New Osmium Hydrides Containing the Bulky Phosphine 1,2-bis(diisopropylphosphino)ethane (dippe)

Article abstract of DOI:10.1016/S0022-328X(98)00577-4

A range of hydride complexes of osmium(II) and oxmium(IV) containing the bulky chelating phosphine dippe have been prepared and characterized.The cationic dichlorohydridoosmium(IV) 1 was obtained by recation of five-coordinate with HCl in dichloromethane, whereas the trihydride 2 was prepared by reaction of cis- with NaBH4/NaBPh4 in ethanol.This compound has shown to be a 'classical' trihydride Os(IV) complex rather than an Os(II) hydrido(dihydrogen) derivative, beong reversibly deprotonated by KOBu^t to yield the neutral dihydride cis- 3. cis reacted with Li in THF affording the chlorohydride trans-(dippe)2> 4.This species dissociates chloride furnishing the 16-electron cationic monohydride (1+), which was detected in solution, but not isolated due to its great tendency to react with traces of oxygen to yield the hydrido(dioxygen) complex trans- 5, which was fully characterized. - Keywords: hydride complexes; dihydrogen complexes; dioxygen complexes; osmium; phosphine.

Full text of DOI:10.1016/S0022-328X(98)00577-4

Journal of Organometallic Chemistry 564 (1998) 21–28
New osmium hydrides containing the bulky phosphine
1,2-bis(diisopropylphosphino)ethane (dippe)
Manuel Jime´nez Tenorio, M. Carmen Puerta *, Isabel Salcedo, Pedro Valerga
Departamento de Ciencia de Materiales e Ingenier´ıa Metalu´rgica y Qu´ımica Inorga´nica, Facultad de Ciencias, Uni6ersidad de Ca´diz, Apartado 40,
11510 Puerto Real, Ca´diz, Spain
Received 15 December 1997; received in revised form 27 March 1998
Abstract
A range of hydride complexes of osmium(II) and osmium(IV) containing the bulky chelating phosphine dippe have been
prepared and characterized. The cationic dichlorohydridoosmium(IV) [OsHCl2(dippe)2][BPh4] 1 was obtained by reaction of
five-coordinate [OsCl(dippe)2][BPh4] with HCl in dichloromethane, whereas the trihydride [OsH3(dippe)2][BPh4] 2 was prepared by
reaction of cis-[OsCl2(dippe)2] with NaBH4/NaBPh4 in ethanol. This compound has shown to be a ‘classical’ trihydride OsIV
complex rather than an OsII hydrido(dihydrogen) derivative, being reversibly deprotonated by KOBut to yield the neutral
dihydride cis-[OsH2(dippe)2] 3. cis-[OsCl2(dippe)2] reacted with Li[HBEt3] in THF affording the chlorohydride trans-[OsH-
Cl(dippe)2] 4. This species dissociates chloride furnishing the 16-electron cationic monohydride [OsH(dippe)2]+, which was
detected in solution, but not isolated due to its great tendency to react with traces of oxygen to yield the hydrido(dioxygen)
complex trans-[OsH(O2)(dippe)2][BPh4] 5, which was fully characterized. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Hydride complexes; Dihydrogen complexes; Dioxygen complexes; Osmium; Phosphine
1. Introduction
than dippe, and they have also reported recently the
X-ray crystal structure of [OsH(O2)(dcpe)2][BPh4] [5].
On the other hand, Morris and co-workers have exten-
sively studied the Ru and Os systems containing 1,2-bis
(diethylphosphino)ethane (depe) [6–10], which appar-
ently do not react with O2 to form stable dioxygen
adducts. In order to complete the systematic study of
the properties of osmium hydrides containing substi-
tuted diphosphines, we recently started to extend the
work carried out with ruthenium and dippe to osmium
[11]. This has led to the isolation of five-coordinate
osmium complexes of the type [OsX(dippe)2][BPh4]
(X=Cl, SPh), as well as the dihydrogen derivative
[OsCl(H2)(dippe)2][BPh4]. In this paper we conclude the
study with the report of the synthesis and properties of
a series of new osmium hydrides relevant to the activa-
tion of dihydrogen and dioxygen, with emphasis in the
dynamic processes which some of these compounds
undergo in solution.
In previous reports, we described the synthesis and
properties of the 16-electron monohydride complex
[RuH(dippe)2][BPh4] [1], which was reactive towards
both H2 and O2 furnishing the corresponding com-
plexes,
namely
[RuH(H2)(dippe)2][BPh4]
and
[RuH(O2)(dippe)2][BPh4]. The preparation of these
compounds proved that dioxygen coordination is possi-
ble at a dihydrogen binding site, and that the steric
bulkiness of the auxiliary ligands plays an important
role on the stabilization of dioxygen coordination. Rigo
and co-workers have prepared related ruthenium and
osmium [2–4] compounds containing 1,2-bis(dicyclo-
hexyl-phosphino)ethane (dcpe), which is even bulkier
* Corresponding author. Tel.: +34 9 56830828; fax: +34 9
56834924; e-mail: carmen.puerta@uca.es
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00577-4

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M. Jime´nez Tenorio et al. / Journal of Organometallic Chemistry 564 (1998) 21–28
Fig. 1. 1H-NMR spectrum of [OsHCl2(dippe)2][BPh4] (CD2Cl2) in the hydride region at r.t.
2. Results and discussion
spectrum displays two signals, centred at 27.0 and 16.8
ppm, which, however, do not show any resolved multi-
plicity due to their relative broadness. Analytical data
are consistent with the formulation as [Os-
HCl2(dippe)2][BPh4] for (Fig. 1) this material (1), which
appears to be a seven-coordinate OsIV dichlorohydride,
formed presumably through an oxidative addition of
one HCl molecule to the coordinatively unsaturated
complex [OsCl(dippe)2][BPh4]. Despite the fact that
seven-coordinate species are very often non-rigid in
solution, NMR data suggest that 1 is stereochemically
rigid in the NMR time scale. Several possible structures
can be proposed for the complex cation, based upon
NMR data:
The reaction of the five-coordinate complex [Os-
Cl(dippe)2][BPh4] [11] with aqueous HCl in CH2Cl2
leads to a purple solution, from which a purple micro-
crystalline material was isolated upon concentration
and precipitation using petroleum ether. This material
1
is diamagnetic, as inferred from its H-NMR spectrum,
which shows one hydride resonance centred at −12.43
ppm, apart from the phosphine protons. This signal
appears as a triplet of triplets, due to coupling to two
sets (two atoms each) of non-equivalent phosphorus
atoms. This corresponds to the X part of an A2M2X
spin system. Consistent with this, the 31P{1H}-NMR

M. Jime´nez Tenorio et al. / Journal of Organometallic Chemistry 564 (1998) 21–28
23
Fig. 2. Variable temperature NMR spectra of [OsH3(dippe)2][BPh4] (acetone-d6): (a) 1H in the hydride region; (b) 31P{1H}.
complexes of the type [WH(N2)2(diphos)2]+ [12], would
be expected. The fact that 1 is deprotonated by a strong
base such as KOBut to yield the neutral dichlorocom-
plex cis-[OsCl2(dippe)2] is also in support of a cisoid
disposition of the phosphine ligands. However, at-
tempts made to obtain 1 from cis-[OsCl2(dippe)2] by
protonation using HBF4 were unsuccessful, resulting in
the formation of paramagnetic species. As far as we are
aware, there are no previous reports of other com-
pounds of the type [OsHCl2(diphos)2]+ in the
literature.
Both structures are derived from a pentagonal
bipyramid. In structures Ia and Ib, the phosphines
adopt a cisoid disposition, with the hydride ligand in
between the two chloride ligands (Ia) or the two phos-
phorus atoms lying on the equatorial plane (Ib). In
structure II, the chloride ligands are in axial positions,
and the two dippe ligands and the hydride are equato-
rial. From these two, structures Ia and Ib seems to be
more consistent with the observed NMR data, since
they both match an A2M2X spin system, whereas with
structure II, a more complex pattern corresponding to
an AA%MM%X spin system, similar to that observed for
The reaction of cis-[OsCl2(dippe)2] with NaBH4 in
EtOH, in the presence of NaBPh4 afforded
[OsH3(dippe)2][BPh4] (2) as a white microcrystalline
solid which was recrystallized from an acetone/
petroleum ether mixture. This material displays one
1
broad wOsH band centred at 1981 cm−1, and its H-
NMR spectrum in acetone-d6 at room temperature
(r.t.) shows one binomial quintet at −10.35 ppm with
a coupling constant JHP=12 Hz, indicative of the

24
M. Jime´nez Tenorio et al. / Journal of Organometallic Chemistry 564 (1998) 21–28
equivalence at this temperature of the three hydride
ligands (Fig. 2). Consistent with this, one sharp singlet
appears in the 31P{1H}-NMR spectrum. As the temper-
ature is lowered, the single hydride resonance in the
1H-NMR spectrum becomes broad and unresolved, and
then splits into two broad signals centred at −9.95 and
−10.65 ppm, respectively. The resonance at lower field
resolves into one quintet at 213 K, having a coupling
constant JHP=21 Hz, whereas the signal at higher field,
which has double intensity, remains broad, although it
shows signs of a partially resolved coupling to phos-
phorus with a reduced coupling constant JHP$7 Hz.
At this temperature, the 31P{1H}-NMR spectrum con-
sists of one broad signal, which splits into two separate
broad resonances at lower temperature (188 K), sug-
gesting that the phosphorus atoms become non-equiva-
lent (Fig. 2). The hydride signals in the 1H-NMR
spectrum become broader at this temperature, although
no significant change in the pattern is observed. The
fact that two resonances appear for metal-bound pro-
tons indicates that there are two different sorts of
hydridic sites, and that protons in these sites undergo
rapid exchange in the NMR time scale averaging their
chemical shifts and JHP coupling constants, as it has
been observed for other related complexes of the type
[OsH3(diphos)2]+ [7]. These osmium derivatives range
from hydride(dihydrogen) complexes to ‘classical’ trihy-
drides passing through intermediate situations contain-
ing an ‘elongated’ dihydrogen ligand, depending upon
the nature of the substituents at the phosphorus atoms
of the diphosphine ligands. In some instances, rapid
equilibria between the hydride and dihydrogen tau-
tomers has been also observed [13]. In our case, mea-
surements of (T1)min (minimum longitudinal relaxation
time) yielded 289 ms for the quintet, and 182 ms for the
broad resonance at higher field (acetone-d6, 400 MHz).
These values need to be corrected in order to account
for the contribution of the rapid hydride exchange
between sites to the overall relaxation [7,13], using the
formula:
drides)). [OsH(H2)(dppe)2]+ is a hydride(dihydrogen)
complex [7], although dppe is a poorer donor than
depe, dippe and dcpe. It is interesting to note that the
complex [OsCl(H…H)(dippe)2][BPh4], recently reported
by us [11], contains an ‘elongated’ dihydrogen ligand
˚
(dHH=1.0–1.3 A). In this sense, the effect of the halide
versus hydride on H–H bonding of the trans-H2 ligand
in complexes of the type [MX(H2)(R2PCH2CH2PR2)2]+
(M=Ru, Os; X=H, halide) has been subject of de-
tailed studies [6,9,10]. Whereas for Ru complexes a
change from halide to hydride involves always a de-
crease in dHH, for their osmium homologues the change
may cause both an increase or a decrease in dHH
,
depending upon the R substituent on the diphospine.
Thus, in our case (R=iPr), there is an increase in dHH
when changing Cl by H, as it also occurs for R=Cy,
although the effect is reversed when R=Et or Ph. The
structure proposed for 2, according to the spectral data,
is derived from a pentagonal bipyramid, with all the
hydrides lying on the equatorial plane, and the phos-
phines adopting a cisoid disposition, as shown.
This structure involves the non-equivalence of the
phosphorus atoms at axial and equatorial positions,
although rapid exchange in solution occurs, rendering
them equivalent on the NMR time scale. In fact, the
31P{1H}-NMR spectra of all compounds of the type
[OsH3(R2PCH2CH2PR2)2]+ reported in the literature
consists of one singlet in the temperature range 200–
300 K. However, in the case of 2 the splitting of the
31P{1H} resonance has been observed at 183 K (Fig. 2).
This has allowed the estimation of the energy barrier
responsible for the exchange process from the variable
temperature 31P{1H}-NMR data [14]. Thus, the rate of
exchange at 203 K is 2433 s−1. An Eyring plot (Fig. 3)
yielded the activation parameters DH" =8.790.5 kcal
1
1
1
=
+
T1(H2)obs T1(H2)true T1(H)obs
mol−1; DS" =190.5 cal K−1 mol−1, and DG298
=
8.490.5 kcal mol−1. This values of DG298 is coincident
with the estimated upper bound for the activation
energy of the exchange process in the complexes
[OsH(H2)(R2PCH2CH2PR2)2]+ (R=Ph, Et) and
[ReH3(dppe)2] [7,13], the small value for DS" being
consistent with an intramolecular mechanism.
This leads to a ‘true’ (T1)min value of 492 ms for the
OsH2 resonance, which corresponds to a dHH in the
˚
range 1.51–1.90 A, suggesting that 2 is a ‘classical’
hydride rather than a dihydrogen complex, and hence
should be formulated as an OsIV trihydride, or better as
a
hydride(dihydride) of the type [OsH(H)2
Compound 2 is reversibly deprotonated by a strong
base such as KOBut yielding the neutral dihydride
cis-[OsH2(dippe)2] (3). This white, crystalline material is
characterized by the presence of a multiplet signal for
(dippe)2][BPh4]. Thus, an increase of the bulk of the
substituents at phosphorus favours the hydride tau-
tomer over the dihydrogen form, as inferred from the
fact that [OsH(H…H)(depe)2]+ is an ‘elongated’ dihy-
drogen complex [7], whereas 2 and also [OsH3(dcpe)2]+
[4] behave as classical trihydrides (or hydride(dihy-
1
the hydride protons in the H-NMR spectrum, whereas
two sharp singlets are observed in the 31P{1H}-NMR
spectrum, consistent with the cis-disposition of the

M. Jime´nez Tenorio et al. / Journal of Organometallic Chemistry 564 (1998) 21–28
25
phosphine ligands. The fact that the phosphorus reso-
nances appear as singlets rather than as multiplets, as it
would correspond to the expected AA%MM%XX% spin
system, is attributed to the cancellation of JPP coupling
constants, probably similar in absolute magnitude but
opposite in sign.
Reaction of 3 with HBF4/D2O yielded a mixture of
the isotopomers [OsH2D(dippe)2]+ and [OsHD2
(dippe)2]+, which showed no evidence for H–D cou-
pling in its 1H-NMR spectrum (JHD$0 Hz), as ex-
pected for a ‘classical’ hydride complex [13].
At variance with its ruthenium homologue, [Ru-
H(H2)(dippe)2][BPh4] [1], which is a labile dihydrogen
complex that dissociates H2 to give the 16-electron
monohydride [RuH(dippe)2][BPh4], 2 seems to be re-
markably stable towards reductive elimination of H2.
For this reason, we attempted the preparation of [Os-
H(dippe)2][BPh4] starting from the chlorohydride com-
plex trans-[OsHCl(dippe)2] (4), which was prepared in
moderated yield by reaction of cis-[OsCl2(dippe)2] with
Li[HBEt3] in THF. This compound, which displays one
quintet at −24.14 ppm in its 1H-NMR spectrum,
reacted with NaBPh4 in ethanol under dinitrogen or
argon to yield a microcrystalline material, which re-
sulted in a mixture of three hydride-containing species,
as inferred from its 1H-NMR spectrum. One of the
signals corresponds to the trihydride complex 2,
whereas the other two resonances, one quintet at −
39.5 ppm, and another quintet at −7.1 ppm, are due to
novel compounds. The ratio of the different signals
varied depending upon the conditions and reaction
times. The signal at very high field is consistent with the
presence of a coordinatively unsaturated osmium hy-
dride, and is hence attributed to [OsH(dippe)2][BPh4],
Scheme 1. Reagents and conditions: (i) MeOH or EtOH, NaBPh4; (ii)
air or traces of oxygen; (iii) H2 or prolonged stirring in alcohol at r.t.
although all efforts to isolate this compound were
unsuccessful. Prolonged reaction times led to the for-
mation of the trihydride 2, presumably by hydrogen
abstraction from the solvent, whereas exposure to oxy-
gen, even at trace level, afforded the hydrido(dioxygen)
complex [OsH(O2)(dippe)2][BPh4] (5), to which corre-
sponds the observed quintet at −7.1 ppm (Scheme 1).
It is clear that [OsH(dippe)2]+ is a very reactive species
having an affinity for O2 even higher than its ruthenium
homologue. The osmium hydrido(dioxygen) complex
[OsH(O2)(dcpe)2][BPh4], analogous to 5, was recently
described [5]. As in our case, it was also obtained by
addition of O2 to the corresponding 16-electron os-
mium monohydride. The NMR properties of 5 match
those of its ruthenium homologue. Thus, the spectra
are temperature dependent, and the hydride quintet at
−7.1 becomes a triplet of triplets as the temperature is
lowered (Fig. 4). The 31P{1H}-NMR spectrum consists
of one broad resonance at r.t., which splits into two
signals at 213 K. The low temperature spectral data
correspond to an A2M2X spin system, suggesting that
the structure of 5 is essentially identical to that found
by X-ray diffraction for its ruthenium homologue [1],
and also for [OsH(O2)(dcpe)2][BPh4] [5] (Scheme 1). In
fact, the crude molecular skeleton resulting from an
X-ray structure analysis made on poor quality crystals
of 5 was consistent with this affirmation, although the
refinement of the model was not good enough to grant
its publication. The dynamic process responsible for the
fluxional behaviour of these hydrido(dioxygen) species
is thought to be the propeller-like spinning of the
dioxygen ligand, similar to that found in dihydrogen
complexes [13,15], the rotation energy barrier of 5
having an estimated value DG298=1391 kcal mol−1
with DH" =991 kcal mol−1, and DS" = −1591
cal K−1 mol−1, as inferred from the analysis of the
variable temperature 31P{1H}-NMR data (Fig. 5). This
calculated energy barrier is similar in value to that
measured for the rotation of p2-alkyne ligands around
the metal-alkyne bond [16], and only slightly higher
than the that recently reported for the restricted rota-
Fig. 3. Plot of Ln(k/T) versus 1/T (K−1) for the phosphorus atom
exchange process in [OsH3(dippe)2][BPh4].

26
M. Jime´nez Tenorio et al. / Journal of Organometallic Chemistry 564 (1998) 21–28
Fig. 4. Variable temperature NMR spectra of [OsH(O2)(dippe)2][BPh4] (CDCl3): (A) 1H in the hydride region; (B) 31P{1H}.
tion of dihydrogen in the complexes [Nb(p5-
C5H4SiMe3)2(H2)(CNR)]+ (R=But, Cy, 2,6-Xylyl)
[15], which falls in the range 8.4–9.1 kcal mol−1, being
apparently consistent with the affirmation that similar
molecular dynamics for the motion of p2-coordinated
dioxygen and other y-ligands such as alkynes or even
dihydrogen is expected in their respective complexes.
vents were deoxygenated immediately before use.
[NH4]2[OsCl6] was supplied by Aldrich. 1,2-Bis(diiso-
propylphosphino)ethane [17], cis-[OsCl2(dippe)2] and
[OsCl(dippe)2][BPh4] [11] were prepared according to
reported procedures. IR spectra were recorded in Nujol
mulls on Perkin Elmer 881 or Perkin Elmer FTIR
Spectrum 1000 spectrophotometers. NMR spectra were
taken on Varian Unity 400 MHz or Varian Gemini 200
MHz equipments. Chemical shifts are given in ppm
from SiMe4 (1H and 13C{1H}) or 85% H3PO4
(31P{1H}). The phosphine protons for all compounds
3. Experimental section
1
All synthetic operations were performed under a dry
dinitrogen or argon atmosphere following conventional
Schlenk or drybox techniques. THF, diethylether and
petroleum ether (boiling point range 40–60°C) were
distilled from the appropriate drying agents. All sol-
appeared in the corresponding H-NMR spectra as a
series of overlapping multiplets in the range 0.5–3 ppm,
and were not assigned. Microanalysis was by Dr
Manuel Arjonilla at the CSIC-Instituto de Ciencias
Marinas de Andaluc´ıa.

M. Jime´nez Tenorio et al. / Journal of Organometallic Chemistry 564 (1998) 21–28
27
3.1. Preparation of [OsHCl2(dippe)2][BPh4] (1)
3.3. cis-[OsH2(dippe)2] (3)
To a solution of [OsCl(dippe)2][BPh4] (0.05 g, ca.
0.064 mmol) in dichloromethane (10 ml), a few drops of
concentrated aquous HCl was added. The initially
brown solution became purple immediately. The mix-
ture was filtered and then concentrated using reduced
pressure. Addition of petroleum ether yielded a precipi-
tate, which was filtered, washed with petroleum ether
and dried in vacuo. Yield: 0.04 g, 60%. Anal. Calc. for
C52H85BCl2OsP4 C, 56.5; H, 7.69. Found C, 56.2; H,
To a solution of 2 (0.15 g, ca. 0.14 mmol) in THF (15
ml), an excess of solid KOBut was added. The mixture
was stirred at r.t. for 30 min. Then, the solvent was
removed, and the residue extracted with petroleum
ether. Centrifugation or filtration through celite, fol-
lowed by concentration and cooling to −20°C af-
forded white crystals, which were filtered off and dried
in vacuo. Yield: 0.06 g, 60%. Anal. Calc. for
C28H66OsP4 C 46.9; H 9.22. Found C 47.1; H 9.14. IR
1
1
8.03. NMR (CD2Cl2): H l −12.43 (triplet of triplets,
(Nujol): wOsH 1951, 1984, 2021 cm−1. NMR (C6D6): H
J
HP=12 Hz, JHP%=44 Hz, OsHCl2).31P{1H} 27.0 (s,
l −14.62 (XX% part of an AA%MM%XX% spin system,
br), 16.8 (s, br).
JHA=55.3 Hz, JHA%$JHM=JHM%=22.8 Hz, OsH2).
31P{1H} 42.8 s, 68.4 s (JPP not resolved).
3.2. [OsH3(dippe)2][BPh4] (2)
3.4. trans-[OsHCl(dippe)2] (4)
A solution of cis-[OsCl2(dippe)2] (0.1 g, ca. 0.13
mmol) in ethanol (15 ml), was treated with an excess of
solid NaBPh4 followed by solid NaBH4 (excess). The
mixture was heated under reflux for 1 h. During this
time, a white precipitate was formed. The mixture was
allowed to cool down to r.t., and then the white micro-
crystalline precipitate was filtered off, washed with
ethanol and petroleum ether and dried in vacuo. Yield:
0.11 g, 85%. Anal. Calc. for C52H87BOsP4 C, 60.2; H,
8.40. Found C, 60.2; H, 8.68. IR (Nujol): wOsH 1972
A solution of cis-[OsCl2(dippe)2] (0.1 g, ca. 0.13
mmol) in THF was treated with a slight excess over the
equimolar amount of Li[HBEt3] (0.15 ml of a 1 M
solution in THF, 0.15 mmol). The mixture was stirred
at r.t. for 1 h. At the end of this time, the solvent was
removed in vacuo, and the residue extracted with
petroleum ether. The resulting yellow solution was
filtered through celite or centrifuged. Removal of the
solvent afforded a yellow product which was thor-
oughly dried in vacuo. Yield: 0.07 g, 72%. Anal. Calc.
for C28H65ClOsP4 C 44.8, H 8.66. Found C 45.1, H
8.94. IR (Nujol): wOsH 2119 cm−1. NMR (acetona-d6):
1H l −24.14 (q, JHP=16 Hz, OsHCl). 31P{1H} 41.1 s.
1
cm−1. NMR (acetone-d6): H l (298 K): −10.32 (q,
JHP=12 Hz, T1=620 ms, OsH3); l (183 K): −9.97 (q,
HP=21 Hz, T1=289 ms, OsH(H)2), −10.80 (br,
J
T1=183 ms, OsH(H)2); 31P{1H}: l (298 K): 55.1 s; l
(183 K): 52.1 br, 58.9 br.
3.5. [OsH(p2-O2)(dippe)2][BPh4] (5)
To a solution of 4 (0.05 g, ca. 0.07 mmol) in ethanol
(10 ml), a slight excess of NaBPh4 was added. Upon
addition, the initially orange brown clear solution be-
comes turbid and reddish. The mixture was stirred in
the air for 24 h. Dark red microcrystals were obtained,
which were filtered off, washed with petroleum ether
and dried in vacuo. Another crop of crystals could be
obtained by concentration and cooling of the mother
liquor. Yield: 0.06 g, 80%. Anal. Calc. for
C52H85BO2OsP4 C 58.5, H 7.97. Found C 58.2, H 8.04.
NMR (CDCl3, 298 K): 1H: l (283 K) −7.10 (q,
J
HP=23.3 Hz, OsH(O2)); l (213 K) −7.10 (triplet of
triplets, JHP=37.6 Hz, JHP%=6.6 Hz). 31P{1H} l (328
K) 33.2 (s br, Dw1 $316 Hz); l (213 K) 27.4 (t, JPP%
=
2
4.8 Hz), 37.0 (s, br).
Acknowledgements
We wish to thank the Ministerio de Educacio´n y
Ciencia of Spain (DGICYT, Project PB94-1306) and
Junta de Andaluc´ıa (Grupo FQM0188) for financial
support.
Fig. 5. Plot of Ln(k/T) versus 1/T (K−1) for the phosphorus atom
exchange process in [OsH(O2)(dippe)2][BPh4].

28
M. Jime´nez Tenorio et al. / Journal of Organometallic Chemistry 564 (1998) 21–28
D’Agostino, Inorg. Chem. 33 (1994) 6278.
[10] P.A. Maltby, M. Schlaf, M. Steinbeck, A.J. Lough, R.H. Morris,
References
W.T. Klooster, T.F. Koetzle, R.C. Srivastava, J. Am. Chem.
Soc. 118 (1996) 5396.
[1] (a) M. Jime´nez Tenorio, M.C. Puerta, P. Valerga, J. Am. Chem.
Soc. 115 (1993) 9794. (b) M. Jime´nez Tenorio, M. C. Puerta, P.
Valerga, Inorg. Chem. 33 (1994) 3515.
[2] A. Mezzetti, A. del Zotto, P. Rigo, N.B. Pahor, J. Chem. Soc.
Dalton Trans. (1989) 1045.
[3] A. Mezzetti, A. del Zotto, P. Rigo, J. Chem. Soc. Dalton Trans.
(1990) 2515.
[4] A. Mezzetti, A. del Zotto, P. Rigo, E. Farnetti, J. Chem. Soc.
Dalton Trans. (1991) 1525.
[11] I. de los Rios, M. Jime´nez Tenorio, M.C. Puerta, I. Salcedo, P.
Valerga, J. Chem. Soc. Dalton Trans. (1997) 4619.
[12] (a) M. Abu Bakar, D.L. Hughes, W. Hussain, G.J. Leigh, C.J.
Macdonald, H.M. Ali, J. Chem. Soc. Dalton Trans. (1988) 2545.
(b) J.E. Barclay, A. Hills, D.L. Hughes, G.J. Leigh, C.J. Mac-
donald, J. Chem. Soc. Dalton Trans. (1990) 2503.
[13] P.G. Jessop, R.H. Morris, Coord. Chem. Rev. 121 (1992) 155.
[14] H. Gu¨nther, NMR Spectroscopy, 2nd ed., Wiley, Chichester,
1995.
[5] A. Mezzetti, E. Zangrado, A. del Zotto, P. Rigo, J. Chem. Soc.
Chem. Commun. (1994) 1597.
[15] A. Antin˜olo, F. Carrillo-Hermosillo, M. Fajardo, et al., J. Am.
Chem. Soc. 119 (1997) 6107.
[6] E.P. Cappellani, P.A. Maltby, R.H. Morris, C.T. Schweitzer,
M.R. Steele, Inorg. Chem. 28 (1989) 25.
[16] I. de los R´ıos, M. Jime´nez Tenorio, M.C. Puerta, P. Valerga, J.
Am. Chem. Soc. 119 (1997) 6529.
[7] K.A. Earl, G. Jia, P.A. Maltby, R.H. Morris, J. Am. Chem. Soc.
113 (1991) 3027.
[17] (a) M.D. Fryzuk, M.D. Jones, F.W.B. Einstein, Organometallics
3 (1984) 185. (b) T.A. Burt, J. Chatt, W. Hussain, G.J. Leigh, J.
Organomet. Chem. 182 (1979) 203.
[8] M.T. Bautista, E.P. Cappellani, S.D. Drouin, et al., J. Am.
Chem. Soc. 113 (1991) 4876.
[9] B. Chin, A.J. Lough, R.H. Morris, C.T. Schweitzer, C.
.
.