + 2BF4]+. H NMR (300 MHz, CD2Cl2, 293
K): δ 7.81-7.29 (m, 10H, Ph), 5.18 (s, 1H, dCHs), 2.87 and 2.59
(s, 6H, CH3CN), 2.51 (m, 6H, PCH), 1.39 (dvt, N ) 14.8, JH-H ) 7.1,
18H, PCHCH3), 1.35 (dvt, N ) 14.9, JH-H ) 6.9, 18H, PCHCH3),
-6.44 (t, JH-P ) 15.9, 1H, OsH). 31P{1H} NMR (121.4 MHz, CD2Cl2,
293 K): δ 30.2 (s). 19F NMR (282.3 MHz, CD2Cl2, 293 K): δ -151.2
(br). 13C{1H}-APT NMR plus HMBC and HSQC (75.4 MHz, CD2Cl2,
293 K): δ 277.9 (t, JC-P ) 7.7, OstC), 169.7 (s, dCPh2), 137.6 and
137.7 (both s, CipsosPh), 135.3 (s, CN), 133.4, 133.1, 130.8, 129.6,
129.5, and 129.4 (all s, CHPh), 131.3 (d, JC-P ) 2.0, CN), 130.5 (s,
sCHd), 27.7 (vt, N ) 13.4, PCH), 19.0 and 18.8 (both s, PCHCH3),
4.1 and 3.4 (both s, CH3CN).
Preparation of OsHCl2(tCCHdCPh2)(PiPr3)2 (10). A red solution
of 5 (150 mg, 0.16 mmol) in 10 mL of 2-propanol were treated with
sodium chloride (46 mg, 0.78 mmol). After stirring the mixture for 6
h at room temperature, the solvent was removed in vacuo. Then, 10
mL of dichloromethane were added, the suspension was filtered through
Celite, and the filtrate was evaporated to dryness. The residue was
washed with pentane to afford a light green solid. Yield: 83 mg (69%).
Anal. Calcd for C33H54Cl2OsP2: C, 51.22; H, 7.03. Found: C, 51.12;
H, 6.97. IR (Nujol, cm-1): ν(OsH) 2168 (m); ν(CdC) 1536 (m). MS:
m/z 774 (M+), 739 [M - Cl]+, 579 [M - Cl - PiPr3]+. 1H NMR (300
MHz, CD2Cl2, 293 K): δ 7.70-7.25 (m, 10H, Ph), 4.91 (s, 1H,
dCHs), 2.60 (m, 6H, PCH), 1.35 (dvt, N ) 13.3, JH-H ) 7.0, 18H,
PCHCH3), 1.33 (dvt, N ) 13.5, JH-H ) 6.9, 18H, PCHCH3), -7.28 (t,
JH-P ) 17.1, 1H, OsH). 31P{1H} NMR (121.4 MHz, CD2Cl2, 293 K):
δ 18.3 (s). 13C{1H}-APT NMR plus HMBC and HSQC (75.4 MHz,
CD2Cl2, 293 K): δ 254.1 (t, JC-P ) 10.8, OstC), 157.2 (s, dCPh2),
141.2 and 138.1 (s, CipsosPh), 135.3 (s, sCHd), 131.2, 130.9, 130.2,
129.6, 129.1 and 128.5 (all s, CHPh), 27.9 (vt, N ) 12.8, PCH), 19.9
and 19.2 (both s, PCHCH3).
Preparation of [OsH(tCCHdCMe2)(CH3CN)2(PiPr3)2][BF4]2 (6).
This complex was prepared as described for 5, starting from 3 (150
mg, 0.20 mmol) and HBF4‚OEt2 (53 µL, 0.40 mmol). A brown solid
was obtained. Yield: 103 mg (63%). Anal. Calcd for C27H56B2F8N2-
OsP2: C, 38.86; H, 6.76; N, 3.36. Found: C, 39.36; H, 6.69; N, 3.54.
IR (Nujol, cm-1): ν(CtN) 2321 (w), 2290 (w); ν(OsH) 2174 (m);
ν(CdC) 1575 (m); ν(BF) 1054 (vs). MS: m/z 834 [M + H]+, 599 [M
1
- 2CH3CN + F]+. H NMR (300 MHz, CD2Cl2, 293 K): δ 4.84 (s,
1H, dCHs), 2.89 and 2.56 (both s, 6H, CH3CN), 2.54 (m, 6H, PCH),
2.14 and 1.81 (both s, 6H, dC(Me)2), 1.44 (dvt, N ) 15.0, JH-H
)
7.4, 18H, PCHCH3), 1.39 (dvt, N ) 14.8, JH-H ) 7.2, 18H, PCHCH3),
-6.66 (t, JH-P ) 15.6, 1H, OsH). 31P{1H} NMR (121.4 MHz, CD2Cl2,
293 K): δ 29.1 (s). 19F NMR (282.3 MHz, CD2Cl2, 293 K): δ -151.9
(br). 13C{1H}-APT NMR plus HMBC and HSQC (75.42 MHz, CD2Cl2,
293 K): δ 280.6 (t, JC-P ) 8.1, OstC), 178.9 (s, dCMe2), 136.2 and
131.5 (both s, CN), 133.7 (s, sCHd), 27.8 and 25.7 (both s, Me),
27.5 (vt, N ) 13.6, PCH), 19.5 and 18.3 (both s, PCHCH3), 4.4 and
3.7 (both s, CH3CN).
Preparation of [OsHCl(tCCHdCPh2)(CH3CN)(PiPr3)2]BF4 (11).
A green solution of 10 (407 mg, 0.53 mmol) in 12 mL of acetonitrile
was treated with AgBF4 (102 mg, 0.53 mmol) in the absence of light.
Immediately, the reaction mixture became orange. After stirring the
mixture for 1 h at room temperature, the suspension was filtered through
Celite and the filtrate was evaporated to dryness. The residue was
washed with diethyl ether to afford an orange solid. Yield: 386 mg
(89%). Anal. Calcd for C35H57BF4ClNOsP2: C, 48.53; H, 6.63; N, 1.62.
Found: C, 48.29; H, 6.58; N, 1.44. IR (Nujol, cm-1): ν(CtN) 2313
(w); ν(OsH) 2178 (m); ν(CdC) 1532 (m) ν(BF) 1055 (vs). MS: m/z
(41) All our attempts to achieve a valid elemental analysis determination for
complex 4 were unsuccessful. Even when we tried with crystals of the
same crop that was used for the X-ray diffraction study, we could not obtain
a satisfactory value.
1
739 [M s CH3CN]+, 579 [M - CH3CN - PiPr3]+. H NMR (300
MHz, CD2Cl2, 293 K): δ 7.79-7.04 (m, 10H, Ph), 5.14 (s, 1H, dCHs
9
J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005 11193

A R T I C L E S
Bolan˜o et al.
Table 4. Crystal Data and Data Collection and Refinement for 4
and 7
), 2.74 (s, 3H, CH3CN), 2.69 (m, 6H, PCH), 1.37 (dvt, N ) 15.8, JH-H
) 7.2, 18H, PCHCH3), 1.34 (dvt, N ) 16.0, JH-H ) 7.2, 18H,
PCHCH3), -6.51 (t, JH-P ) 16.8, 1H, OsH). 31P{1H} NMR (121.4
MHz, CD2Cl2, 293 K): δ 25.5 (s). 19F NMR (282.3 MHz, CD2Cl2,
293 K): δ -153.0 (br). 13C{1H}-APT NMR plus HMBC and HSQC
(75.4 MHz, CD2Cl2, 293 K): δ 256.9 (t, JC-P ) 13.2, OstC), 164.0
(s, dCPh2), 138.9 and 138.2 (both s, CipsosPh), 132.3, 132.2, 132.0,
129.5, 129.3 and 128.8 (all s, CHPh), 130.6 (s, sCHd), 128.8 (s, CN),
27.0 (vt, N ) 17.8, PCH), 19.2 and 18.8 (both s, PCHCH3), 3.8 (s,
CH3CN).
Preparation of [OsCl(dCHCHdCPh2)(CH3CN)2(PiPr3)2]BF4 (12).
An orange solution of 11 (300 mg, 0.35 mmol) in 12 mL of acetonitrile
was heated under reflux 5 h. The solution was filtered through Celite,
and the solvent was removed in vacuo. The addition of diethyl ether
to the resulting residue led to a yellow solid, which was washed with
diethyl ether and dried in vacuo. Yield: 286 mg (91%). Anal. Calcd
for C39H60BF4N2ClOsP2: C, 48.98; H, 6.66; N, 3.09. Found: C, 48.48;
H, 6.60; N, 3.01. IR (Nujol, cm-1): ν(CtN) 2323 (w), 2269 (w);
ν(CdC) 1527 (m); ν(BF) 1061 (vs). MS: m/z 739 [M - 2CH3CN]+,
661 [M - PiPr3]+, 579 [M - 2CH3CN - PiPr3]+. 1H NMR (300 MHz,
CD2Cl2, 233 K): δ 20.29 (d, JH-H ) 13.2, 1H, OsdCH), 7.98 (d, JH-H
) 13.3, 1H, sCHd), 7.65-7.21 (m, 10H, Ph), 3.18 and 2.85 (both s,
6H, CH3CN), 2.48 (m, 6H, PCH), 1.20 (m, 36H, PCHCH3). 31P{1H}
NMR (121.4 MHz, CD2Cl2, 293 K): δ -6.3 (s). 19F NMR (282.3 MHz,
CD2Cl2, 293 K): δ -152.6 (br). 13C{1H}-APT NMR plus HMBC and
HSQC (75.4 MHz, CD2Cl2, 233 K): δ 252.0 (t, JC-P ) 8.3, OsdCH),
148.8 (s, sCHd), 143.1 and 142.4 (both s, CipsosPh), 140.6 (s, dCPh2),
129.8, 129.6, 128.62, 128.4, 127.7 and 127.6 (all s, CHPh), 123.0 and
122.7 (both s, CN), 24.9 (br, PCH), 19.1 and 18.6 (both s, PCHCH3),
5.1 and 4.5 (both s, CH3CN).
4
7
Crystal Data
formula
C33H58B2F8O2OsP2‚CH2Cl2
C39H63B2F8N3OsP2
molecular wt
color and habit
997.48
irregular block
red
999.68
irregular block
red
symmetry, space group monoclinic, P21/n
monoclinic, P21/c
18.2946(17)
10.9593(10)
21.991(2)
92.074(2)
4406.2(7)
4
a, Å
b, Å
c, Å
12.3817(8)
11.1746(7)
30.4532(19)
100.8100(10)
4138.7(5)
4
â, deg
V, Å3
Z
D calcd, g cm-3
1.601
1.507
Data Collection and Refinement
diffractometer
λ(Mo KR), Å
monochromator
scan type
Bruker Smart APEX
0.710 73
graphite oriented
ω scans
3.353
µ, mm-1
3.031
2θ, range deg
temp, K
3, 57
100
3, 57
100
no. of data collect
no. of unique data
50 882
10 313 (Rint ) 0.0544)
46 145
10 876 (Rint ) 0.0730)
no. of params/restrains 475/40
517/0
0.0392
0.0564
0.819
R1a [F2 > 2σ(F2)]
wR2b [all data]
Sc [all data]
0.0553
0.1276
1.103
a R1(F) ) Σ||Fo| - |Fc||/Σ|Fo|. b ωR2(F2) ) {Σ[ω(Fo - Fc )2]/
2
2
2
2
συâυΣ[ω(Fo )2]}1/2 c GOF ) S ) {Σ[(Fo2 - Fc )2]/(n - p)}1/2, where n is
.
the number of reflections and p is the number of refined parameters.
Preparation of [Os(dCHCHdCPh2)(CH3CN)2(CO)(PiPr3)2][BF4]2
(15). A solution of 5 (150 mg, 0.16 mmol) in 8 mL of dichloromethane
was stirred under carbon monoxide atmosphere for 1 h. The color turned
from red to orange, and the solution was filtered through Celite. The
solvent was removed in vacuo. The residue was washed with diethyl
ether to afford an orange solid. Yield: 130 mg (90%). Anal. Calcd for
C38H60B2F8N2OOsP2: C, 46.26; H, 6.13; N, 2.84. Found: C, 46.15;
H, 6.56; N, 2.93. IR (Nujol, cm-1): ν(CtN) 2323 (w), 2289 (w);
ν(CtO) 1970 (s); ν(CdC) 1509 (m); ν(BF) 1059 (vs). MS: m/z 751
acetonitrile region of 1H{31P} NMR spectra of these compounds were
achieved using the program gNMR (Cherwell Scientific Publishing
Limited). The rate constants for various temperatures were obtained
by fitting calculated to experimental spectra by full line-shape iterations.
The transverse relaxation time, T2, was estimated at the lowest
temperature. Activation parameters ∆Hq and ∆Sq were obtained by least-
squares fit of the Eyring plot. Errors were computed by published
methods.42
1
[M - 2CH3CN + F]+, 723 [M - 2CH3CN + F - CO]+. H NMR
Computational Details. The calculations have been carried out using
the Gaussian 03 computational package.43 All the structures have been
optimized using DFT and the B3LYP functional. The 6-31 g** basis
set has been used for all the atoms but the Os,44 where the LANL2DZ
basis and pseudopotential has been used instead. The transition states
found have been confirmed by frequency calculations, and the con-
nection between the starting and final reactants has been checked by
slightly perturbing the TS geometry toward the minima geometries and
reoptimizing.
(300 MHz, CD2Cl2, 293 K): δ 16.27 (d, JH-H ) 13.9, 1H, OsdCH),
8.48 (d, JH-H ) 13.9, 1H, sCHd), 7.77-7.17 (m, 10H, Ph), 2.81 and
2.74 (both s, 6H, CH3CN), 2.52 (m, 6H, PCH), 1.32 (dvt, N ) 15.1,
JH-H ) 7.0, 18H, PCHCH3), 1.31 (dvt, N ) 14.2, JH-H ) 7.0, 18H,
PCHCH3). 31P{1H} NMR (121.4 MHz, CD2Cl2, 293 K): δ 21.1 (s).
19F NMR (282.3 MHz, CD2Cl2, 293 K): δ -151.8 (br). 13C{1H}-APT
NMR plus HMBC and HSQC (75.4 MHz, CD2Cl2, 293 K): δ 270.5
(t, JC-P ) 4.7, OsdCH), 179.8 (t, JC-P ) 8.3, CtO), 161.2 (s, dCPh2),
148.6 (s, sCHd), 139.0 and 137.9 (both s, CipsosPh), 134.8 and 128.1
(both s, CN), 133.7, 131.1, 130.8, 130.2, 129.2 and 128.9 (all s, CHPh),
26.3 (vt, N ) 12.7, PCH), 19.5 and 18.8 (both s, PCHCH3), 4.3 and
4.0 (both s, CH3CN).
X-ray Analysis of 4 and 7. Two irregular crystals of size 0.38 ×
0.10 × 0.08 mm3 (4) and 0.34 × 0.10 × 0.04 mm3 (7) were mounted
on a Bruker Smart APEX CCD diffractometer at 100.0(2) K equipped
with a normal focus, 2.4 kW sealed tube source (Molybdenum radiation,
λ ) 0.710 73 Å) operating at 50 kV and 30 mA. Data were collected
over the complete sphere by a combination of four sets. Each frame
exposure time was 10 s covering 0.3° in ω. The cell parameters were
determined and refined by least-squares fit of 9710 (4) or 5041 (7)
collected reflections. The first 100 frames were collected at the end of
the data collection to monitor crystal decay. Absorption correction was
performed with the SADABS program (this is based on the method of
Kinetic Analysis for the Hydride-Alkenylcarbyne to Alkenyl-
carbene Transformations. Formation of 7, 8, and 12 was followed
1
quantitatively by H NMR spectroscopy in CD3CN. The increase of
the intensity of low field carbene-proton was measured automatically
at intervals in a Varian Gemini 2000 spectrometer. Rate constants and
errors were obtained fitting the data to an exponential decay function
using the routine programs of the spectrometer. Activation parameters
∆Hq and ∆Sq were obtained by least-squares fit of the Eyring plot.
Errors were computed according to published methods.42
(43) Pople, J. A. et al. Gaussian 03, revision B.05; Gaussian, Inc., Wallingford
CT, 2004.
Determination of the Rotational Barrier of Carbene Ligands of
Complexes 7, 8, and 12. Complete line-shape analyses of the
(44) Following the suggestion of one of the referees, we have checked the
influence of an additional f polarization function on Os (see ref 45). The
difference in energy between compound 10t and TS3 is 26.6 kcal mol-1
,
(42) Morse, P. M.; Spencer, M. O.; Wilson, S. R.; Girolami; G. S. Organo-
metallics 1994, 13, 1646.
only 0.3 kcal mol-1 higher than that reported in the text. No further
recalculations have been made given the small difference found.
9
11194 J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005

Hydride-Alkenylcarbyne to Alkenylcarbene
A R T I C L E S
Blessing46). Lorentz and polarization corrections were also performed.
The structures were solved by Patterson and Fourier methods and
refined by full matrix least-squares using the Bruker SHELXTL
program package47 minimizing ω(Fo2 - Fc2)2. The hydrogen atoms were
observed or calculated and refined riding to bonded carbon atoms. The
hydride ligand of 4 was observed in the difference Fourier maps but
not refined properly. Finally a restrained geometry was used for the
last cycles of refinement. For 4 a molecule of dichloromethane was
observed in the unit cell, and a molecule of BF4 is disordered over two
sites. Weighted R factors (Rw) and goodness of fit (S) are based on F2,
and conventional R factors are based on F. Crystal data and details of
the data collection and refinement are given in Table 4.
Acknowledgment. Financial support from the MCYT of
Spain (Project BQU2002-00606) is acknowledged. R.C. thanks
CSIC and the European Social Fund for funding through the
I3P Program. Dedicated to Professor Pierre H. Dixneuf on the
occasion of his 65th birthday.
Supporting Information Available: Crystal structure deter-
minations, including bond lengths and angles of compounds 4
and 7. Full authors of ref 43. This material is available free of
charge via the Internet at http://pubs.acs.org.
(45) Ehlers, A. W.; Bo¨hme, M.; Dapprich, S.; Gobbi, A.; Ho¨llwarth, A.; Jonas,
V.; Ko¨hler, K. F.; Stegmann, R.; Veldkamp, A.; Frenking, G. Chem. Phys.
Lett. 1993, 208, 111.
(46) Blessing, R. H. Acta Crystallogr., Sect. A. 1995, 51, 33.
(47) SHELXTL program v. 6.1; Bruker Analytical, X-ray Systems: Madison,
Wisconsin, 2000.
JA053186G
9
J. AM. CHEM. SOC. VOL. 127, NO. 31, 2005 11195