Carbon-carbon coupling and carbon-hydrogen activation reactions in bis(triisopropylphosphine)osmium complexes

Article abstract of DOI:10.1021/ja952186l

Reaction of the alkenyl complex OsCl(E-CH=CHPh)(CO)(PⁱPr₃)₂ (1) with phenyllithium gives OsH-{C₆H₄-2-(E-CH=CHPh)}(CO)(PⁱPr ₃)₂ (2). The structure of 2 (isomer 2a) has been determined by X-ray diffraction: triclinic, P1, a = 9.230(1) ?, b = 10.092(1) ?, c = 18.525(2) ?, α = 88.667(7)°, β = 87.172(7)°. γ = 71.110(6)°, V = 1630.6(3), Z = 2, R (F, F_o ≥ 4σ(F_o)) = 4.01, wR (F², all reflections) = 9.94%. The geometry around the osmium can be described as a distorted octahedron with the two triisopropylphosphine ligands occupying two relative trans positions. The remaining perpendicular plane is formed by the carbonyl and the 2-(E-1′-styryl)-phenyl ligands mutually trans disposed, the hydride ligand and one olefinic hydrogen of the 2-(E-1′-styryl)phenyl ligand, which shows an agostic interaction with the osmium atom (distance 2.05(7) ?). The solutions of 2 show equilibria between the agostic isomer (2a) and a nonagostic isomer (2b). The thermodynamic magnitudes involved in the equilibrium as well as the activation parameters for the conversion between the two isomers were determined in toluene-d₈ by ¹H NMR spectroscopy. The values obtained were ΔH° = -1.6 (±0.1) Kcal mol^-1 and ΔS° = -9.6 (±0.6) cal K^-1 mol^-1 for the formation of the agostic isomer, whereas the activation parameters for the breaking of the agostic interaction were ΔH? = 7.6 (±0.2) Kcal mol^-1 and ΔS? = -1.0 (±0.7) cal K^-1 mol^-1. 2 reacts with CO to give the octahedral complex OsH{C₆H₄-2-(E-CH=CHPh)}(CO)₂(P ⁱPr₃)₂ (3). Reactions of 1 with methyllithium and CD₃Li give OsH{C₆H₄-2-(E-CH=CHCH₃)}(CO)(P ⁱPr₃)₂ (4) and OsH{C₆H₄-2-(E-CH=CHCD₃)}-(CO)(P ⁱPr₃)₂ (4-d₃), respectively. The spectra of these complexes indicate that in solution they also show equilibria between agostic and nonagostic isomers. Reactions of 4 with P(OMe)₃ and CO afford OsH{C₆H₄-2-(E-CH=CHCH₃)(CO){P(OMe) ₃}(PⁱPr₃)₂ (5) and OsH{C₆H₄-2-(E-CH=CHCH₃)}(CO)₂(P ⁱPr₃)₂ (6), respectively, in which the incoming ligands coordinate trans to the hydride. 4 and 4-d₃ isomerize in solution to give OsH(η³-CH₂CHCHPh)-(CO)(PⁱPr ₃)₂ (11) and OsD(η³-CD₂CHCHPh)(CO)(PⁱPr ₃)₂ (11-d₃), respectively. Reaction of 11 with CO leads to OsH(η¹-CH₂CH=CHPh)(CO)₂(P ⁱPr₃)₂ (12). The first order constants k_obs and k_obs-d3 for the isomerization of 4 and 4-d₃ to 11 and 11-d₃ were obtained in CDCl₃, giving activation parameters of ΔH? = 20.8 (±1.7) Kcal mol^-1 and ΔS? = -2.8 (±2.0) cal K^-1 mol^-1 for the isomerization of 4 to 11 and a relation k_obs/k_obs-d3 = 3.6 at 303 K.

Full text of DOI:10.1021/ja952186l

J. Am. Chem. Soc. 1996, 118, 89-99
89
Carbon-Carbon Coupling and Carbon-Hydrogen Activation
Reactions in Bis(triisopropylphosphine)osmium Complexes†
Miguel A. Esteruelas,* Fernando J. Lahoz, Enrique On˜ate, Luis A. Oro, and
Eduardo Sola
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 July 5, 1995X
Abstract: Reaction of the alkenyl complex OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) with phenyllithium gives OsH-
{C6H4-2-(E-CHdCHPh)}(CO)(PiPr3)2 (2). The structure of 2 (isomer 2a) has been determined by X-ray
diffraction: triclinic, P1h, a ) 9.230(1) Å, b ) 10.092(1) Å, c ) 18.525(2) Å, R ) 88.667(7)°, ) 87.172(7)°,
) 71.110(6)°, V ) 1630.6(3), Z ) 2, R (F, Fo g 4 (Fo)) ) 4.01, wR (F2, all reflections) ) 9.94%. The geometry
around the osmium can be described as a distorted octahedron with the two triisopropylphosphine ligands occupying
two relative trans positions. The remaining perpendicular plane is formed by the carbonyl and the 2-(E-1′-styryl)-
phenyl ligands mutually trans disposed, the hydride ligand and one olefinic hydrogen of the 2-(E-1′-styryl)phenyl
ligand, which shows an agostic interaction with the osmium atom (distance 2.05(7) Å). The solutions of 2 show
equilibria between the agostic isomer (2a) and a nonagostic isomer (2b). The thermodynamic magnitudes involved
in the equilibrium as well as the activation parameters for the conversion between the two isomers were determined
1
in toluene-d8 by H NMR spectroscopy. The values obtained were ∆H° ) -1.6 ((0.1) Kcal mol-1 and ∆S° )
-9.6 ((0.6) cal K-1 mol-1 for the formation of the agostic isomer, whereas the activation parameters for the breaking
of the agostic interaction were ∆Hq ) 7.6 ((0.2) Kcal mol-1 and ∆Sq ) -1.0 ((0.7) cal K-1 mol-1. 2 reacts with
CO to give the octahedral complex OsH{C6H4-2-(E-CHdCHPh)}(CO)2(PiPr3)2 (3). Reactions of 1 with methyl-
lithium and CD3Li give OsH{C6H4-2-(E-CHdCHCH3)}(CO)(PiPr3)2 (4) and OsH{C6H4-2-(E-CHdCHCD3)}-
(CO)(PiPr3)2 (4-d3), respectively. The spectra of these complexes indicate that in solution they also show equi-
libria between agostic and nonagostic isomers. Reactions of 4 with P(OMe)3 and CO afford OsH{C6H4-2-(E-
CHdCHCH3)}(CO){P(OMe)3}(PiPr3)2 (5) and OsH{C6H4-2-(E-CHdCHCH3)}(CO)2(PiPr3)2 (6), respectively, in which
the incoming ligands coordinate trans to the hydride. 4 and 4-d3 isomerize in solution to give OsH( 3-CH2CHCHPh)-
(CO)(PiPr3)2 (11) and OsD( 3-CD2CHCHPh)(CO)(PiPr3)2 (11-d3), respectively. Reaction of 11 with CO leads to
OsH( 1-CH2CHdCHPh)(CO)2(PiPr3)2 (12). The first order constants kobs and kobs-d for the isomerization of 4 and
3
4-d3 to 11 and 11-d3 were obtained in CDCl3, giving activation parameters of ∆Hq ) 20.8 ((1.7) Kcal mol-1 and
∆Sq ) -2.8 ((2.0) cal K-1 mol-1 for the isomerization of 4 to 11 and a relation kobs/kobs-d ) 3.6 at 303 K.
3
Introduction
concentrated to develop homogeneous systems adequate to
activate C-H bonds. Representative examples of these systems
include the complexes: FeH2(dmpe)2 (dmpe ) 1,2-bis(dimeth-
The design of homogeneous systems effective in the synthesis
of functionalized organic molecules from basic hydrocarbon
units is both challenging and industrially important. In this
respect, obtaining systems which consecutively promote carbon-
carbon bond formation and C-H activation is significant and
of general interest.
5
ylphosphino)ethane),3 Os( 6-arene)(CO)2,4 RhCl(CO)(PR3)2
and Tp*Ir(C2H4)2 (Tp* ) HB(3,5-Me2pz)3),6 and metallic
fragments generated “in situ” such as Cp*ML (M ) Rh, Ir; L
) CO, PMe3),7 M(PMe3)4 (M ) Ru, Os),8 M{P(OMe)3}2-
(2) (a) Shilov, A. E. ActiVation of Saturated Hydrocarbons by Transition
Metal Complexes; D. Riedel Publishing Co.: Dordrecht, The Netherlands,
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A. Homogeneous Hydrogenation; Kluwer Academic Publishers: Dordrecht,
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Int. Ed. Engl. 1989, 28, 1690.
The formation of carbon-carbon bonds mediated by transi-
tion metal compounds has emerged in its own right over the
last few years as an important step in organic synthesis. These
reactions can involve migratory cis-ligand insertion, the coupling
of adjacent carbon-metal bonds, and the attack of a reagent to
an unsaturated organic ligand without metal-reagent bond
formation.1
The oxidative addition of C-H bonds to transition metal
compounds also possess a considerable interest in connection
with organic synthesis and catalysis,2 where efforts have been
† Dedicated to Professor Rafael Uso´n on the occasion of his 70th birthday.
X Abstract published in AdVance ACS Abstracts, December 1, 1995.
(1) (a) Stille, J. K. Chemistry of the Metal-Carbon Bond; Hartley, F.
R., Patal, S., Ed.; Wiley: Chichester, 1985; Vol. 2. (b) Hayashi, T.; Kumada,
M. Asymmetric Synthesis; Morrison, J. D., Ed.; Academic: New York, 1985;
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0002-7863/96/1518-0089$12.00/0 © 1996 American Chemical Society

90 J. Am. Chem. Soc., Vol. 118, No. 1, 1996
Esteruelas et al.
(PMe3)2 (M ) Ru, Os),9 or IrCl(PR3)2.10 Detailed mechanistic
studies have led to a relative understanding of the factors which
govern the process. Greater attention has been paid to the
kinetic and thermodynamic aspects of C-H activation, and in
particular there has been an increased effort to determine the
selectivity patterns and the origin of these selectivities.3e,7f-g,l,m,8b,e,f
However, in many cases the feasibility of the mechanistic studies
is restricted by the reaction conditions, which frequently require
photochemical or thermal generation of the reactive metallic
fragment.
Previously, we have reported the reactions of hydrido-
osmium compounds with terminal alkynes which allow the
preparation of specific organometallic complexes (vinyl, car-
bene, hydrido-carbyne, hydrido-vinylidene, and hydrido-
dihydrogen-alkynyl), provided that the number of hydrido
ligands and the electronic properties of the starting materials
are appropriately selected.11 As a continuation of this work,
the reactivity of the above mentioned 1-organometallic com-
pounds with organic fragments is being studied, in the search
for metal-mediated reactions of use in organic synthesis and
catalysis. In this paper we report the reactions of the five-
coordinate derivative OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) with
organolithium reagents. The results obtained show the occur-
rence under mild conditions of C-C coupling reactions followed
by C-H activation processes.
Figure 1. Molecular diagram of the complex OsH{C6H4-2-(E-
CHdCHPh)}(CO)(PiPr3)2 (2a).
The osmium atom is coordinated in a somewhat distorted-
octahedral fashion with the two phosphine ligands in trans
position (P(1)-Os-P(2) ) 163.10(6)°). The perpendicular
coordination plane is formed by the atoms C(1) and H(8), by
the carbonyl group disposed trans to C(1) (C(1)-Os-C(15) )
173.3(3)°) and the hydrido ligand disposed trans to H(8). The
bending of the phosphorus-metal-phosphorus axis points to
the direction of the smallest ligand (hydride). The position of
this ligand was not determined by the X-ray analysis, but it
was included in the location estimated with the HYDEX
program.12 In contrast to the hydrido ligand, the agostic
hydrogen H(8) was located in the difference Fourier maps and
refined as an isotropic atom together with the rest of the non-
hydrogen atoms of the structure, giving a Os-H(8) distance of
2.05(7) Å and a Os‚‚‚H(8)-C(8) angle of 118(6)°. These
distances and angles are similar to those found for other remote
agostic interactions in structurally related compounds.13-15
The Os-C(1) bond distance of 2.136(7) Å is in agreement
with the values previously reported for Os-C(aryl) bond lengths
(mean 2.09(3) Å).16 The C(2)-C(7) (1.486(9) Å), C(7)-C(8)
(1.349(11) Å), and C(8)-C(9) bond lengths (1.458(9) Å)
compare well with the values found for the carbon-carbon
double bond (1.327 Å) and the adjacent carbon-carbon single
bonds (1.472 Å) in the free trans-stilbene.17 The relative slight
elongation of the olefinic bond and shortening of the saturated
Results and Discussion
Reactions of 1 with Phenyllithium and Methyllithium.
Reaction of the five-coordinate alkenyl complex OsCl(E-CHd
CHPh)(CO)(PiPr3)2 (1) with a diethyl ether solution of phenyl-
lithium at 60 °C gives a yellow solution from which the complex
OsH{C6H4-2-(E-CHdCHPh)}(CO)(PiPr3)2 (2) was isolated as
a yellow solid in 65% yield. Compound 2 was characterized
by elemental analysis, IR and 1H, 31P{1H}, and 13C{1H} NMR
spectroscopies, and X-ray diffraction.
Figure 1 shows the molecular diagram of the structure of 2
(isomer 2a); selected bond distances and angles are listed in
Table 1. The most remarkable feature of this structure is the
presence of an agostic interaction between the metal atom and
one olefinic hydrogen (H(8)) of the 2-(E-1′-styryl)phenyl ligand,
which is also bonded to the osmium atom by an aromatic carbon
atom (C(1)).
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Bis(triisopropylphosphine)osmium Complexes
J. Am. Chem. Soc., Vol. 118, No. 1, 1996 91
Table 1. Selected Bond Lengths (Å) and Angles (deg) for the Complex OsH{C6H4-2-(E-CHdCHPh)}(CO)(PiPr3)2 (2a)
Os-P(1)
2.393(2)
2.377(2)
2.136(7)
1.871(8)
2.05(7)
1.421(10)
1.408(8)
1.402(12)
1.376(10)
1.388(14)
1.365(12)
1.486(9)
1.350(11)
1.458(9)
1.02(9)
P(1)-Os-P(2)
P(1)-Os-C(1)
P(1)-Os-C(15)
P(2)-Os-C(1)
P(2)-Os-C(15)
C(1)-Os-C(15)
P(1)-Os‚‚‚H(8)
P(2)-Os‚‚‚H(8)
C(1)-Os‚‚‚H(8)
C(15)-Os‚‚‚H(8)
163.10(6)
89.2(2)
88.7(2)
90.3(2)
93.5(2)
173.3(3)
113(2)
84(2)
Os-C(1)-C(2)
C(1)-C(2)-C(7)
C(2)-C(7)-C(8)
C(7)-C(8)-C(9)
C(7)-C(8)-H(8)
Os-C(15)-O(1)
Os‚‚‚H(8)-C(8)
118.1(4)
119.4(6)
123.9(7)
126.2(7)
126(4)
176.7(6)
118(6)
Os-P(2)
Os-C(1)
Os-C(15)
Os‚‚‚H(8)
C(1)-C(2)
C(1)-C(6)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(5)-C(6)
C(2)-C(7)
C(7)-C(8)
C(8)-C(9)
C(8)-H(8)
C(15)-O(1)
85(3)
90(2)
1.166(10)
a Esd’s are given in parentheses.
toluene-d8, between 177 and 303 K. At 177 K, the spectrum
contains two broad hydrido resonances at -9.5 and -18.6 ppm.
On raising the temperature they coalesce, and the resulting
averaged signal finally sharpens to give a triplet, the chemical
shift of this triplet being temperature-dependent. This behavior
can be understood as the result of the equilibrium shown in eq
1, which involves the cleavage of the agostic interaction present
in 2a to give the nonagostic isomer 2b. The higher field hydrido
resonance at -18.6 ppm is assignable to the unsaturated species
2b, in the view of the trans disposition of the hydrido ligand
and the coordination vacancy.
1
Figure 2. Hydrido region of the H NMR spectrum of 2 at different
temperatures: experimental in toluene-d8 (left) and calculated
(right).
C(2)-C(7) and C(8)-C(9) bonds reflect the greater electronic
delocalization of the coordinated ligand. The Os-P, Os-CO,
and CtO distances are clearly in the expected range and deserve
no further comments.
The equilibrium constants K () k1/k-1) were measured in
the range from 177 to 303 K (Table 2). The temperature
dependence of the equilibrium (Figure 3) gives the values ∆H°
) -1.6 ((0.1) Kcal mol-1 and ∆S° ) -9.6 ((0.6) cal K-1
mol-1 for the formation of 2a. The negative entropy incre-
ment is consistent with the less ordered character of 2b,
which is always the mayor species in the temperature range
studied. The value of ∆H° reveals the small stabilization
achieved by means of the agostic interaction. This small value
could be justified to be not only due to the weakness of the
agostic bond but also to the destabilization due to steric repulsion
between the phenyl ring and the bulky phosphines in 2a. The
strength of this agostic interaction in comparison with other
systems can be estimated using the rbp parameter defined by
Crabtree et al.14 From the structural data of 2a the resulting
value of rbp is 0.82, which lies in the range of relatiVely strong
interactions.
Line shape analysis of the spectra of Figure 2 allow the
calculation of the rate constants for the agostic bond cleavage
(k-1) at different temperatures. The activation parameters
obtained from the Eyring analysis (Figure 4) are ∆Hq ) 7.6
((0.2) Kcal mol-1 and ∆Sq ) -1.0 ((0.7) cal K-1 mol-1. The
activation entropy is nearly zero, as expected for an intramo-
lecular process. The activation enthalpy lies in the range of
other reported exchange processes in which agostic interactions
are breaking and reforming.18 No evidence has been found for
The spectroscopic data obtained for solutions of 2 are in
agreement with the presence of the 2-(E-1′-styryl)phenyl ligand.
The 13C{1H} NMR spectrum at room temperature shows a triplet
at 177.3 ppm (JCP ) 10.6 Hz) assignable to the aromatic carbon
bonded to the osmium. The rest of carbon atoms of the
metalated phenyl ring give resonances at 155.4 (t, JCP ) 2.3
Hz, quaternary carbon), 142.9, 139.7, 129.8 (broad triplets with
JCP < 1 Hz), and 126.5 (s) ppm. A singlet at 121.8 ppm and
a broad singlet at 106.2 ppm are assigned to the olefinic carbons.
The 31P{1H} spectrum contains a singlet at 22.7 ppm. The 1H
NMR spectrum of 2 at room temperature shows a triplet at
-17.83 (JHP ) 21.0 Hz) for the hydrido ligand. The expected
resonances for the metalated and nonmetalated phenyl ring
protons are observed in the range 6.7-7.6 ppm, together with
a doublet at 7.56 (JHH ) 13.6 Hz) which corresponds to one of
the two hydrogens atoms of the olefinic bond. This spectrum
does not show any resonance attributable to the other olefinic
proton, although the 1H COSY spectrum indicates that the signal
lies at 1.05 ppm, hidden by the phosphine methyl groups. The
chemical shift of this resonance, at higher field than that
expected for an olefinic proton, suggests that some agostic
interaction is also present in solution.
The spectra of solutions of 2 are temperature-dependent.
1
Figure 2 shows the hydrido region of the H NMR spectra in
(16) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.
(17) Bouwstra, J. A.; Schouten, A.; Kroon, J. Acta Crystallogr., Sect C
1984, 40, 428.

92 J. Am. Chem. Soc., Vol. 118, No. 1, 1996
Esteruelas et al.
Table 2. Equilibrium Constants of Agostic Bond Formation and
Rates of Agostic Bond Cleavage for the Complex
OsH{C6H4-2-(E-CHdCHPh)}(CO)(PiPr3)2 (2) in Toluene-d8
temp (K)
K
k-1 (s-1
)
177
183
193
203
213
223
243
253
263
293
303
0.742
0.639
1.1 × 103
1.9 × 103
8.0 × 103
1.8 × 104
3.7 × 104
1.2 × 105
6.0 × 106
0.367
0.309
0.227
0.199
0.167
0.128
0.108
1.5 × 107
Figure 3. Arrhenius plot of the equilibrium constants for agostic Os‚‚‚H
bond formation in 2.
the occurrence of hydrogen exchange between the hydrido li-
gand and the agostic proton in complex 2. This agrees with
the behavior of the compound mer-[(Me3P)3IrH{Z-1-(2′-furyl)-
3,3-dimethyl-1-butyl}], in which the hydride and the agostic
bond are also in trans relative positions.19 Nevertheless, such
an exchange has been observed in complexes containing both
agostic C-H bonds and hydrido ligands in cis relative posi-
tions.20
As expected from the lability of the agostic bond, the reaction
of 2 with CO gives the cis-dicarbonyl complex OsH{C6H4-2-
(E-CHdCHPh)}(CO)2(PiPr3)2 (3), in which the incoming ligand
coordinates trans to the hydrido position, releasing the C-H
bond from the metal coordination sphere (eq 2).
Figure 4. Eyring plot of the rate constants for agostic Os‚‚‚H bond
cleavage in 2.
The spectroscopic data obtained for complex 3 support the
proposed octahedral structure. The cis relative position of the
carbonyl ligands was inferred from the IR spectrum, which
shows, together with a (Os-H) band at 2032 cm-1, two strong
(CO) absorptions at 1966 and 1894 cm-1, a typical pattern
for mononuclear cis-dicarbonyl complexes. The 13C{1H} NMR
spectrum also supports this proposal, showing two triplets at
190.4 ppm (JCP ) 5.5 Hz) and at 185.2 ppm (JCP ) 8.3 Hz)
attributable to the carbonyl ligands. This spectrum also contains
the expected resonances for the 2-(E-1′-styryl)phenyl ligand.
The two olefinic carbon atoms were assigned to singlets at 141.7
and 156.9 ppm, shifted about 35 ppm toward lower field with
regard to the olefinic carbons of 2. The CH groups of the
phosphine ligands give a virtual triplet at 26.5 ppm (N ) 27.0
Hz), which is characteristic of two equivalent phosphine ligands
in trans relative position. This is in agreement with the singlet
Figure 5. Low field region of the 13C{1H} NMR spectrum of 4 (CDCl3,
263 K), and proposed assignment.
1
at 19.1 ppm found in the 31P{1H} NMR spectrum. The H
spectrum of 3 shows the hydrido resonance at -6.09 ppm as a
triplet (JHP ) 21.3 Hz). The olefinic protons of the 2-(E-1′-
styryl)phenyl ligand display two doublets at 8.37 and 6.97 ppm
with a H-H coupling constant of 16.2 Hz, in agreement with
their trans relative position at the carbon-carbon double bond.
Reaction of 1 with CH3Li in hexane gives a yellow solution
from which the complex OsH{C6H4-2-(E-CHdCHCH3)}(CO)(Pi-
Pr3)2 (4) was isolated as a yellow solid in 89% yield. The
presence of a 2-(E-1′-propenyl)phenyl ligand in 4 is supported
1
by the 13C{1H} and H NMR spectra.
The 13C{1H} NMR spectrum of a CDCl3 solution of 4 (Figure
(18) Morse, P. M.; Spencer, M. O.; Wilson, S. R.; Girolami, G. S.
Organometallics 1994, 13, 1646, and references therein.
(19) Selnau, H. E.; Merola, J. S. Organometallics 1993, 12, 3800.
(20) (a) Ogasawara, M.; Saburi, M. Organometallics 1994, 13, 1911.
(b) Ogasawara, M.; Aoyagi, K.; Saburi, M. Organometallics 1993, 12, 3393.
(c) McLoughlin, M. A.; Flesher, R. J.; Kaska, W. C.; Mayer, H. A.
Organometallics 1994, 13, 3816.
5) exhibits six different resonances for the aromatic carbon
atoms of the 1-carbon ligand: a triplet at 151.5 ppm (JCP
)
10.4 Hz) due to the metalated carbon, triplets at 152.3, 137.7,
125.1, and 119.8 ppm with coupling constants JCP in the range
of 1 to 2.5 Hz and a singlet at 123.8 ppm. The olefinic carbon

Bis(triisopropylphosphine)osmium Complexes
J. Am. Chem. Soc., Vol. 118, No. 1, 1996 93
atoms appear as broad signals at 87.1 and 75.3 ppm, whereas
the methyl group gives a singlet at 16.2 ppm. The virtual triplet
at 26.6 ppm (N ) 25.7 Hz) displayed by the CH groups of the
phosphines indicates the equivalence and mutual trans disposi-
tion of these ligands. This is confirmed by the singlet at 18.8
ppm found in the 31P{1H} NMR spectrum. At room temper-
1
ature, the H NMR spectrum shows a triplet at -13.33 ppm
(JHP ) 24.0 Hz) for the hydrido ligand. The aromatic region
consists of four different resonances at 7.54 (d), 7.05 (t), 6.97
(t), and 6.81 (d), whereas the olefinic protons appear as a
multiplet at 2.67 ppm and a doublet at 5.82 (JHH ) 10.8 Hz).
This large JHH coupling constant strongly supports the mutual
trans disposition of the hydrogen atoms at the carbon-carbon
double bond. The methyl substituent of the olefinic group gives
a doublet at 2.14 ppm (JHH ) 5.7 Hz).
Reaction of the alkenyl complex 1 with CD3Li, under the
same conditions as those employed for the synthesis of 4, gives
the hydrido-complex OsH{C6H4-2-(E-CHdCHCD3)}(CO)(Pi-
Pr3)2 (4-d3) as unique product, in 84% yield. The presence of
a deuterated methyl group in 4-d3 was inferred from its 2H NMR
spectrum in benzene which shows a singlet at 2.0 ppm as a
Figure 6. Hydrido and olefinic region of the 1H NMR spectra of 4-d3
at different temperatures in toluene-d8.
1
The spectroscopic data obtained for these complexes support
the proposed octahedral structures. The 31P{1H} NMR spectrum
of 5 consists of a triplet at 95.3 ppm and a doublet at 12.5 ppm
(JPP ) 20.3 Hz), in agreement with a phosphite ligand cis to
two equivalent PiPr3 ligands. The proposed trans disposition
of hydrido and phosphite ligands is supported by the 1H
spectrum, which contains at -8.34 ppm a doublet (JHP ) 143.4
Hz) of triplets (JHP ) 29.1 Hz). In the low field region, the
spectrum exhibits the expected resonances for the phosphorus
donor ligands and for the four aromatic protons, along with a
doublet of quartets at 5.94 ppm (JHH ) 6.6 and 15.6 Hz), a
doublet at 8.06 ppm (JHH ) 15.6 Hz), and a doublet at 1.98
(JHH ) 6.6 Hz) assigned to the 1-propenyl fragment. The
striking difference in the olefinic proton chemical shifts with
regard to those observed in complex 4 indicates the nonagostic
nature of the 1-propenyl moiety in complex 5. The 13C{1H}
spectrum shows two apparent quartets at 188.5 ppm (JCP ) 9.5
Hz) and 155.6 ppm (JCP ) 12.0 Hz) corresponding to the
carbonyl ligand and the metalated carbon atom of the phenyl
group respectively. The multiplicity and the values of coupling
constants confirm the cis disposition of these groups with respect
to the three phosphorous donor ligands.
unique signal. In agreement with this, the H NMR spectrum
does not contain any resonance in the region 2.14 ppm, and the
multiplet at 2.67 ppm is simplified into a broad doublet with a
H-H coupling constant of about 10 Hz.
The unusual chemical shifts obtained for the carbons and
protons of the 1-propenyl moiety suggest that the substituted
phenyl ligands of 4 and 4-d3 are involved in agostic interactions
1
similar to that found in 2 (eq 3). In fact, the H NMR spectra
of the complexes 4 and 4-d3 are also temperature-dependent,
as illustrated for 4-d3 in Figure 6. On lowering the temperature
a remarkable shift of the hydrido resonance is observed, along
with a significant broadening of the signal. Simultaneously,
the olefinic resonances also shift and broaden.
The mutual cis disposition of the carbonyl ligands in 6 is
supported by the 13C{1H} NMR spectrum which shows two
separate resonances at 190.3 ppm (JCP ) 6.0 Hz) and 185.3
ppm (JCP ) 8.3 Hz) and by the IR spectrum, which contains in
the terminal carbonyl region two very strong absorptions at 1965
and 1980 cm-1. A singlet at 18.4 ppm in the 31P{1H} spectrum
confirms the equivalence of the phosphines. In addition, the
high field signal of the H NMR spectrum, a triplet at -6.23
ppm (JHP ) 21.7 Hz), is in agreement with a hydride cis
disposed to both triisopropylphosphine ligands.
The exclusive formation of 4-d3 and the trans position of
the two substituentssthe metalated phenyl and the R groupsat
the carbon-carbon double bond of 2 (R ) Ph), 4 (R ) CH3),
and 4-d3 (R ) CD3) suggest that the reactions of 1 with
phenyllithium and methyllithium follow the steps shown in
Scheme 1. The reactions could initially involve the replacement
of the Cl- anion by the R group to give R-styrylosmium(II)
species (7, 8, and 8-d3). Subsequently, the carbon-carbon
reductive coupling should afford osmium(0) intermediates (9,
10, and 10-d3), containing a coordinated olefin ligand. Because
the reductive carbon-carbon coupling is a concerted process,
the stereochemistry at the carbon-carbon double bond is
retained, thus, the phenyl and the R groups are mutually trans
In contrast to that found for 2, at the lowest temperature
attained the conversion rate between 4a and 4b is still fast in
the NMR time scale, and thus the observed hydrido resonance
is a result of an average of the two signals. As found for 2, the
lowering of the temperature might favor the agostic complex,
hence the hydrido resonance shifts to lower fields. Replacement
of the CD3 substituent by CH3 has no detectable effect in the
position of the equilibrium, as the hydrido chemical shifts
observed for 4 and 4-d3 are nearly the same at any temperature.
Similarly to 2, complex 4 reacts with Lewis bases such as
P(OMe)3 and CO to give the corresponding adducts OsH{C6H4-
2-(E-CHdCHCH3)}(CO){P(OMe)3}(PiPr3)2 (5) and OsH{C6H4-
2-(E-CHdCHCH3)}(CO)2(PiPr3)2 (6) (eq 4).
1

94 J. Am. Chem. Soc., Vol. 118, No. 1, 1996
Esteruelas et al.
The 31P{1H}spectrum of 11 shows an AB pattern centered
at 21.9 ppm with a P-P coupling constant of 208.9 Hz, which
3
requires a trans disposition of the phosphine ligands. The
coordination of the 1-phenylallyl ligand is also suggested by
the 13C{1H} spectrum, in which the allylic carbons signals con-
sist of a doublet of doublets at 16.3 ppm (JCP ) 6.0, 3.2 Hz)
for the terminal CH2, a doublet at 49.7 ppm (JCP ) 1.0 Hz) for
the phenyl-substituted terminal carbon, and a singlet at 79.8
ppm for the meso-CH. The carbonyl ligand gives a doublet of
doublets at 192.9 ppm (JCP ) 10.8, 8.5 Hz) in agreement with
its cis location relative to the two phosphine ligands.
In the structure proposed for 11, shown in eq 5, the hydrido
ligand occupies one position cisoid to the terminal CH2 group
of the allyl ligand. This postulation bares relation to the
structure of complex 12, which was prepared by reaction of 11
with carbon monoxide (eq 6).
Figure 7. Low field region of the 1H COSY spectrum of 11 in C6D6.
disposed. According to this proposal we have recently found
that the reactions of complex 1 and its ruthenium analogue with
vinylmagnesium bromide afford 1-phenylbutadieneosmium(0)
and -ruthenium(0) derivatives. The reactions proceed via bis-
vinyl intermediates, which can be detected in the case of
ruthenium.21 Finally the C-H activation of the ortho-CH bond
of the phenyl group should lead to the reaction products.
The IR spectrum of 12 contains the absorption attributable
to the (Os-H) vibration at 2015 cm-1 and two (CO) bands
at 1950 and 1885 cm-1, in agreement with a cis arrangement
of the carbonyl groups. The 13C{1H} spectrum is consistent
with a 1 coordination of the phenylallyl ligand, showing a triplet
at -4.5 ppm (JCP ) 6.9 Hz) for the R methylenic carbon atom
and singlets at 120.9 and 147.8 ppm for the carbon atoms in
Isomerization of 4. In solution, after ca. 20 min. at room
3
temperature, complex 4 transforms into the complex OsH(
-
1
and positions, respectively. In the H spectrum, the protons
CH2CHCHPh)(CO)(PiPr3)2 (11) (eq 5), which can be isolated
in and positions give rise to a doublet of triplets at 7.10
ppm (JHH ) 15.3 and 9.0 Hz) and a doublet at 6.14 ppm (JHH
) 15.3 Hz), respectively. The large JHH constant confirms their
relative trans position at the double bond, in agreement with
the syn conformation proposed for the 3-allyl ligand of 11.
Both R hydrogens appear as a sole doublet of triplets at 1.82
ppm (JHH ) 9.0 Hz, JHP ) 8.2 Hz). The 31P{1H} NMR
spectrum shows a singlet at 22.8 ppm.
in 85% yield by precipitation in methanol.
The deuterated complex 4-d3 also isomerizes in solution to
give the complex OsD( 3-CD2CHCHPh)(CO)(PiPr3)2 (11-d3),
as is illustrated in eq 7. In this case the reaction requires several
hours for completion.
The spectroscopic data of 11, an isomer of 4, agree with the
presence of the 1-phenylallyl ligand coordinated in a mode.
The 1H NMR spectrum shows at high field a doublet of doublets
(-11.52 ppm, JHP ) 31.5, 23.5 Hz), attributable to a hydrido
ligand disposed cis to two chemically inequivalent phosphine
ligands. In the low field region the spectrum exhibits the
resonances due to the phosphine ligands and the phenyl group,
along with three multiplets at 5.32, 4.79, and.1.78 ppm, each
one corresponding to one proton. The 1H NMR COSY
spectrum shows a fourth multiplet corresponding to the 1-phen-
ylallyl ligand buried under the phosphine methyl groups
resonances (Figure 7). The different coupling constants mixed
2
The H NMR spectrum of 11-d3 shows a broad doublet of
1
doublets at -11.5 ppm, together with two broad signals centered
at 1.0 and 1.7 ppm, revealing that the compound is deuterated
at the hydride and the methylenic allyl carbon. Consequently,
up in these multiplets have been deduced by means of the H-
{31P} spectrum and selective homonuclear irradiation in the 1H
spectrum and are reported in the Experimental Section. The
JHH coupling constant between the CHPh and meso-CH protons
(8.7 Hz) suggests a syn conformation for the 1-phenylallyl
ligand.22 This syn conformation seems to be sterically more
favored, being the only form observed in previously reported
complexes containing this ligand structurally characterized by
X-ray diffraction.23
(22) For examples, see: (a) Clark, H. C.; Hampden-Smith, M. J.;
Ruegger, H. Organometallics 1988, 7, 2085. (b) Krivykh, V. V.; Gusev,
O. V.; Petrovskii, P. V.; Rybinskaya, M. I. J. Organomet. Chem. 1989,
366, 109.
(23) (a) Tulip, T. H.; Ibers, J. A. J. Am. Chem. Soc. 1979, 101, 4201.
(b) Murrall, N. W.; Welch, A. J. J. Organomet. Chem. 1986, 301, 109. (c)
Cotton, F. A.; Luck, R. L. Acta Crystallogr., C (Cr.yst Struct. Commun.)
1990, 46, 138. (d) Faller, J. W.; Lambert, C.; Mazzieri, M. R. J. Organomet.
Chem. 1990, 383, 161. (e) Henly, T. J.; Wilson, S. R.; Shapley, J. R Inorg.
Chem. 1988, 27, 2551.
(21) Bohanna, C.; Esteruelas, M. A.; Lahoz, F.; On˜ate, E.; Oro, L. A.;
Sola, E. Organometallics 1995, 14, 4825.

Bis(triisopropylphosphine)osmium Complexes
J. Am. Chem. Soc., Vol. 118, No. 1, 1996 95
consistent with an intramolecular process. Table 3 also includes
the values of the first order rate constant kobs-d obtained for the
3
isomerization of the deuterated complex 4-d3 (eq 6). A primary
isotope effect25 is evidenced by the value kobs/kobs-d ) 3.6 at
3
303 K. This indicates that the rate-determining step of the
isomerization reaction involves the cleavage of one C-H bond
of the methyl group.
In the view of the trans relative position at the CdC bond of
the metalated phenyl ring and the methyl substituent, the methyl
group C-H activation step seems unlikely to occur in 4. Thus,
the isomerization reaction might involve an initial step consisting
of the reductive elimination of 1-phenylpropene from 4 to give
the unsaturated osmium(0) intermediate 10, as shown in eq 8.
This intermediate26 is consistent with the observation that no
H/D scrambling occurs between the ortho phenyl position and
the methyl group during the isomerization of 4-d3. The second
and slow step of the reaction would consist in the C-H
activation of the methyl group of the 1-phenylpropene in 10 to
give 11.27
Figure 8. Stacked spectra illustrating the isomerization of complex 4
to 11 in CDCl3 at 303 K.
Table 3. Rates of Isomerization of Complex 4 to 11 in CDCl3
complex
temp (K)
kobs (s-1 104)
4
308
303
301
295
290
313
303
299
25.9 ( 0.9
15.2 ( 0.5
12.3 ( 0.4
5.9 ( 0.2
2.9 ( 0.1
14.1 ( 0.4
4.2 ( 0.1
2.7 ( 0.1
4-d3
Despite of the fact that the C-H activation of the methyl
group in 10 (k3) is the slow step of the isomerization, no signal
corresponding to 10 can be spectroscopically detected in the
course of the reaction. Moreover, the only signals observable
during the reaction are those corresponding to 4 and 11. The
fact that 10 does not accumulate in solution suggests that a C-H
activation process in 10 to reform 4 (k-2) is faster than
conversion of 10 to 11. This is also in agreement with the
formation of 4 via the Scheme 1.
The reactions shown in eq 8 may be considered as two
competitive C-H activation processes in a undetected osmium-
(0) complex. One of these processes, kinetically favored and
reversible at room temperature, consists of the activation of the
ortho C-H bond of the phenyl ring to give the product of kinetic
control 4. The other, which requires a larger activation enthalpy,
leads to the isomer 11. Because the 3-allyl coordination is
expected to give a more stable complex than the 1-phenyl
coordination, complex 11 is the product of thermodynamic
control. This is in agreement with the proposal of Jones and
Feher, who have suggested that for competitive intramolecular
Figure 9. Eyring plot of the first order rate constants (kobs) for the
isomerization of 4 to 11 (white), and for the isomerization of 4-d3 to
11-d3 (black) in CDCl3.
1
these resonances are absent in the H spectrum of 11-d3. The
31P{1H} NMR spectrum also suggests the deuteration at the
hydrido position, showing a small P-D coupling of 3.6 Hz.
The isomerization reaction24 depicted in eq 5 was followed
1
by H NMR spectroscopy by measuring the disappearance of
the hydrido signal of 4 as a function of time. As shown in
Figure 8, the decrease of 4 (with the corresponding increase of
11) in CDCl3 is an exponential function of time, in agreement
with a first order process. The values obtained for the first order
rate constant kobs in the temperature range studied are reported
in Table 3. The activation parameters of the reaction were
obtained from the Eyring analysis shown in Figure 9, giving
values of ∆Hq ) 20.8 ((1.7) Kcal mol-1 and ∆Sq ) -2.8
((2.0) cal K-1 mol-1. The near zero activation entropy is
(25) Connors, K. A. Chemical Kinetics, The Study of Reaction Rates in
Solution; VCH Publishers, Inc.: 1990.
(26) Unsaturated osmium(0) species have been proposed as intermediates
in some C-H activation reactions (refs 8 and 9c). In addition some stable
16 electron osmium(0) complexes have been reported: (a) Werner, H.;
Flu¨gel, R.; Windmu¨ller, B.; Michenfelder, A.; Wolf, J. Organometallics
1995, 14, 61. (b) Werner, H.; Michenfelder, A.; Schulz, M. Angew. Chem.,
Int. Ed. Engl. 1991, 30, 596.
(24) An example of an isomerization reaction similar to that of 4 to 11
1
has been previously reported. The complex Cp*IrH{
,
2-C6H4-2-(CH2-
CHdCH2)}, which contains an isomeric ligand of the 2-(E-1′-propenyl)-
(27) For examples on the activation of propene or substituted propenes
to give hydrido allyl complexes, see: (a) Heyn, R. H.; Caulton, K. G. J.
Am. Chem. Soc. 1993, 115, 3354. (b) Zhuang, J.-M.; Sutton, D. Organo-
metallics 1991, 10, 1516. (c) Reference 24.
3
phenyl ligand of 4, partially isomerizes on heating to the species Cp*IrH(
-
1-phenylallyl). See: McGhee, W. D.; Bergman, R. G. J. Am. Chem. Soc.
1988, 110, 4246.

96 J. Am. Chem. Soc., Vol. 118, No. 1, 1996
Esteruelas et al.
Table 4. Atomic Coordinates (×104; ×105 for Os Atom) and
Scheme 1
Equivalent Isotropic Displacement Coefficients (Å2, ×103; Å2, ×104
for Os Atom) for the Compound
OsH{C6H4-2-(E-CHdCHPh)}(CO)(PiPr3)2 (2a)
a
Atom
X/a
Y/b
Z/c
Ueq
H(1)b
H(8)c
Os
P(1)
P(2)
O(1)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
C(31)
C(32)
C(33)
9375
5703
7116
5456(94)
76029(3)
8197(2)
7710(2)
8829(8)
6482(7)
4908(8)
4073(9)
4753(11)
6294(10)
7107(9)
4089(8)
4633(7)
3877(8)
2492(10)
1801(11)
2475(12)
3832(12)
4524(9)
8391(8)
7131(9)
7908(12)
5566(11)
8231(9)
8743(12)
6802(11)
10203(9)
11397(10)
10474(11)
5874(9)
4842(10)
5044(13)
8579(9)
8360(13)
10277(10)
8823(10)
10411(10)
8840(15)
7882(79)
64831(2)
4519(2)
8036(2)
8009(6)
5441(6)
5627(7)
4964(8)
4121(8)
3902(8)
4522(7)
6571(7)
7501(7)
8455(7)
8461(9)
9386(9)
10334(9)
10352(8)
9419(8)
7427(7)
3241(7)
1730(8)
3762(10)
4974(7)
3718(9)
6081(9)
3339(8)
4055(11)
2755(9)
9300(8)
8541(11)
10399(10)
7088(7)
7934(9)
6256(10)
9226(7)
8520(10)
10320(10)
7639(41)
74446(1)
8256(1)
6474(1)
8533(3)
6784(3)
6946(3)
6559(4)
5982(4)
5812(4)
6205(3)
7544(3)
7854(3)
8438(3)
8772(4)
9316(5)
9554(4)
9221(5)
8677(4)
8100(3)
8204(4)
8425(5)
8614(6)
9231(3)
9746(4)
9507(4)
8093(4)
8235(5)
7317(4)
6152(4)
5892(6)
6725(6)
5626(3)
4909(4)
5686(4)
6683(4)
6928(5)
6098(5)
53(22)
276(1)
30(1)
33(1)
62(2)
31(1)
36(1)
47(2)
58(2)
51(2)
39(2)
42(2)
35(1)
40(2)
55(2)
67(2)
68(3)
65(2)
50(2)
37(1)
46(2)
66(2)
72(3)
43(2)
63(2)
62(2)
48(2)
72(3)
64(2)
52(2)
74(3)
86(4)
41(2)
68(3)
64(2)
48(2)
60(2)
83(3)
C-H activation reactions the selectivity is determined by the
thermodynamic stability of the reaction products rather than by
the strength of the C-H bond to be activated.7h
Products obtained from the oxidative addition of the olefinic
C-H bonds have not been observed during this work, in spite
of the fact that the activation of these bonds is an expected
process in intermediates such as 9 and 10.3ab,7gl,10c,28 The lack
of products from these activations does not necessarily imply
that these processes are kinetically disfavored with regard to
the activations of the ortho phenyl or methyl group C-H bonds.
In fact, low activation barriers should be expected for all the
possible intramolecular C-H activations in osmium(0) inter-
mediates like 10, in view of the mild isomerization conditions
and the values of activation enthalpies reported for this kind of
reactions.7j Thus, the nonobservation of hydrido-vinyl com-
plexes could be a consequence of their lower thermodynamic
stability compared to the hydrido-phenyl derivatives.29 This
was also suggested by previous studies showing that metal-
phenyl bonds are stronger that metal-vinyl ones.2f,7h In the
light of these considerations, the hydrido-phenyl complexes 2
and 4 may be tentatively considered as products of thermody-
namic control among those C-H activations kinetically favored.
In this context, the additional stabilization given by the agostic
interaction found in 2 and 4, albeit small, may have an influence
in directing the selectivity of the C-H activation to the ortho
C-H bonds.
a
Equivalent isotropic U defined as one-third of the trace of the
orthogonalized Uij tensor. b The coordinates of the hydride were
calculated by the HYDEX program. c The agostic hydrogen H(8) was
refined as a free isotropic atom.
ates containing an olefinic ligand. This ligand is a result of
the reductive carbon-carbon coupling between the styryl and
R groups. The metallic center of these osmium(0) intermediates
is capable of activating a C-H bond of one substituent of the
coordinated olefin to afford hydridoosmium(II) derivatives. The
nature of the C-H activation products can be rationalized on
the basis of the substituents present at the alkene ligand of the
osmium(0) intermediate and in the light of thermodynamic and
kinetic considerations. When the alkene ligand has a phenyl
substituent, the activation of an ortho position of this phenyl
ring is kinetically favored. The products of these activations
show an agostic interaction between the osmium center and one
of the olefinic C-H bonds. When the alkene ligand has a
methyl substituent, the final product of the reaction is a
hydrido-allyl complex. This reaction requires larger activation
energy but gives a complex thermodynamically more stable.
In recent years our group has studied a series of catalytic
processes performed by phosphino-osmium complexes. The
mechanistic studies carried out in catalytic reactions such as
hydrogenation,30,11b hydrosililation,31 or hydrogen transfer re-
Conclusion
This study has revealed that the five-coordinate complex
OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) is an useful starting mate-
rial to perform, in consecutive steps, carbon-carbon bond
formation and C-H activation reactions.
Treatment of complex 1 with RLi (R ) Ph, CH3) leads to
new hydridoosmium(II) derivatives, via osmium(0) intermedi-
(28) For examples on oxidative addition of alkenes to give hydrido vinyl
complexes, see: (a) Stoutland, P. O.; Bergman, R. G.; J. Am. Chem. Soc.
1985, 107, 4581. (b) Silvestre, J.; Calhorda, M. J.; Hoffman, R.; Stoutland,
P. O.; Bergman, R. G. Organometallics 1986, 5, 1841. (c) Haddleton, D.
M.; Perutz, R. N. J. Chem. Soc., Chem. Commun. 1986, 1734. (d) Bell, T.
W.; Haddleton, D. M.; McCamley, A.; Partridge, M. G.; Perutz, R. N.;
Willner, H J. Am. Chem. Soc. 1990, 112, 9212. (e) Bianchini, C.; Barbaro,
P.; Meli, A.; Peruzzini, M.; Vacca, A.; Vizza, F. Organometallics 1993,
12, 2505.
(29) Recent work on styrene derivatives of osmium indicates that the
products of activation of the phenyl ring are thermodynamically favored
with respect to the activation of the olefinic C-H bonds. Nevertheless, in
solution the products of both C-H activation processes are in equilibrium.
Albe´niz, M. J.; Esteruelas, M. A.; Lledo´s, A.; Maseras, F.; On˜ate, E.; Oro,
L. A.; Sola, E.; Zeier, B. Submitted for publication.
(30) (a) Esteruelas, M. A.; Sola, E.; Oro, L. A.; Meyer, U.; Werner, H.
Angew. Chem., Int. Ed. Engl. 1988, 27, 1563. (c) Esteruelas, M. A.; Oro,
L. A.; Valero, C. Organometallics 1992, 11, 3362.

Bis(triisopropylphosphine)osmium Complexes
J. Am. Chem. Soc., Vol. 118, No. 1, 1996 97
Table 5. Crystal Data and Data Collection and Refinement for
OsH{C6H4-2-(E-CHdCHPh)}(CO)(PiPr3)2 (2a)
Preparation of OsH{C6H4-2-(E-CHdCHPh)}(CO)(PiPr3)2 (2). A
solution of OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) (150 mg, 0.23 mmol)
in 6 mL of toluene was treated with 0.3 mL of a 1 M solution of C6H5-
Li in diethyl ether, and the resulting solution was heated at 60 °C for
1 h. The resultant suspension was filtered through kieselgur, and the
solvent was removed to yield a yellow residue. Treatment of this
residue with methanol gave a yellow solid, which was washed with
methanol and dried in vacuo: yield 98.6 mg (65%); IR (Nujol mull,
Crystal Data
formula
mol wt
C33H54OOsP2
718.94
color and habit
crystal size, mm
space group
a, Å
yellow, irregular prism
0.29 × 0.27 × 0.12
triclinic, P1h (no. 2)
9.230(1)
1
cm-1) 2197 (m, (OsH)), 1904 (s, (CO)); H NMR (CDCl3, 293 K)
b, Å
10.092(1)
-17.83 (t, JHP ) 21.0 Hz, 1H, Os-H), 0.97 (dvt, N ) 13.8 Hz, JHH
) 6.8 Hz, 18H, PCH(CH3)2), 1.09 (dvt, N ) 13.8 Hz, JHH ) 6.8 Hz,
18H, PCH(CH3)2), 2.2 (m, 6H, PCH(CH3)2), 6.72 (vt, JHH ) 7.2 Hz,
1H), 6.80 (vt, JHH ) 7.2, 1H), 7.09 (d, JHH ) 7.2 Hz, 1H), 7.15 (t, JHH
) 7.6 Hz, 1H, Hpara-Ph), 7.29 (vt, JHH ) 7.6 Hz, 2H, Hmeta-Ph), 7.51 (d,
JHH ) 7.2 Hz, 1H), 7.56 (d, JHH ) 13.6 Hz, 1H, dCH), 7.61 (d, JHH
) 7.6 Hz, 2H, Hortho-Ph); 31P{1H} NMR (CDCl3, 293 K) 22.8 (s);
13C{1H} NMR (C6D6, 293 K) 19.5 (s, PCH(CH3)2), 19.9 (s, PCH-
(CH3)2), 27.3 (vt, N ) 22.8 Hz, PCH(CH3)2), 106.2 (br, dCH), 121.8
(s, dCH), 126.5 (s, CH), 127.0 (s, CHpara-Ph), 127.2 (s, CHmeta-Ph), 128.7
(s, CHortho-Ph), 129.8 (brt, CH), 139.7 (brt, CH), 141.0 (s, Cipso-Ph), 142.9
(brt, CH), 155.4 (t, JCP ) 2.3 Hz, C-CHd), 177.3 (t, JCP ) 10.6 Hz,
Os-C), 191.3 (t, JCP ) 8.8 Hz, CO). Anal. Calcd for C33H54OP2Os:
C, 55.14; H, 7.57. Found: C, 54.71, H, 8.26.
c, Å
R, deg
, deg
18.525(2)
88.667(7)
87.172(7)
, deg
71.110(6)
1630.6(3)
V, Å3
Z
2
D(calcd), g cm-1
1.464
Data Collection and Refinement
diffractometer
(Mo KR), Å; technique
monochromator
, mm-1
4-Circle Siemens-P4
0.71073, bisecting geometry
graphite oriented
4.034
/2
scan type
2
range, deg
3 e 2 e 53°
298
Preparation of OsH{C6H4-2-(E-CHdCHPh)}(CO)2(PiPr3)2 (3).
Carbon monoxide was bubbled through a suspension of OsH{C6H4-
2-(E-CHdCHPh)}(CO)(PiPr3)2 (2) (100 mg, 0.14 mmol) in 5 mL of
methanol. After a 10 min reaction a white solid was formed, which
was decanted, washed with methanol, and dried in vacuo: yield 88.0
mg (84%); IR (Nujol mull, cm-1) 2032 (s, (OsH)), 1966, 1894 (s,
temp, K
no. of data collected
no. of unique data
no. of params refined
Ra (Fo g 4.0 (Fo))
wRb (all data)
Sc
7458
6171
339
0.0401
0.0994
1.008
1
(CO)); H NMR (C6D6, 293 K) -6.09 (t, JHP ) 21.3 Hz, 1H, Os-
2
a R(F) ) ∑||Fo| - |Fc||/∑||Fo|. b wR(F2) ) [∑{w(Fo - Fc2)2}/
H), 1.06 (dvt, N ) 12.3 Hz, JHH ) 6.3 Hz, 18H, PCH(CH3)2), 1.08
(dvt, N ) 12.3 Hz, JHH ) 6.3 Hz, 18H, PCH(CH3)2), 2.06 (m, 6H,
PCH(CH3)2), 6.77 (td, JHH ) 7.8 Hz, JHH ) 1.2 Hz, 1H), 6.97 (d, JHH
) 16.2 Hz, 1H, dCH), 7.02 (vt, JHH ) 7.8 Hz, 1H), 7.06 (t, JHH ) 7.5
2
2
2
∑{w(Fo )2}]0.5; w-1
)
2(Fo ) + (aP)2 + bP, where P ) [max(Fo , 0)
+ 2Fc2]/3, a ) 0.0381 and b ) 0. c S ) [∑{w(Fo - Fc2)2}/(n-p)]0.5
where n is the number of number of data and p is the number of
,
2
parameters.
Hz, 1H, Hpara-Ph), 7.28 (vt, JHH ) 7.6 Hz, 2H, Hmeta-Ph), 7.71 (dd, JHH
)
7.8 Hz, JHH ) 1.2 Hz 1H), 7.84 (d, JHH ) 7.5 Hz, 2H, Hortho-Ph), 8.37
(d, JHH ) 16.2 Hz, 1H, dCH), 8.63 (d, JHH ) 7.8 Hz, 1H); 31P{1H}
NMR (C6D6, 293 K) 19.1 (s); 13C{1H} NMR (C6D6, 293 K) 19.3
(s, PCH(CH3)2), 20.0 (s, PCH(CH3)2), 26.5 (vt, N ) 27.0 Hz, PCH-
(CH3)2), 123.5 (br, CH), 125.5 (br, CH), 126.0 (br, CH), 126.8 (s, CHpara-
Ph), 126.9 (s, CHmeta-Ph), 128.9 (s, CHortho-Ph), 139.5 (s, Cipso-Ph), 141.7
(s, dCH), 148.8 (brt, C-CHd), 152.6 (t, JCP ) 12.0 Hz, Os-C), 156.9
(s, dCH), 185.2 (t, JCP ) 8.3 Hz, CO), 190.4 (t, JCP ) 5.5 Hz, CO).
Anal. Calcd for C34H54O2P2Os: C, 54.68; H, 7.29. Found: C, 54.26
, H, 7.10.
ductions32 indicate that the catalytic cycles of these processes
involve osmium(II) and osmium(IV) intermediates. The present
work has shown that very reactive osmium(0) intermediates can
also be generated under mild conditions, suggesting that the
field of application of these osmium complexes can be extended
to other catalytic processes involving carbon-carbon bond
formation and C-H oxidative addition steps.
Experimental Section
Preparation of OsH{C6H4-2-(E-CHdCHCH3)}(CO)(PiPr3)2 (4).
A solution of OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) (100 mg, 0.15
mmol) in 10 mL of hexane was treated with 0.1 mL of a 1.6 M solu-
tion of CH3Li in diethyl ether. The reaction mixture became yellow,
was cooled to 0 °C and quickly filtered through kieselgur. The sol-
vent was removed at 0 °C to yield a yellow residue. Treatment of
this residue with cold methanol gave a yellow solid, which was
washed with methanol and dried in vacuo: yield 86.4 mg (89%); IR
(Nujol mull, cm-1) 2245 (m, (OsH)), 1910 (s, (CO)); 1H NMR
(C6D6, 293 K) -13.33 (t, JHP ) 24.0 Hz, 1H, Os-H), 1.06 (dvt, N )
12.9 Hz, JHH ) 6.9 Hz, 18H, PCH(CH3)2), 1.11 (dvt, N ) 12.9 Hz,
JHH ) 6.9 Hz, 18H, PCH(CH3)2), 2.14 (d, JHH ) 5.7 Hz, 3H, CH3),
Physical Measurements. Infrared spectra were recorded as Nujol
mulls on polyethylene sheets using a Perkin-Elmer 883 or a Nicolet
550 spectrometer. NMR spectra were recorded on a Varian UNITY
300 or on a Bruker ARX 300. The probe temperature of the NMR
spectrometers was calibrated against a methanol standard. 1H and 13C-
{1H} chemical shifts were measured relative to partially deuterated
solvent peaks but are reported relative to tetramethylsilane. 31P{1H}
chemical shifts are reported relative to H3PO4 (85%). 2H chemical shifts
were measured relative to C6D6 (7.15 ppm) used as internal reference.
1
Coupling constants J and N (N ) J(HP) + J(HP’′ for H, and N )
J(CP) + J(CP′) for 13C) are given in Hertz. In general, spectra
assignment was achieved with the aid of 1H COSY and 13C DEPT
experiments. C,H analysis were carried out in a Perkin-Elmer 2400
CHNS/O analyzer.
2.20 (m, 6H, PCH(CH3)2), 2.67 (m, 1H, CH3-CHd), 5.82 (d, JHH
)
10.8 Hz, 1H, CH3-CHdCH), 6.81 (d, JHH ) 7.2 Hz, 1H), 6.97 (vt, JHH
) 7.2 Hz, 1H), 7.05 (vt, JHH ) 7.2 Hz, 1H), 7.54 (d, JHH ) 7.2 Hz,
Synthesis. All reactions were carried out with exclusion of air by
using standard Schlenk techniques. Solvents were dried by known
procedures and distilled under argon prior to use. The complex OsCl-
(E-CHdCHPh)(CO)(PiPr3)2 (1) was prepared according with the
literature method.11a
1H); 31P{1H} NMR (C6D6, 293 K)
18.8 (s); 13C{1H} NMR
(CDCl3, 263 K): 16.2 (s, CH3), 19.6 (s, PCH(CH3)2), 20.2 (s, PCH-
(CH3)2), 26.7 (vt, N ) 25.7 Hz, PCH(CH3)2), 75.3 (br, dCH), 87.1
(br, dCH), 119.9 (t, JCP ) 1.0 Hz, CH), 123.9 (s, CH), 125.2 (t, JCP
)
2.0 Hz, CH), 142.9 (t, JCP ) 1.5 Hz, CH), 155.4 (t, JCP ) 2.5 Hz,
C-CHd), 177.3 (t, JCP ) 10.6 Hz, Os-C), 191.3 (t, JCP ) 8.3 Hz,
CO). Anal. Calcd for C28H52OP2Os: C, 51.20; H, 7.98. Found: C,
50.79, H, 7.78.
(31) Esteruelas, M. A.; Oro, L. A.; Valero, C. Organometallics 1991,
10, 462.
(32) (a) Esteruelas, M. A.; Sola, E.; Oro, L. A.; Werner, H; Meyer, U.
J. Mol. Catal. 1988, 45, 1. (b) Esteruelas, M. A.; Sola, E.; Oro, L. A.;
Werner, H; Meyer, U. J. Mol. Catal. 1989, 53, 43. (c) Esteruelas, M. A.;
Valero, C.; Oro, L. A.; Meyer, U.; Werner, H. Inorg. Chem. 1991, 30, 1159.
(d) Esteruelas, M. A.; Garc´ıa, M. P.; Lo´pez, A. M.; Oro, L. A.; Ruiz, N.;
Schlu¨nken, C.; Valero, C.; Werner, H. Inorg. Chem. 1992, 31, 5580.
Preparation of OsH{C6H4-2-(E-CHdCHCD3)}(CO)(PiPr3)2 (4-
d3). A solution of OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) (100 mg, 0.15
mmol) in 10 mL of hexane was treated with 0.3 mL of a 0.5 M solution
of CD3Li in diethyl ether. After 5 min of reaction, the resulting

98 J. Am. Chem. Soc., Vol. 118, No. 1, 1996
Esteruelas et al.
suspension was filtered through kieselgur, and the solvent was removed
to leave a yellow residue. Treatment of this residue with methanol
gave a yellow solid, which was washed with methanol and dried in
vacuo: yield 81.6 mg (84%); IR (Nujol mull, cm-1) 2245 (m, (OsH)),
1910 (s, (CO)); 1H NMR (C6D6, 293 K) -13.22 (t, JHP ) 24.6 Hz,
1H, Os-H), 1.05 (dvt, N ) 13.0 Hz, JHH ) 7.0 Hz, 18H, PCH(CH3)2),
1.11 (dvt, N ) 12.9 Hz, JHH ) 6.9 Hz, 18H, PCH(CH3)2), 2.20 (m,
6H, PCH(CH3)2), 2.69 (d, JHH ) 10.9 Hz, 1H, CD3CHd), 5.80 (d, JHH
) 10.9 Hz, 1H, CD3CHdCH), 6.81 (d, JHH ) 7.4 Hz, 1H), 6.98 (vt,
JHH ) 7.4 Hz, 1H), 7.04 (vt, JHH ) 7.4 Hz, 1H), 7.54 (d, JHH ) 7.4
Hz, 1H); 31P{1H} NMR (C6D6, 293 K) 18.6 (s); 2H NMR (C6H6, 293
K) 2.0 (s, CD3). Anal. Calcd for C28H49D3OP2Os: C, 50.95; H,
7.97. Found: C, 50.47 , H, 8.43.
(Nujol mull, cm-1) 2120 (m, (OsH)), 1875 (s, (CO)); 1H NMR (C6D6,
293 K) -11.52 (dd, JHP ) 31.5 Hz, JHP ) 23.5 Hz 1H, Os-H), 0.98
(dd, JHP ) 12.8 Hz, JHH ) 7.1 Hz, 9H, PCH(CH3)2), 0.99 (dd, JHP
)
12.0 Hz, JHH ) 6.7 Hz, 9H, PCH(CH3)2), 1.21 (dd, JHP ) 12.7 Hz, JHH
) 6.0 Hz, 9H, PCH(CH3)2), 1.23 (dd, JHP ) 12.7 Hz, JHH ) 6.0 Hz,
9H, PCH(CH3)2), 1.78 (m, JHH ) 6.6 Hz, JHH ) 2.0 Hz, JHP ) 2.0 Hz,
1H, allyl-CH2 (syn)), 2.01 (m, 3H, PCH(CH3)2), 2.22 (m, 3H, PCH(CH3)2),
4.79 (dd, JHP ) 9.6 Hz, JHH ) 8.7 Hz, 1H, allyl-CHPh), 5.32 (m, JHH
) 8.9 Hz, JHH ) 8.7 Hz, JHH ) 6.6 Hz, JHP ) 8.0 Hz, 1H, allyl-CHmeso),
7.07 (t, JHH ) 7.5 Hz, 1H, Hpara-Ph), 7.25 (vt, JHH ) 7.5 Hz, 2H, Hmeta-
Ph), 7.82 (d, JHH ) 7.5 Hz, 2H, Hortho-Ph); 31P{1H} NMR (C6D6, 293 K)
AB system
) 20.5,
) 23.3, JAB ) 208.9 Hz; 13C{1H} NMR
A
B
(C6D6, 293 K) 16.3 (dd, JCP ) 6.0 Hz, JCP ) 3.2 Hz, allyl-CH2),
20.1 (s, PCH(CH3)2), 20.2 (s, PCH(CH3)2), 20.6 (s, PCH(CH3)2), 20.7
(s, PCH(CH3)2), 27.7 (dd, JCP ) 21.6 Hz, JCP ) 2.8 Hz, PCH(CH3)2),
28.4 (dd, JCP ) 23.2 Hz, JCP ) 3.5 Hz, PCH(CH3)2), 49.7 (s, allyl-
CHPh), 79.8 (d, JCP ) 1.0 Hz, allyl-CHmeso), 124.7 (s, CHpara-Ph), 128.2
Preparation of OsH{C6H4-2-(E-CHdCHCH3)}(CO){(P(OMe)3}-
(PiPr3)2 (5). A solution of OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) (100
mg, 0.15 mmol) in 10 mL of hexane was treated with 0.1 mL of a 1.6
M solution of CH3Li in diethyl ether. The reaction mixture became
yellow, was cooled to 0 °C, and quickly filtered through kieselgur.
Addition of P(OMe)3 (18 L, 0.15 mmol) gave a colorless solution
which was dried to leave a white residue. Treatment of this residue
with methanol gave a white solid, which was washed with methanol
and dried in vacuo: yield 70 mg (59%); IR (Nujol mull, cm-1) 2110
(s, CHmeta-Ph), 129.4 (s, CHortho-Ph), 145.4 (s, Cipso-Ph), 192.9 (dd, JCP
)
10.8 Hz, JCP ) 8.8 Hz, CO). Anal. Calcd for C28H52OP2Os: C, 51.20;
H, 7.98. Found: C, 51.89, H, 8.98.
Preparation of OsD(η3-CD2CHCHPh)(CO)(PiPr3)2 (11-d3).
A
solution of OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) (100 mg, 0.15 mmol)
in 10 mL of hexane was treated with 0.3 mL of a 0.5 M solution of
CD3Li in diethyl ether, and the resulting suspension was stirred
during 2 h at 50 °C. The obtained suspension was filtered through
kieselgur, and the solvent was removed to leave a yellow residue.
Treatment of this residue with methanol gave a white solid, which was
washed with methanol and dried in vacuo: yield 82 mg (82%); IR
1
(m, (OsH)), 1895 (s, (CO)); H NMR (C6D6, 293 K) -8.34 (dt,
JHP ) 143.4 Hz, JHP ) 24.1 Hz, 1H, Os-H), 1.18 (dvt, N ) 12.0 Hz,
JHH ) 6.9 Hz, 18H, PCH(CH3)2), 1.24 (dvt, N ) 13.6 Hz, JHH ) 7.0
Hz, 18H, PCH(CH3)2), 1.98 (d, JHH ) 6.3 Hz, 3H, CH3), 2.35 (m, 6H,
PCH(CH3)2), 3.41 (d, JHP ) 9.6 Hz, 9H, P(OCH3)3), 5.94 (dq, JHH
)
15.6 Hz, JHH ) 6.6 Hz, 1H, CH3CHd), 6.90 (vt, JHH ) 7.5 Hz, 1H),
7.15 (vt, JHH ) 7.5 Hz, 1H), 7.69 (d, JHH ) 7.5 Hz, 1H), 8.06 (d, JHH
) 15.6 Hz, 1H, CH3CHdCH), 8.55 (d, JHH ) 7.5 Hz, 1H); 31P{1H}
1
(Nujol mull, cm-1) 1875 (s, (CO)); H NMR (C6D6, 293 K) 0.99
(dd, JHP ) 13.2 Hz, JHH ) 6.9 Hz, 9H, PCH(CH3)2), 1.01 (dd, JHP
)
NMR (C6D6, 293 K) 12.5 (d, JPP ) 19.4 Hz, PiPr3), 95.3 (d, JPP
)
13.2 Hz, JHH ) 6.9 Hz, 9H, PCH(CH3)2), 1.21 (dd, JHP ) 12.1 Hz, JHH
) 6.6 Hz, 9H, PCH(CH3)2), 1.23 (dd, JHP ) 12.1 Hz, JHH ) 6.6 Hz,
9H, PCH(CH3)2, 2.02 (m, 3H, PCH(CH3)2), 2.22 (m, 3H, PCH(CH3)2),
4.79 (vt, JHP ) 8.7 Hz, JHH ) 8.7 Hz, 1H, allyl-CHPh), 5.35 (vt, JHH
) 8.7 Hz, JHP ) 8.7 Hz, 1H, allyl-CHmeso), 7.10 (t, JHH ) 7.6 Hz, 1H,
19.4 Hz, P(OMe3)3); 13C{1H} NMR (C6D6, 293 K) 18.8 (s, CH3),
20.5 (s, PCH(CH3)2), 27.0 (vtd, N ) 25.3 Hz, JCP ) 2.8 Hz, PCH-
(CH3)2), 53.3 (d, JCP ) 11.54 Hz, P(OCH3)3), 119.1 (s, CH), 122.74
(s, CH), 124.4 (dt, JCP ) 4.1 Hz, JCP ) 1.4 Hz, CH), 124.6 (brt, CH),
147.0 (dbrt, JCP ) 5.0 Hz, CH), 147.7 (dt, JCP ) 2.3 Hz, JCP ) 1.3 Hz,
CH), 153.8 (dt, JCP ) 18.4 Hz, JCP ) 1.4 Hz, C-CHd), 155.6 (vq, JCP
) 12.0 Hz, Os-C), 188.5 (vq, JCP ) 9.53 Hz, CO). Anal. Calcd for
C31H61O4P3Os: C, 47.67; H, 7.87. Found: C, 48.29, H, 7.76.
H
para-Ph), 7.30 (vt, JHH ) 7.6 Hz, 2H, Hmeta-Ph), 7.85 (d, JHH ) 7.6 Hz,
2H, Hortho-Ph); 31P{1H} NMR (C6D6, 293 K) ABX system (X ) 2H)
A
2
) 20.5,
) 23.3, JAB ) 208.9 Hz, JAX ) JBX ) 3.6 Hz; H NMR
B
(C6H6, 293 K) -11.5 (brdd, OsD), 1.0 (br, allyl-CD2(anti)), 1.7 (br,
Preparation of OsH{C6H4-2-(E-CHdCHCH3)}(CO)2(PiPr3)2 (6).
A solution of OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) (100 mg, 0.15 mmol)
in 10 mL of hexane was treated with 0.1 mL of a 1.6 M solution of
CH3Li in diethyl ether. The reaction mixture became yellow, was
cooled to 0 °C, and quickly filtered through kieselgur. Carbon
monoxide was bubbled until the solution became colorless (ca. 10 min),
and then the solvent was removed to leave a white residue. Treatment
of this residue with methanol gave a white solid, which was washed
with methanol and dried in vacuo: yield 79 mg (76%); IR (Nujol mull,
allyl-CD2(syn)).
Preparation of OsH(η1-CH2CHdCHPh)(CO)2(PiPr3)2 (12).
A
solution OsH( 3-CH2CHCHPh)(CO)(PiPr3)2 (11) (100 mg, 0.15 mmol)
in 10 mL of hexane was stirred under CO atmosphere (P ) 1 atm)
during 24 h at room temperature. The resulting suspension was
decanted, and the white solid was washed with hexane and dried in
vacuo: yield 76 mg (74%); IR (Nujol mull, cm-1) 2015 (s, (OsH)),
1
1950, 1885 (s, (CO)); H NMR (C6D6, 293 K) -7.54 (t, JHP
)
22.6 Hz, 1H, Os-H), 1.15 (dvt, N ) 13.5 Hz, JHH ) 6.9 Hz, 18H,
PCH(CH3)2), 1.16 (dvt, N ) 13.5 Hz, JHH ) 6.9 Hz, 18H, PCH-
(CH3)2), 1.82 (dt, JHH ) 9.0 Hz, JHP ) 8.2 Hz, 2H, Os-CH2), 2.25 (m,
6H, PCH(CH3)2), 6.14 (d, JHH ) 15.3 Hz, 1H, Os-CH2-CHdCH),
7.01 (t, JHH ) 7.5 Hz, 1H, Hpara-Ph), 7.10 (dt, JHH ) 15.3 Hz, JHH ) 9.0
Hz, 1H, Os-CH2CHd), 7.25 (vt, JHH ) 7.5 Hz, 2H, Hmeta-Ph), 7.53 (d,
JHH ) 7.5 Hz, 2H, Hortho-Ph); 31P{1H} NMR (C6D6, 293 K) 22.8 (s);
13C{1H} NMR (C6D6, 293 K) -4.5 (t, JCP ) 6.9 Hz, Os-CH2),
19.1 (s, PCH(CH3)2), 19.2 (s, PCH(CH3)2), 25.5 (vt, N ) 13.3 Hz,
PCH(CH3)2), 121.0 (s, Os-CH2CHd), 125.1 (s, CHpara-Ph), 125.4 (s,
CHmeta-Ph), 128.8 (s, CHortho-Ph), 140.8 (s, Cipso-Ph), 147.8 (s, Os-CH2-
CHdCH), 182.4 (t, JCP ) 8.2 Hz, CO), 190.6 (t, JCP ) 6.0 Hz, CO).
Anal. Calcd for C29H52O2P2Os: C, 50.85; H, 7.65. Found: C, 50.45,
H, 7.03.
1
cm-1) 2010 (s, (OsH)), 1965, 1890 (s, (CO)); H NMR (C6D6, 293
K) -6.23 (t, JHP ) 21.7 Hz, 1H, Os-H), 1.09 (dvt, N ) 13.0 Hz, JHH
) 7.1 Hz, 18H, PCH(CH3)2), 1.11 (dvt, N ) 13.4 Hz, JHH ) 7.2 Hz,
18H, PCH(CH3)2), 2.05 (dd, JHH ) 6.7 Hz, JHH ) 1.6 Hz, 3H, CH3),
2.10 (m, 6H, PCH(CH3)2), 5.91 (dq, JHH ) 15.5 Hz, JHH ) 6.7 Hz,
1H, CH3CHd), 6.80 (vtd, JHH ) 7.6 Hz, JHH ) 1.6 Hz, 1H), 7.07 (vt,
JHH ) 7.6 Hz, 1H), 7.51 (dd, JHH ) 7.6 Hz, JHH ) 1.6 Hz, 1H), 7.59
(dq, JHH ) 15.5 Hz, JHH ) 1.6 Hz, 1H, CH3CHdCH), 8.55 (d, JHH
)
7.6 Hz, 1H); 31P{1H} NMR (C6D6, 293 K) 18.4 (s); 13C{1H} NMR
(C6D6, 293 K) 18.5 (s, CH3), 19.4 (s, PCH(CH3)2), 20.0 (s, PCH-
(CH3)2), 26.6 (vt, N ) 27.2 Hz, PCH(CH3)2), 123.1 (s, CH), 123.4 (t,
JCP ) 1.4 Hz, CH), 124.9 (t, JCP ) 1.4 Hz, CH), 126.0 (t, JCP ) 1.4
Hz, CH), 144.4 (s, CH), 149.8 (t, JCP ) 1.4 Hz, CH), 149.9 (t, JCP
)
6.9 Hz, Os-C), 156.1 (t, JCP ) 1.8 Hz, C-CHd), 185.3 (t, JCP ) 8.3
Hz, CO), 190.3 (t, JCP ) 6.0 Hz, CO). Anal. Calcd for C29H52O2P2-
Os: C, 50.85; H, 7.65. Found: C, 50.91, H, 8.62.
X-ray Structure Analysis of OsH{C6H4-2-(E-CHdCHPh)}(CO)-
(PiPr3)2 (2a). Crystals suitable for X-ray diffraction were obtained from
a saturated solution of 2 in methanol at -20 °C. Atomic coordinates
and Ueq values are listed in Table 4. A summary of crystal data,
intensity collection procedure, and refinement is reported in Table 5.
A yellow prismatic crystal was glued on a glass fiber and mounted on
a Siemens P4 diffractometer. Cell constants were obtained from the
least-squares fit of the setting angles of 37 reflections in the range 10
e 2 e 30. The 7458 recorded reflections were corrected for Lorentz
and polarization effects. Three orientation and intensity standards were
monitorized every 100 reflections; variation was less than 5%.
Preparation of OsH(η3-CH2CHCHPh)(CO)(PiPr3)2 (11). A solu-
tion of OsCl(E-CHdCHPh)(CO)(PiPr3)2 (1) (100 mg, 0.15 mmol) in
10 mL of hexane was treated with 0.1 mL of a 1.6 M solution of CH3-
Li in diethyl ether, and the resulting suspension was stirred for 2 h at
room temperature. The resultant suspension was filtered through
kieselgur, and the solvent was removed to leave a yellow residue.
Treatment of this residue with methanol gave a white solid, which was
washed with methanol and dried in vacuo: yield 84 mg (85%); IR

Bis(triisopropylphosphine)osmium Complexes
J. Am. Chem. Soc., Vol. 118, No. 1, 1996 99
Reflections were also corrected for absorption by an semiempirical (Ψ-
scan) method.33 The structure was solved by Patterson (Os atom) and
conventional Fourier techniques. Refinement was carried out by full-
matrix least-squares with initial isotropic thermal parameters. Aniso-
tropic thermal parameters were used in the last cycles of refinement
for all non-hydrogen atoms. Hydrogen atoms, except the hydride H(1)
and the agostic hydrogen H(8), were observed or calculated (C-H )
0.96 Å) and included in the refinement riding on carbon atoms with a
common isotropic thermal parameter. The agostic hydrogen H(8) was
located in the difference Fourier maps and refined as a free isotropic
atom. Although a reasonable peak was observed in the spatial zone
assignable to the hydrido ligand, it does not support a proper refinement.
As alternative, an electrostatic potential energy calculation based on
the whole molecule with an ideal value for the Os-H bond distance
of 1.66 Å12 was carried out, giving only one minimum. Atomic
scattering factors, corrected for anomalous dispersion for Os and P,
were taken from ref 34. Final R(F, Fo > 4.0 (Fo)) and wR(F2, all
reflections) values were 0.0401 and 0.0994. All calculations were
performed by the use of the SHELXTL-PLUS35 and SHELXL9336
system of computer programs.
Kinetic Analysis. The equilibrium constants K ) k1/k-1 ) [2a]/
[2b] were calculated by 1H NMR spectroscopy in toluene-d8. At
temperatures below the coalescence point the ratio was calculated by
integration of the hydrido signals corresponding to 2a and 2b, and above
the coalescence temperature by measuring the chemical shift of the
exchange averaged hydrido resonance. A least-squares fit of the values
of ln K vs 1/T gave the thermodynamic magnitudes ∆H° and ∆S°
involved in this equilibrium. Error analysis assumed a 10% error in
the value of the equilibrium constant, whereas the error in temperature
was estimated at 1 K. Errors were computed by standard error
propagation formulas for least-squares fitting.37
observed and calculated spectra. Due to the broadness of the signals
obtained at the lowest temperature reached, the individual coupling
constants JHP for the two hydrides could not be evaluated; thus the
averaged value of JHP was used for both hydrides. The transverse
relaxation time T2 used was common for the two signals and was
obtained from the line width of the exchange averaged resonance above
the fast exchange limit. To avoid the influence of these mentioned
simplifications in the calculation of activation parameters, only data
for the spectra that exhibited significant line broadening were included.
The activation parameters ∆Hq and ∆Sq were calculated by least-squares
fit of ln(k-1/T) vs 1/T (Eyring equation). Error analysis assumed a
10% error in the rate constant and 1 K in the temperature. Errors were
computed by published methods.18
The isomerization of complex 4 to 11 was followed quantitatively
1
by H NMR spectroscopy in CDCl3. The decrease of the intensity of
the hydrido signal of complexes 4 and 4-d3 was measured automatically
at intervals in a Varian UNITY 300 spectrometer. The rate constants
and the errors were obtained by fitting the data to an exponential
decay function, using the routine programs of the spectrometer.
Activation parameters ∆Hq and ∆Sq were obtained by a least-squares
fit of the Eyring plot. Error analysis assumed a 4.3% error in the rate
constant (the maximun value found in the experimental determinations)
and 1 K in the temperature. Errors were computed by published
methods.18
Acknowledgment. We thank the D.G.I.C.Y.T. (Project PB
92-0092, Programa de Promocio´n General del Conocimiento)
and E.U. (Project: Selective Processes and Catalysis Involving
Small Molecules) for financial support. E.O. thanks the
Diputacio´n General de Arago´n (D.G.A.) for a grant.
The two parameters K and k1 (or k-1) are sufficient to characterize
and simulate the hydrido regions of the variable-temperature 1H NMR
spectra. Complete line shape analysis of the spectra was achieved using
the program DNMR6 (QCPE, Indiana University). The rate constants
(k-1) for various temperatures were obtained by visually matching
Supporting Information Available: Tables of anisotropic
thermal parameters, atomic coordinates for hydrogen atoms,
experimental details of the X-ray study, bond distances and
angles, and interatomic distances for 2a (20 pages). This
material is contained in many libraries on microfiche, im-
mediately follows this article in the microfilm version of the
journal, can be ordered from the ACS, and can be downloaded
from the Internet; see any current masthead page for ordering
information and Internet access instructions.
(33) North, A. C. T.; Phillips, D. C.; Mathews, F. S. Acta Crystallogr.,
Sect. A 1968, 24, 351.
(34) International Tables for Crystallography; Kluwer Academic
Publishers: Dordrecht, The Netherlands, 1992; Vol. C.
(35) Sheldrick, G. M. SHELXTL PLUS; Siemens Analytical X-ray
Instruments: Madison, WI, 1990.
(36) Sheldrick, G. M. J. Appl. Crystallogr., manuscript in preparation.
(37) Bevington, P. R. Data Reduction and Error Analysis for the Physical
Sciences; McGraw-Hill, New York, 1969; Chapter 4.
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