Preparation and characterization of novel Os-diolefin dimers: New entry to Os-cyclooctadiene complexes

Article abstract of DOI:10.1021/ic0612799

The complex [H(EtOH)₂][{OsCl(η⁴-COD)} ₂(μ-H)(μ-Cl)₂] (1) has been prepared in high yield by treatment of OsCl₃· 3H₂O (54% Os) with 1,5-cyclooctadiene in ethanol under reflux. Under air, it is unstable and undergoes oxidation by action of O₂ to afford the neutral derivative {OsCl(η⁴-COD)}₂(μ-H)(μ-Cl)₂ (2). The terminal chlorine ligands of the anion of 1 are activated toward nucleophilic substitution. Thus, reaction of the salt [NBu₄] [{OsCl(η⁴-COD)}₂-(μ-H)(μ-Cl)₂] (1a) with NaCp in toluene gives [NBu₄][{Os(η¹-C ₅H₅)(η⁴-COD)}(μ-H)(μ-Cl) ₂{OsCl(η⁴-COD)}] (3) as a result of the replacement of one of the terminal chlorine atoms by the cyclopentadienyl ligand. The CH ₂ group of the latter can be deprotonated by the bridging methoxy ligand of the iridium dimer [Ir(μ-OMe)(η⁴-COD)]₂. The reaction leads to the trinuclear derivative [NBu₄] [{(η⁴-COD)Ir(η⁵-C₅H₄- η¹)Os(η⁴-COD)}(μ-H)(μ-Cl) ₂{OsCl(η⁴-COD)}] (4) containing a bridging C ₅H₄ ligand that is η¹-coordinated to an osmium atom of the dimeric unit and η⁵-coordinated to the Ir(η⁴-COD) moiety. Salt 1a also reacts with LiC≡CPh. In this case, the reaction produces the substitution of both terminal chlorine ligands to afford the bis(alkynyl) derivative [NBu₄][{Os(C≡CPh) (η⁴-COD)}₂(μ-H)(μ-Cl)₂] (5). Complexes 1, 2, 3, and 4 have been characterized by X-ray diffraction analysis. Although the separations between the osmium atoms are short, between 2.6696(4) and 2.8633(5) A, theoretical calculations indicate that only in 2 is there direct metal-metal interaction, as the bond order is 0.5.

Full text of DOI:10.1021/ic0612799

Inorg. Chem. 2006, 45, 10162−10171
Preparation and Characterization of Novel Os
Entry to Os Cyclooctadiene Complexes
−Diolefin Dimers: New
−
Miguel A. Esteruelas,* Cristina Garc´ıa-Yebra, Montserrat Oliva´n, and Enrique On˜ate
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n, UniVersidad
de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received July 11, 2006
The complex [H(EtOH)2][
3H2O (54% Os) with 1,5-cyclooctadiene in ethanol under reflux. Under air, it is unstable and undergoes oxidation
by action of O2 to afford the neutral derivative OsCl( 2 µ-H)( -Cl)2 (2). The terminal chlorine ligands of
4-COD)
the anion of 1 are activated toward nucleophilic substitution. Thus, reaction of the salt [NBu4][ OsCl(
4-COD)
-H)( -Cl)2] (1a) with NaCp in toluene gives [NBu4][ Os( -H)( -Cl)2 OsCl(
1-C5H5)( 4-COD) 4-COD)
a result of the replacement of one of the terminal chlorine atoms by the cyclopentadienyl ligand. The CH2 group
of the latter can be deprotonated by the bridging methoxy ligand of the iridium dimer [Ir( -OMe)(
4-COD)]2. The
reaction leads to the trinuclear derivative [NBu4][ -H)( -Cl)2 OsCl(
4-COD)Ir( 5-C5H4- 1)Os( 4-COD) 4-COD)
(4) containing a bridging C5H4 ligand that is
1-coordinated to an osmium atom of the dimeric unit and 5-coordinated
to the Ir( CPh. In this case, the reaction produces the substitution
4-COD) moiety. Salt 1a also reacts with LiC
of both terminal chlorine ligands to afford the bis(alkynyl) derivative [NBu4][ Os(C CPh)( 2 µ-H)( -Cl)2]
4-COD)
{OsCl(η }2(µ-H)(µ-Cl)2] (1) has been prepared in high yield by treatment of OsCl3‚
4-COD)
{
η
}
(
µ
{
η
} -
2
(
µ
µ
{
η
η
}
(µ
µ
{
η
}] (3) as
µ
η
{(η
η
η
η
}(µ
µ
{
η
}]
η
η
η
t
{
t
η
}
(
µ
(5). Complexes 1, 2, 3, and 4 have been characterized by X-ray diffraction analysis. Although the separations
between the osmium atoms are short, between 2.6696(4) and 2.8633(5) Å, theoretical calculations indicate that
only in 2 is there direct metal−metal interaction, as the bond order is 0.5.
Introduction
which have promoted development of rich chemistry in both
stoichiometric and catalytic transformations.3
There are complexes that are determinant for development
of the chemistry of each particular transition metal. They
are obtained in high yield directly from commercially
available inorganic salts of the element and the origin of a
genealogical tree of compounds families.
Osmium is more reducing than ruthenium and prefers
coordination saturation and redox isomers with more metal-
carbon bonds.4 As a consequence of these characteristics,
the chemistry of osmium is more complex and versatile than
that of ruthenium.5 Thus, one should expect that, in the future,
the potentiality of osmium will become greater than that of
ruthenium. The current lower development of osmium
chemistry is in part a consequence of the lower effort to find
Success in the ruthenium chemistry during the past decade
has been, in part, due to the ready accessibility of a wide
range of this type of starting materials. For instance, the
ruthenium polymer [RuCl2(COD)]x1 (COD ) 1,5-cyclooc-
tadiene) is prepared in 90% yield from RuCl3‚3H2O and 1,5-
cyclooctadiene in refluxing ethanol.2 This complex has
proved to be a useful precursor for wide series of derivatives
(3) See, for example: (a) Trost, B. M. Chem. Ber. 1996, 129, 1313. (b)
Naota, T.; Takaya, H.; Murahashi, S.-I. Chem. ReV. 1998, 98, 2599.
(c) Cucullu, M. E.; Nolan, S. P.; Belderrain, T. R.; Grubbs, R. H.
Organometallics 1999, 18, 1299. (d) Coalter, J. N., III; Caulton, K.
G. New J. Chem. 2001, 25, 679. (e) Alvarez, P.; Gimeno, J.; Lastra,
E.; Garc´ıa-Granda, S.; Van der Maelen, J. F.; Bassetti, M. Organo-
metallics 2001, 20, 3762.
(4) Caulton, K. G. J. Organomet. Chem. 2001, 617-618, 56.
(5) (a) Sa´nchez-Delgado, R. A.; Rosales M.; Esteruelas, M. A.; Oro, L.
A. J. Mol. Catal. A: Chem. 1995, 96, 231. (b) Esteruelas, M. A.;
Oro, L. A. Chem. ReV. 1998, 98, 577. (c) Esteruelas, M. A.; Oro, L.
A. AdV. Organomet. Chem. 2001, 47, 1. (d) Esteruelas, M. A.; Lo´pez,
A. M. In Recent AdVances in Hydride Chemistry; Peruzzini, M., Poli,
R., Eds.; Elsevier: Amsterdam, 2001; Chapter 7, pp 189-248. (e)
Esteruelas, M. A.; Lo´pez, A. M. Organometallics 2005, 24, 3584.
* Towhomcorrespondenceshouldbeaddressed.E-mail: maester@unizar.es.
(1) Bennett, M. A.; Wilkinson, G. Chem. Ind. (London) 1959, 1516.
(2) (a) Mu¨ller, J.; Fischer, E. O. J. Organomet. Chem. 1966, 5, 275. (b)
Ibers, M. O.; Singleton, E.; Yates, J. E. Inorg. Synth. 1989, 26, 253.
(c) Geneˆt, J. P.; Pinel, C.; Ratovelomanana-Vidal, V.; Mallart, S.;
Pfister, X.; Can˜o de Andrade, M. C.; Laffitte, J. A. Tetrahedron:
Asymmetry 1994, 5, 665.
10162 Inorganic Chemistry, Vol. 45, No. 25, 2006
10.1021/ic0612799 CCC: $33.50
© 2006 American Chemical Society
Published on Web 11/08/2006

Characterization of NoWel Os-Diolefin Dimers
starting materials from OsCl3‚3H2O, or related salts, and
optimize the synthetic procedures leading to them.
In 1966, Winkhaus et al. described the preparation of the
counterpart osmium polymer [OsCl2(COD)]x in 35% yield
by reaction of H2OsCl6 with 1,5-cyclooctadiene in boiling
isoamyl alcohol.6 In 1974, Schrock and co-workers reported
a high-yield procedure for this polymer (90%) which involves
heating OsO4 in a mixture of concentrated HCl and isoamyl
alcohol, adding 1,5-cyclooctadiene, and distilling off the
solvent to afford the yellow-brown product.7 However, by
this procedure Girolami’s group only obtains yields of 15-
20%. The difficulty in obtaining [OsCl2(COD)]x in high
yields has prompted Girolami and co-workers to prepare the
bromo analogue [OsBr2(COD)]x, which has shown to be a
useful starting material for any array of osmium complexes.8
This compound is obtained in 90% yield by reaction of H2-
OsBr6 with excess 1,5-cyclooctadiene in boiling tert-butyl
alcohol. H2OsBr6 is generated by addition of HBr to OsO4.
Figure 1. Molecular diagram of complex 1. Selected bond lengths (Å)
and angles (deg): Os(1)-Cl(1) 2.452(2), Os(1)-Cl(2) 2.452(3), Os(1)-
Cl(3) 2.408(3), Os(2)-Cl(1) 2.449(2), Os(2)-Cl(2) 2.449(3), Os(2)-Cl-
(4) 2.417(3), Os(1)-H(01) 1.86(7), Os(2)-H(01) 1.86(7), Os(1)-C(1)
2.144(9), Os(1)-C(2) 2.147(10), Os(1)-C(5) 2.130(11), Os(1)-C(6) 2.152-
(10), Os(2)-C(9) 2.145(10), Os(2)-C(10) 2.129(10), Os(2)-C(13) 2.151-
(10), Os(2)-C(14) 2.149(10), C(1)-C(2) 1.397(14), C(5)-C(6) 1.393(15),
C(9)-C(10) 1.407(15), C(13)-C(14) 1.422(14), O(1)‚‚‚H(02) 1.37(12),
O(2)‚‚‚H(02) 1.07(12), O(1)-O(2) 2.400(13), Os(1)‚‚‚Os(2) 2.8065(6), Cl-
(3)‚‚‚H(1A) 2.13, Cl(4)‚‚‚H(2A) 2.13, Cl(3)-Os(1)-H(01) 161(3), Cl(4)-
Os(2)-H(01) 160(3).
The choice of the solvent is critical for the course of this
type of reaction involving metallic salts. A clear example is
the synthesis of the triisopropylphosphine complexes OsHCl-
(CO)(PiPr3)2 and OsH2Cl2(PiPr3)2,10 which are obtained
9
under the same conditions but using different solvents. While
the first one is formed in methanol, the second one
precipitates in 2-propanol. In addition, it should be mentioned
that OsO4 is a toxic and dangerous compound which should
be avoided in this type of procedure. A recommendable
alternative is OsCl3‚3H2O.
In the search for a new and original osmium starting
material containing the 1,5-cyclooctadiene diolefin, we
carried out the reaction of OsCl3‚3H2O with 1,5-cycloocta-
diene in ethanol. In this paper we report the discovery,
characterization, and first reactions of the novel compound
[H(EtOH)2][{OsCl(η4-COD)}2(µ-H)(µ-Cl)2] which, in con-
trast to the polymers [MCl2(COD)]x (M ) Ru, Os), is
dinuclear and anionic.
Complex 1 was characterized by X-ray diffraction analysis.
The structure proves formation of the anion [{OsCl(η4-
COD)}2(µ-H)(µ-Cl)2]- and the bis(ethanol)hydrogen
cation [H(EtOH)2]+, which are connected by Cl‚‚‚H hydrogen
bonds. Figure 1 shows a view of the geometry of both
ions.
The anion can be described as a bioctahedral face-shared
M2L9 dimer with conical OsCl(η4-COD) units, two bridging
chlorine atoms (Cl(1) and Cl(2)), and a bridging hydride
ligand (H(01)). At 223 K, the latter was located in the
difference Fourier maps and refined symmetrically as an
isotropic atom together with the remaining of non-hydrogen
atoms of the structure, giving Os(1)-H and Os(2)-H
distances of 1.86(7) Å. In solution, the presence of the
hydride ligand is revealed by the 1H NMR spectrum, which
in benzene-d6 shows a singlet at -21.10 ppm. In agreement
with the dinuclear character of the anion, in the MALDI-
TOF MS the highest m/z peak is observed at 741 with the
isotope pattern as expected (Figure 2).
The separation between the osmium atoms (2.8065(6) Å)
is shorter than those reported for complexes [{OsH2(PiPr3)2}2-
(µ-Cl)3]+ (3.5385(11) Å)11 or {Os(η5-C5Me5)Br}2(µ-Br)2
(2.970(1) Å).12 However, it agrees well with the metal-metal
distance in the ruthenium bisoctahedral anion [{RuH-
(PPh3)2}2(µ-H)(µ-Cl)2]- (2.8251(5) Å) for which a Ru-Ru
single bond has been proposed to exist.13 Both separations
are consistent with the osmium-osmium single bond dis-
tances found in the triosmium cluster Os3(µ-H)(µ3-η2-
Results and Discussion
1. Preparation and Characterization of [H(EtOH)2]-
[{OsCl(η4-COD)}2(µ-H)(µ-Cl)2]. Treatment of OsCl3‚3H2O
(54% Os) with about 8 equiv of 1,5-cyclooctadiene in ethanol
under reflux for 60 h leads to a green solution. After the
solvent is replaced by pentane, [H(EtOH)2][{OsCl(η4-COD)}2-
(µ-H)(µ-Cl)2] (1) is isolated in 76% yield (eq 1).
(6) Winkhaus, G.; Sanger, H.; Kricke, M. Z. Naturforsch., B: Chem. Sci.
1966, 21, 1109.
(7) Schrock, R. R.; Johnson, B. F. G.; Lewis, J. J. Chem. Soc., Dalton
Trans. 1974, 951.
(8) Dickinson, P. W.; Girolami, G. S. Inorg. Chem. 2006, 45, 5215.
(9) Esteruelas, M. A.; Werner, H. J. Organomet. Chem. 1986, 303, 221.
(10) Aracama, M.; Esteruelas, M. A.; Lahoz, F. J.; Lo´pez, J. A.; Meyer,
U.; Oro, L. A.; Werner, H. Inorg. Chem. 1991, 30, 288.
(11) Kuhlman, R.; Streib, W. E.; Caulton, K. G. Inorg. Chem. 1995, 34,
1788.
(12) Gross, C. L.; Wilson, S. R.; Girolami, G. S. J. Am. Chem. Soc. 1994,
116, 10294.
(13) MacFarlane, K. S.; Joshi, A. M.; Rettig, S. J.; James, B. R. Chem.
Commun. 1997, 1363.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10163

Esteruelas et al.
Figure 2. (a) Selected region of the MALDI-TOF MS spectrum showing
the isotopic distribution for the anion of 1 (highest peak at m/z 740.9). (b)
Simulated pattern for the molecular formula C16H25Cl4Os2 corresponding
to the anion of 1.
Figure 3. Electron density map (a) and Laplacian (b) for complex 1 in
the plane Os-H-Os.
HapyPh-N,N)(CO)9 (H2apyPh ) 2-amino-6-phenylpyridine;
2.8141(6), 2.7765(6), and 2.7873(6) Å)14 and only about 0.1
Å shorter than the osmium-osmium bond length reported
for Os2(µ-bdt)(CO)6 (bdt ) benzene-1,2-dithiolate; 2.686-
(2) Å).15
Like 1, complexes (η5-C5H5)2Mo(µ-H)(µ-CO)Co(CO)3,16
[{IrH(PPh3)2}2(µ-H)2(µ-O2CR)]+ (R ) (R)-CH(OMe)Ph),17
and (PiPr3)2(CO)HRu(µ-H)(µ-OMe)Ir(η4-COD)18 contain a
bridging hydride ligand and the separations between the
metal centers are short and consistent with the corresponding
metal-metal bonds. However, theoretical calculations sug-
gest that these species do not exhibit any direct metal-metal
interaction. To establish whether the short Os(1)-Os(2)
separation in 1 is due to some direct interaction between the
metal atoms, we performed a topological analysis of the
electron density on the basis of Bader’s atom-in-molecules
(AIM) theory.19 Both the electron density map and its
Laplacian in the Os-H-Os plane are shown in Figure 3.
Analysis of the Laplacian of the electron density and
calculations of critical points in the region between Os(1)
and Os(2) indicate the absence of any direct metal-metal
interaction. Density functional theory (DFT) calculations20
on 1 help to understand the absence of a bond between Os-
(1) and Os(2). Figure 4 shows the occupancy for the S ) 0
associated state of metal-based t2g-derived orbitals, which
are split into a pair of orbitals of σ symmetry with regard to
the Os(1)-Os(2) axis and a double pair with δ and π
Figure 4. Schematic representation of the metal-metal manifold for the
face-shared complex 1.
character. Because in 1 12 electrons of 2 d6 centers occupy
all osmium-osmium bonding and antibonding orbitals, a
metal-metal bond is precluded.
(14) Cabeza, J. A.; del R´ıo, I.; Riera, V.; Sua´rez, M.; Garc´ıa-Granda, S.
Organometallics 2004, 23, 1107.
(15) Cabeza, J. A.; Mart´ınez-Garc´ıa, M. A.; Riera, V.; Ardura, D.; Garc´ıa-
Granda, S. Organometallics 1998, 17, 1471.
(16) Tsai, J.-C.; Wheeler, R. A.; Khan, M. A.; Nicholas, K. M. Organo-
metallics 1991, 10, 1344.
(17) Esteruelas, M. A.; Garc´ıa, M. P.; Lahoz, F. J.; Mart´ın, M.; Modrego,
J.; On˜ate, E.; Oro, L. A. Inorg. Chem. 1994, 33, 3473.
(18) Buil, M. L.; Esteruelas, M. A.; Modrego, J.; On˜ate, E. New J. Chem.
1999, 23, 403.
(19) (a) Bader, R. F. W. Atoms in Molecules: A Quantum Theory; Oxford
University Press: New York, 1990. (b) Bader, R. F. W. Chem. ReV.
1991, 91, 893.
(20) (a) Stranger, R.; Macgregor, S. A.; Lovell, T.; McGrady, J. E.; Heath,
G. A. J. Chem. Soc., Dalton Trans. 1996, 4485. (b) Cavigliasso, G.;
Lovell, T.; Stranger, R. Dalton Trans. 2006, 2017.
The terminal chlorine atoms are pseudo-trans-disposed to
the bridging hydride ligand with Cl(3)-Os(1)-H(01) and
Cl(4)-Os(2)-H(01) angles of 161(3)° and 160(3)°, respec-
tively. The terminal Os(1)-Cl(3) and Os(2)-Cl(4) bond
lengths of 2.408(3) and 2.417(3) Å are statistically identical
and about 0.04 Å shorter than the bridging Os-Cl distances,
between 2.452(3) and 2.449(3) Å, which are also statistically
identical. The 1,5-cyclooctadiene ligand takes its customary
“tub” conformation. The olefinic bond distances, between
1.422(14) and 1.393(15) Å, lie within the range reported for
10164 Inorganic Chemistry, Vol. 45, No. 25, 2006

Characterization of NoWel Os-Diolefin Dimers
transition-metal complexes (1.340-1.455 Å).21 They are also
statistically identical and longer than those found in the free
1,5-cyclooctadiene molecule (1.34 Å),22 in agreement with
the usual Chatt, Dewar, and Duncanson metal-bonding
scheme. The osmium-diene coordination exhibits Os-C
distances between 2.129(10) and 2.152(10) Å, which agree
well with those found in other osmium-olefin complexes
(2.13-2.28 Å).23
bonding is presently attracting considerable interest in the
chemistry of the transition metals.28
In benzene-d6 at room temperature some interaction
between the anion and the cation of 1 also exist. This is
strongly supported by the chemical shifts of the resonances
1
corresponding to the hydride ligand of the anion in the H
NMR spectrum of the [H(EtOH)2]+ and [NBu4]+ salts, 1 and
1a, respectively. Because the bridging hydride is trans-
disposed to both terminal chlorine ligands, which are the
atoms of the anion involved in the anion-cation interaction
in 1, the chemical shifts of the hydride resonance depend
on the nature of the cation of the salt. Thus, the resonance
due to the hydride of 1a appears at -19.6 ppm, shifted 1.4
ppm toward lower field with regard to that of 1. The
interaction between the anion and the cation does not hinder
any fluxional process, which makes the OH protons of the
cation and the 1,5-cyclooctadiene ligands of the anion of 1
equivalent. The bridging and terminal OH protons display
only one resonance, which appears at 11.42 ppm as a broad
singlet, whereas the olefinic protons of the dienes give rise
to two complex signals between 4.64 and 4.54 ppm and
between 4.28 and 4.16 ppm. In agreement with the 1H NMR
spectrum, the 13C{1H} NMR spectrum of 1 contains two
resonances at 67.1 and 62.5 ppm for the C(sp2) atoms of the
1,5-cyclooctadiene ligands. The chemical shift of these
resonances is consistent with that previously reported for
other osmium 1,5-cyclooctadiene compounds.8,23a,29
The [H(EtOH)2]+ cation can be regarded as an ethyl-
disubstituted [H5O2]+ ion.24 The acid proton lies between
the two oxygen atoms, which are separated by 2.400(13) Å.
The O(1)-O(2) separation is about 0.2 Å longer than that
found in the bis(methanol)hydrogen cation [H(MeOH)2]+ of
the salt [H(MeOH)2][NaMn2(2-OH-SALPN)2(OAc)4]‚2H2O
(2-OH-SALPN ) N,N′-disalicylidene-2-hydroxy-propylene-
diamine).25 The terminal OH protons point toward the
terminal chlorine ligands of the anion. The separation
between them (2.13 Å) is shorter than the sum of the van
der Waals radii of hydrogen and chlorine [rvdw(H) ) 1.20,
r
vdw(Cl) ) 1.80 Å],26 supporting the anion-cation Cl‚‚‚H-O
hydrogen bonds, as a result of the electrostatic interaction
of the electronegative chlorine ligands and the electropositive
O-H hydrogen atoms. The anion-cation hydrogen bonds
are also supported by the IR spectrum of 1 in KBr, which
shows two strong ν(OH) bands at 2042 and 1967 cm-1. In
agreement with this assignment, they are not observed in
the IR spectra of the salts [NBu4][{OsCl(η4-COD)}2(µ-H)-
(µ-Cl)2] (1a) and [PPh3(CH2Ph)][{OsCl(η4-COD)}2(µ-H)(µ-
Cl)2] (1b), which were obtained by stirring 1 with [NBu4]-
[PF6] and [PPh3(CH2Ph)]Cl, respectively, in ethanol. Of great
importance in biological and organic chemistry,27 hydrogen
2. Oxidation of 1: Preparation and Characterization
of {OsCl(η4-COD)}2(µ-H)(µ-Cl)2. A noticeable result of the
DFT calculations on 1 is that the energy of the HOMO orbital
is -2.5 eV. This suggests that one electron of the anion can
be easily removed to afford the neutral species {OsCl(η4-
COD)}2(µ-H)(µ-Cl)2 (2). To confirm this, we carried out an
electrochemical study on 1a in dichloromethane. Figure 5
shows a simple voltammetric profile.
(21) Allen, F. H.; Davies, J. E.; Galloy, J. J.; Johnson, O.; Kennard, O.;
Macrae, C. F.; Mitchell, E. M.; Mitchell, G. F.; Smith, J. M.; Watson,
D. G. J. Chem. Inf. Comput. Sci. 1991, 31, 187.
Complex 1a undergoes reversible (iP,O/iP,O′ ≈ 1) diffusion-
controlled (iP/V1/2 is nearly constant for scan rates varying
between 50 and 200 mV s-1) one-electron oxidation (∆Ep
(22) Churchill, M. R.; Bezman, S. A. Inorg. Chem. 1973, 12, 531.
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E.; Oro, L. A.; Tolosa, J. I. Organometallics 1997, 16, 1316. (c)
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M. A.; Gutie´rrez-Puebla, E. Organometallics 1998, 17, 3141. (e) Buil,
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(28) See, for example: (a) Stevens, R. C.; Bau, R.; Milstein, D.; Blum,
O.; Koetzle, T. F. J. Chem. Soc., Dalton, Trans. 1990, 1429. (b) Lough,
A. J.; Park, S.; Ramachandran, R.; Morris, R. H. J. Am. Chem. Soc.
1994, 116, 8356. (c) Peris, E.; Lee, J. C. L.; Rambo, J. R.; Eisenstein,
O.; Crabtree, R. H. J. Am. Chem. Soc. 1995, 117, 3485. (d) Crabtree,
R. H.; Eisenstein, O.; Sini, G.; Peris, E. J. Organomet. Chem. 1998,
567, 7. (e) Crabtree, R. H. J. Organomet. Chem. 1998, 557, 111. (f)
Gusev, D. G.; Lough, A. J.; Morris, R. H. J. Am. Chem. Soc. 1998,
120, 13138. (g) Buil, M. L.; Esteruelas, M. A.; On˜ate, E.; Ruiz, N.
Organometallics 1998, 17, 3346. (h) Esteruelas, M. A.; Oliva´n, M.;
On˜ate, E.; Ruiz, N.; Tajada, M. A. Organometallics 1999, 18, 2953.
(i) Lee, D.-H.; Kwon, H. J.; Patel, B. P.; Liable-Sands, L. M.;
Rheingold, A. L.; Crabtree, R. H. Organometallics 1999, 18, 1615.
(j) Esteruelas, M. A.; Gutie´rrez-Puebla, E.; Lo´pez, A. M.; On˜ate, E.;
Tolosa, J. I. Organometallics 2000, 19, 275. (k) Castarlenas, R.;
Esteruelas, M. A.; On˜ate, E. Organometallics 2000, 19, 5454. (l)
Castarlenas, R.; Esteruelas, M. A.; Gutie´rrez-Puebla, E.; On˜ate, E.
Organometallics 2001, 20, 1545. (m) Clot, E.; Eisenstein, O.; Crabtree,
R. H. New J. Chem. 2001, 25, 66. (n) Barrio, P.; Esteruelas, M. A.;
On˜ate, E. Organometallics 2002, 21, 2491. (o) Esteruelas, M. A.;
Lledo´s, A.; Oliva´n, M.; On˜ate, E.; Tajada, M. A.; Ujaque, G.
Organometallics 2003, 22, 3753. (p) Buil, M. L.; Esteruelas, M. A.;
Goni, E.; Oliva´n, M.; On˜ate, E. Organometallics 2006, 25, 3076.
(29) (a) Johnson, T. J.; Huffman, J. C.; Caulton, K. G.; Jackson, S.;
Eisenstein, O. Organometallics 1989, 8, 2073. (b) Li, Z.-.W.; Harman,
W. D.; Lay, P. A.; Taube, H. Inorg. Chem. 1994, 33, 3635
(24) Mootz, D.; Steffen, M. Angew. Chem., Int. Ed. Engl. 1981, 20, 196.
(25) Bonadies, J. A.; Kirk, M. L.; Lah, M. S.; Kessissoglou, D. P.; Hatfield,
W. E.; Pecoraro, V. L. Inorg. Chem. 1989, 28, 2037.
(26) Barrio, P.; Esteruelas, M. A.; Lledo´s, A.; On˜ate, E.; Toma`s, J.
Organometallics 2004, 23, 3008.
(27) Jeffrey, G. A.; Saenger, W. Hydrogen Bonding in Biological Structures;
Springer: Berlin, 1991.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10165

Esteruelas et al.
of 1.81 Å, which support a symmetrical bridge and compare
well with those of 1.
The DFT calculations also show that removal of the
electron of the HOMO of anion 1 produces a stabilization
of the orbital to afford 2 with a half-occupied HOMO at
-6.4 eV. Because this orbital has mainly antibonding metal-
metal character, oxidation of 1 to give 2 involves an increase
of the osmium-osmium bond order from 0 to 0.5. This rise
in order results in an approach of the metal centers. Thus,
the separation between Os(1) and Os(2) in 2, 2.6696(4) Å,
is about 0.14 Å shorter than that of 1.
Figure 5. Cyclic voltammogram of a solution 0.5 mM in 1a and 0.1 M
in [NBu4]PF6/CH2Cl2. Scan initiated at 0 V versus SCE in the positive
direction. Scan rate (V): (a) 200, (b) 100, (c) 50 mV/s. ESCE1/2 ) +0.68 V.
Oxidation of 1 also produces a shortening of the terminal
Os-Cl distances. Thus, the Os(1)-Cl(1) and Os(2)-Cl(4)
bond lengths, 2.3900(14) and 2.3920(14) Å, respectively, are
statistically identical and about 0.014 Å shorter than the
terminal Os-Cl distances in 1. Like in the latter, the terminal
Os-Cl distances in 2 are about 0.04 Å shorter than the
bridging Os-Cl bond lengths, between 2.4279(14) and
2.4380(14) Å. The distances between the coordinated C(sp2)
atoms of the 1,5-cyclooctadiene ligands, between 1.382(8)
and 1.407(8) Å, as well as the Os-C(sp2) bond lengths,
between 2.148(6) and 2.191(6) Å, compare well with those
of 1.
Figure 6. Molecular diagram of complex 2. Selected bond lengths (Å):
Os(1)-Cl(1) 2.3900(14), Os(1)-Cl(2) 2.4380(14), Os(1)-Cl(3) 2.4360-
(14), Os(2)-Cl(2) 2.4371(14), Os(2)-Cl(3) 2.4279(14), Os(2)-Cl(4)
2.3920(14), Os(1)-H(01) 1.6823, Os(2)-H(01) 2.0031, Os(1)-C(1) 2.196-
(6), Os(1)-C(2) 2.158(6), Os(1)-C(5) 2.148(6), Os(1)-C(6) 2.187(6), Os-
(2)-C(9) 2.180(6), Os(2)-C(10) 2.165(6), Os(2)-C(13) 2.165(6), Os(2)-
C(14) 2.191(6), C(1)-C(2) 1.395(8), C(5)-C(6) 1.382(8), C(9)-C(10)
1.406(8), C(13)-C(14) 1.407(8), Os(1)‚‚‚Os(2) 2.6696(4).
3. Reactions of 1a with Main-Group Organometallic
Compounds. Treatment of 1a with 2.5 equiv of sodium
cyclopentadienyl in toluene at room temperature gives rise
to replacement of one of the terminal chlorine ligands of
the starting compound by a cyclopentadienyl group to afford
the η1-cyclopentadienyl derivative [NBu4][{Os(η1-C5H5)(η4-
COD)}(µ-H)(µ-Cl)2{OsCl(η4-COD)}] (3). This complex was
isolated as a red solid in 70% yield. The solid is a 3:2 mixture
of the two possible isomers resulting from σ coordination
of the five-membered ring through a C(sp2) atom disposed
in the R position (a) or alternating in the â position (b) with
regard to the C(sp3) atom (Scheme 1).
) 0.08 V) to give 2 with ESCE(2,1) ) +0.68 V. This value
corresponds to E°(2,1) ) +0.92 V.30 Since E°(O2,H2O) )
1.23 V, one should expect the oxidation of 1 to afford 2 by
action of atmospheric oxygen, according to eq 2. In fact,
when a benzene solution of 1 is left to stand at room
temperature for 24 h under air, complex 2 is formed.
Figure 7 shows a view of the structure of the anion of
isomer 3a. The species can be described as an asymmetrical
dimer formed by the conical Os(η1-C5H5)(η4-COD) and
OsCl(η4-COD) moieties, which are joined by two bridging
chlorine atoms and a bridging hydride ligand. The separation
between the metal centers, 2.8633(5) Å, agrees well with
that of 1. The cyclopentadienyl group is bonded to one of
the osmium atoms with an Os(1)-C(1) bond length of 2.089-
(7) Å, which compares well with the Os-C(sp2) single bond
distances found in osmium-alkenyl complexes.23e,31
Paramagnetic complex 2 was isolated as dark green
needles in 68% yield and characterized by X-ray diffraction
analysis. Figure 6 shows a view of the molecular geometry.
The molecule can be described as a bioctahedral face-
shared M2L9 dimer with OsCl(η4-COD) units, two bridging
chlorine atoms, Cl(2) and Cl(3), and a bridging hydride
ligand, H(01). At 100 K, the hydride was located in the
difference Fourier maps. However, in contrast to that of 1,
it does not refine. The obtained Os-H distances, 1.6823 (Os-
(1)-H(01)) and 2.0031 (Os(2)-H(01)) Å, are certainly
underestimated. In this context, it should be mentioned that
DFT calculations on the structure of 2 yield Os-H distances
The C(1)-C(2) distance of 1.370(9) Å is statistically
identical with the C(3)-C(4) bond length, 1.354(11) Å, and
both of them agree with the average carbon-carbon distance
(31) See, for example: (a) Werner, H.; Esteruelas, M. A.; Otto, H.
Organometallics 1986, 5, 2295. (b) Werner, H.; Weinand, R.; Otto,
H. J. Organomet. Chem. 1986, 307, 49. (c) Espuelas, J.; Esteruelas,
M. A.; Lahoz, F. J.; Oro, L. A.; Valero, C. Organometallics 1993,
12, 663. (d) Buil, M. L.; Esteruelas, M. A.; Lo´pez, A. M.; On˜ate, E.
Organometallics 1997, 16, 3169. (e) Esteruelas, M. A.; Garc´ıa-Yebra,
C.; Oliva´n, M.; On˜ate, E.; Tajada, M. A. Organometallics 2000, 19,
5098. (f) Castarlenas, R.; Esteruelas, M. A.; On˜ate, E. Organometallics
2001, 20, 2294. (g) Barrio, P.; Esteruelas, M. A.; On˜ate, E. J. Am.
Chem. Soc. 2004, 126, 1946. (h) Bolan˜o, T.; Castarlenas, R.;
Esteruelas, M. A.; On˜ate, E. J. Am. Chem. Soc. 2006, 128, 3965.
(30) E° ) ESCE + 0.24.
10166 Inorganic Chemistry, Vol. 45, No. 25, 2006

Characterization of NoWel Os-Diolefin Dimers
Scheme 1
Figure 7. Molecular diagram of the anion of 3a. Selected bond lengths
(Å): Os(1)-Cl(1) 2.4522(17), Os(1)-Cl(2) 2.4585(16), Os(2)-Cl(1)
2.4409(18), Os(2)-Cl(2) 2.4703(15), Os(2)-Cl(3) 2.4292(14), Os(1)-C(1)
2.089(7), Os(1)-C(6) 2.143(6), Os(1)-C(7) 2.113(7), Os(1)-C(10) 2.138-
(6), Os(1)-C(11) 2.134(6), Os(2)-C(14) 2.139(6), Os(2)-C(15) 2.116-
(5), Os(2)-C(18) 2.072(8), Os(2)-C(19) 2.135(6), C(1)-C(2) 1.370(9),
C(2)-C(3) 1.472(10), C(3)-C(4) 1.354(11), C(4)-C(5) 1.451(11), C(1)-
C(5) 1.506(10), C(6)-C(7) 1.410(9), C(10)-C(11) 1.409(9), C(14)-C(15)
1.408(8), C(18)-C(19) 1.407(9), Os(1)‚‚‚Os(2) 2.8633(5).
NMR spectrum the cyclopentadienyl resonances appear at
148.4 (CH), 135.4 (OsC), 134.4 and 126.9 (CH), and 42.2
(CH2) ppm, while the C(sp2) resonances of the dienes are
observed at 61.4, 61.3, 57.0, and 56.4 ppm. In this case, in
the 1H, 13C{1H}-HMBC spectrum, the CH2 1H resonance at
3.09 ppm has cross-peaks with the C(sp2) 13C resonances at
126.9 and 148.4 ppm.
for a C(sp2)-C(sp2) double bond (1.32(1) Å).32 The C(2)-
C(3) bond length of 1.472(10) Å also compares well with
the distance expected for a C(sp2)-C(sp2) single bond (about
1.48 Å). The C(1)-C(5) and C(4)-C(5) distances are 1.506-
(10) and 1.451(11) Å, respectively.
The methoxide group of [Ir(µ-OMe)(olefin)]2 complexes
has shown to be a very good leaving group in reactions with
molecules containing relatively acidic protons.33 This prompted
us to investigate the reaction of 3 with [Ir(µ-OMe)(η4-COD)]2
since one should expect that the CH2 group of the coordinated
cyclopentadienyl ligand was fairly acidic. Treatment of 3
with the iridium dimer in a 2:1 molar ratio, in acetone at
room temperature, leads to a red-brown solution from which
the trinuclear species [NBu4][{(η4-COD)Ir(η5-C5H4-η1)Os-
(η4-COD)}(µ-H)(µ-Cl)2{OsCl(η4-COD)} ] (4) is isolated as
red-brown needles in 54% yield according to Scheme 1.
Complex 4 has been characterized by X-ray diffraction
analysis. Figure 8 shows an ORTEP drawing of the anion.
The structure proves the formation of 4 containing a bridging
five-membered C5H4 ligand which is η1-coordinated to an
osmium atom of the dimeric unit and η5-coordinated to the
Ir(η4-COD) moiety. Complexes containing this type of ligand
are rare.34 Some examples involving osmium include {µ2-
η1:η5-C5(tBu)2H2}2Os2(CO)435 and [{Os(η5-C5H5)}2(µ2-η1:η5-
C5H4)2][PF6]2.36
The 1H and 13C{1H} NMR spectra of 3a in dichlo-
romethane-d2 at room temperature are consistent with the
structure shown in Figure 7. The cyclopentadienyl protons
display four resonances in the 1H NMR spectrum. Those due
to the C(sp2)-H protons are observed between 6.51 and 6.45
and at 6.39 ppm, while that corresponding to the CH2 group
appears at 3.39 ppm. The resonances due to the C(sp2)H
protons of the coordinated dienes are observed between 3.85
and 3.43 ppm. The hydride resonance appears at -13.65
ppm. In the 13C{1H} NMR spectrum the C(sp2) resonances
of the cyclopentadienyl ligands are observed at 145.7 (OsC),
135, 133.5, and 131.7 (CH), while the CH2 resonance appears
at 53.6 ppm. The C(sp2) atoms of the dienes display singlets
at 62.1, 61.5, 57.4, and 57.1 ppm. In agreement with
coordination of the cyclopentadienyl ligand to the osmium
atom by a CR atom with regard to the CH2 group, the 1H,13C-
{1H} HMBC spectrum shows cross-peaks between the CH2
resonance at 3.39 ppm and the C(sp2) 13C resonances at 145.7
and 133.5 ppm.
Deprotonation of the CH2 group of the C5H5 ligand of 3
and subsequent coordination of the Ir(η4-COD) unit has no
influence on the σ-Os bond. Thus, the Os(1)-C(1) distance,
1
The H and 13C{1H} NMR spectra of 3b are consistent
1
with those of 3a. In the H NMR spectrum the cyclopenta-
(33) Esteruelas, M. A.; Oro, L. A. Coord. Chem. ReV. 1999, 193-195,
557.
(34) (a) Cullen, W. R.; Rettig, S. J.; Zheng, T.-C. Organometallics 1992,
11, 277. (b) Cullen, W. R.; Rettig, S. J.; Zheng, T.-C. Can. J. Chem.
1993, 71, 1. 399. (c) Cullen, W. R.; Rettig, S. J.; Zheng, T.-C. J.
Organomet. Chem. 1993, 452, 97.
dienyl resonances appear at 6.98, 6.26, and 6.19 (CH) and
3.09 (CH2) ppm, while the C(sp2)H resonances of the dienes
are also observed between 3.85 and 3.43 ppm. The hydride
ligand gives rise to a singlet at -13.52 ppm. In the 13C{1H}
(35) Zhu, B.; Miljanic´, O. Sˇ.; Vollhardt, K. P. C.; West, M. J. Synthesis
2005, 3373.
(32) Orpen, G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D. G.;
(36) Droege, M. W.; Harman, W. D.; Taube, H. Inorg. Chem. 1987, 26,
1309.
Taylor, R. J. Chem. Soc., Dalton Trans 1989, S1.
Inorganic Chemistry, Vol. 45, No. 25, 2006 10167

Esteruelas et al.
ppm. The 1H NMR spectrum contains the hydride resonance
at -8.00 ppm.
Concluding Remarks
This study shows the preparation, characterization, and first
reactions of a novel osmium-1,5-cyclooctadiene starting
material obtained from a commercially available inorganic
salt. In contrast to ruthenium, treatment of OsCl3‚3H2O with
1,5-cyclooctadiene in ethanol under reflux leads to the salt
[H(EtOH)2][{OsCl(η4-COD)}2(µ-H)(µ-Cl)2], where the anion
can be described as two conical OsCl(η4-COD) moieties
joined by two bridging chlorine atoms and a hydride ligand.
Although the separation between the osmium atoms is short,
a topological analysis of the electron density in the region
between the osmium atoms, on the basis of Bader’s atom-
in-molecules theory, indicates the absence of a direct metal-
metal interaction. In agreement, DFT calculations show that
the 12 electrons of the d6 centers occupy all osmium bonding
and antibonding orbitals.
The DFT calculations also indicate that the HOMO of the
dimer anion is poorly stabilized. As a consequence, it is easily
oxidized to afford the neutral species {OsCl(η4-COD)}2(µ-
H)(µ-Cl)2, with a stabilized half-occupied HOMO orbital and
an osmium-osmium bond order of 0.5. The terminal chlorine
ligands of the dimer anion are activated toward nucleophilic
substitution. Thus, reaction of the [NBu4] salt with LiCt
CPh and NaCp leads to [NBu4][{Os(CtCPh)(η4-COD)}2-
(µ-H)(µ-Cl)2] and [NBu4][{Os(η1-C5H5)(η4-COD)}(µ-H)(µ-
Cl)2{OsCl(η4-COD)}], respectively. The CH2 group of the
cyclopentadienyl ligand of the latter is easily deprotonated
by the bridging methoxy ligand of the dimer [Ir(µ-OMe)-
(η4-COD)]2 to give the trinuclear derivative [NBu4][{(η4-
COD)Ir(η5-C5H4-η1)Os(η4-COD)}(µ-H)(µ-Cl)2{OsCl(η4-
COD)}] containing a bridging five-membered C5H4 ligand
which is η1-coordinated to an osmium atom of the dimeric
unit and η5-coordinated to the Ir(η4-COD) moiety.
Figure 8. Molecular diagram of the anion of 4. Selected bond lengths
(Å): Os(1)-Cl(1) 2.4343(2), Os(1)-Cl(2) 2.469(2), Os(2)-Cl(1) 2.452-
(3), Os(2)-Cl(2) 2.468(2), Os(2)-Cl(3) 2.416(3), Os(1)-C(1) 2.117(10),
Os(1)-C(14) 2.131(9), Os(1)-C(15) 2.138(10), Os(1)-C(18) 2.124(10),
Os(1)-C(19) 2.132(10), Os(2)-C(22) 2.118(10), Os(2)-C(23) 2.153(10),
Os(2)-C(26) 2.139(9), Os(2)-C(27) 2.120(11), Ir-C(1) 2.322(9), Ir-C(2)
2.260(10), Ir-C(3) 2.235(10), Ir-C(4) 2.225(10), Ir-C(5) 2.183(9), Ir-
C(6) 2.112(9), Ir-C(7) 2.125(9), Ir-C(10) 2.083(10), Ir-C(11) 2.124(8),
C(6)-C(7) 1.437(14), C(10)-C(11) 1.439(5), C(14)-C(15) 1.438(14),
C(18)-C(19) 1.406(15), C(22)-C(23) 1.452(16), C(26)-C(27) 1.414(14),
Os(1)‚‚‚Os(2) 2.8598(6).
2.117(10) Å, is statistically identical with the Os(1)-C(1)
bond length in 3a. The C5H4 ligand coordinates to the iridium
atom with Ir-C distances between 2.183(9) and 2.322(9)
Å, which agree well with those reported for related half-
sandwich iridium compounds.37
The 1H and 13C{1H} NMR spectra of 4 in dichlo-
romethane-d2 at room temperature are consistent with the
1
structure shown in Figure 8. In the H NMR spectrum the
C5H4 ligand gives rise to an AA′BB′ spin system between
5.0 and 5.3 ppm. The hydride resonance is observed at
-14.31 ppm. In the 13C{1H} NMR spectrum the resonances
due to the C5H5 ligands appear at 89.9 (OsC) and 92.9 and
77.5 (CH) ppm, whereas those corresponding to the C(sp2)
atoms of the dienes bonded to osmium are observed at 61.7,
61.6, 57.1, and 56.7 ppm. The C(sp2) atoms of the diene
coordinated to iridium give rise to a singlet at 45.2 ppm.
The latter agrees well with those previously reported for Ir-
(η5-C5R5)(η4-COD) complexes.38
Complex 1a also reacts with lithium phenylacetylide. The
reaction leads to the bis(acetylide) derivative [NBu4][{Os-
(CtCPh)(η4-COD)}2(µ-H)(µ-Cl)2] (5) as a result of the
replacement of both terminal chlorine atoms of the starting
compound by alkynyl ligands. Complex 5 is isolated as dark
yellow crystals in 73% yield according to Scheme 1.
The presence of the alkynyl ligands in the complex is
mainly supported by the IR and 13C{1H} NMR spectra. In
the IR spectrum in KBr, the most noticeable feature is a Ct
C band at 2105 cm-1. In the 13C{1H} NMR spectrum the
resonances due to the C(sp) atoms of the alkynyl groups
appear at 110.3 and 96.1 ppm. In agreement with 1, the
spectrum also shows two olefinic resonances at 58.4 and 55.7
In conclusion, we report the preparation and full charac-
terization of the dimer [{OsCl(η4-COD)}2(µ-H)(µ-Cl)2]-,
which is directly obtained from OsCl3‚3H2O, and it is
particularly useful for development of the dinuclear chemistry
of the Os(η4-COD) moiety.
Experimental Section
All reactions were carried out under an argon atmosphere using
Schlenk tube techniques. Solvents were dried and purified by known
procedures and distilled under argon prior to use. Infrared spectra
were recorded on a Spectrum One spectrometer as solids (KBr
pellets). 1H, 13C{1H}, and 31P{1H} NMR spectra were recorded on
a Varian GEMINI 2000-300 MHz, a Bruker Avance 300, or a
Bruker ARX Avance 400 spectrometer. Chemical shifts are
referenced to residual solvent peaks (1H, 13C{1H}) or external H3-
PO4 (85%) (31P{1H}). Coupling constants, J, are given in hertz.
MALDI-MS measurements were performed on a reflex time-of-
flying instrument (Bruker Daltonics Microflex Analyser) equipped
with a target micro-SCOUT ion source, operating in the negative
reflection mode with pulsed extraction. Ions were formed by a
pulsed UV laser beam (nitrogen laser, λ ) 337 nm) and using
dithranol (DIT) as a matrix. Cyclic voltammetric studies were
performed under argon using an EG&G model 273 potentiostat in
(37) See, for example: (a) Pannetier, G.; Tabrizi, D.; Bannaire, R. J. Less-
Common Met. 1971, 24, 470. (b) Day, V. W.; Eberspacher, T. A.;
Klemperer, W. G.; Zhong, B. J. Am. Chem. Soc. 1994, 116, 3119. (c)
Komatsu, H.; Yamazaki, H. J. Organomet. Chem. 2001, 634, 109.
(38) Sowa, J. R.; Angelici, R. J. J. Am. Chem. Soc. 1991, 113, 2537.
10168 Inorganic Chemistry, Vol. 45, No. 25, 2006

Characterization of NoWel Os-Diolefin Dimers
conjunction with a three-electrode cell. The three-electrode system
consists of a platinum disk working electrode, a platinum wire
auxiliary electrode, and a saturated calomel reference electrode
(SCE) separated from the test compartment by a fine-porosity frit.
C, H, and N analyses were measured on a Perkin-Elmer 2400
CHNS/O analyzer. [Ir(µ-OMe)(η4-COD)]2 was prepared as reported
previously.39
{OsCl(η4-COD)}2(µ-H)(µ-Cl)2 (2). A solution of 1 (50 mg, 0.06
mmol) in a minimum amount of benzene was left to stand at room
temperature 24 h in the air. The initially dark green solution turned
purple, and dark green crystals were isolated (30 mg, 0.04 mmol,
68%). Anal. Calcd for C16H25Cl4Os2: C, 25.98; H, 3.41. Found:
C, 26.00; H, 3.31. IR (KBr, cm-1): 1616 (νCdC). MS (MALDI-
TOF): m/z 741 (100), [M]-.
Preparation of [H(EtOH)2][{OsCl(η4-COD)}2(µ-H)(µ-Cl)2]
(1). A solution of OsCl3‚3H2O (54%) (1 g, 2.84 mmol) and 1,5-
cyclooctadiene (2.8 mL, 22.6 mmol) in ethanol (30 mL) was
refluxed for 60 h. After that, the solvent was replaced by pentane
to precipitate a dark green solid that was washed twice with pentane
and dried in vacuo (900 mg, 1.08 mmol, 76% yield). Anal. Calcd
for C20H38Cl4O2Os2: C, 28.84; H, 4.60. Found: C, 28.97; H, 4.21.
IR (KBr, cm-1): 2042, 1967 [νOH (H(EtOH)2)]. MS (MALDI-
Preparation of [NBu4][{Os(η1-C5H5)(η4-COD)}(µ-H)(µ-Cl)2-
{OsCl(η4-COD)}] (3). To a mixture of complex 1a (322 mg, 0.33
mmol) and NaCp (72.2 mg, 0.82 mmol) was added toluene (9 mL)
at room temperature. The reaction mixture was stirred for 4 h and
then filtered to separate salts. The filtrate was dried in vacuo, and
the brown-red residue was washed twice with pentane to give a
red solid. A 3:2 mixture of isomers 3a:3b was obtained (235 mg,
0.23 mmol, 70%). Anal. Calcd for C37H66Cl3NOs2: C, 43.92; H,
6.58; N, 1.38. Found: C, 43.84; H, 6.13; N, 1.41. MS (MALDI-
TOF): m/z 771 (100), [M]-. Major isomer 3a. 1H NMR (400 MHz,
CD2Cl2, 293 K): δ 6.51-6.45 (2 H, CH-C5H5), 6.39 (m, 1 H,
CH-C5H5), 3.85-3.78 (2 H, CH-COD), 3.60-3.52 (4 H, CH-
COD), 3.52-3.43 (2 H, CH-COD), 3.39 (m, 2 H, CH2-C5H5),
3.10 [m, 8 H, N(CH2CH2CH2CH3)4], 2.52-2.32 (6 H, CH2-COD),
2.08-1.90 (4 H, CH2-COD), 1.80-1.66 (6 H, CH2-COD), 1.57
[m, 8 H, N(CH2CH2CH2CH3)4], 1.40 [m, 8 H, N(CH2CH2CH2-
1
TOF): m/z 741 (100), [M]-. H NMR (300 MHz, C6D6, 293 K):
δ 11.42 [br s, 3 H, H(EtOH)2], 4.64-4.54 (4 H, CH-COD), 4.28-
4.16 (4 H, CH-COD), 3.51 (q, 3JHH ) 6.8 Hz, 4 H, CH3CH2OH),
2.88-2.61 (4 H, CH2-COD), 2.20-1.90 (12 H, CH2-COD), 0.85
(t, 3JHH ) 6.8 Hz, 6 H, CH3CH2OH), -21.03 (s, 1 H, Os-H). 13C-
{1H} NMR (75.47 MHz, C6D6, 293 K): δ 67.1, 62.5 (both s, CH-
COD), 60.4 (s, CH3CH2OH), 35.8, 31.2 (both s, CH2-COD), 15.3
(s, CH3CH2OH).
Preparation of [NBu4][{OsCl(η4-COD)}2(µ-H)(µ-Cl)2] (1a).
A solution of 1 (1.10 g, 1.32 mmol) and [NBu4][PF6] (560 mg,
1.45 mmol) in ethanol (40 mL) was stirred overnight at room
temperature. The reaction evolves with formation of a green
precipitate that was isolated by filtration and washed twice with
diethyl ether (973 mg, 0.99 mmol, 75% yield). Anal. Calcd for
C32H61Cl4NOs2: C, 39.13; H, 6.26; N, 1.43. Found: C, 39.23; H,
6.04; N, 1.20. 1H NMR (400 MHz, C6D6, 293 K): δ 4.70-4.55 (4
H, CH-COD), 4.35-4.25 (4 H, CH-COD), 3.02-2.90 (4 H,
CH2-COD), 2.80 [m, 8 H, N(CH2CH2CH2CH3)4], 2.30-2.07 (12
H, CH2-COD), 1.30-1.15 [16 H, N(CH2CH2CH2CH3)4], 0.83 [t,
3JHH ) 7.0 Hz, 12 H, N(CH2CH2CH2CH3)4], -19.6 (s, 1 H, Os-
H). 13C{1H} NMR (100.62 MHz, C6D6, 293 K): δ 66.0, 60.9 (both
s, CH-COD), 58.5 [s, N(CH2CH2CH2CH3)4], 36.2, 31.8 (both s,
CH2-COD), 24.3 [s, N(CH2CH2CH2CH3)4], 20.1 [s, N(CH2CH2CH2-
CH3)4], 14.0 [s, N(CH2CH2CH2CH3)4].
3
CH3)4], 1.00 [t, JHH ) 7.2, 12 H, N(CH2CH2CH2CH3)4], -13.65
(s, 1 H, Os-H). 13C{1H} NMR (100.62 MHz, CD2Cl2, 293 K): δ
145.7 (s, COs, C5H5), 135.0, 133.5, 131.7 (all s, CH, C5H5), 62.1,
61.5, 57.4, 57.1 (all s, CH-COD), 59.5 [s, N(CH2CH2CH2CH3)4],
53.6 (s, CH2COs, C5H5), 36.5, 34.7, 33.1, 31.2 (all s, CH2-COD),
24.6 [s, N(CH2CH2CH2CH3)4], 20.6 [s, N(CH2CH2CH2CH3)4], 14.1
1
[s, N(CH2CH2CH2CH3)4]. Minor isomer 3b. H NMR (400 MHz,
CD2Cl2, 293 K): δ 6.98 (m, 1 H, CH-C5H5), 6.26 (m, 1 H, CH-
C5H5), 6.19 (m, 1 H, CH-C5H5), 3.85-3.78 (2 H, CH-COD),
3.60-3.52 (4 H, CH-COD), 3.52-3.43 (2 H, CH-COD), 3.09
(m, 2 H, CH2-C5H5, overlapped signal), 3.09 [m, 8 H, N(CH2-
CH2CH2CH3)4], 2.52-2.32 (6 H, CH2-COD), 2.08-1.90 (4 H,
CH2-COD), 1.80-1.66 (6 H, CH2-COD), 1.57 [m, 8 H, N(CH2CH2-
3
CH2CH3)4], 1.39 [m, 8 H, N(CH2CH2CH2CH3)4], 1.00 [t, JHH
)
7.2, 12 H, N(CH2CH2CH2CH3)4], -13.52 (s, 1 H, Os-H). 13C-
{1H} NMR (100.62 MHz, CD2Cl2, 293 K): δ 148.4 (s, CHCOs,
C5H5), 135.4 (s, COs, C5H5), 134.4 (s, CHCHCOs, C5H5), 126.9
(s, CH2CHCOs, C5H5), 61.4, 61.3, 57.0, 56.4 (all s, CH-COD),
59.5 [s, N(CH2CH2CH2CH3)4], 42.2 (s, CH2CHCOs, C5H5), 36.5,
34.7, 33.1, 31.2 (all s, CH2-COD), 24.6 [s, N(CH2CH2CH2CH3)4],
20.3 [s, N(CH2CH2CH2CH3)4], 14.1 [s, N(CH2CH2CH2CH3)4].
Preparation of [PPh3(CH2Ph)][{OsCl(η4-COD)}2(µ-H)(µ-
Cl)2] (1b). A solution of 1 (779 mg, 0.93 mmol) and [PPh3(CH2-
Ph)]Cl (364 mg, 0.93 mmol) in ethanol (30 mL) was stirred
overnight at room temperature. The reaction evolves with formation
of a green precipitate that was isolated by filtration and washed
once with ethanol and twice with diethyl ether (826 mg, 0.75 mmol,
81% yield). Anal. Calcd for C41H47Cl4Os2P: C, 45.05; H, 4.23.
Preparation of [NBu4][{(η4-COD)Ir(η5-C5H4-η1)Os(η4-COD)}-
(µ-H)(µ-Cl)2{OsCl(η4-COD)}] (4). To a mixture of complexes 3
(100 mg, 0.1 mmol) and [Ir(µ-OMe)(COD)]2 (33 mg, 0.05 mmol)
was added 3 mL of acetone, and the reaction was stirred at room
temperature for 22 h. The red-brown solution thus obtained was
dried in vacuo, and the residue was recrystallized in a mixture CH2-
Cl2/pentane to give red-brown needles (70 mg, 0.05 mmol, 54%).
Anal. Calcd for C45H77Cl3IrNOs2: C, 41.22; H, 5.92; N, 1.07.
1
Found: C, 45.06; H, 4.35. H NMR (300 MHz, CD2Cl2, 293 K):
δ 7.83 [m, 3 H, P(C6H5)3], 7.74-7.44 [12 H, P(C6H5)3], 7.30 (m,
1 H, PCH2C6H5), 7.20 (m, 2 H, PCH2C6H5), 7.01 (m, 2 H,
PCH2C6H5), 4.88 (d, 2JHP ) 14.1 Hz, 2 H, PCH2C6H5), 4.05-3.79
(8 H, CH-COD), 2.57-2.39 (4 H, CH2-COD), 2.36-2.10 (8 H,
CH2-COD), 2.08-1.93 (4 H, CH2-COD), -20.15 (s, 1 H, Os-
H). 13C{1H} NMR (75.5 MHz, CD2Cl2, 293 K): δ 135.9 (d, JCP
)
1
Found: C, 41.39; H, 5.69; N, 1.09. H NMR (400 MHz, CD2Cl2,
2.5 Hz, arom-CH, PCH2Ph), 135.1 (d, 3JCP ) 9.7 Hz, m-CH, PPh3),
293 K): δ 5.30-5.00 (AA′BB′, 4 H, C5H4), 3.78 (m, 2 H, CH-
COD-Os), 3.68-3.62 (4 H, CH-COD-Ir), 3.59 (m, 2 H, CH-
COD-Os), 3.52 (m, 2 H, CH-COD-Os), 3.46 (m, 2 H, CH-
COD-Os), 3.15 [m, 8 H, N(CH2CH2CH2CH3)4], 2.64-2.58 (2 H,
CH2-COD-Os), 2.51-2.45 (2 H, CH2-COD-Os), 2.42-2.36 (4
H, CH2-COD-Os), 2.07-2.00 (2 H, CH2-COD-Os), 2.02-1.95
(4 H, CH2-COD-Ir), 1.85-1.78 (6 H, CH2-COD-Os), 1.72 (m,
4 H, CH2-COD-Ir), 1.61 [m, 8 H, N(CH2CH2CH2CH3)4], 1.52
4
2
132.1 (d, JCP ) 5.5 Hz, p-CH, PPh3), 130.9 (d, JCP ) 12.4 Hz,
o-CH, PPh3), 129.6 (d, JCP ) 3.7 Hz, arom-CH, PCH2Ph), 129.3
1
(d, JCP ) 3.7 Hz, arom-CH, PCH2Ph), 127.7 (d, JCP ) 8.3 Hz,
ipso-C, PCH2C6H5), 117.9 [d, 1JCP ) 86.0 Hz, ipso-C, PPh3], 65.8,
61.1 (both s, CH-COD), 36.1, 31.5 (both s, CH2-COD), 32.05
1
(d, JCP ) 47.9 Hz, PCH2Ph). 31P{1H} NMR (121.5 MHz, CD2-
Cl2, 293 K): δ 25.0.
3
[m, 8 H, N(CH2CH2CH2CH3)4], 1.04 [t, JHH ) 7.2 Hz, 12 H,
(39) Uso´n, R.; Oro, L. A.; Cabeza, J. A. Inorg. Synth. 1985, 23, 126.
N(CH2CH2CH2CH3)4], -14.31 (s, 1 H, Os-H). 13C{1H} NMR
Inorganic Chemistry, Vol. 45, No. 25, 2006 10169

Esteruelas et al.
Table 1. Crystal Data Collection and Refinement for 1, 2, 3a, and 4
1
2
3a
4
crystal data
formula
mol wt
C16H25Cl4Os2‚C4H13O2
832.70
C16H25Cl4Os2‚2C6H6
895.78
C37H66Cl3NOs2
1011.66
C45H77Cl3IrNOs2
1311.03
color and habit
size, mm
symmetry, space group
irregular block, dark orange
0.24, 0.24, 0.16
monoclinic, P2(1)
9.0837(14)
8.6975(13)
15.876(2)
97.064(3)
1244.7(3)
2
irregular block, orange
0.26, 0.08, 0.08
monoclinic, P2(1)/n
10.8680(15)
15.263(2)
16.438(2)
90.322(2)
2726.7(6)
4
orange, prism
0.18, 0.06, 0.04
orthorhombic, Pna2(1)
17.941(3)
12.671(2)
16.640(3)
orange, prism
0.36, 0.10, 0.06
orthorhombic, Pbcn
39.752(4)
11.0636(12)
19.758(2)
a, Å
b, Å
c, Å
â, deg
V, Å3
Z
3782.7(11)
4
1.776
8689.6(16)
8
2.004
D
calcd, g cm-3
2.222
2.182
data collection and refinement
diffractometer
λ(Mo-KR), Å
monochromator
scan type
Bruker Smart APEX
0.71073
graphite oriented
ω scans
10.642
µ, mm-1
9.720
6.950
9.107
2θ, range deg
temp, K
4, 58
223.0(2)
4, 58
4, 57
4, 58
100.0(2)
33757
6776 (Rint ) 0.0631)
333/0
100.0(2)
32331
9174 (Rint ) 0.0584)
437/6
0.007(6)
0.0327
0.0457
100.0(2)
104440
11076 (Rint ) 0.1000)
487/134
no. of data collect
no. of unique data
no. of params/restrains
Flack parameter
R1a [F2 > 2σ(F2)]
wR2b [all data]
Sc [all data]
15632
6002 (Rint ) 0.0446)
266/3
0.001(12)
0.0394
0.0848
0.0340
0.0631
0.958
0.0539
0.1241
1.024
0.961
0.816
2
2
2
2
2
a R1(F) ) ∑||Fo| - |Fc||/∑|Fo|. b wR2(F2) ) {∑[w(Fo - Fc )2]/∑[ w(Fo )2]}1/2
.
c Goof ) S ) {∑[Fo - Fc )2]/(n - p)}1/2, where n is the number of
reflections and p is the number of refined parameters.
(100.62 MHz, CD2Cl2, 293 K): δ 92.9 (s, CHCOs, C5H4), 89.9 (s,
COs, C5H4), 77.5 (s, CHCHCOs, C5H4), 61.7, 61.6 (both s, CH-
COD-Os), 59.0 [s, N(CH2CH2CH2CH3)4], 57.1, 56.7 (both s, CH-
COD-Os), 45.2 (s, CH-COD-Ir), 35.9, 34.6 (both s, CH2-
COD-Os), 34.3 (s, CH2-COD-Ir), 32.3, 30.7 (both s, CH2-
COD-Os),24.0[s,N(CH2CH2CH2CH3)4],19.8[s,N(CH2CH2CH2CH3)4],
13.5 [s, N(CH2CH2CH2CH3)4].
at the B3LYP-DFT level with the Gaussian 03 program.40 The basis
sets used were LANL2DZ basis and pseudopotentials for Os,
6-31G(d,p) for hydrogens and 6-31G(d) for the rest of atoms.
Structural Analysis of Complexes 1, 2, 3a, and 4. X-ray data
were collected for all complexes on a Bruker Smart APEX CCD
diffractometer equipped with a normal focus, 2.4 kW sealed tube
source (Mo radiation, λ ) 0.71073 Å) operating at 50 kV and 30
(1, 3a, and 4) or 40 (2) mA. Data were collected over the complete
sphere. Each frame exposure time was 10 s (20 s for 3a) covering
0.3° in ω. Data were corrected for absorption using a multiscan
method applied with the SADABS program.41 The structures of
all compounds were solved by the Patterson method. Refinement,
by full-matrix least squares on F2 with SHELXL97,42 was similar
for all complexes, including isotropic and subsequently anisotropic
displacement parameters for non-hydrogen atoms. Hydrogen atoms
Preparation of [NBu4][{Os(CtCPh)(η4-COD)}2(µ-H)(µ-Cl)2]
(5). To a mixture of complex 1a (350 mg, 0.36 mmol) and PhCt
CLi (175 mg, 1.62 mmol) was added THF (10 mL) at -60 °C,
and the reaction was stirred while the temperature was slowly
raising to 0 °C (3 h). Then, the solvent was removed in vacuo, and
the product was extracted with CH2Cl2 (2 × 3 mL) and recrystal-
lized in CH2Cl2/Et2O mixture to give dark yellow crystals (289
mg, 0.26 mmol, 73%). Anal. Calcd for C48H71Cl2NOs2: C, 51.78;
H, 6.43; N, 1.26. Found: C, 51.67; H, 6.06; N, 1.26. IR (KBr,
cm-1): ν 2105 (νCtC). MS (MALDI-TOF): m/z 871 (100), [M]-.
(40) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.; Kudin,
K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone,
V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G.
A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.;
Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,
O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P.
Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas,
O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J.
B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.;
Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.;
Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.;
Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen,
W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, Revision
C.02; Gaussian, Inc.: Wallingford, CT, 2004.
3
1H NMR (300 MHz, CD2Cl2, 293 K): δ 7.41 (d, JHH ) 7.2 Hz,
3
3
4 H, o-C6H5), 7.24 (dd, JHH ) 7.5 Hz, JHH ) 7.2 Hz, 4 H,
3
m-C6H5), 7.07 (t, JHH ) 7.5 Hz, 2 H, p-C6H5), 3.55-3.35 (8 H,
CH-COD), 3.00 [m, 8 H, N(CH2CH2CH2CH3)4], 2.73-2.65 (4 H,
CH2-COD), 2.62-2.53 (m, 4 H, CH2-COD), 1.96-1.85 (m, 4
H, CH2-COD), 1.85-1.76 (4 H, CH2-COD), 1.53-1.27 [16 H,
3
N(CH2CH2CH2CH3)4], 1.00 [t, JHH ) 7.2 Hz, 12 H, N(CH2CH2-
CH2CH3)4], -8.00 (s, 1 H, Os-H).13C{1H} NMR (75 MHz, CD2-
Cl2, 293 K): δ 131.7 (s, o-C6H5), 128.4 (s, m-C6H5), 124.6 (s,
p-C6H5), 110.3 (s, CtCPh), 96.1 (s, CtCPh), 59.6 [s, N(CH2CH2-
CH2CH3)4], 58.4, 55.7 (both s, CH-COD), 35.2, 32.8 (both s,
CH2-COD), 24.5 [s, N(CH2CH2CH2CH3)4], 20.3 [s, N(CH2CH2CH2-
CH3)4], 14.1 [s, N(CH2CH2CH2CH3)4].
(41) Blessing, R. H. Acta Crystallogr. 1995, A51, 33. SADABS: Area-
detector absorption correction; Bruker- AXS: Madison, WI, 1996.
(42) SHELXTL Package (V) 6.10; Bruker-AXS: Madison, WI, 2000.
Sheldrick, G. M. SHELXS-86 and SHELXL-97; University of Go¨ttin-
gen: Go¨ttingen, Germany, 1997.
Computational Details. Theoretical calculations were carried
out on the model complexes (1 and 2) by optimizing the structure
10170 Inorganic Chemistry, Vol. 45, No. 25, 2006

Characterization of NoWel Os-Diolefin Dimers
were observed in the difference Fourier maps and refined as free
isotropic atoms or included in calculated positions and refined riding
on their respective carbon atoms with the thermal parameter related
to the bonded atoms. Hydride ligands were observed, but unfor-
tunately they did not refine properly, and models with fixed
positions (2, 3a, and 4) or restrained geometry (1) were used. Crystal
data and details of the data collection and refinement are given in
Table 1.
For 2, two molecules of benzene were observed in the asym-
metric unit as crystallization solvent. For 4, the NBu4 cation was
observed disordered. The anion was defined with two moieties,
complementary occupancy factors, isotropic atoms, and restrained
geometry. The presence of a residual peak very close to the C(11)
atom of 4 gives rise to unreasonable anisotropic thermal parameters
and bond distances. The poor thermal displacements could be
improved by use of the ISOR facility, while the bond distances
where restrained to be the same to the other olefinic bonds in the
molecule.
Acknowledgment. Financial support from the MEC of
Spain (Project CTQ2005-00656) is acknowledged. C.G.-Y.
thanks the Spanish MEC and the University of Zaragoza for
funding through the “Ramo´n y Cajal” Program.
Supporting Information Available: Tables of crystallographic
data and bond lengths and angles of complexes 1, 2, 3a, and 4.
This material is available free of charge via the Internet at
http://pubs.acs.org.
IC0612799
Inorganic Chemistry, Vol. 45, No. 25, 2006 10171