Synthesis, characterization, and theoretical study of stable hydride-azavinylidene osmium(IV) complexes

Article abstract of DOI:10.1021/om000208t

The dihydride-dichloro complex OsH₂Cl₂(PⁱPr₃)₂ (1) reacts with cyclohexanone oxime in toluene under reflux to give after 12 h OsHCl₂{N=C(CH₂)₄CH₂}(P ⁱPr₃)₂ (2), which can be also obtained by reaction of the oximate compound, OsH₂Cl{κ-N,κ-O[ON=C(CH₂)₄CH ₂]}(PⁱPr₃)₂ (3) with HCl. Complex OsHCl₂{N=C(CH₃)₂}(PⁱPr ₃)₂ (4) has been similarly prepared by treatment of compound OsH₂Cl{κ-N,κ-O[ON=C(CH₃)₂]}(P ⁱPr₃)₂ (5) with HCl. When the reaction of 1 and cyclohexanone oxime, in toluene under reflux, was quenched after 1 h, a mixture of 1, 2, 3, and the trichloroazavinylidene OsCl₃{N=C(CH₂)₄CH₂}(P ⁱPr₃)₂ (6) was obtained. The structures in the solid state of 2 and 6 have been determined by X-ray diffraction studies. In both cases, the geometry around the metal center can be described as a distorted octahedron with the phosphorus atoms of the phosphines occupying trans positions and the C=N group and the carbon atoms bonded to this group lying in a plane that is parallel to the Cl-Os-Cl plane. CCSD(T)//B3LYP calculations on the model complexes OsXCl₂(N=CH₂)(PH₃)₂ [X = H (2t), X = Cl (6t)] state that the above-mentioned conformation is 15.3 (2t) or 12.1 (6t) kcal mol^-1 more stable than that with the azavinylidene ligand parallel to the P-Os-P plane. In solution the azavinylidene ligands of 2 and 4 rotate around the Os-N-C axis. The activation parameters of the process are ΔH = 14.4 ± 0.8 kcal mol^-1 and ΔS = -1.1 ± 1.3 cal mol^-1 K^-1 for 2 and ΔH = 13.1 ± 0.8 kcal mol^-1 and ΔS = 0.0 ± 2.8 cal mol^-1 K^-1 for 4.

Full text of DOI:10.1021/om000208t

3100
Organometallics 2000, 19, 3100-3108
Syn th esis, Ch a r a cter iza tion , a n d Th eor etica l Stu d y of
Sta ble Hyd r id e-Aza vin ylid en e Osm iu m (IV) Com p lexes
Ricardo Castarlenas,† Miguel A. Esteruelas,*,† Enrique Gutie´rrez-Puebla,‡
Yves J ean,*,§ Agust´ı Lledo´s,*,| Marta Mart´ın,† Enrique On˜ate,† and
J aume Toma`s|
Departamento de Quı´mica Ino´rganica-Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain; Instituto de Ciencia de Materiales de
Madrid, CSIC, Campus de Cantoblanco, 28049 Madrid, Spain; Laboratoire de Chimie
Physique, Baˆtiment 490, Universite´ de Paris Sud, 91405 Orsay Cedex, France; and
Departament de Quı´mica, Universitat Auto`noma de Barcelona,
08193 Bellaterra, Barcelona, Spain
Received March 6, 2000
The dihydride-dichloro complex OsH2Cl2(PiPr3)2 (1) reacts with cyclohexanone oxime in
toluene under reflux to give after 12 h OsHCl2{NdC(CH2)4CH2}(PiPr3)2 (2), which can be
also obtained by reaction of the oximate compound, OsH2Cl{κ-N,κ-O[ONdC(CH2)4CH2]}-
(PiPr3)2 (3) with HCl. Complex OsHCl2{NdC(CH3)2}(PiPr3)2 (4) has been similarly prepared
by treatment of compound OsH2Cl{κ-N,κ-O[ONdC(CH3)2]}(PiPr3)2 (5) with HCl. When the
reaction of 1 and cyclohexanone oxime, in toluene under reflux, was quenched after 1 h, a
mixture of 1, 2, 3, and the trichloroazavinylidene OsCl3{NdC(CH2)4CH2}(PiPr3)2 (6) was
obtained. The structures in the solid state of 2 and 6 have been determined by X-ray
diffraction studies. In both cases, the geometry around the metal center can be described as
a distorted octahedron with the phosphorus atoms of the phosphines occupying trans positions
and the CdN group and the carbon atoms bonded to this group lying in a plane that is
parallel to the Cl-Os-Cl plane. CCSD(T)//B3LYP calculations on the model complexes
OsXCl2(NdCH2)(PH3)2 [X ) H (2t), X ) Cl (6t)] state that the above-mentioned conformation
is 15.3 (2t) or 12.1 (6t) kcal mol-1 more stable than that with the azavinylidene ligand parallel
to the P-Os-P plane. In solution the azavinylidene ligands of 2 and 4 rotate around the
Os-N-C axis. The activation parameters of the process are ∆Hq ) 14.4 ( 0.8 kcal mol-1
and ∆Sq ) -1.1 ( 1.3 cal mol-1 K-1 for 2 and ∆Hq ) 13.1 ( 0.8 kcal mol-1 and ∆Sq ) 0.0 (
2.8 cal mol-1 K-1 for 4.
In tr od u ction
corresponding alkenyl derivatives, as a result of the
migratory insertion of the vinylidene group into the
M-H bond.4a,c,e,k Werner and co-workers have also
reported that in solution the hydride-vinylidene cations
[IrHCl(CdCHR)(PiPr3)2]+ (R ) H, CH3) smoothly rear-
range by 1,3-hydride shift to afford the corresponding
carbyne isomers [IrCl(CCH2R)(PiPr3)2]+.4b
Vinylidene complexes have attracted a great deal of
attention in recent years,1 in particular, hydride-
vinylidene derivatives, which are considered important
intermediates in several homogeneous and heteroge-
neous catalytic reactions, including alkene oligomeriza-
tion, polimerization, metathesis of olefins,2 and Fischer-
Tropsch synthesis.3
Few hydride-vinylidene complexes have been iso-
lated,4 since they appear to be thermodynamically and
kinetically unstable and evolve in solution into the
Azavinylidene complexes, which contain nitrogen
instead of carbon in the R-position of the unsaturated
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1998, 17, 4500. (k) Buil, M. L.; Esteruelas, M. A. Organometallics 1999,
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† Universidad de Zaragoza-CSIC.
‡ Instituto de Ciencia de Materiales de Madrid.
§ Universite´ de Paris Sud.
| Universitat Auto`noma de Barcelona.
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10.1021/om000208t CCC: $19.00 © 2000 American Chemical Society
Publication on Web 07/06/2000

Stable Hydride-Azavinylidene Os(IV) Complexes
Organometallics, Vol. 19, No. 16, 2000 3101
ligands, have been proposed as intermediates in the
catalytic and stoichiometric reduction of nitriles5 and
in the ammoxidation of propylene.6 In comparison, less
is known about azavinylidenes. The azavinylidene
compounds previously reported are Sc,7 Ti,8 Zr,9 Cr,10
Mo,11 W,5c,d,6,12 Re,13 Ru,14 Os,15 Ir,16 and U17 complexes.
The osmium derivatives are cationic arene d6 species,
while neutral d4 species are not known.
A situation of instability similar to that previously
mentioned for the hydride-vinylidene complexes is
observed in the related family of the hydride-azavi-
nylidene compounds. Although, the addition of H+ or
H- to azavinylidenes to give imines and/or nitrenes
(the compounds related to alkenyls and carbynes
with a nitrogen atom in the R-position) has been
described,5b,12c,e,h only two hydride-azavinylidene de-
rivatives have been reported: the five-coordinate d6
species MH(NdCPh2)(CO)(PiPr3)2 (M ) Ru,18 Os19).
These complexes have been obtained by reaction of the
corresponding chloro-hydrides MHCl(CO)(PiPr3)2 (M )
Ru, Os) with LiNdCPh2. In methanol, they are unstable
and decompose into the orthometalated benzophenone
imine derivatives MH{NHdC(Ph)C6H4}(CO)(PiPr3)2 (M
) Ru, Os) by a process similar to the orthopalladation.18
The orthometalated benzophenone imine osmium com-
pound can also be prepared by reaction of the dihy-
dride-1-butene complex OsH2(η2-CH2dCHEt)(CO)(Pi-
Pr3)2 with benzophenone imine.20
Conformational preferences and rotational barriers
arise from the π-ligand properties of azavinylidenes. In
a nonsymmetrical ligand field, different orientations are
possible for both vinylidene and azavinylidene ligands.
If the rotational barriers around the MdE (E ) C, N)
axis are high enough, an equilibrium between the rota-
tional isomers can be detected spectroscopically.4g,12,21
Several quantitative theoretical studies have been
recently reported for the case of vinylidene ligands,4i,22
but such studies are lacking for the azavinylidene ones.
The six-coordinate complex OsH2Cl2(PiPr3)2 (1) is a
unique species with a chemical behavior completely
different from that of previously reported compounds.
It not only catalyzes the reduction of ketones, olefins,
and diolefins23 but also is a useful starting material to
prepare dihydrogen,24 polyhydride,25 carbyne,26 diole-
fin,27 and cyclopentadienyl28 derivatives of osmium(II)
and osmium(IV). We have now observed that the
complex OsH2Cl2(PiPr3)2 is also useful to prepare
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3102 Organometallics, Vol. 19, No. 16, 2000
Castarlenas et al.
Sch em e 1
Sch em e 2
[ONdC(CH3)2]}(PiPr3)2 (5) with HCl (eq 1). Complex 4
was isolated as a green microcrystalline solid in 84%
yield.
hydride-azavinylidene compounds of osmium(IV), which
are of interest not only because they are the first
d4-hydride-azavinylidene derivatives and the first
d4-azavinylidene species of osmium but also because
they are thermodynamically and kinetically more stable
than the corresponding imine and nitrene isomers.
Resu lts a n d Discu ssion
1. Syn th esis a n d Ch a r a cter iza tion of OsHCl2(Nd
CR2)(P iP r 3)2 [CR2dC(CH2)4CH2, C(CH3)2] an d OsCl3-
{NdC(CH2)4CH2}(P iP r 3)2. Treatment of a toluene
solution of OsH2Cl2(PiPr3)2 (1) with 1.2 equiv of cyclo-
hexanone oxime under reflux affords after 12 h a green
solution, from which the hydride-azavinylidene com-
When the reaction of 1 and cyclohexanone oxime, in
toluene under reflux, was quenched after 1 h, a mixture
of complexes 1, 2, 3, and that corresponding to the signal
at -60.9 ppm in the 31P{1H} NMR spectrum was also
obtained. The successive crystallizations of the mixture
in toluene-methanol afford a few yellow crystals, which
show a singlet at -60.9 ppm in the 31P{1H} NMR
spectrum. The crystals were characterized (vide infra)
plex OsHCl2{NdC(CH2)4CH2}(PiPr3)2 (2) was isolated
by addition of pentane, as a green solid in 70% yield. In
addition, a sticky residue was obtained from the result-
ing pentane solution. The 31P{1H} NMR spectrum of this
residue in benzene-d6 shows two singlets at 12.3 and
-60.9 ppm, in a 1:4 intensity ratio. The first singlet was
assigned to the previously reported oximate complex
as the azavinylidene complex OsCl3{NdC(CH2)4CH2}-
(PiPr3)2 (6).
OsH2Cl{κ-N,κ-O[ONdC(CH2)4CH2}(PiPr3)229 (3) by com-
parison of the above-mentioned spectrum with a pure
sample.
The formation of 6 can be rationalized according to
Scheme 2. The HCl acid, which is generated from the
reaction of 1 with the oxime to give 3, should react with
1 to afford molecular hydrogen and the previously
reported monohydride OsHCl3(PiPr3)2 (7).30 In this way
the subsequent reaction of 7 with cyclohexanone oxime
should yield 6, by a process similar to the reaction of 1
with the oxime.
The hydride-azavinylidene complexes 2 and 4 were
characterized by MS, elemental analysis, IR, and 1H,
31P{1H}, and 13C{1H} NMR spectroscopy. Complex 2
was further characterized by an X-ray crystallographic
study. The structure has two chemically equivalent but
crystallographically independent molecules of complex
2 in the asymmetric unit. A drawing of one of them is
shown in Figure 1. Selected bond distances and angles
for both molecules are listed in Table 1.
When the reaction was carried out at room temper-
ature, after 1 h, a brown solid was obtained by addition
of methanol. The 31P{1H} NMR spectrum of the solid
in benzene-d6 indicates that it is a mixture of four
compounds: 1 (about 40%), 3 (about 35%), 2 (about
20%), and that corresponding to the signal at -60.9 ppm
(traces). This suggests that the formation of 2 takes
place in two steps (Scheme 1). Initially, complex 1 reacts
with cyclohexanone oxime to give HCl and the oximate
complex 3. Subsequently, the generated HCl attacks the
oximate group of 3 to afford 2 and water. In agreement
with Scheme 1, we have also observed that the treat-
ment at room temperature of 1 with a stoichiometric
amount of cyclohexanone oxime in the presence of 5
equiv of Et3N gives 3 in 82% yield and that the addition
of 1.7 equiv of HCl in water to a toluene solution of 3
affords 2 in 80% yield. The related hydride-aza-
vinylidene complex OsHCl2{NdC(CH3)2}(PiPr3)2 (4)
was similarly prepared, by reaction of OsH2Cl{κ-N, κ-O-
(29) Castarlenas, R.; Esteruelas, M. A.; Gutie´rrez-Puebla, E.; J ean,
Y.; Lledo´s, A.; Mart´ın, M.; Toma´s, J . Organometallics 1999, 18, 4296.
(30) Kuhlman, R.; Gusev, D. G.; Eremenko, I. L.; Berke, H.;
Huffman, J . C.; Caulton, K. G. J . Organomet. Chem. 1997, 536, 139.

Stable Hydride-Azavinylidene Os(IV) Complexes
Organometallics, Vol. 19, No. 16, 2000 3103
The most conspicuous feature of the structure is the
very short Os-N bond length of 1.789(12) Å in molecule
a and 1.777(12) Å in molecule b, which are fully con-
sistent with a Os-N double-bond formulation. Os-
N(azavinylidene) bond lengths previously reported are
between 1.81(2)15f and 1.882(6)15c Å. So, the Os-N bond
lengths in 2 are the shortest known osmium-azavi-
nylidene distances. This could be related to the different
oxidation states of the metallic centers, IV in 2 and II
in the previously reported compounds.
The C-N distances in 2 [N(1)-C(15) ) 1.30(2) Å,
N(2)-C(61) ) 1.28(2) Å] are similar to those in other
azavinylidene transition metal complexes (about 1.30
Å)7-15 and also agree with the N-C bond lengths found
in organic azaallenium cations (between 1.23 and 1.33
Å)31 and in the 2-azaallenyl complexes Cr{C(OEt)dNd
CtBu2}(CO)5 [1.272(5) and 1.264(5) Å],32 Cr{C(Ph)dNd
CHPh}(CO)5 [1.260(4) and 1.265(4) Å],33 and [Ru(η5-
C5H5){C(CHdCPh2)dNdCPh2}(CO)(PiPr3)]BF4 [1.283(9)
and 1.252(9) Å].34
The Os-N-C chain is almost linear [Os(1)-N(1)-
C(1) ) 173.1(12)°, Os(2)-N(2)-C(61) ) 179.3(10)°] and
forms a plane with C(52) and C(56) (molecule a ) or C(62)
and C(66) (molecule b) perpendicular to the best plane
containing the phosphorus atoms of the phosphine
ligands and the osmium atom (angle: 89.4° in molecule
a , and 88.1° in molecule b).
Figu r e 1. Molecular diagram for OsHCl2{NdC(CH2)4CH2}(Pi-
Pr3)2 (2). Thermal ellipsoids are shown at 50% probability.
In addition, it should be mentioned that the dis-
tance between the osmium atom and the chloride
disposed trans to the azavinylidene group [Os(1)-Cl(2)
) 2.418(4) Å, Os(2)-Cl(3) ) 2.425(3) Å] is between 0.04
and 0.06 Å shorter than between the osmium atom and
the chloride disposed trans to the hydride [Os(1)-Cl(1)
) 2.474(3) Å, Os(2)-Cl(4) ) 2.463(4) Å], which can be
assigned to the different trans-influence of the azavi-
nylidene and hydride ligands.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for th e Com p lex
OsHCl2{NdC(CH2)4CH2}(P iP r 3)2 (2)
molecule a
molecule b
Os(1)-P(1)
2.414(4)
2.410(4)
2.418(4)
2.474(3)
1.789(12)
Os(2)-P(3)
2.420(4)
2.402(4)
2.425(3)
2.463(4)
1.777(12)
1.65(11)
1.28(2)
Os(1)-P(2)
Os(1)-Cl(2)
Os(1)-Cl(1)
Os(1)-N(1)
Os(2)-P(4)
Os(2)-Cl(3)
Os(2)-Cl(4)
Os(2)-N(2)
Os(2)-H(2)
N(2)-C(61)
1
The H NMR spectrum in toluene-d8 of 2 agrees well
N(1)-C(51)
1.30(2)
with the structure shown in Figure 1. Because the
azavinylidene ligand is disposed cis to both hydride and
chloride ligands and the CdN group and the CH2 carbon
atoms bonded to the CdN group lie within the plane
containing the metallic center, the hydride, and the
chloride ligands (the dihedral angle formed by the least-
squares planes through both groups of atoms is 7.0° in
molecule a and 7.9° in molecule b), the CH2 groups are
inequivalent. In accordance with this, the spectrum at
263 K shows two CH2CN resonances at 3.65 and 3.25
ppm. On raising the temperature, they coalesce to give
one resonance. This behavior can be understood as the
result of the rotation of the azavinylidene ligand around
the Os-N-C axis. Line-shape analysis of the spectra
of Figure 2 allows the calculation of the rate constants
P(1)-Os(1)-P(2)
169.27(13) P(3)-Os(2)-P(4)
169.86(14)
P(3)-Os(2)-Cl(3) 88.36(12)
P(1)-Os(1)-Cl(2) 89.31(14)
P(1)-Os(1)-Cl(1) 94.88(13)
P(3)-Os(2)-Cl(4) 94.27(13)
P(1)-Os(1)-N(1)
90.1(4)
P(3)-Os(2)-N(2)
P(3)-Os(2)-H(2)
90.0(3)
82(4)
P(2)-Os(1)-Cl(2) 89.39(13)
P(2)-Os(1)-Cl(1) 95.70(12)
P(2)-Os(1)-N(1)
P(4)-Os(2)-Cl(3) 89.39(13)
P(4)-Os(2)-Cl(4) 95.47(13)
P(4)-Os(2)-N(2)
P(4)-Os(2)-H(2)
90.3(4)
90.6(3)
88(4)
Cl(2)-Os(1)-Cl(1) 87.23(13)
Cl(2)-Os(1)-N(1) 175.1(4)
Cl(3)-Os(2)-Cl(4) 86.60(14)
Cl(3)-Os(2)-N(2) 170.6(4)
Cl(3)-Os(2)-H(2) 80(3)
Cl(4)-Os(2)-N(2) 102.7(4)
Cl(4)-Os(2)-H(2) 167(3)
N(2)-Os(2)-H(2) 90(3)
Os(2)-N(2)-C(61) 179.3(10)
Cl(1)-Os(1)-N(1) 97.6(4)
Os(1)-N(1)-C(1)
173.1(12)
The coordination geometry around the osmium atom
can be rationalized as derived from a distorted octahe-
dron with the triisopropylphosphine ligands occupying
trans positions [P(1)-Os(1)-P(2) ) 169.27(13)°, P(3)-
Os(2)-P(4) ) 169.86(14)°] at opposite sites of an ideal
coordination plane defined by the two chloride ligands
mutually cis disposed [Cl(2)-Os(1)-Cl(1) ) 87.23(13)°,
Cl(3)-Os(2)-Cl(4) ) 86.60(14)°], the hydride, and the
nitrogen atom of the azavinylidene group disposed trans
to Cl(2) in molecule a [Cl(2)-Os(1)-N(1) ) 175.1(4)°]
and to Cl(3) in molecule b [Cl(3)-Os(2)-N(2) ) 170.6-
(4)°].
(31) (a) J ochims, J . C.; Abu-El-Halawa, R.; J ibril, I.; Huttner, G.
Chem. Ber. 1984, 117, 1900. (b) Al-Talib, M.; J ibril, I.; Wu¨rthwein,
E.-U.; J ochims, J . C.; Huttner, G. Chem. Ber. 1984, 117, 3365. (c) Al-
Talib, M.; J ochims, J . C. Chem. Ber. 1984, 117, 3222. (d) Kupfer, R.;
Wu¨rthwein, E.-U.; Nagel, M.; Allmann, R. Chem. Ber. 1985, 118, 643.
(e) Al-Talib, M.; J ibril, I.; Huttner, G.; J ochims, J . C. Chem. Ber. 1985,
118, 1876. (f) Al-Talib, M.; J ochims, J . C.; Zsolnai, L.; Huttner, G.
Chem. Ber. 1985, 118, 1887. (g) Wu¨rthwein, E.-U.; Kupfer, R.; Allmann,
R.; Nagel, M. Chem. Ber. 1985, 118, 3632. (h) Krestel, M.; Kupfer, R.;
Wu¨rthwein, E.-U. Chem. Ber. 1987, 120, 1271.
(32) Seitz, F.; Fischer, H.; Riede, J . J . Organomet. Chem. 1985, 287,
87.
(33) Aumann, R.; Althans, S.; Kru¨ger, S.; Betz, P. Chem. Ber. 1989,
122, 357.
(34) Esteruelas, M. A.; Go´mez, A. V.; Lahoz, F. J .; Lo´pez, A. M.;
On˜ate, E. Oro, L. A. Organometallics 1996, 15, 3423.

3104 Organometallics, Vol. 19, No. 16, 2000
Castarlenas et al.
F igu r e 3. Eyring plot of the rate constants for the
(CH2)2CdN proton exchange for OsHCl2{NdC(CH2)4CH2}(Pi-
Pr3)2 (2).
The hydride ligand also gives rise to a ν(Os-H) band
at 2146 cm-1 in the IR spectrum in KBr. In addition,
the spectrum contains a ν(CdN) absorption at 1679
cm-1. The 13C{1H} NMR spectrum at 233 K is consistent
F igu r e 2. Experimental (a) and calculated (b) variable-
temperature 300 MHz H NMR spectra in the CH2 region
1
1
with the H NMR spectrum at the same temperature.
Thus, it shows two CH2 resonances due to the carbon
atoms bonded to the CdN group at 13.4 and 9.9 ppm.
The CdN carbon atom gives rise to a broad signal at
148.7 ppm. The 31P{1H} NMR spectrum shows at -13.8
ppm a singlet, which under off-resonance conditions is
split into a doublet, as a consequence of the spin-
coupling with the hydride ligand.
of OsHCl2{NdC(CH2)4CH2}(PiPr3)2 (2) in toluene-d8.
Ta ble 2. Ra te Con sta n ts for Aza vin ylid en e
Rota tion a r ou n d th e Os-N-C Axis of Com p lexes 2
a n d 4
rates (s-1
)
T (K)
2
4
The spectroscopic data of 4 agree well with those of
353
343
333
323
313
308
303
293
283
273
268
263
258
253
248
243
233
6.76 × 103
2.25 × 103
8.41 × 102
6.56 × 102
3.30 × 102
1
2. In the H NMR spectrum in toluene-d8 at 233 K, the
methyl groups of the azavinylidene ligand give rise to
two singlets at 3.82 and 3.66 ppm, whereas the hydride
ligand displays at -0.90 ppm a triplet with a H-P
coupling constant of 14.4 Hz. On raising the tempera-
ture, the methyl resonances coalesce to give one reso-
nance. As for 2, line-shape analysis of the obtained
spectra (Figure 4) allows the calculation of the rate
constants for the rotation process (Table 2). The activa-
tion parameters obtained from the corresponding Eyring
analysis (Figure 5) are in this case ∆Hq ) 13.1 ( 0.8
kcal mol-1 and ∆Sq ) 0.0 ( 2.8 cal mol-1 K-1. The IR
spectrum in KBr contains the ν(Os-H) and ν(CdN)
bands at 2155 and 1685 cm-1. The 13C{1H} NMR
spectrum at 233 K shows two triplets at 1.9 and -2.0
ppm with C-P coupling constants of 18.9 and 17.6 Hz,
respectively, corresponding to the methyl groups of the
azavinylidene ligand. The resonance of the CdN carbon
atom is observed at 147.4 ppm as a broad signal. The
31P{1H} spectrum contains a singlet at -14.9 ppm,
which is split into a doublet under off-resonance condi-
tions.
3.23 × 103
1.73 × 103
8.22 × 102
5.80 × 102
2.05 × 102
1.63 × 102
1.76 × 102
95.3
30.0
9.81
2.39
99.0
68.6
42.1
23.5
7.26
1.20
for the rotation (Table 2). The activation parameters
obtained from the Eyring analysis (Figure 3) are ∆Hq
) 14.4 ( 0.8 kcal mol-1 and ∆Sq ) -1.1 ( 1.3 cal mol-1
K-1. The activation entropy is nearly zero, suggesting
that the process is intramolecular, whereas the value
of the activation enthalpy is in agreement with those
found in azavinylidene-tungsten complexes (between
9 and 19 kcal mol-1).12d,e,h
Similarly to 2, the trichloroazavinylidene complex 6
was characterized by MS, elemental analysis, IR, and
1H, 31P{1H}, and 13C{1H} NMR spectroscopy and an
X-ray crystallographic study. In this case, the structure
also has two chemically equivalent but crystallographi-
cally independent molecules of complex 6 in the asym-
metric unit. A drawing of one of them is shown in Figure
1
The H NMR spectrum also shows at -0.89 ppm the
hydride resonance as a triplet with a H-P coupling
constant of 14.1 Hz. It should be noted the unusual
chemical shift of this signal, which appears to significant
lower field than that observed for the previously re-
ported hydride-osmium(IV) complexes.25 Similar chemi-
cal shifts to the hydride of 2 have been observed for
hydrides disposed trans to a linear nitrosyl group in six-
coordinate dihydride-nitrosyl-osmium(II) complexes.35
(35) (a) Werner, H.; Flu¨gel, R.; Windmu¨ller, B.; Michenfelder, A.;
Wolf, J . Organometallics 1995, 14, 612. (b) Yandulov, D. V.; Streib,
W. E.; Caulton, K. G. Inorg. Chim. Acta 1998, 280, 125.

Stable Hydride-Azavinylidene Os(IV) Complexes
Organometallics, Vol. 19, No. 16, 2000 3105
F igu r e 4. Experimental (a) and calculated (b) variable-
Figu r e 6. Molecular diagram for OsCl3{NdC(CH2)4CH2}(Pi-
Pr3)2 (6). Thermal ellipsoids are shown at 50% probability.
1
temperature 300 MHz H NMR spectra in the CH3 region
of OsHCl2{NdC(CH3)2}(PiPr3)2 (4) in toluene-d8.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for th e Com p lex
OsCl3{NdC(CH2)4CH2}(P iP r 3)2 (6)
molecule a
molecule b
Os(1)-P(11)
2.480(3)
2.481(3)
2.402(3)
2.383(4)
2.365(4)
1.808(10)
1.26(2)
Os(2)-P(21)
2.481(3)
2.482(4)
2.410(3)
2.382(3)
2.372(3)
1.806(10)
1.28(2)
Os(1)-P(12)
Os(1)-Cl(11)
Os(1)-Cl(12)
Os(1)-Cl(13)
Os(1)-N(11)
N(11)-C(11)
Os(2)-P(22)
Os(2)-Cl(21)
Os(2)-Cl(22)
Os(2)-Cl(23)
Os(2)-N(21)
N(21)-C(21)
P(11)-Os(1)-P(12)
177.05(11) P(21)-Os(2)-P(22)
178.09(11)
P(11)-Os(1)-Cl(11) 84.88(11)
P(11)-Os(1)-Cl(12) 95.39(12)
P(11)-Os(1)-Cl(13) 90.94(12)
P(21)-Os(2)-Cl(21) 85.08(11)
P(21)-Os(2)-Cl(22) 94.55(12)
P(21)-Os(2)-Cl(23) 92.13(11)
P(11)-Os(1)-N(11)
89.1(3)
P(21)-Os(2)-N(21)
89.6(4)
P(12)-Os(1)-Cl(11) 93.09(11)
P(12)-Os(1)-Cl(12) 86.54(12)
P(12)-Os(1)-Cl(13) 86.80(12)
P(22)-Os(2)-Cl(21) 93.19(11)
P(22)-Os(2)-Cl(22) 86.10(12)
P(22)-Os(2)-Cl(23) 86.95(12)
F igu r e 5. Eyring plot of the rate constants for the
(CH3)2CdN proton exchange for OsHCl2{NdC(CH3)2}(Pi-
Pr3)2 (4).
P(12)-Os(1)-N(11)
93.1(3)
P(22)-Os(2)-N(21)
92.2(4)
Cl(11)-Os(1)-Cl(12) 85.11(13)
Cl(11)-Os(1)-Cl(13) 86.53(13)
Cl(11)-Os(1)-N(11) 172.7(3)
Cl(21)-Os(2)-Cl(22) 84.92(13)
Cl(21)-Os(2)-Cl(23) 86.65(13)
Cl(21)-Os(2)-N(21) 174.3(4)
Cl(12)-Os(1)-Cl(13) 169.01(12) Cl(22)-Os(2)-Cl(23) 168.76(12)
Cl(12)-Os(1)-N(11) 91.4(4)
Cl(13)-Os(1)-N(11) 97.6(4)
Os(1)-N(11)-C(11) 175.4(11)
Cl(22)-Os(2)-N(21) 93.7(3)
Cl(23)-Os(2)-N(21) 95.4(3)
Os(2)-N(21)-C(21) 176.5(10)
6. Selected bond distances and angles for both molecules
are listed in Table 3.
The coordination geometry around the osmium atom
can be rationalized as derived from a distorted octahe-
dron with the triisopropylphosphine ligands occupying
trans positions [P(11)-Os(1)-P(12) ) 177.05(11)°, P(21)-
Os(2)-P(22) ) 178.09(11)°] at opposite sites of an ideal
coordination plane defined by the chloride and azavi-
nylidene ligands. The Os-N [Os(1)-N(1) ) 1.808(10)
Å, Os(2)-N(21) ) 1.806(10) Å] bond lengths as well
as the N-C [N(11)-C(11) ) 1.26(2), N(21)-C(21) )
1.28(2) Å] distances are similar to those found in 2 and
fully consistent with the azavinylidene formulation. The
Os-N-C chain is also almost linear [Os(1)-N(11)-
C(11) ) 175.4(11)°, Os(2)-N(21)-C(21) ) 176.5(10)°]
and forms a plane with C(12) and C(16) (molecule a ) or
C(22) and C(26) (molecule b) perpendicular to the best
plane containing the phosphorus atoms of the phosphine
ligands and the osmium atom (angle: 91.8° in molecule
a , and 89.4° in molecule b).
The previously mentioned 31P{1H} NMR spectrum
1
and the IR and the H and 13C{1H} NMR spectra of 6
are consistent with the structure shown in Figure 6. The
IR spectrum in KBr shows the ν(CdN) band at 1671
1
cm-1. The H NMR spectrum in benzene-d6 contains a
multiplet at 4.18 ppm, corresponding to the four CH2-
CN protons. In the 13C{1H} NMR spectrum both CH2
carbon atoms bonded to the CdN group give rise to a
singlet at 10.0 ppm, whereas the resonance correspond-
ing to the CdN carbon atom appears at 154.1 ppm, as
a triplet with a C-P coupling constant of 2.5 Hz. As
has been previously mentioned, the 31P{1H} NMR
spectrum shows a singlet at -60.9 ppm.
2. Th eor etica l An a lysis on Con for m a tion a l P r ef-
er en ces a n d Rota tion a l Ba r r ier s. The structures
shown in Figures 1 and 6 and the 1H and 13C{1H} NMR
spectra of 2 and 4 indicate that the CdN group and the

3106 Organometallics, Vol. 19, No. 16, 2000
Castarlenas et al.
preferred orientation (minima structures) the azavi-
nylidene ligand is in the Cl-Os-Cl plane (2t and 6t, θ
) 0°), whereas conformations with θ ) 90° correspond
to the transition states for the rotational process around
the NdC bond (2t-TS and 6t-TS, respectively). A slight
distortion from the regular octahedron is found in the
2t-TS and 6t-TS structures. The distortion is due to the
bending of the phosphine ligands toward the chloride
trans to the azavinylidene ligand. Other interesting
geometrical features are the Os-Cl(1) bond elongation
that can be seen for the 2t-TS complex compared to 2t
and the subtle balance in the Os-N and Os-Cl(2)
distances on going from the minimum to the transition
state structures, reflecting the competition between the
chloride and azavinylidene ligands for the electronic
density.
A reliable energetic comparison between the minima
and TS structures can be obtained through CCSD(T)
single-point energy calculations on the B3LYP optimized
structures. A good agreement was actually found be-
tween the experimental ∆Hq values and the calculated
energy for the corresponding model complex 2t (about
14.4 vs 15.3 kcal mol-1). For complex 6t, in which the
hydride ligand of complex 2t has been replaced by a
chloride ligand, the rotational barrier is slightly lower
(12.1 kcal/mol at the CCSD(T)/B3LYP level of theory).
The nitrene and imine isomers of 2t, resulting from
the 1,3- and 1,2-hydride shifts, are respectively 2.7 and
6.9 kcal mol-1 more stable than 2t-Ts. However, the
participation of these intermediates in the rotation of
the azavinylidene must be rejected, since the activation
barriers for the 1,3- and 1,2-hydride shifts are very high,
more than 90 kcal mol-1 for the 1,3-hydride shift and
43.8 kcal mol-1 for the 1,2-hydride shift.
F igu r e 7. B3LYP optimized structures of OsHCl2(Nd
CH2)(PH3)2 (2t, 2t-TS) and OsCl3(NdCH2)(PH3)2 (6t, 6t-
TS).
Ta ble 4. B3LYP Op tim ized Geom etr ica l
P a r a m eter s Associa ted w ith OsHCl2(NdCH2)(P H3)2
(2t, 2t-TS) a n d OsCl3(NdCH2)(P H3)2 (6t, 6t-TS)
Com p lexes
2t
2t-TS
6t
6t-TS
Os-Cl(1)
Os-Cl(2)
Os-H
2.474
2.475
1.621
2.568
2.491
1.619
2.434
2.434
2.465
2.484
The above-mentioned values indicate that the 1,3- and
1,2-hydride shifts in hydride-azavinylidene complexes
of the type OsHCl2(NdCR2)(PR′3)2 are thermodynami-
cally and kinetically unfavorable processes.
Os-Cl(3)
Os-N
2.448
1.808
2.382
1.261
95.2
2.465
1.783
2.392
1.265
89.9
1.808
2.369
1.267
107.8
86.8
1.779
2.383
1.269
89.9
90.8
87.3
Os-P
N-C(2)
N-Os-Cl(1)
Cl(1)-Os-Cl(2)
Cl(2)-Os-H
Cl(2)-Os-Cl(3)
H-Os-N
Cl(3)-Os-N
P-Os-P
Con clu d in g Rem a r k s
86.8
90.1
74.7
This study has revealed that the dihydride-dichloro
complex OsH2Cl2(PiPr3)2 reacts with oximes to afford
the novel hydride-azavinylidene compounds OsHCl2-
(NdCR2)(PiPr3)2, via the oximate intermediates OsH2-
Cl{κ-N,κ-O[ONdCR2]}(PiPr3)2.
85.9
90.1
90.7
91.9
92.1
171.2
89.9
154.2
170.5
154.6
carbon atoms bonded to this group lie in a plane that is
parallel to the plane containing the chlorine and osmium
atoms. Furthermore, the behavior of the 1H NMR
spectra of 2 and 4 with the temperature suggests that
in solution the azavinylidene ligands of these com-
pounds rotate around the Os-N-C axis (Table 2). To
understand these results, high-level ab initio calcula-
tions have been performed on the OsXCl2(NdCH2)-
(PH3)2 [X ) H (2t), Cl (6t)] model complexes.
The structures of complexes 2t and 6t were optimized
within the Cs symmetry constraint at the B3LYP level
of theory. Two conformations were studied, the NdCH2
ligand lying either in the Cl-Os-Cl (θ ) 0°) plane or
perpendicular to that plane (θ ) 90°). The main geo-
metrical parameters are listed in Table 4, while the
optimized structures are depicted in Figure 7.
The structure of these azavinylidene complexes is
octahedral, with the phosphines occupying trans posi-
tions and the CdN group and the carbon atoms bonded
to this group lying in a plane that is parallel to the Cl-
Os-Cl plane. This conformation is about 14-15 kcal
mol-1 more stable than that with the azavinylidene
ligand parallel to the P-Os-P plane. In solution, the
azavinylidene ligands rotate around the Os-N-C axis.
The mechanism of the process can be described as the
change of position of the substituents of the unsaturated
ligands through the less favored conformation and
involves only minor motion of the other ligands. In these
compounds, the hydride and azavinylidene ligands are
mutually cis disposed. Despite this, they are stable and
do not evolve by 1,3- or 1,2-hydride shifts into the corre-
sponding OsCl2(NCHR2)(PiPr3)2 or OsCl2(NHdCR2)(Pi-
Pr3)2 isomers. The reason for their stability is both
thermodynamic and kinetic in origin.
The conformational preference of the azavinylidene
ligand is well reproduced by the calculations. In the

Stable Hydride-Azavinylidene Os(IV) Complexes
Organometallics, Vol. 19, No. 16, 2000 3107
Ta ble 5. Cr ysta l Da ta a n d Da ta Collection a n d
Refin em en t for Com p lex
Exp er im en ta l Section
All reactions were carried out with rigorous exclusion of air
using Schlenk-tube techniques. Solvents were dried by the
usual procedures and distilled under argon prior to use. The
starting materials OsH2Cl2(PiPr3)2 (1), OsH2Cl{κ-N,κ-O[ONd
OsHCl2{NdC(CH2)4CH2}(P iP r 3)2 (2) a n d
OsCl3{NdC(CH2)4CH2}(P iP r 3)2 (6)
2
6
C(CH2)4CH2]}(PiPr3)2 (3), and OsH2Cl{κ-N,κ-O[ONdC(CH3)2]}-
(PiPr3)2 (5) were prepared by the published method.23,29
In the NMR spectra, chemical shifts are expressed in ppm
downfield from Me4Si (1H and 13C) and 85% H3PO4 (31P).
Coupling constants, J , are given in hertz.
formula
mol wt
color, habit
space group
a, Å
C24H53Cl2NOsP20.5CH3OH C24H52Cl3NOsP2
694.73
713.16
green, prismatic
monoclinic, P21
11.5766(8)
15.7639(11)
18.0123(12)
90
108.536(1)
90
3116.6(4)
4
yellow, prismatic
monoclinic, P1h
11.8753(8)
15.2571(10)
17.2013(11)
89.348(1)
73.346(1)
89.644(1)
2985.6(3)
4
b, Å
c, Å
1
Kin etic An a lysis. Complete line-shape analyses of the H
NMR spectra of 2 and 4 were achieved using the program
gNMR v3.6 for Macintosh, Cherwell Scientific Publishing
Limited. The transverse relaxation time T2 used was common
for the two signals for all temperatures recorded and was
obtained from the line width of the exchange-averaged reso-
nance above the fast-exchange limit. The activation param-
eters ∆Hq and ∆Sq were calculated by least-squares fit of ln(k/
T) vs 1/T (Eyring equation). Error analysis assumed a 2% error
in the rate constant and 1 K in the temperature. Errors were
computed by published methods.36
R, deg
â, deg
ø, deg
V, Å3
Z
D(calc), g cm-3
µ, mm-1
scan type
θ range, deg
temp, K
no. of data
collected
1.480
1.587
4.379
4.660
ω scans at different æ values
2 e θ e 24
193.0(2)
8166
153.0(2)
11 856
Com p u ta tion a l Deta ils. Calculations were performed with
the GAUSSIAN94 series of programs.37 Geometry optimiza-
tions were carried out using the density functional theory
(DFT)38 with the B3LYP functional.39 An effective core poten-
tial operator was used to represent the 60 innermost electrons
of the osmium atom.40 The basis set for the metal was that
associated with the pseudopotential,40 with a standard valence
double-ú LANL2DZ contraction.37 The basis set for the hydro-
gen atom directly attached to the metal was a double-ú
supplemented with a polarization p shell.41a,b A 6-31G(d) basis
was used for Cl, P, and N atoms.41c The rest of the atoms were
described using a 6-31G basis set.41a
no. of unique data 5370
(Rint ) 0.0384)
695
8181
(Rint ) 0.0686)
no. of params
refined
391
a
R1 (F2 > 2σ(F2))
0.0384
0.0827
1.056 (a ) 0.0323,
b ) 0)
0.0621
0.1598
0.996 (a ) 0.0765,
b ) 51.1130)
b
wR2 (all data)
Sc (all data)
a
b
2
R1(F) ) ∑||Fo| - |Fc||/∑|Fo|. wR2 (F2) ) [∑[w(Fo - Fc2)2]/
∑[w(Fo2)2]1/2; w-1 ) [σ2(Fo2) + (aP)2 + bP], where P ) [max(Fo2, 0)
+ 2Fc2)]/3. c S ) [∑[w(Fo2 - Fc2)2/(n - p)]1/2, where n is the number
of reflections and p the number of refined parameters.
To obtain accurate energetic estimations, the geometries
were optimized at the B3LYP level and energies recalculated
using coupled-cluster theory with single, double, and a non-
iterative estimation of triple excitations (CCSD(T)//B3LYP).42
evaporated to dryness, and addition of 5 mL of methanol
yielded a green precipitate that was decanted and washed with
methanol (2 × 2 mL) and pentane (4 × 5 mL) and dried in
vacuo. Yield: 165 mg (80%). Anal. Calcd for C24H53NCl2OsP2:
C, 42.47; H, 7.87; N, 2.06. Found: C, 42.33; H, 7.67; N, 2.06.
IR (KBr, cm-1): ν(Os-H) 2146 s; ν(CdN) 1679 m. 1H NMR
(300 MHz, C6D6, 293 K): δ 3.65 (br, 2H, -CH2CdN); 3.25 (br,
2H, -CH2CdN); 2.54 (m, 6H, PCH); 1.43 and 1.29 (both dvt,
J H-H ) 6.6 Hz, N ) 12.9 Hz, 36H, PCHCH3); 1.00 (m, 6H, Cy);
-0.89 (t, J P-H ) 14.1, 1H, OsH). 13C{1H} plus DEPT
NMR (75.4 MHz, toluene-d8, 233 K): δ 148.7 (br, CdNdOs);
28.3, 28.1 and 24.2 (all s, CH2 Cy); 23.4 (vt, N ) 23.7 Hz, PCH);
19.5 and 19.2 (both s, PCHCH3); 13.4 and 9.9 (both s, CH2Cd
N). 31P{1H} NMR (121.4 MHz, C6D6, 293 K): δ -13.8 (s, d off
resonance). MS (FAB+): m/z ) 679 (M+) and 644 (M+ - Cl).
P r ep a r a tion of OsHCl2{NdC(CH3)2}(P iP r 3)2 (4). This
complex was prepared as described for 2 (method b) starting
from 200 mg (0.32 mmol) of 5 and 500 µL of a water solution
of HCl (1 N, 0.5 mmol). A green microcrystaline solid was
obtained. Yield: 173 mg (84%). Anal. Calcd for C21H49NCl2-
OsP2: C, 39.49; H, 7.73; N, 2.19. Found: C, 39.39; H, 7.52; N,
2.10. IR (KBr, cm-1): ν(Os-H) 2155 s; ν(CdN) 1685 m. 1H
NMR (300 MHz, CD2Cl2, 233 K): δ 3.82 and 3.66 (both s, 6H,
CH3CdN); 2.55 (m, 6H, PCH); 1.35 and 1.27 (both dvt, J H-H
) 6.3 Hz, N ) 12.9 Hz, 36H, PCHCH3); -0.90 (t, J P-H ) 14.4,
1H, OsH). 13C{1H} plus DEPT NMR (75.4 MHz, CD2Cl2, 233
K): δ 147.4 (br, CdNdOs); 23.3 (br, PCH); 19.3-18.6 (m,
P r ep a r a tion of OsHCl2{NdC(CH 2)4CH2}(P iP r 3)2 (2).
Method A: A brown solution of 1 (200 mg, 0.34 mmol) in
toluene was treated with cyclohexanone oxime (40 mg, 0.35
mmol) and was heated under reflux during 12 h. After
concentrating the toluene to ca. 1 mL addition of pentane
yielded a green precipitate that was washed two times with
pentane and dried in vacuo. Yield: 144 mg (70%). Method B:
A yellow solution of 3 (200 mg, 0.30 mmol) in toluene was
treated with HCl in water (500 µL, 1 N, 0.5 mmol) and was
stirred for 25 min at room temperature. The blue solution was
(36) Morse, P. M.; Spencer, M. D.; Wilson, S. R.; Girolami, G. S.
Organometallics 1994, 13, 1646, and references therein.
(37) Frisch, M. J .; Trucks, G. W.; Schlegel, H. B.; Gill, P. M. W.;
J ohnson, B. G.; Robb, M. A.; Cheeseman, J . R.; Keith, T. A.; Petersson,
G. A.; Montgomery, J . A.; Raghavachari, K.; Al-Laham, M. A.;
Zakrzewski, V. G.; Ortiz, J . V.; Foresman, J . B.; Cioslowski, J .;
Stefanov, B. B.; Nanayakkara, A.; Challacombe, M.; Peng, C. Y.; Ayala,
P. Y.; Chen, W.; Wong, M. W.; Andre´s, J . L.; Replogle, E. S.; Gomperts,
R.; Mart´ın, R. L.; Fox, D. J .; Binkley, J . S.; Defrees, D. J .; Baker, J .;
Stewart, J . P.; Head-Gordon, M.; Gonzalez, C.; Pople, J . A. Gaussian
94; Gaussian Inc.: Pittsburgh, PA, 1995.
(38) Parr, R. G.; Yang, W. Density-Functional Theory of Atoms and
Molecules; Oxford University Press: Oxford, U.K., 1989.
(39) (a) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785.
(b) Becke, A. D. J . Chem. Phys. 1993, 98, 5648. (c) Stephens, P. J .;
Devlin, F. J .; Chabalowski, C. F.; Frisch, M. J . J . Phys. Chem. 1994,
98, 11623.
(40) Hay, P. J .; Wadt, W. R. J . Chem. Phys. 1985, 82, 299.
(41) (a) Hehre, W. J .; Ditchfield, R.; Pople, J . A. J . Chem. Phys. 1972,
56, 2257. (b) Hariharan, P. C.; Pople, J . A. Theor. Chim. Acta 1973,
28, 213. (c) Francl, M. M.; Pietro, W. J .; Hehre, W. J .; Binkley, J . S.;
Gordon, M. S.; DeFrees, D. J .; Pople, J . A. J . Chem. Phys. 1982, 77,
3654.
(42) (a) Bartlett, R. J . J . Phys. Chem. 1989, 93, 1697. (b) Bartlett,
R. J .; Watts, J . D.; Kucharski, S. A.; Noga, J . Chem. Phys. Lett. 1990,
165, 513.
PCHCH3); 1.9 (d, J P-C ) 18.9 Hz, CH3CdN) -2.0 (d, J P-C
)
17.6 Hz CH3CdN). 31P{1H} NMR (121.4 MHz, CD2Cl2, 233
K): δ -14.9 (s, d off resonance). MS (FAB+): m/z ) 604
(M+ - Cl).
P r ep a r a tion of OsCl3{NdC(CH2)4CH2}(P iP r 3)2 (6). A
brown solution of 1 (200 mg, 0.34 mmol) in 30 mL of toluene
was treated with cyclohexanone oxime (40 mg, 0.35 mmol) and
was heated under reflux during 1 h. The solution was
concentrated to 3 mL, and addition of methanol yielded a

3108 Organometallics, Vol. 19, No. 16, 2000
Castarlenas et al.
yellow precipitate that was washed (3 × 2 mL) and dried in
vacuo. Yield: 25 mg (15%). Anal. Calcd for C24H52NCl3OsP2:
C, 40.42; H, 7.35; N, 1.96. Found: C, 40.43; H, 7.39; N, 1.77.
IR (KBr, cm-1): ν(CdN) 1671 m. 1H NMR (300 MHz, C6D6,
293 K): δ 4.18 (m, 4H, CH2CdN); 3.00 (m, 6H, PCH); 1.44
(dvt, J H-H ) 6.9 Hz, N ) 13.2 Hz, 36H, PCHCH3); 1.30-1.00
(m, 6H, Cy). 13C{1H} plus DEPT NMR (75.4 MHz, C6D6, 293
K): δ 154.1 (t, J C-H ) 2.5 Hz, CdNdOs); 28.2, (s, Nd
CCH2CH2); 24.2 (s,NdCCH2CH2CH2); 23.4 (t, J C-H ) 10.6,
PCH); 19.2 (s, PCHCH3); 10.0 (s, NdCCH2). 31P{1H} NMR
(121.4 MHz, C6D6, 293 K): δ -60.9 (s). MS (FAB+): m/z 677
(M+ - Cl).
collection to monitor crystal decay. The absortion correction
was made using SADABS.43 The structure was solved by
Multan and Fourier methods using SHELXS.43 Full-matrix
least-squares refinement was carried out using SHELXTL43
minimizing w(Fo - Fc2)2. Weighted R factors (Rw) and all
2
goodness of fit S values are based on F2; conventional R factors
(R) are based on F.
Ackn owledgm en t. Financial support from the DGES
of Spain (Projects PB98-0916-02-01 and PB98-1591) is
acknowledged. J .T. acknowledges the “Direccio´ General
de Recerca de la Generalitat de Catalunya” for a grant.
R.C. thanks also the “Ministerio de Educacio´n y Cul-
tura” for a grant. The use of computational facilities of
the Centre de Supercomputacio´ i Comunicacions de
Catalunya is gratefully appreciated as well.
X-r a y
St r u ct u r e
Det er m in a t ion
of
OsH Cl2-
{NdC(CH2)4CH2}(P iP r 3)2 (2) a n d OsCl3{NdC(CH2)4CH2}-
(P iP r 3)2 (6). A summary of the fundamental crystal and
refinement data of the compounds 2 and 6 is given in Table 5.
Crystals of 2 and 6 showing well-defined faces were mounted
on a Bruker-Siemens Smart CCD diffractometer equipped with
a normal focus, 2.4 kW sealed tube X-ray source (Molybdenum
radiation, λ ) 0.71073 Å) operating at 50 kV and 20 mA. Data
were collected over a quadrant of the reciprocal space by a
combination of two frame sets for 2 and over a hemisphere by
a combination of three sets for 6. The cell parameter were
determinated and refined by least-squares fit of all reflections
collected. Each frame exposure time was 10 s, covering 0.3°
in ω. The crystal to detector distance was 6.05 cm. Coverage
of the unique sets was over 100% complete to at least 27° in
θ. The first 50 frames were recollected at the end of the data
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and equivalent isotropic displacement coefficients,
anisotropic thermal parameters, experimental details of the
X-ray studies, and bond distances and angles for 2 and 6. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM000208T
(43) Sheldrick, G. M. SHELXTL; University of Go¨ttingen, Go¨ttingen,
Germany, 1997.