Synthesis, characterization, and molecular structure of the first closo-hydrido complexes of osmium with carborane ligands: Closo-3,3-(PPh3)2-3-H-3-Cl-3,1,2-OsC2B 9H11 and closo-3,3-(PPh3)<

Article abstract of DOI:10.1021/om950967p

Novel 12-vertex closo-hydridometallacarboranes 3,1,2-[(PPh₃)₂OsHXC₂B₉H ₁₁] (1a,b: X = Cl, H) and 3,1,2-[(PPh₃)₂OsH₂-1,2-Me₂C ₂B₉H

Full text of DOI:10.1021/om950967p

Organometallics 1996, 15, 2619-2623
2619
Syn th esis, Ch a r a cter iza tion , a n d Molecu la r Str u ctu r e of
th e F ir st closo-Hyd r id o Com p lexes of Osm iu m w ith
Ca r bor a n e Liga n d s:
closo-3,3-(P P h 3)2-3-H-3-Cl-3,1,2-OsC2B9H11 a n d
closo-3,3-(P P h 3)2-3,3-H2-1,2-Me2-3,1,2-OsC2B9H9
Igor T. Chizhevsky,* Pavel V. Petrovskii, Pavel V. Sorokin, Vladimir I. Bregadze,
Fedor M. Dolgushin, Aleksandr I. Yanovsky, and Yuri T. Struchkov†
A. N. Nesmeyanov Institute of Organoelement Compounds, 28 Vavilov Str.,
117813 Moscow, Russian Federation
Albert Demonceau and Alfred F. Noels
Institute of Chemistry, B6, University of Liege, B-4000 Sart Tilman, Belgium
Received December 18, 1995X
Novel 12-vertex closo-hydridometallacarboranes 3,1,2-[(PPh3)2OsHXC2B9H11] (1a ,b: X )
Cl, H) and 3,1,2-[(PPh3)2OsH2-1,2-Me2C2B9H9] (1c) have been synthesized via oxidative
addition of K+ salts of the nido-carborane anions [nido-7,8-R2-7,8-C2B9H10]- (R ) H, Me),
respectively, to OsCl2(PPh3)3 and characterized by spectroscopic (NMR and IR) as well as
by single-crystal X-ray diffraction studies of 1a ,c.
Hydridometallacarborane clusters of closo and exo-
nido types have played an important role in the devel-
opment of metallacarborane chemistry1 and since the
discovery of their catalytic activity2 have found wide-
spread use as catalyst precursors in numerous organic
processes.3,4 Although now the variety of closo-hydri-
dometallacarboranes of platinum group metals derived
from nido-C2B9H122- is very extensive,5-8 examples of
closo-hydridoosmacarboranes are still lacking. This is
particularly surprising taking into account the known
ability of osmium to form stable closo-osmaborane
clusters9 and also in view of well-documented chemistry
of related closo-hydridoruthenacarboranes.6-8 A suc-
cessful synthesis of the latter by the oxidative addition
of 7,8- and 7,9-C2B9H12- to coordinatively unsaturated
Ru(II) species6,7 or by thermal rearrangement of some
exo-nido-ruthenacarboranes8 prompted us to examine
these possible routes for the preparation of 12-vertex
osmium congeners. We now report the synthesis of
closo-3,3-(PPh3)2-3-H-3-X-1,2-R2-3,1,2-OsC2B9H9 (1a , R
) H, X ) Cl; 1b, R ) X ) H; 1c, R ) Me, X ) H) and
X-ray structural characterization of two of them, namely
1a ,c.
Complexes 1a -c proved to be readily obtained by
gentle reflux of a suspension of freshly prepared OsCl2-
(PPh3)3 (2)10 with a slight excess of corresponding
carborane monoanions in the form of their potassium
salts [nido-7,8-R2-7,8-C2B9H10]-K+ (3a , R ) H; 3b, R )
Me) in a deoxygenated ethanol for 6-8 h (Schemes 1
and 2). The reaction of 2 with unsubstituted carborane
salt 3a produced a mixture of two hydrido complexes
1a ,b in an approximately 1:1 ratio, along with a byprod-
uct which was identified as Os(CO)ClH(PPh3)3 (4) by
comparison of its NMR spectra with those of an au-
thentic sample.10 This crude mixture of complexes was
† Deceased on August 16, 1995.
X Abstract published in Advance ACS Abstracts, April 15, 1996.
(1) (a) Kelb, W. C.; Demidowich, Z.; Speckman, D. M.; Knobler, C.
B.; Teller, R. G.; Hawthorne, M. F. Inorg. Chem. 1982, 21, 4027. (b)
Zheng, L.; Baker, R. T.; Knobler, C. B.; Walker, J . A.; Hawthorne, M.
F. Inorg. Chem. 1983, 22, 3350. (c) Behnken, P. E.; Marder, T. B.;
Baker, R. T.; Knobler, C. B.; Thompson, M. R.; Hawthorne, M. F. J .
Am. Chem. Soc. 1985, 107, 932. (d) Walker, J . A.; Knobler, C. B.;
Hawthorne, M. F. Inorg. Chem. 1985, 24, 2688. (e) Walker, J . A.;
Zheng, L.; Knobler, C. B.; Soto, J .; Hawthorne, M. F. Inorg. Chem.
1987, 26, 1608. (f) Zakharkin, L. I.; Chizhevsky, I. T.; Zhigareva, G.
G.; Petrovskii, P. V.; Polyakov, A. V.; Yanovsky, A. I.; Struchkov, Yu.
T. J . Organomet. Chem. 1988, 358, 449. (g) Chizhevsky, I. T.;
Lobanova, I. A.; Pisareva, I. V.; Zinevich, T. V.; Bregadze, V. I.;
Yanovsky, A. I.; Struchkov, Yu. T.; Knobler, C. B.; Hawthorne, M. F.
In Current Topics in the Chemistry of Boron; Kabalka, G. W., Ed.; Royal
Society of Chemistry: Cambridge, U.K., 1994; p 301. For the latest
review see: Grimes, R. N. In Comprehensive Organometallic Chemistry
II; Abel, E. F., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon Press:
Oxford, U.K., 1995; Vol. 1, Chapter 9, p 373.
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Long, J . A.; Behnken, P. E.; Hawthorne, M. F. J . Am. Chem. Soc. 1984,
106, 2990 and references therein. (b) Hewes, J . D.; Thompson, M.;
Hawthorne, M. F. Organometallics 1985, 4, 13. (c) Doi, J . A.; Teller,
R. G.; Hawthorne, M. F. J . Chem. Soc., Chem. Commun. 1980, 80. (d)
Delaney, M. S.; Knobler, C. B.; Hawthorne, M. F. Inorg. Chem. 1981,
20, 1341. (e) Delaney, M. S.; Teller, R. G.; Hawthorne, M. F. J . Chem.
Soc., Chem. Commun. 1981, 235. (f) Busby, D. C.; Hawthorne, M. F.
Inorg. Chem. 1982, 21, 4101.
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1976, 257.
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Chem. U.S.S.R. 1991, 4, 469 (English translation).
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Chem. 1983, 249, 11. (b) Bould, J .; Crook, J . K.; Greenwood, N. N.;
Kennedy, J . D. J . Chem. Soc., Chem. Commun. 1983, 951. (c)
Elrington, M.; Greenwood, N. N.; Kennedy, J . D.; Thornton-Pett, M.
J . Chem. Soc., Chem. Commun. 1984, 1398. (d) Elrington, M.;
Greenwood, N. N.; Kennedy, J . D.; Thornton-Pett, M. J . Chem. Soc.,
Dalton Trans. 1986, 2277. (e) Bown, M.; Greenwood, N. N.; Kennedy,
J . D. J . Organomet. Chem. 1986, 309, C67.
(2) Paxon, T. E.; Hawthorne, M. F. J . Am. Chem. Soc. 1974, 96, 4674.
(3) See for examples: (a) Delaney, M. S.; Knobler, C. B.; Hawthorne,
M. F. J . Chem. Soc., Chem. Commun. 1980, 849. (b) Belmont, J . A.;
Soto, J .; King, R. E., III; Donaldson, A. J .; Hewes, J . D.; Hawthorne,
M. F. J . Am. Chem. Soc. 1989, 111, 7475 and references therein. (c)
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Zakharkin, L. I.; Zhigareva, G. G. Izv. Akad. Nauk SSSR, Ser. Khim.
1992, 41, 1284 (English translation).
(4) Demonceau, A.; Saive, E.; de Froidmont, Y.; Noels, A. F.; Hubert,
A. J .; Chizhevsky, I. T.; Lobanova, I. A.; Bregadze, V. I. Tetrahedron
Lett. 1992, 33, 2009.
(10) Oudeman, A.; Van Rantwijk, F.; Van Bekkum, H. J . Coord.
Chem. 1974, 4, 1.
S0276-7333(95)00967-8 CCC: $12.00 © 1996 American Chemical Society

2620 Organometallics, Vol. 15, No. 11, 1996
Chizhevsky et al.
Sch em e 1
formulated as symmetrical exo-nido-[Cl(PPh)3)2Os]-7,8-
Me2C2B9H9 (5) wherein three two-electron, three-center
B-H‚‚‚Os bonds are present;11 the exo-nido-ruthena-
carboranes with three, one, or two analogous B-H‚‚‚Ru
bonds have been previously reported by us12 and oth-
ers.13
Remarkably, in view of these results, our attempt to
prepare the ruthenium congener of 1c, closo-3,3-(PPh3)2-
3,3-H2-1,2-Me2-3,1,2-RuC2B9H9, by the reaction of RuCl2-
(PPh3)3 with 3b in boiling ethanol solution failed and
the known exo-nido-5,6,10-[Cl(PPh3)2Ru]-5,6,10-µ-(H)3-
12
10-H-7,8-Me2C2B9H6 (72% yield) was obtained as the
sole product. As shown previously,12 this complex exists
in solution as an equilibrium mixture of symmetrical
and nonsymmetrical exo-nido isomers and, by contrast
with the unsubstituted analog, could not be converted
into the corresponding closo isomer even upon heating
to 110 °C in toluene.8 All of these findings, taken
together, reveal rather unexpected differences in the
stability and solution behavior of closo and exo-nido
complexes within the family of the apparently closely
related ruthena- and osmacarboranes of this type.
Sch em e 2
Since little attention has been given in literature to
closo-osmacarborane clusters14 and, in particular, no
osmium closo complexes derived from the extensively
studied C2B9H112- ligand have been so far structurally
characterized, we have determined the structure of the
two complexes 1a ,c by X-ray diffraction study. The high
quality of single crystals grown from both samples
allowed us to locate objectively and reliably refine all
hydrogen atoms including hydride atoms. The struc-
tures of 1a ,c are shown in Figures 1 and 2, respectively.
successfully separated by fractional crystallization into
yellow 1a (36% yield) and white-grayish 1b (42% yield)
crystalline solids whose structures were assigned by
spectroscopic and, for 1a , crystallographic means. Thus,
the 400.13 MHz 1H and 161.98 MHz 31P{1H} NMR
spectra of 1a ,b in CD2Cl2 in each case showed high-field
proton triplets with characteristic coupling constants
J H-P ) 36 and 33 Hz and single phosphorous resonances
at -11.3 and 17.5 ppm, respectively, as expected for the
presence of terminal monodentate hydrido ligands and
equivalent PPh3 groups at the metal centers. The IR
spectra of 1a ,b revealed strong bands at 2450-2575
cm-1 and moderate singlets or doublets located near
2150 cm-1 which were assigned to νBH and νOsH absorp-
tions, respectively.
The compounds 1a ,c should be formulated as 18
electron closo-osmacarboranes with formally seven-
coordinate osmium(IV) atoms. The overall geometry of
1a and the orientation of P2OsHCl moiety relative to
the pentagonal plane of the carborane cage proved to
be very similar to those found in closo-3,3-(PPh3)2-3-H-
3-Cl-3,1,2-RuC2B9H11 (6).8,15 The P(1)‚‚‚P(2) vector in
1a is approximately parallel to the C(1)‚‚‚C(2) vector of
the coordinating five-membered carborane open face
(the angle formed by the two vectors being equal to
13.2°), whereas the Cl-Os-H plane bisects the C(1)-
C(2) bond and the Cl(1) ligand occupies a nearly trans
position to the B(8) atom (Figure 3a). Bonding of the
osmium atom to the C2B3 carborane open face in 1a is
essentially symmetric, with Os-B and Os-C distances
in the range 2.217(3)-2.314(4) Å.
By contrast, the reaction of 2 with dimethyl-substi-
tuted monoanion 3b under exactly the same conditions
gave an osmacarborane complex of the closo type, 1c,
besides the byproduct 4. The former was isolated as
pure white-grayish crystals after recrystallization of the
crude solid from a CH2Cl2/n-hexane mixture in 68%
yield. No traces of closo-3,3-(PPh3)2-3-H-3-Cl-1,2-Me2-
1
3,1,2-OsC2B9H9 were detected by H NMR among with
the reaction products either in the crude solid precipi-
tate or in the mother liquor, as would be expected by
the analogy with the reaction discussed above. Higher
steric requirements of a Cl ligand relative to the C2B3
face conflicting in this case with the generally over-
crowded environment due to the presence of two sub-
stituents at the cage carbon atoms may account for the
instability of the latter chloro complex. However, the
1H NMR spectra of the crude solid precipitate in CD2-
Cl2 solution indicated the formation of one more carb-
aborane-containing osmium species in an approximately
1:5 ratio relative to 1c. On the basis of the 1H and
31P{1H} NMR data {[CD2Cl2, δ (ppm)]: 1H NMR 7.20
(overlapped m), 1.11 (s, 6H, Me), -0.82 (m br, 1H, B10H),
-6.3 (m br, 2H, BH), -16.1 [m br, 1H, BH]; 31P{1H}
NMR -0.21 (s br)}, this species can be tentatively
(11) Further investigations in order to elucidate the exact geometry
of 5 and to establish whether 5 exists in solution solely as exo-nido
isomer or is involved in a slow interconverting equilibrium with 1c
are in progress.
(12) Chizhevsky, I. T.; Lobanova, I. A.; Bregadze, V. I.; Petrovskii,
P. V.; Antonovich, V. A.; Polyakov, A. V.; Yanovsky, A. I.; Struckhov,
Yu. T. Mendeleev Commun. 1991, 47.
(13) (a) Teixidor, F.; Ayllo´n, J . A.; Vin˜as, C.; Kiveka¨s, R.; Sillanpa¨a¨,
R.; Casabo´, J . J . Chem. Soc., Chem. Commun. 1992, 1281. (b) Teixidor,
F.; Ayllo´n, J . A.; Vin˜as, C.; Kiveka¨s, R.; Sillanpa¨a¨, R.; Casabo´, J .
Organometallics 1994, 13, 2751. (c) Teixidor, F.; Vin˜as, C.; Casabo´,
J .; Romerosa, A. M.; Rius, J .; Miravitlles, C. Organometallics 1994,
13, 914. (d) Vin˜as, C.; Nun˜ez, R.; Flores, M. A.; Teixidor, F.; Kiveka¨s,
R.; Sillanpa¨a¨, R. Organometallics 1995, 14, 3952.
(14) (a) Hanusa, T. P.; Huffman, J . C.; Curtis, T. L.; Todd, L. J . Inorg.
Chem. 1985, 24, 787. (b) Davis, J . H.; Sinn, E., J r.; Grimes, R. N. J .
Am. Chem. Soc. 1989, 111, 4776. (c) Hosmane, N. S.; Sirmokadam,
N. N. Organometallics 1984, 3, 1119. (d) Bown, M.; Fontaine, X. L.
R.; Greenwood, N. N.; Kennedy, J . D.; Thornton-Pett, M. J . Chem. Soc.,
Chem. Commun. 1987, 1650.

closo-Hydrido Complexes of Osmium
Organometallics, Vol. 15, No. 11, 1996 2621
F igu r e 1. Molecular structure of complex 1a . Thermal
ellipsoids of non-hydrogen atoms are drawn at the 50%
probability level. All hydrogen atoms except H(3) have
been omitted for clarity. Selected interatomic distances (Å)
and angles (deg): Os(3)-B(4) ) 2.314(4), Os(3)-B(8) )
2.313(4), Os(3)-B(7) ) 2.253(3), Os(3)-C(1) ) 2.254(3), Os-
(3)-C(2) ) 2.217(3), Os(3)-P(1) ) 2.3834(12), Os(3)-P(2)
) 2.372(2), Os(3)-Cl ) 2.432(2), Os(3)-H(3) ) 1.39(4),
B(8)-H‚‚‚H-Os(3) ) 2.42(7); P(2)-Os(3)-Cl(1) ) 83.26-
(5), P(1)-Os(3)-Cl(1) ) 82.87(5), P(2)-Os(3)-P(1) ) 109.45-
(4), Cl(1)-Os(3)-H(3) ) 131(2), P(1)-Os(3)-H(3) ) P(2)-
Os(3)-H(3) ) 70(2).
F igu r e 2. Molecular structure of complex 1c. Thermal
ellipsoids of non-hydrogen atoms are drawn at the 50%
probability level. All hydrogen atoms except H(3A) and
H(3B) have been omitted for clarity. Selected interatomic
distances (Å) and angles (deg): Os(3)-B(4) ) 2.310(3), Os-
(3)-B(8) ) 2.259(3), Os(3)-B(7) ) 2.249(3), Os(3)-C(1) )
2.375(3), Os(3)-C(2) ) 2.338(3), C(1)-C(13) ) 1.519(3),
C(2)-C(14) ) 1.531(3), Os(3)-P(1) ) 2.3275(14), Os(3)-
P(2) ) 2.373(2), Os(3)-H(3A) ) 1.55(4), Os(3)-H(3B) )
1.52(4); P(1)-Os(3)-H(3A) ) 72(2), P(2)-Os(3)-H(3A) )
73(2), P(1)-Os(3)-H(3B) ) 75.9(14), P(2)-Os(3)-H(3B) )
70.2(14), P(1)-Os(3)-P(2) ) 100.46(5).
The metal atom in 1c, by contrast, is markedly shifted
parallel to the open face in the direction of its boron
atoms so that the cage carbon atoms are about 0.12 Å
further than in 1a and atom B(8) is 0.05 Å closer to the
Os center. This difference is apparently due to the
sterically overcrowded solid-state conformation of the
(PPh3)2OsH2 moiety relative to the cage open face of 1c
wherein one of the two PPh3 groups is disposed not as
far away as possible from the cage substituents as one
might have expected. Thus the Os-P(1) bond projects
over the midpoint of the B(7)-B(8) bond of the coordi-
nating C2B3 open face while Os-P(2) almost eclipses the
C(1)-Me bond. Consequently, the hydride ligands are
located approximately trans to C(2) and B(4) atoms of
the open carborane face (Figure 3b).
F igu r e 3. View of the P2OsHCl and P2OsH2 moieties and
the C2B3 face coordinated to osmium in 1a ,c, respectively.
The observed difference in the relative orientations
of the P2OsHX moieties with respect to the C2B3 open
face in 1a ,c seems to be rather unexpected. The
extended Hu¨ckel molecular orbital studies of closo-
mined by geometrically optimal conditions of the overlap
of the HOMO-LUMO nodal planes of the metal-
containing and π-dicarbollyl ligands, respectively. There-
fore, the differences in the solid-state conformations of
1a ,c may reflect possible differences in the geometry of
the HOMO-LUMO interaction between the corre-
sponding orbitals of the π-dicarbollyl ligand and P2-
OsHCl and P2OsH2 moieties. In order to understand
this phenomena in more detail, extended Hu¨ckel or
more profound quantum chemical calculations on these
complexes or their hypothetical model compounds closo-
3,3-(PH3)2-3-H-3-X-1,2-R2-3,1,2-OsC2B9H9 (7a , R ) H,
X ) Cl; 7b, R ) Me, X ) H) are required.
metallacarboranes of the [3,1,2-L2MC2B9H11]16 and [3,1,2-
17
HL2MC2B9H11
]
types showed that the orientation of
ML2 and ML2H moieties with respect to the coordinating
C2B3 planes of the carborane cage is primarily deter-
(15) In spite of the similarity of the solid-state structural geometry
of 1a and 6, comparison of their 1H NMR spectra reveals one striking
difference. The hydride resonance in the 1H NMR spectra of 6 is
observed as a doublet of triplets (J t ) 28.9 Hz, J d ) 10.3 Hz), by
contrast to a triplet in the spectra of 1a . On the basis of the proton
decoupling NMR experiment an additional splitting of the former signal
was proved to result from the unique HB(8)‚‚‚HRu through-space spin-
spin interaction. Indeed, according to the X-ray data the B(8)-H‚‚‚H-
Os distance in 1a [2.42(7) Å] is significantly longer than the corre-
sponding B(8)-H‚‚‚H-Ru distance found in 6 [2.11(8) Å].8 There are
also noticeable differences in the corresponding angles between M-H
bonds and the coordinating C2B3 planes in 1a and 6 which are equal
19.2 and 9.3°, respectively. These are apparently consistent with the
above phenomena observed for the 1H NMR spectra of 6.
In conclusion, the first fully characterized closo-
hydridoosmacarborane complexes 1a -c were prepared
by simple oxidative addition reactions. The reaction
provides a simple route to useful new starting materials
(17) Mingos, D. M. P.; Minshall, P. C.; Hursthouse, M. B.; Malik,
(16) Mingos, D. M. P. J . Chem. Soc., Dalton Trans. 1977, 602.
K. M. A.; Willoughby, S. D. J . Organomet. Chem. 1979, 181, 169.

2622 Organometallics, Vol. 15, No. 11, 1996
Chizhevsky et al.
Ta ble 1. Cr ysta l Da ta a n d Deta ils of th e X-r a y Exp er im en ts for 1a ,c
compd
1a
1c
formula
mol wt
C38H42B9ClP2Os‚1.5C6H6
1000.76
C40H47B9P2Os
877.21
cryst color, habit
cryst size, mm
cryst system
space group
cell constants
a, Å
pale yellow prisms
0.15 × 0.20 × 0.25
triclinic
white-grayish prisms
0.15 × 0.20 × 0.20
triclinic
P1h
P1h
12.177(3)
13.362(5)
16.353(9)
102.26(4)
110.78(4)
100.31(3)
2335(2)
11.311(8)
11.322(6)
16.099(11)
83.98(5)
80.63(6)
71.78(5)
1929(2)
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
2
2
D
calcd, g cm-3
1.423
1.510
diffractometer
temp, K
CAD4 Enraf Nonius
296
Siemens P3/PC
146
radiation (Å)
scan mode
2θmax, deg
tot. unique refls collcd
abs coeff, µ(Mo KR), cm-1
R1 (on F for refls with I > 2σ(I))
wR2 (on F2 for all refls)
Mo KR (λ ) 0.710 73)
Mo KR (λ ) 0.710 73)
θ-5/3θ
θ-2θ
52
9156
28.9
0.0275 (8219 refls)
0.0786 (9106 refls)
64
13 319
34.2
0.0260 (11 686 refls)
0.0694 (13 268 refls)
2132 cm-1. The examination of the NMR spectra of the crude
product taken before benzene extraction in CD2Cl2 solution
revealed the existence of the byproduct 4 in ratio of 1:4 to 1a .
1H NMR [25 °C, CD2Cl2, J (Hz)]: δ 7.14-7.60 (m, 45H, PPh3),
-6.90 (dt, J d ) 86.2, J t ) 24.7). 31P{1H} NMR [25 °C, CD2Cl2,
J (Hz)]: δ -9.1 (t, 1P, J t ) 11.2), 7.9 (d, 2P, J d ) 11.2).
P r ep a r a tion of closo-3,3-(P P h 3)2-3,3-H2-1,2-Me2-3,1,2-
OsC2B9H9 (1c). Using a procedure similar to those for 1a ,b,
a mixture of OsCl2(PPh3)3 (0.40 g, 0.38 mmol) and [nido-7,8-
Me2-7,8-C2B9H10]-K+ (0.09 g, 0.45 mmol) in 40 mL of deoxy-
genated absolute ethanol was stirred at reflux temperature
for 6 h. After the mixture was cooled to room temperature,
the precipitate formed was separated by filtration, dissolved
in 8 mL of CH2Cl2, and layered approximately in half with
n-hexane. From the solution which was cooled overnight at 0
°C white-grayish microcrystals of 1c (0.23 g, 68%) were
obtained. Anal. Calcd for C40H47B9P2Os: C, 54.77; H, 5.36;
B, 11.09; P, 7.07; Os, 21.70. Found: C, 54.96; H, 5.56; B, 11.27;
P, 7.06; Os, 21.72. 1H NMR [25 °C, CD2Cl2, J (Hz)]: δ 7.20-
for the development of chemistry of these rare osmac-
arborane clusters.
Exp er im en ta l Section
Gen er a l P r oced u r es. All reactions were performed under
argon atmosphere using standard Schlenk techniques. Sol-
vents for reactions and purification procedures were dried with
an appropriate drying agents and distilled under argon prior
to use. The 1H and 31P NMR spectra were recorded on a
Bruker AMX-400 spectrometer using TMS as an internal
reference and 85% H3PO4 as an external reference. All IR
spectra were obtained on a Specord M-82 in KBr pellets.
Microanalyses were performed at the Analytical Laboratory
of the Institute of Organoelement Compounds of the Russian
Academy of Sciences.
P r epar ation of closo-3,3-(P P h 3)2-3-H-3-Cl-3,1,2-OsC2B9H11
(1a ) a n d closo-3,3-(P P h 3)2-3,3-H2-3,1,2-OsC2B9H11 (1b). To
a stirred suspension of freshly prepared OsCl2(PPh3)3 (0.55 g,
0.53 mmol) in deoxygenated absolute ethanol (40 mL) was
added [nido-7,8-C2B9H12]-K+ (0.1 g, 0.58 mmol) as a solid, and
the mixture was heated at reflux temperature under an argon
atmosphere for ca. 8 h. After the mixture was cooled to room
temperature, the resulting light yellow precipitate was sepa-
rated under pressure of argon using an internal frit of medium
porosity. The residue was extracted by hot benzene (10 mL),
and the yellow solution obtained was transferred into a 25 mL
round-bottom flask, layered in half with hot n-hexane, and
slowly cooled to 0 °C, yielding 0.17 g (36%) of pure 1a as pale
yellow crystals. Anal. Calcd for C38H42B9ClP2Os‚0.5C6H6: C,
53.37; H, 4.88; B, 10.54; Cl, 3.85; P, 6.73; Os, 20.63. Found:
C, 53.31; H, 5.01; B, 10.66; Cl, 3.52; P, 6.78; Os, 20.63. 1H
NMR [25 °C, CD2Cl2, J (Hz)]: δ 7.20-7.62 (m, ∼30H, PPh3),
3.94 (s, 2H, CH), -11.60 (t, 1H, J H-P ) 36, Os-H). 31P{1H}
7.65 (m, 30H, PPh3), 1.57 (s, 6H, Me), -10.42 (t, 2H, J H-P
)
34, Os-H). 31P{1H} NMR (25 °C, CH2Cl2): δ 11.7 (s). 11B{1H}
NMR (128.33 MHz, CH2Cl2, BF3‚Et2O as external standard):
1.2 (2B), -6.0 (2B), -8.3 (1B), -9.2 (2B), -14.0 (2B). IR
(KBr): νBH 2542 cm-1, νOsH 2175, 2107 cm-1
.
X-r a y Da ta Collection , Str u ctu r e Deter m in a tion , a n d
R efin em en t for 1a ,c. Single crystals of 1a ,c were slowly
grown from the diluted solutions in benzene-n-hexane (1a )18
and methylene chloride-n-hexane (1c) mixtures at approxi-
mately 10 °C. Accurate unit cell parameters and orientation
matrices were obtained by least-squares refinement of care-
fully centered 24 reflections in the 26 e 2θ e 27° ranges.
Three standard reflections were monitored every 1 h for 1a
and every 97 reflections for 1c and showed no significant
variations in either case. Data were corrected for Lorentz and
polarization effects. Carefully chosen rather small well formed
and essentially isometric single-crystal samples, the quality
NMR (25 °C, CD2Cl2): δ -11.3 (s). IR (KBr): νBH 2568 cm-1
,
νOsH 2178 cm-1, νOsCl 310 cm-1
.
The combined solid residue
from benzene extraction was treated by CH2Cl2 (8 mL) followed
by addition of n-hexane (2-3 mL), and after refrigerating of
the solution overnight 0.19 g (42%) of analytically pure white-
grayish crystals of 1b were filtered off. Anal. Calcd for
(18) The crystals suitable for X-ray diffraction experiment were
grown from the benzene-n-hexane mixture enriched in benzene (5:1,
respectively) as compared with that used for the synthetic procedures
(see above). Therefore, the sample of 1a which was employed for
elemental analyses turned out to be the benzene semisolvate, whereas
the specimen subjected to the diffraction experiment was proved to
contain 1.5 benzene molecules per molecule of the complex.
C
38H43B9P2Os: C, 53.75; H, 5.07; B, 11.46; P, 7.31; Os, 22.42.
Found: C, 53.60; H, 5.31; B, 11.60; P, 7.26; Os, 22.43. 1H NMR
[25 °C, CD2Cl2, J (Hz)]: δ 7.24-7.65 (m, 30H, PPh3), 2.78 (s,
2H, CH), -10.58 (t, 2H, J H-P ) 33, Os-H). 31P{1H} NMR (25
°C, CD2Cl2): δ 17.5 (s). IR (KBr): νBH 2574 cm-1, νOsH 2163,

closo-Hydrido Complexes of Osmium
Organometallics, Vol. 15, No. 11, 1996 2623
of the obtained results, and the relatively low absorption
coefficient values justified no necessity for absorption correc-
tions.
The structures were solved by direct methods and subse-
quent difference Fourier maps. All H atoms of both molecules
including the hydride ligands were located in the difference
syntheses and refined in the isotropic approximation. All
calculations were carried out on an IBM PC with the SHELX-
TL PLUS 5 (gamma-version) programs. Crystal data and
details of the X-ray experiments are given in Table 1.
Science Foundation (Grant. Nos. M4P000, SAU000, and
M04000). We are also grateful to Dr. I. G. Bara-
kovskaya for performing special research in order to
obtain full analytical data for the osmium clusters
prepared.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data collection parameters, atom coordinates and U values,
bond distances and angles, and anisotropic parameters, a
thermal ellipsoid plot, and the full and high-field region of the
1H NMR spectrum of complex 1c with the hydride signals of
the exo-nido-osmacarbaborane 5 (12 pages). Ordering infor-
mation is given on any current masthead page.
Ack n ow led gm en t. This research has been sup-
ported in part by INTAS 94-541. I.T.C., P.V.P., V.I.B.,
F.M.D., and A.I.Y. also gratefully acknowledge the
financial support of the Russian Foundation for Basic
Research (Grant No. 94-03-08838) and International
OM950967P