Synthesis and reactivity of [OsH{C6H4(CH=CHH)}(CO)(PPri3) 2] and the formato compounds [Os{(E)-CH=CHPh}(η2-O2CH)-(CO)(PPri 3)2] and [OsH(η2-O2CH)(CO)(PPri3) 2]

Article abstract of DOI:10.1039/a604486g

The complex [OsH{C₆H₄(CH=CHH)}(CO)(PPrⁱ₃) ₂] has been prepared by reaction of the five-co-ordinate [Os{(E)-CH=CHPh}Cl(CO)(PPrⁱ₃)₂] with LiBuⁿ in hexane. It reacts with P(OMe)₃ and CO to give [OsH{(E)CH=CHPh}(CO){P(OMe)₃}(PPrⁱ₃) ₂] and [OsH{(E)-CH=CHPh}(CO)₂(PPrⁱ₃)₂], while under a CO₂ atmosphere the formate derivative [Os{(E)-CH=CHPh}(η²-O₂CH)(CO)(PPrⁱ ₃)₂] is obtained. Carbonylation of the latter leads to the monodentate formato complex [Os{(E)-CH=CHPh} {η¹-OC(O)H}(CO)₂(PPrⁱ₃) ₂] and under a hydrogen atmosphere it affords styrene and [OsH(η²-O₂CH)(CO)(PPrⁱ₃) ₂], which can be also prepared by reaction of [OsH₂(η²-CH₂=CHEt)(CO)(PPrⁱ ₃)₂] with CO₂. The complex [OsH(η²-O₂CH)(CO)(PPrⁱ₃) ₂] reacts with CO, P(OMe)₃ and MeO₂CC≡CCO₂Me to give [OsH{η¹-OC(O)H}(CO)L(PPrⁱ₃)₂] [L = CO, P(OMe)₃ or MeO₂CC≡ CCO₂Me]; the carbon atom of its formate ligand is attacked by NEt₂H leading to the carbamato compound [OsH(η²-O₂CNEt₂)(CO)(PPrⁱ ₃)₂] and molecular hydrogen. Similarly treatment of [Os{(E)-CH=CHPh}(η²-O₂CH)(CO)(PPrⁱ ₃)₂] with NEt₂H afforded [Os{(E)-CH=CHPh}(η²-O₂CNEt₂)(CO)(PPr ⁱ₃)₂]. The former complex also reacts with HBF₄·OEt₂, giving two different derivatives depending upon the conditions: in diethyl ether as solvent and in the presence of acetonitrile the vinyl complex [Os{(E)-CH=CHPh}(CO)(MeCN)₂(PPrⁱ₃) ₂]BF₄ is formed, while the carbene derivative [Os(η²-O₂CH)(=CHCH₂Ph)(CO)(PPr ⁱ₃)₂]BF₄ is obtained in chloroform. The products formed by reaction of [OsH(η²-O₂CH)(CO)(PPrⁱ₃) ₂] with HBF₄·OEt₂ also depend upon the reaction conditions: in diethyl ether and in the presence of MeCN the hydrido compound [OsH(CO)(MeCN)₂(PPrⁱ₃)₂]BF ₄ is obtained; however a mixture of products, mainly dihydrogen derivatives, is formed in CDCl₃. On the basis of theoretical calculations and T₁ measurements, the nature and structure of these dihydrogen compounds are discussed.

Full text of DOI:10.1039/a604486g

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Synthesis and reactivity of [OsH{C H (CH᎐CHH)}(CO)(PPri ) ]
᎐
6
4
3 2
and the formato compounds [Os{(E )-CH᎐CHPh}(ç2-O CH)-
᎐
2
(CO)(PPri3)2] and [OsH(ç2-O2CH)(CO)(PPri3)2]*
María J. Albéniz,a Miguel A. Esteruelas,a Agustí Lledós,b Feliu Maseras,b Enrique Oñate,a
Luis A. Oro,a Eduardo Sola a and Bernd Zeier a
a
Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón,
Universidad de Zaragoza, CSIC, 50009 Zaragoza, Spain
b Departament de Química, Universitat Autónoma de Barcelona, 08193 Bellaterra,
Barcelona, Spain
The complex [OsH{C H (CH᎐CHH)}(CO)(PPri ) ] has been prepared by reaction of the five-co-ordinate
᎐
6
4
3 2
[Os{(E )-CH᎐CHPh}Cl(CO)(PPri ) ] with LiBun in hexane. It reacts with P(OMe) and CO to give [OsH{(E )-
᎐
3
2
3
CH᎐CHPh}(CO){P(OMe) }(PPri ) ] and [OsH{(E )-CH᎐CHPh}(CO) (PPri ) ], while under a CO atmosphere the
᎐
᎐
3
3
2
2
3
2
2
formato derivative [Os{(E )-CH᎐CHPh}(η2-O CH)(CO)(PPri ) ] is obtained. Carbonylation of the latter leads to
᎐
2
3 2
the monodentate formato complex [Os{(E )-CH᎐CHPh}{η1-OC(O)H}(CO) (PPri ) ] and under a hydrogen
᎐
2
3 2
atmosphere it affords styrene and [OsH(η2-O2CH)(CO)(PPri3)2], which can be also prepared by reaction of
[OsH (η2-CH ᎐CHEt)(CO)(PPri ) ] with CO . The complex [OsH(η2-O CH)(CO)(PPri ) ] reacts with CO,
᎐
2
2
3
2
2
2
3 2
1
i
᎐
᎐
᎐
P(OMe) and MeO CC᎐CCO Me to give [OsH{η -OC(O)H}(CO)L(PPr ) ] [L = CO, P(OMe) or MeO CC᎐
᎐
3
2
2
3
2
3
2
CCO2Me]; the carbon atom of its formate ligand is attacked by NEt2H leading to the carbamato compound
[OsH(η2-O CNEt )(CO)(PPri ) ] and molecular hydrogen. Similarly treatment of [Os{(E )-CH᎐CHPh}-
᎐
2
2
3 2
(η2-O CH)(CO)(PPri ) ] with NEt H afforded [Os{(E )-CH᎐CHPh}(η2-O CNEt )(CO)(PPri ) ]. The former
᎐
2
3
2
2
2
2
3 2
complex also reacts with HBF4ؒOEt2, giving two different derivatives depending upon the conditions: in diethyl
ether as solvent and in the presence of acetonitrile the vinyl complex [Os{(E )-CH᎐CHPh}(CO)(MeCN) -
᎐
2
(PPri ) ]BF is formed, while the carbene derivative [Os(η2-O CH)(᎐CHCH Ph)(CO)(PPri ) ]BF is obtained in
᎐
3
2
4
2
2
3
2
4
chloroform. The products formed by reaction of [OsH(η2-O2CH)(CO)(PPri3)2] with HBF4ؒOEt2 also depend upon
the reaction conditions: in diethyl ether and in the presence of MeCN the hydrido compound [OsH(CO)-
(MeCN)2(PPri3)2]BF4 is obtained; however a mixture of products, mainly dihydrogen derivatives, is formed in
CDCl3. On the basis of theoretical calculations and T1 measurements, the nature and structure of these
dihydrogen compounds are discussed.
In the search for homogeneous transition-metal systems effect-
ive in the synthesis of functionalized organic molecules from
basic hydrocarbons, we have recently observed that treatment
dynamic
product
[OsH(η3-CH2CHCHPh)(CO)(PPri3)2]
(Scheme 1).2
Products from the oxidative addition of the olefinic C᎐H
bonds of trans-methylstyrene were not observed. This does not
necessarily imply that the olefinic C᎐H activation in
of the alkenylosmium() complexes [Os{(E )-CH᎐CHR}-
᎐
Cl(CO)(PPri3)2] (R = H or Ph) with main-group organometallic
compounds leads to osmium(0) species containing olefin lig-
ands. As shown in Scheme 1 for LiMe, these transformations
involve replacement of the ClϪ anion by the organic frag-
ments of the main-group organometallic compounds, and sub-
sequent reductive carbon–carbon coupling of the η1-carbon
ligands.†,1,2
[Os(η2-MeCH᎐CHPh)(CO)(PPri ) ] is kinetically disfavoured
᎐
3
2
with regard to C᎐H activation of the phenyl ring. At first
glance, low activation barriers should be expected for all the
possible intramolecular C᎐H activations in osmium(0) inter-
mediates like [Os(η2-MeCH᎐CHPh)(CO)(PPri ) ], in view of
᎐
3
2
the mild isomerization conditions and the values of the acti-
vation enthalpies reported for this kind of reaction.3 So, the
non-observation of hydridoalkenyl complexes could prob-
For butadiene and phenylbutadiene the osmium(0) species
are stable, and do not undergo subsequent transformation.1
However, for trans-stilbene and trans-methylstyrene, the metal-
lic centre is capable of activating a C᎐H bond of the substitu-
ents of the co-ordinated olefin to afford hydridoosmium()
derivatives.2 The C᎐H activation products depend upon the
substituents present at the alkene ligand, and can be rational-
ized in the light of thermodynamic and kinetic considerations.
Thus, when the alkene ligand is trans-methylstyrene, the acti-
vation of an ortho position of the phenyl ring is kinetically
favoured. The product of this activation, which shows an
agostic interaction between the osmium centre and one of the
olefinic C᎐H bonds, evolves to the more favoured thermo-
ably be
a consequence of their lower thermodynamic
stability compared to the hydridophenyl derivative
[OsH{C H [(E )-CH᎐CHMe]-2}(CO)(PPri ) ].
᎐
6
4
3 2
As a continuation of our work in this field, and with the idea
of casting some light on olefinic C᎐H activation compared to
C᎐H activation of the ortho position of the phenyl ring in
osmium(0)–phenyl–olefin species, we have now studied the
reaction of [Os{(E )-CH᎐CHPh}Cl(CO)(PPri ) ] with LiBun. In
᎐
3
2
this paper, we also report the synthesis and characterization of
[OsH{C H (CH᎐CHH)}(CO)(PPri ) ], [Os{(E )-CH᎐CHPh}-
᎐
᎐
6
4
3 2
(η2-O2CH)(CO)(PPri3)2] and [OsH(η2-O2CH)(CO)(PPri3)2], and
the reactivity of the formato compounds towards CO,
P(OMe)3, H2, NEt2H, alkynes and HBF4. On the basis of
† Non-SI unit employed: cal = 4.184 J.
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192
181

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Scheme 3
The 1H NMR spectrum in C6D6 shows in the hydrido region
a triplet at δ Ϫ8.01 with a P᎐H coupling constant of 27.3 Hz.
The low-field region contains the expected resonances for the 2-
vinylphenyl ligand. The PhCH᎐ proton appears at δ 4.95 as a
᎐
doublet of doublets with H᎐H coupling constants of 9.0 and
7.7 Hz. The olefinic proton disposed cis to this appears at δ 2.74
as a doublet while that disposed trans, consistent with the agos-
tic interaction, displays a doublet of triplets with a P᎐H coup-
ling constant of 5.7 Hz. In the 13C-{1H} NMR spectrum the
olefinic carbon atoms gave rise to two broad signals at δ 50.5
and 46.3. The aryl carbon atom linked to the metal is ob-
served at δ 138.6 as a triplet with a P᎐C coupling constant of
10.0 Hz. The 31P-{1H} NMR spectrum has a singlet at δ
16.7 indicating that both phosphine ligands are equivalent
and mutually trans disposed. These spectroscopic data agree
well with those previously reported for the related complexes
Scheme 1 (i) LiMe
[OsH{C H [(E )-CH᎐CHR]-2}(CO)(PPri ) ] where a Osؒ ؒ ؒH
᎐
6
4
3 2
agostic interaction has been confirmed by X-ray diffraction.2
Complex 2 reacts with trimethyl phosphite and carbon mon-
oxide in hexane at room temperature to give the six-co-ordinate
hydridostyryl derivatives [OsH{(E )-CH᎐CHPh}(CO)L(PPri ) ]
᎐
3
2
[L = P(OMe)3 3 or CO 4] (Scheme 3) which were isolated as
white solids in good yields [85 (3), 72% (4)]. The IR spectrum of
3 in Nujol shows two absorptions at 2050 and 1910 cmϪ1, which
were assigned to the ν(Os᎐H) and ν(CO) vibrations, respect-
ively. The 31P-{1H} NMR spectrum contains a triplet at δ 102.4
[P(OMe)3] and a doublet at δ 17.5 (PPri3) with a P᎐P coupling
constant of 18.6 Hz, consistent with two equivalent PPri3 lig-
ands both cis disposed to the trimethyl phosphite group. The
relative trans position of the hydride and phosphite ligands was
1
inferred from the hydrido signal in the H NMR spectrum,
which appears as a doublet (JP᎐H = 134.4 Hz) of triplets
(JP᎐H = 24.5 Hz) of doublets (JH ᎐H = 1.6 Hz) at δ Ϫ8.94. In the
low-field region the most noticeable resonances are those corre-
sponding to the vinyl protons of the styryl ligand, which appear
Scheme 2
at δ 8.78 (OsCH᎐) and 7.03 (᎐CHPh). The trans stereo-
᎐
᎐
spectroscopic data and theoretical calculations, the nature of
the compounds formed by addition of HBF4 to [OsH(η2-O2-
CH)(CO)(PPri3)2] is also discussed.
chemistry of the two hydrogen atoms at the C᎐C double bond is
᎐
supported by the value of the H᎐H coupling constant (18.3
Hz), which is typical for this arrangement.5 In the 13C-{1H}
NMR spectrum the Cα carbon atom of the styryl ligand
appears at δ 143.3 as a virtual quartet with a P᎐C coupling
constant of 13.4 Hz, while the Cβ carbon atom displays at δ
144.4 a doublet of triplets with P᎐C coupling constants of 10.1
and 4.2 Hz.
Results and Discussion
Reaction of [Os{(E)-CH᎐CHPh}Cl(CO)(PPri ) ] with LiBun
᎐
3
2
Reaction of the five-co-ordinate alkenyl complex [Os{(E )-
CH᎐CHPh}Cl(CO)(PPri ) ] 1 with LiBun in hexane at room
᎐
3
2
The spectroscopic data obtained for complex 4 also support
the structure proposed in Scheme 3. The cis relative position of
the carbonyl ligands was inferred from the IR spectrum in
Nujol, which shows, together with the ν(Os᎐H) band at 1990
temperature gives a yellow solution from which the hydridoaryl
derivative [OsH{C H (CH᎐CHH)}(CO)(PPri ) ] 2 (Scheme 2)
᎐
6
4
3 2
was isolated as a colourless oil in quantitative yield. In the pres-
ence of a trace of water this compound evolves into the previ-
cmϪ1, two strong ν(CO) absorptions at 1945 and 1865 cmϪ1
,
ously reported [OsH (η2-CH ᎐CHPh)(CO)(PPri ) ].4
typical for mononuclear cis-dicarbonyl complexes. The
᎐
2
2
3 2
182
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192

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Scheme 5 (i) LiBun; (ii) P(OMe)3
only the C᎐H bond disposed trans to the phenyl group is
activated.
Scheme 4 (i) LiBun; (ii) P(OMe)3
Consistent with the high selectivity observed for the olefinic
C᎐H activation, the reaction of the deuteriated complex
[Os{(E )-CH᎐CDPh}Cl(CO)(PPri ) ] 1a with LiBun leads to
᎐
3
2
13C-{1H} NMR spectrum also supports this proposal, showing
two triplets at δ 190.4 (JP᎐C = 5.5) and 185.5 (JP᎐C = 7.8 Hz)
attributable to the carbonyl ligands. It also contains the
expected resonances for the vinylic carbon atoms of the styryl
ligand, which appear at δ 142.5 (Cβ) and 135.2 (Cα) as triplets
with P᎐C coupling constants of 3.7 and 12.9 Hz, respectively.
The CH groups of the phosphine ligands give a virtual triplet at
δ 26.2 (N = 27.6 Hz), which is characteristic of the two equiva-
lent phosphine ligands in a trans relative position. This is con-
sistent with the singlet at δ 19.0 found in the 31P-{1H} NMR
spectrum. The 1H NMR spectrum shows the hydrido resonance
at δ Ϫ7.13 as a triplet (JP᎐H = 22.0 Hz) of doublets (JH ᎐H = 5.0
Hz). The vinylic protons of the styryl ligand appear at δ 8.34
[OsH{C H (CD᎐CHH)}(CO)(PPri ) ] 2a, and the addition of
᎐
6
4
3 2
trimethyl phosphite to 2a affords [OsH{(E )-CH᎐CDPh}-
᎐
(CO){P(OMe)3}(PPri3)2] 3a containing the deuterium atom at
the Cβ carbon atom of the styryl ligand (Scheme 5). The posit-
ion of the deuterium atoms in these compounds was inferred
from the 2H NMR spectra, which contain resonances at δ 5.03
(2a) and 7.01 (3a).
The reaction of the C -deuteriated complex [Os{(E )-CD᎐
᎐
α
CHPh}Cl(CO)(PPri3)2] (1b) with LiBun, in contrast to that of Cβ-
deuteriated 1a, produces a mixture of four deuteriated deriva-
tives in approximately 1:1:1:1 molar ratio, as shown by the 2H
NMR spectrum which contains four resonances with the same
1
intensity at δ 6.52, 3.68, 2.65 and Ϫ8.02. According to the H
(OsCH᎐) and 7.20 (᎐CHPh). The value of the H ᎐H coupling
᎐
᎐
α
β
NMR spectrum of 2, these resonances were respectively
assigned to the complexes 2b, 2c, 2d and 2e of Scheme 6. The
presence of 2b, 2d and 2e in the mixture suggests that in 2 the
terminal olefinic carbon atom interacts with the hydride ligand,
thus the migration of the hydride onto the olefinic terminal
carbon atom and subsequent hydrogen extraction from the
resulting methyl group could explain the deuterium distribu-
tion. Direct migration of the hydride from the osmium atom
onto the terminal olefinic carbon atom does not seem likely in
view of the mutually trans disposition of the hydride and the
agostic interaction. Hence it could be proposed that the
exchange process proceeds by a five-co-cordinate aryl inter-
mediate, resulting from cleavage of the agostic interaction.
Although this intermediate has not been detected by NMR
spectroscopy, even at Ϫ80 ЊC, one should assume it, giving
that at high temperatures important amounts of the relative
constant (16.1 Hz) is also in agreement with the proposed E
stereochemistry at the C᎐C double bond.
᎐
On the basis of our previous reports1,2,6 the reactions shown
in Schemes 2 and 3 can be rationalized according to Scheme 4.
The reaction of 1 with LiBun to give 2 most probably involves
replacement of the ClϪ anion by a butyl group to afford the
intermediate 5, which by subsequent hydrogen β elimination
could give 6. In this context, it should be mentioned that the
reaction of the five-co-ordinate complex [OsH(Cl)(CO)-
(PPri3)2] with LiBun affords [OsH (η2-CH ᎐CHEt)(CO)-
᎐
2
2
(PPri3)2].6 The reductive elimination of styrene from 6 followed
by the C᎐H activation of the o-aryl proton should lead to 2 via
the styreneosmium(0) intermediate 7. In spite of the fact that 2
is the only species detected in solution, the formation of 3 and 4
from 2 (Scheme 3) suggests that in solution complex 2 is in
equilibrium with no detectable concentrations of 6. This
implies that 7 is easily accessible and can give rise to activation
reactions at both the olefinic and the ortho phenyl C᎐H bonds
of the co-ordinated styrene. Although 2 is more stable than 6,
the latter is more substitution labile. In addition, it should be
pointed out that the olefinic C᎐H activation is selective, thus
five-co-ordinate aryl derivatives [OsH{C H (CH᎐CHR)}(CO)-
᎐
6
4
(PPri3)2] are in equilibrium with the six-co-ordinate complexes
[OsH{C H (CH᎐CHR)}(CO)(PPri ) ] (R = Me or Ph).2
᎐
6
4
3 2
2
The H NMR spectrum of the solution formed by addition
of ca. 1 equivalent of trimethyl phosphite to the mixture of
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192
183

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Scheme 6 (i) LiBun; (ii) P(OMe)3
can be easily rationalized as the transfer of the hydride ligand
from 6 to the carbon atom of the CO2 molecule.
The η2 co-ordination mode of the formate ligand in complex
8 is indicated by the IR spectrum in Nujol, which contains
bands at 1300 and 1560 cmϪ1 assignable to the symmetric and
asymmetric (OCO) stretching frequencies, respectively.7 The
value of the asymmetric ν(OCO) stretching is very similar to
that of 1565 cmϪ1 for [RuH(η2-O2CH)(PPh3)3], which contains
a chelating formate ligand as confirmed by X-ray diffraction.8
This value is also in agreement with those previously reported
for the complexes [MoH(η2-O2CH)(dppe)2] (dppe = Ph2P-
CH2CH2PPh2; 1550 cmϪ1)9 and [RuH(η2-O2CH){PhP[CH2CH2-
CH2P(C6H11)2]2}] (1575 cmϪ1).10 Other characteristic bands are
observed at 1900 and 1540 cmϪ1 and were assigned to the ν(CO)
and ν(C᎐C) stretchings, respectively. The 1H NMR spectrum in
᎐
C6D6 shows resonances due to the triisopropylphosphine lig-
ands and the phenyl group, along with a doublet at δ 9.09
(JH ᎐H = 15.6 Hz), a triplet at δ 8.63 (JP᎐H = 1.9 Hz) and a doublet
of triplets at δ 6.46 (JH ᎐H = 15.6, JP᎐H < 1 Hz), which were
Scheme 7
assigned to the Os᎐CH᎐, O CH and ᎐CHPh protons, respect-
᎐
᎐
2
ively. The most noticeable signals in the 13C-{1H} NMR spec-
trum are three triplets at δ 174.4 (JP᎐C = 1.4), 137.0 (JP᎐C = 9.7
Hz) and 132.8 (JP᎐C = 2.7 Hz). The triplet at δ 174.4 was assigned
to the carbon atom of the formato group by comparison of this
spectrum with that previously reported for the complex [Re(η2-
O2CH)(dppe)2] (δ 171.9).11 The other two triplets were assigned
to the Cα and Cβ carbon atoms of the vinyl ligand. The
31P-{1H} NMR spectrum has a singlet at δ 15.6, indicating that
the two phosphine ligands are equivalent and are mutually
trans disposed.
complexes 2b–2e in benzene shows two broad singlets at δ 8.81
and 7.46 and a doublet at δ Ϫ8.88, with a P᎐D coupling constant
of 20.2 Hz. According to the H NMR spectrum of 3, the
singlets correspond to complexes 3b and 3c of Scheme 6,
respectively, while the doublet is due to the derivative 3d. The
formation of these compounds is new evidence in favour of the
equilibrium between 2 and 6 (Scheme 4). Thus complex 3b is the
product of the reaction of 2c with P(OMe)3, 3c is formed from
2b and 2e in the presence of the phosphite, while 3d is a result of
the addition of the ligand to 2d.
1
Carbonylation of the bidentate formato complex 8 leads to
formation of the monodentate formato derivative 9 (Scheme 8).
The reaction was carried out in hexane, and complex 9 was
isolated as a white solid in 83% yield. In agreement with the
mutually cis disposition of the two carbonyl ligands, the IR
spectrum in Nujol shows two ν(CO) absorptions at 2020 and
1940 cmϪ1. Furthermore, the carboxylato region reflects the
conversion of the formato group from bi- to mono-dentate.
Thus the symmetric and asymmetric ν(OCO) stretchings
appear at 1295 and 1625 cmϪ1 in agreement with those of other
Synthesis and reactivity of [Os{(E )-CH᎐CHPh}(ç2-O CH)-
᎐
2
(CO)(PPri3)2] and [OsH(ç2-O2CH)(CO)(PPri3)2]
Passing a slow stream of carbon dioxide through a hexane solu-
tion of complex 2 affords the formato complex [Os{(E )-CH᎐
᎐
CHPh}(η2-O2CH)(CO)(PPri3)2] 8 (Scheme 7). This compound
was isolated at Ϫ78 ЊC as a microcrystalline solid in 75% yield.
The formation of 8 from the reaction of 2 with CO2 is consist-
ent with the proposal that in solution 2 is in equilibrium with no
detectable concentrations of 6 (Scheme 4). Thus, the reaction
1
monodentate formato species.12 In the H NMR spectrum the
184
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192

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Scheme 10
Scheme 8
bands, at 2050, 1975 and 1915 cmϪ1. The first band was
assigned to the ν(Os᎐H) absorption, and the other two to
ν(CO) absorptions, in agreement with a cis arrangement of
1
these ligands. In the H NMR spectrum in C6D6 the hydride
ligand appears at δ Ϫ4.29 as a triplet with a P᎐H coupling
constant of 21.0 Hz. The chemical shift of this signal is very
close to that previously reported for the hydride ligand disposed
trans to a carbonyl group in the complex [OsH(Cl)(CO)2-
(PPri3)2] (δ Ϫ4.70).14 The proton of the formato group gives rise
to a singlet at δ 7.88. The 31P-{1H} NMR spectrum shows a
singlet at δ 29.1.
Complex 13 was isolated as a white solid in 80% yield. The
IR spectrum in Nujol shows the symmetric and asymmetric
ν(OCO) stretchings at 1380 and 1650 cmϪ1. The 31P-{1H}
NMR contains a triplet at δ 102.9 [P(OMe)3] and a doublet at δ
20.8 (PPri3). The value of the P᎐P coupling constant is 17.9 Hz.
The proposed trans disposition of hydride and phosphite lig-
1
ands is supported by the H NMR spectrum in C6D6, which
contains a doublet of triplets at δ Ϫ6.30, with P᎐H coupling
constants of 149.0 and 23.8 Hz. The proton of the formato
group appears at δ 8.37 as a singlet.
Scheme 9
Attempts to prepare complex 8 by reaction of 10 with phenyl-
acetylene were unsuccessful. Complex 10 is not only inert
towards phenylacetylene but also towards cyclohexylacetylene
and methyl propiolate. However, addition of the stoichiometric
amount of methyl acetylenedicarboxylate to a hexane suspen-
sion of 10 leads to a white solid in 80% yield, which was charac-
terized as the π-alkyne compound [OsH{η1-OC(O)H}(η2-
formato proton gives a singlet at δ 8.11. The α-vinyl proton
appears at δ 8.68 as a doublet of triplets with a H᎐H coupling
constant of 17.0 Hz and a P᎐H coupling constant <1 Hz,
whereas the proton in β position is masked by the C6D6 signal.
In the 13C-{1H} NMR spectrum the carbon atom of the for-
mate ligand appears at δ 168.4 as a singlet, while the Cβ and Cα
carbon atoms of the styryl ligand display triplets, at δ 143.2
(JP᎐C = 2.3) and 140.0 (JP᎐C = 4.6 Hz), respectively. The 31P-{1H}
NMR spectrum shows a singlet at δ 9.3.
i
᎐
MeO CC᎐CCO Me)(CO)(PPr ) ] 14. The π co-ordination of
᎐
2
2
3 2
the alkyne is strongly supported by the IR spectrum of 14 in
Nujol which shows a strong absorption at 1880 cmϪ1, character-
15
᎐
Under a hydrogen atmosphere complex 8 quantitatively
yields styrene and the hydridoformato complex [OsH(η2-O2-
CH)(CO)(PPri3)2] 10,13 which can be also prepared in 82% yield
by bubbling carbon dioxide through a hexane solution of the
istic of a ν(C᎐C) vibration. Furthermore, the spectrum con-
᎐
tains bands at 2040, 1955 and 1710 cmϪ1, which were assigned
to v(Os᎐H), ν(CO) (carbonyl ligand) and ν(CO) (CO2Me
groups of the alkyne), along with the asymmetric and sym-
metric ν(OCO) vibrations of the monodentate formate ligand,
at 1620 and 1375 cmϪ1 respectively.
dihydrido complex [OsH (η2-CH ᎐CHEt)(CO)(PPri ) ] 11
᎐
2
2
3 2
(Scheme 9). As for 8, the bidentate formate ligand of 10 is
converted into a monodentate group by carbonylation. Thus,
the reaction of 10 with carbon monoxide affords [OsH{η1-OC-
(O)H}(CO)2(PPri3)2] 12. Similarly, the addition of a stoichio-
metric amount of P(OMe)3 to a hexane solution of 10 yields
[OsH{η1-OC(O)H}(CO)}(CO){P(OMe)3}(PPri3)2] 13 (Scheme
10). The behaviour of 10 towards carbon monoxide contrasts to
that previously reported for the related ruthenium compound
[RuH(η2-O2CH)(PPh3)3], which reacts with CO to give [RuH2-
(CO)(PPh3)3] and CO2.8
Complex 12 was isolated as a white solid in 82% yield. The
monohapto nature of the formate ligand is supported by the
values of the symmetric and asymmetric ν(OCO) stretchings, in
the IR spectrum in Nujol, which appear at 1370 and 1643 cmϪ1
respectively. In the 2000 cmϪ1 region the spectrum shows three
According to the H, 13C-{1H} and 31P-{1H} NMR spectra
1
of complex 14, in solution, this compound partially dissociates
the alkyne (Scheme 11). At room temperature in C6D6 the
14:10 molar ratio is 1:1. Characteristic signals for 14 in the 1H
NMR spectrum are two singlets at δ 7.63 and 3.74, and a triplet
with a P᎐H coupling constant of 28.3 Hz at δ Ϫ2.28. The sing-
lets were assigned to the O2CH and CO2CH3 protons, respect-
ively, and the triplet to the hydride ligand. The chemical shift
of this ligand agrees well with that previously reported for
2
i
᎐
the complex [OsH(Cl)(η -MeO CC᎐CCO Me)(CO)(PPr ) ] (δ
᎐
2 2 3 2
Ϫ2.80), where a trans disposition of the hydride and π-alkyne
ligands has also been proposed.16 In contrast to the behaviour
of the related chloro-derivative, insertion of the alkyne into the
osmium–hydride bond of 14 is not observed. In the 13C-{1H}
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192
185

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Scheme 13
Scheme 11
and 15. After 24 h at room temperature the composition con-
sists of only 15(60) and 16(40%). Bubbling molecular hydrogen
through this solution does not affect the 15:16 molar ratio,
even after 6 h. These results can be rationalized according to
schemes 9, 12 and 13. As for 10, the carbon atom of the formate
ligand of 8 is susceptible to attack by nucleophiles. Thus, the
reaction of this complex with diethylamine leads to the styryl-
carbamato derivative 16 (Scheme 13). The molecular hydrogen
generated from the nucleophilic substitution reacts with 8 to
give 10 and styrene (Scheme 9). Complex 10 then reacts further
with the amine to afford 15 and molecular hydrogen (Scheme
12).
1
In the H NMR spectrum the most noticeable signals for
complex 16 are those corresponding to the styryl and carba-
mate ligands. The vinyl protons of the styryl ligand display a
doublet at δ 9.37 with a H᎐H coupling constants of 15.6 Hz,
and a doublet of triplets at δ 6.57 with a P᎐H coupling con-
stant < 1 Hz, assigned to the α- and β-proton respectively. Simi-
larly to 15, the ethyl protons of the carbamate ligand appear as
two quartets at δ 3.14 and 3.04 and two triplets at δ 0.93 and
0.91. In the 13C-{1H} NMR spectrum the central carbon atom
of the carbamato group appears as a singlet at δ 165.0, the
α-carbon atom of the styryl ligand appears at δ 138.7 as a trip-
let with a P᎐C coupling constant of 7.7 Hz, and the β-carbon
atom gives rise to a broad singlet at δ 132.3. A singlet at δ 16.1
in the 31P-{1H} NMR spectrum is also characteristic of 16.
Scheme 12
NMR spectrum the acetylenic carbon atoms appear at δ 107.3
as a triplet with a P᎐C coupling constant of 3.3 Hz. The reson-
ance due to the carbon atom of the formato group is observed
at δ 166.2, as a triplet with a P᎐C coupling constant of 5.3 Hz.
A singlet at δ 30.8 in the 31P-{1H} NMR spectrum is also charac-
teristic of 14.
The carbon atom of the formate ligand of complex 10 is an
electrophilic centre susceptible to attack by nucleophiles. Ad-
dition of 1 equivalent of diethylamine to a NMR tube contain-
ing a C6D6 solution of 10 yields, after 1 h at 60 ЊC, the carb-
amato derivative [OsH(η2-O2CNEt2)(CO)(PPri3)2] 15 in quanti-
tative yield, (Scheme 12). The 1H NMR spectrum of 15 exhibits
two quartets at δ 3.14 and 3.02 and two triplets at δ 0.95 and
0.91, corresponding to two inequivalent ethyl groups. The
inequivalence of the ethyl groups of the carbamate ligand
indicates that the molecule has no mirror plane of symmetry
containing the P᎐Os᎐P unit, in agreement with the structure
shown. The hydride ligand appears at δ Ϫ20.37 as a triplet with
a P᎐H coupling constant of 16.2 Hz. In the 13C-{1H} NMR
spectrum the ethyl groups display four singlets, two for the CH2
carbon atom at δ 39.3 and 39.0 and two for the CH3 carbon
atoms at δ 14.2 and 14.2. The central carbon atom of the
carbamato group appears at δ 165.4. The chemical shift of this
resonance compares well with those previously reported for
related compounds (δ 170–160).17 The 31P-{1H} NMR spec-
trum shows a singlet at δ 38.4.
Protonation of complexes 8 and 10
Complex 8 also reacts with HBF4ؒOEt2, leading to different
derivatives depending upon the conditions. In diethyl ether as
solvent one of the two oxygen atoms of the formate ligand
undergoes electrophilic attack of the proton of the acid to give
the unsaturated [Os{(E )-CH᎐CHPh}(CO)(PPri ) ]+ fragment,
᎐
3
2
which can be trapped as [Os{(E )-CH᎐CHPh}(CO)(MeCN) -
᎐
2
(PPri3)2]BF4 17 in the presence of acetonitrile. While, in chloro-
form as solvent, electrophilic attack of the proton takes place
at the β-carbon atom of the styryl ligand. In this case the
compound formed is the carbene derivative [Os(η2-O2CH)-
(᎐CHCH Ph)(CO)(PPri ) ]BF 18 (Scheme 14).
᎐
2
3
2
4
Complex 17 was isolated as a white solid in 80% yield. The
IR spectrum in Nujol shows the absorption due to the [BF4]Ϫ
anion with Td symmetry, at about 1100 cmϪ1 indicating that this
anion is not co-ordinated to the metal. Consistent with the
mutually cis disposition of the acetonitrile ligands, the 1H
NMR spectrum shows two singlets for their protons, at δ 2.68
and 2.57. The α-vinylic proton of the styryl group appears at δ
8.28 as a doublet with a H᎐H coupling constant of 17.3 Hz,
while the β-vinylic proton appears at δ 6.42 as a doublet of
triplets with a P᎐H coupling constant 1 Hz. In the 13C-{1H}
NMR spectrum the acetonitrile ligands also give rise to two
singlets at δ 126.0 and 125.5. The Cα and Cβ atoms of the vinyl
The H, 13C-{1H} and 31P-{1H} NMR spectra of the solu-
1
tion formed by addition of ca. 1 equivalent of diethylamine to
complex 8 in C6D6 show, after 3 h at room temperature, the
presence of styrene and resonances that were assigned to the
complexes 8(41), 10(10), 15(12) and the styrylcarbamato deriva-
tive [Os{(E )-CH᎐CHPh}(η2-O CNEt )(CO)(PPri ) ] 16 (37%),
᎐
2
2
3 2
by comparison of these spectra with those recorded for 8, 10
186
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192

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Table 1 Selected geometrical parameters (Å and Њ) of the MP2 opti-
mized structures. The atom numbering is that defined in Figs. 2 and 3;
X corresponds to a point at the centre of the straight line between
H(10) and H(11)
Structure
10a
20a
21a
22a
23a
Os(1)᎐P(2)
Os(1)᎐P(3)
Os(1)᎐C(4)
Os(1)᎐O(6)
Os(1)᎐O(8)
Os(1)᎐H(10)
Os(1)᎐H(11)
Os(1)᎐X
2.404
2.404
1.837
2.419
2.253
1.588
—
2.460
2.460
1.876
2.156
2.244
1.688
1.688
1.623
0.930
2.482
2.476
1.839
1.979
3.390
1.728
1.729
1.669
0.894
2.484
2.502
1.936
1.987
3.463
1.594
1.594
0.810
2.745
2.489
2.495
1.889
2.000
3.460
1.603
1.592
1.400
1.534
—
—
H(10)᎐H(11)
P(2)᎐Os(1)᎐P(3)
P(2)᎐Os(1)᎐C(4)
P(2)᎐Os(1)᎐O(6)
P(2)᎐Os(1)᎐X
172.4
93.6
89.9
—
169.3
93.0
84.9
170.1
90.8
89.9
170.3
103.6
93.9
165.2
98.2
90.6
Scheme 14 (i) HBF4, MeCN, Et2O; (ii) HBF4, CHCl3
94.5
93.8
53.3
96.7
C(4)᎐Os(1)᎐O(6)
C(4)᎐Os(1)᎐X
114.1
—
104.8
94.5
110.6
93.8
162.5
53.3
150.9
96.7
C(4)᎐Os(1)᎐O(6)
C(4)᎐Os(1)᎐X
114.1
—
104.8
89.0
110.6
88.2
162.5
50.3
150.9
81.9
O(6)᎐Os(1)᎐X
H(10)᎐Os(1)᎐H(11)
—
—
166.2
32.0
160.8
30.0
147.2
118.9
127.0
57.4
Fig. 1 Proton NMR spectrum (CDCl3) of the mixture resulting from
the reaction of [OsH(η2-O2CH)(CO)(PPri3)2] 10 with HBF4ؒOEt2 in the
hydrido region, at different reaction times
Fig.
2
The MP2 optimized geometry of the reactant species
[OsH(η2-O2CH)(CO)(PH3)2] 10a. Hydrogen atoms of phosphine
ligand display triplets at δ 132.7 and 136.2, with P᎐C coupling
constants of 8.9 and 3.0 Hz, respectively. The 31P-{1H} NMR
spectrum contains a singlet at δ 3.1.
ligands are omitted for clarity
Complex 18 was isolated as a green oil in quantitative yield,
hydride ligand and/or at the metal to give a mixture of prod-
ucts. Fig. 1 shows the high-field region of the H NMR spec-
1
1
and was characterized in solution by IR, H, 13C-{1H} and
31P-{1H} NMR spectroscopy. The IR spectrum in dichloro-
methane shows two bands at 1560 and 1355 cmϪ1, supporting
the bidentate co-ordination of the formato group. The presence
trum at different reaction times. After 5 min the spectrum
mainly contains four signals A–D. After 45 min signal D
disappears, and the B:A intensity ratio increases. A variable-
temperature 300 MHz T1 study of the peaks A–C gave T1(min)
values of 17, 21 and 260 ms, respectively, suggesting that A and
B correspond to dihydrogen compounds, while C is due to a
dihydrido derivative. The correlation of the spectra shown in
Fig. 1 with the 31P-{1H} NMR spectra registered at the same
reaction times (5, 20 and 45 min) indicates that the signals A
and B are related with singlets at δ 25.6 and 41.8, respectively,
while the D may be related with a broad resonance centred at δ
35.6. The signal C could not be clearly correlated.
In order to cast light on the nature and structure of the prod-
ucts of the reaction of complex 10 with HBF4ؒOEt2 in CDCl3,
ab initio theoretical calculations have been carried out. They
were performed at the Møller–Plesset Perturbatia (MP)2 and 4
levels using PH3 in place of the triisopropylphosphine ligand.
The geometry optimizations were carried out at the MP2 level.
Fig. 2 shows a plot of the optimized structure for the com-
plex [OsH(η2-O2CH)(CO)(PH3)2] 10a. The most significant
parameters are included in Table 1. As expected the co-
1
of a carbene ligand was inferred from the H and 13C-{1H}
NMR spectra in CDCl3. The 1H NMR spectrum contains at δ
17.63 a triplet with a H᎐H coupling constant of 6.1, and at δ
3.52 a doublet with the same H᎐H coupling constant. These
resonances were assigned to the Os᎐CH and CH Ph protons,
᎐
2
respectively. The proton of the formato group appears at δ 9.19,
as a singlet. In the 13C-{1H} spectrum the Cα carbon atom of
the carbene ligand appears at δ 290.8 as a broad signal. The
carbon atom of the formato group gives rise to a singlet at δ
168.7. The 31P-{1H} NMR spectrum contains a singlet at δ
38.3.
The reaction of complex 10 with HBF4ؒOEt2 also leads to
different derivatives depending upon the conditions. Similarly
to 8, in diethyl ether as solvent, the reaction produces a very
unsaturated [OsH(CO)(PPri3)2]+ fragment, which can be
trapped with acetonitrile to afford the previously reported
compound [OsH(CO)(MeCN)2(PPri3)2]BF4 19.18 However, in
CDCl3 the electrophilic attack of the proton occurs at the
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192
187

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Table 2 The MP2 and MP4 relative energies (kcal molϪ1) of different
isomers of [OsH2(O2CH)(CO)(PH3)2]+. Geometries are optimized at the
MP2 level
Geometry
20a
21a
22a
23a
MP2
MP4
0.00
0.00
15.97
15.91
12.00
12.42
11.87
12.36
ordination geometry around the metal is distorted octahedral.
The distortion is due to the small angle of the bidentate for-
mato group [O(6)᎐Os(1)᎐O(8) 57.9Њ].
Since protonation of complex 10 leads a mixture of products
containing dihydrogen and dihydride ligands, all the reasonable
dihydrogen and dihydrido structures containing the formate
ligand co-ordinated in mono- or di-hapto manner, and with the
phosphine ligands mutually trans disposed, were considered.*
The MP2 optimizations lead to the species 20a–23a, presented
in Fig. 3. The most significant geometrical parameters are
collected in Table 1, with MP2 and MP4 relative energies in
Table 2.
The theoretical calculations suggest that two dihydrogen and
two dihydrido derivatives are possible. Thermodynamically, the
most stable complex is the six-co-ordinated η2-formato (di-
hydrogen) 20a, where the two hydrogen atoms of the dihydrogen
ligand are separated by 0.930 Å. Its stability is in agreement
with its nature as a d6 ML6 complex. According to Fig. 1, the
most stable species displays signal B, which shows a T1(min)
value of 21 ms at 300 MHz. This value corresponds to a
hydrogen–hydrogen distance of 0.94 Å (fast spinning).† So we
propose that signal B is characteristic of the η2-formato (di-
hydrogen) cation [Os(η2-O2CH)(η2-H2)(CO)(PPri3)2]+ 20.
Signal A is also characteristic of a dihydrogen derivative, its
T1(min) value (17 ms at 300 MHz) corresponding to a hydrogen–
hydrogen distance of 0.90 Å (fast spinning). Species 21a has a
square-pyramidal structure (Fig. 3) with a larger distortion cor-
responding to the C(4)᎐Os(1)᎐O(6) angle (110.6Њ, Table 1). It is
a dihydrogen complex [H(10)᎐H(11) 0.894 Å], and its nature as
a monodentate formate compound is indisputable [Os(1) ؒ ؒ ؒ
O(8) 3.390 Å]. Thus, at first glance, one could propose that
signal A corresponds to a five-co-ordinate η1-formato (dihy-
drogen) derivative with the carbonyl group in the apical pos-
ition. However, it should be noted that (i) 20a is 15.91 kcal
molϪ1 more stable than 21a and (ii) a high kinetic barrier would
not be expected for the η1-formato → η2-formato transform-
ation. Hence, we believe that this signal corresponds to a six-co-
ordinate η1-formato (dihydrogen) species, stabilized by co-
ordination of a diethyl ether molecule (21), originating from the
HBF4ؒOEt2 solution used in the reaction. The co-ordination of
the ether molecule cis to the dihydrogen ligand should increase
the kinetic barrier for the η1-formato → η2-formato trans-
formation without affecting the metal–dihydrogen interaction
and, therefore, the hydrogen–hydrogen separation.
Fig. 3 The MP2 optimized geometries of the dihydrogen complexes
[Os(η2-O2CH)(η2-H2)(CO)(PH3)2]+ 20a and [Os{η1-OC(O)H}(η2-H2)-
(CO)(PH3)2]+ 21a and of the dihydrido complexes [OsH2{η1-OC(O)H}-
(CO)(PH3)2]+ 22a and 23a. Hydrogen atoms of phosphine ligands are
omitted for clarity
Signal C is characteristic of a dihydrido derivative containing
non-equivalent phosphine ligands. The T1(min) value for this
signal is 260 ms at 300 MHz. Complex 22a is not octahedral
[H(10)᎐Os(1)᎐H(11) 118.9Њ] but a bicapped tetrahedron, a co-
ordination polyhedron characteristic for d4 ML6 complexes.21,22
The bicapped tetrahedron 22a contains non-equivalent phos-
phine ligands [Os(1)᎐P(2) 2.484, Os(1)᎐P(3) 2.502 Å], and they
cannot be interconverted through reorientation of the formate
ligand. The hydrogen–hydrogen separation in 22a is 2.745 Å.
For this distance a T1(min) value of 224 ms at 300 MHz‡ is
expected. The experimental properties of signal C seem well
suited to that inferred for 22a from the theoretical calcul-
ations. So, we correlate it to the derivative [OsH2{η1-OC(O)-
* The mutually trans disposition for the phosphine ligands is a reason-
able assumption in the view of the steric demands of the PPri3 ligand.
Trigonal-bipyramidal geometries were not considered because they are
not likely in d6 ML5 species like this one.19
† At the temperature of minimum T1, τ = 0.62/2πν, and the equation for
‡ It has been recently shown that, for polyhydrido complexes, T1(min)
can be calculated by using internuclear distances obtained from
neutron, X-ray diffraction 23a and theoretical studies.23b
1
6
-
dipolar relaxation simplifies to rH ᎐H = 4.611 (T1min/ν) for rapid rota-
tion (ν/MHz, T1/s).20
188
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192

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acetonitrile. In chloroform, complex 8 leads to the carbene
[Os(η2-O CH)(᎐CHCH Ph)(CO)(PPri ) ]+ 18, and 10 gives a
᎐
2
2
3 2
mixture of products, mainly dihydrogen derivatives. On the
basis of theoretical calculations and T1 measurements, we pro-
pose that these derivatives could be the cations [Os(η2-O2-
CH)(η2-H2)(CO)(PPri3)2]+ 20 and [Os{η1-OC(O)H}(η2-H2)-
(Et2O)(CO)(PPri3)2]+ 21.
Experimental
All reactions were carried out with rigorous exclusion of air by
using Schlenk-tube techniques. Solvents were dried by known
procedures and distilled under argon prior to use.
Physical measurements
Infrared spectra were recorded as Nujol mulls on polyethylene
sheets or NaCl cell windows using a Perkin-Elmer 883 or a
Nicolet 550 spectrometer, NMR spectra on a Varian UNITY
300 or Brucker 300 AXR spectrometer. Proton and 13C-{1H}
chemical shifts were measured relative to partially deuteriated
solvent peaks but are reported relative to tetramethylsilane,
31P-{1H} chemical shifts relative to external 85% H3PO4. Coup-
H}(CO)(PPri3)2]+ 22, which may have the structure shown in
Fig. 3.
Signal D rapidly disappears, and it cannot be studied. It may
be assigned to species 23a.
ling constants J and N [᎐ J(PH) + J(PЈH) for 1H, J(PC) +
᎐
J(PЈC) for 13C] are given in Hz. The C, H and N analyses were
carried out in a Perkin-Elmer 2400 CHNS/O analyser. The
starting materials [Os{(E )-CH᎐CHPh}Cl(CO)(PPri ) ] 1 and
The reactions of complex 10 with HBF4ؒOEt2 to give 19, and
20, and 21, as well as the protonations of 8 to afford 17 and
18, can be rationalized via the intermediates 24 and 25. The
electrophilic attack of the proton could initially take place at
one of the two oxygen atoms of the formate ligands of both 10
and 8. Thus, in the presence of acetonitrile the displacement of
the resulting formic acid by the nitrogen-donor ligand should
yield 19 and 17, while in the absence of this ligand the transfer
of the proton from the oxygen atom to the hydride and vinyl
ligands could afford the thermodynamically more stable com-
pounds 21 and 18.
᎐
3
2
[OsH (η2-CH ᎐CHEt)(CO)(PPri ) ] 11 were prepared by pub-
᎐
2
2
3 2
lished methods.5,6 The deuteriated complexes [Os{(E )-CH᎐
᎐
CDPh}Cl(CO)(PPri ) ] 1a and [Os{(E )-CD᎐CHPh}Cl(CO)-
᎐
3
2
(PPri3)2] 1b were prepared by reaction of [OsD(Cl)(CO)(PPri3)2]
i
᎐
᎐
with PhC᎐CH and [OsH(Cl)(CO)(PPr ) ] with PhC᎐CD,
᎐
᎐
3
2
respectively.
Preparations
[OsH{C H (CH᎐CHH)}(CO)(PPri ) ] 2.
A
solution of
᎐
6
4
3 2
[Os{(E )-CH᎐CHPh}Cl(CO)(PPri ) ] 1 (100 mg, 0.15 mmol) in
᎐
3
2
hexane (5 cm3) was treated with LiBun (0.01 cm3, 1.6 mol dmϪ3
solution in hexane) and stirred during ca. 5 min at room tem-
perature. The mixture changed from dark blue to pale yellow.
The resulting suspension was filtered through Kieselguhr and
the filtrate was dried in vacuo to give a colourless oil. NMR
Conclusion
This study has shown that the reaction of the five-co-ordinate
compound [Os{(E )-CH᎐CHPh}Cl(CO)(PPri ) ] 1 with LiBun
᎐
3
2
1
leads to [OsH{C H (CH᎐CHH)}(CO)(PPri ) ] 2 in equilibrium
(C6D6, 20 ЊC): H, δ 7.26 (d, JH ᎐H = 7.1, 1 H, HPh), 7.03 (t,
᎐
6
4
3 2
JH ᎐H = 7.1, 1 H, HPh), 6.90 (t, JH ᎐H = 7.1, 1 H, HPh), 6.56 (d,
with the co-ordinatively unsaturated complex [OsH{(E )-CH᎐
᎐
CHPh}(CO)(PPri3)2] 6. Complexes 2 and 6 are connected by the
JH ᎐H = 7.1, 1 H, HPh), 4.95 (dd, JH ᎐H = 9.0, J 7.7, 1 H, CH᎐), 3.71
᎐
osmium(0) intermediate [Os(η2-CH ᎐CHPh)(CO)(PPri ) ] 7,
(dt, JH ᎐H = 9.0, JP᎐H = 5.7, 1 H, ᎐CH ), 2.74 (d, J
= 7.7, 1 H,
᎐
᎐
2
H ᎐H
2
3 2
᎐CH ), 2.15 (m, 6 H, PCHCH ), 1.05 (dvt, N = 13.5, J
= 6.3,
which gives rise to C᎐H activation reactions in the terminal
olefinic and the ortho-phenyl C᎐H bonds of the co-ordinated
styrene. Complex 6 cannot be detected in solution, most prob-
ably due to the higher stability of its 18-electron isomer 2. How-
ever, the reactivity of 2 can easily be understood as a result of
the reactions of the more labile isomer 6. Thus, the for-
᎐
2
3
H ᎐H
36 H, PCHCH3) and Ϫ8.01 (t, JP᎐H = 27.3, 1 H, OsH); 13C-
{1H}, d 187.9 (t, JP᎐C = 8.0, CO), 152.2 (t, JP᎐C = 2.0, CPh), 138.6
(t, JP᎐C = 10.0, CPh), 135.8 (br, CHPh), 126.1 (br, CHPh), 122.9
(br, CHPh), 121.0 (br, CHPh), 50.5 (br, CH᎐), 46.3 (br, ᎐CH ),
᎐
᎐
2
26.6 (vt, N = 26.4 Hz, PCHCH3), 20.1 (s, PCHCH3) and 20.0
(s, PCHCH3); 31P-{1H}, δ 16.7 (s).
mato complex [Os{(E )-CH᎐CHPh}(η2-O CH)(CO)(PPri ) ] 8,
᎐
2
3 2
formed by passing a slow stream of carbon dioxide through a
hexane solution of 2, can be rationalized from the insertion of
the CO2 molecule into the Os–H bond of 6. Hydrogenation of 8
gives styrene and the hydrido complex [OsH(η2-O2CH)(CO)-
(PPri3)2] 10.
[OsH{(E )-CH᎐CHPh}(CO){P(OMe) }(PPri ) ] 3. A solution
᎐
3
3 2
of complex 1 (100 mg, 0.15 mmol) in hexane (5 cm3) was treated
with LiBun (0.01 cm3, 1.6 mol dmϪ3 solution in hexane) and
stirred during ca. 5 min at room temperature. The resulting
suspension was filtered through Kieselguhr and treated with
P(OMe)3 (17 µl, 0.15 mmol). After 30 min of reaction a white
solid was formed, decanted, washed with hexane and dried in
vacuo. Yield 95.7 mg (85%) (Found: C, 47.5; H, 8.2. Calc. for
C30H59O4OsP3: C, 47.0; H, 7.75%). IR (Nujol, cmϪ1): ν(Os᎐H)
The reactivity of complexes 8 and 10 towards CO, NEt2H
and HBF4 has been also studied. By carbonylation, the biden-
tate formate ligand of these compounds becomes monodentate.
In the presence of diethylamine, the central carbon atoms of
the bidentate formato groups undergo nucleophilic attack
affording the carbamato derivatives [OsR(η2-O2CNEt2)(CO)-
2050s, ν(CO) 1910s, ν(C᎐C) 1540m. NMR (C D , 20 ЊC): 1H, δ
᎐
6
6
(PPri ) ] (R = H 15 or CH᎐CHPh 16). The reactions of 8 and 10
8.78 (tq, JH ᎐H = 18.3, JP᎐H = 18.3, JH ᎐H 1.6 Hz, JH ᎐H = 1.6, 1 H,
᎐
3
2
with HBF4 lead to different derivatives depending upon the
conditions. In diethyl ether as solvent the formato groups of
both compounds undergo electrophilic attack by protons to
give fragments of the type [OsR(CO)(PPri3)2]+ (R = H or
OsCH᎐CHPh), 7.46 (d, J = 7.3, 2 H, o-H of Ph), 7.23 (t,
JH ᎐H = 7.3, 2 H, m-H of Ph), 7.03 (dt, JH ᎐H = 18.3, JP᎐H = 2.5, 1 H,
᎐
H ᎐H
OsCH᎐CHPh), 6.96 (t, J = 7.3, 1 H, p-H of Ph, 3.39 (d,
᎐
H ᎐H
JP᎐H = 10.1, 9 H, POMe), 2.47 (m, 6 H, PCHCH3), 1.27 (dvt,
N = 14.0, JH ᎐H = 7.1 18 H, PCHCH3), 1.20 (dvt, N = 11.9,
CH᎐CHPh), which can be trapped in the presence of
᎐
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192
189

View Article Online
JH ᎐H = 7.1 18 H, PCHCH3) and Ϫ8.94 (dtd, JP᎐H = 134.4,
JP᎐H = 24.5, JH ᎐H = 1.6, 1 H, OsH); 13C-{1H}, δ 190.8 (vq,
JP᎐C = 8.3 CO), 145.3 (t, JP᎐C = 2.3 ipso-C of Ph), 144.4 (dt,
JP᎐C = 10.1, 4.2, OsCH᎐CHPh), 143.3 (vq, J = 13.4, OsCH᎐
CHPh), 128.6 (s, o-CH of Ph), 124.4 (s, m-CH of Ph), 124.0 (s,
p-CH of Ph), 51.6 (d, JP᎐C = 8.8 POMe), 26.0 (vtd, N = 26.8,
JP᎐C = 2.3, PCHCH3), 20.8 (s, PCHCH3) and 18.7 (s, PCHCH3);
31P-{1H}, δ 102.4 (t, JP᎐P = 18.6 POMe) and 17.5 (d, JP᎐P = 18.6
Hz, PPri3).
2.65 (s, ᎐CHD) and Ϫ8.02 (s, OsD); 31P-{1H} (C6D6, 20 ЊC),
δ 17.1 (s).
᎐
[OsH{(E )-CD᎐CHPh}(CO){P(OMe) }(PPri ) ] 3b, [OsH-
᎐
᎐
P᎐C
᎐
3
3 2
{(E )-CH᎐CHC H D}(CO){P(OMe) }(PPri ) ] 3c and [OsD-
᎐
6
4
3
3 2
{(E )-CH᎐CHPh}(CO){P(OMe) }(PPri ) 3d. The complexes
᎐
3
3 2
were prepared using the procedure described for 3 (100 mg, 0.15
mmol), starting from [Os{(E )-CD᎐CHPh}Cl(CO)(PPri ) ].
᎐
3
2
1
NMR: H (C6D6, 20 ЊC), δ 8.78 (t, JH ᎐H = 18.3, JP᎐H = 18.3,
OsCH᎐CHPh), 7.46 (d, J = 7.3, o-H of Ph), 7.23 (t,
᎐
H ᎐H
[OsH{(E )-CH᎐CHPh}(CO) (PPri ) ] 4. A solution of com-
᎐
2
3 2
JH ᎐H = 7.3, 2 H, m-H of Ph), 7.03 (br d, JH ᎐H = 18.3, OsCH᎐
᎐
plex 1 (100 mg, 0.15 mmol) in hexane (5 cm3) was treated with
LiBun (0.01 cm3, 1.6 mol dmϪ3 solution in hexane) and stirred
during ca. 5 min at room temperature. The resulting suspension
was filtered through Kieselguhr and a slow stream of carbon
monoxide was bubbled through it. After 30 min of reaction a
white solid was formed, decanted, washed with hexane and
dried in vacuo. Yield 74 mg (72%) (Found: C, 50.6; H, 8.4. Calc.
for C28H50O2OsP2: C, 50.15; H, 7.55%). IR (Nujol, cmϪ1):
CHPh), 6.96 (t, JH ᎐H = 7.3, 1 H, p-H of Ph), 3.39 (d, JP᎐H = 10.1, 9
H, POMe), 2.47 (m, 6 H, PCHCH3), 1.27 (dvt, N = 14.0,
JH ᎐H = 7.1, 18 H, PCHCH3), 1.20 (dvt, N = 11.9, JH ᎐H = 7.1, 18
2
H, PCHCH3) and Ϫ8.94 (dt, JP᎐H = 134.4, J 24.5, OsH); H
(C H , 20 ЊC), δ 8.81 (s, OsCD᎐CHPh), 7.46 (s, o-D of Ph) and
᎐
6
6
Ϫ8.88 (d, JP᎐D = 20.2, OsD); 31P-{1H} (C6D6, 20 ЊC), δ 103.0 (dt,
JP᎐D = 20.2, JP᎐P = 18.6, POMe) and 17.5 (d, JP᎐P = 18.6 Hz,
PPri3).
ν(OsH) 1990s, ν(CO) 1945s, 1865s, 1570m, ν(C᎐C). NMR
᎐
(C6D6, 20 ЊC): 1H, δ 8.34 (br d, JH ᎐H = 16.1, 1 H, OsCH᎐CHPh),
[Os{(E )-CH᎐CHPh}(ç2-O CH)(CO)(PPri ) ] 8. A solution
᎐
᎐
2
3 2
of complex 1 (100 mg, 0.15 mmol) in hexane (5 cm3) was treated
with LiBun (0.01 cm3, 1.6 mol dmϪ3 solution in hexane) and
stirred during ca. 5 min at room temperature. The resulting pale
yellow suspension was filtered through Kieselguhr and a slow
stream of carbon dioxide was bubbled through it for ca. 30 min.
The solution was cooled at Ϫ78 ЊC, resulting in crystallization
of a yellow solid. This was decanted and dried in vacuo. Yield
77.3 mg (75%) (Found: C, 48.89; H, 7.2. Calc. for
C28H50O3OsP2: C, 48.95; H, 7.35%). IR (Nujol, cmϪ1): ν(CO)
7.41 (d, JH ᎐H = 7.3, 2 H, o-H of Ph), 7.23, (t, JH ᎐H = 7.3, 2 H, m-H
of Ph), 7.20 (d, JH ᎐H = 16.1, 1 H, OsCH᎐CHPh), 6.98 (t,
᎐
JH ᎐H = 7.3, 1 H, p-H of Ph), 2.24 (m, 6 H, PCHCH3), 1.16 (dvt,
N = 13.5, JH ᎐H = 6.9, 32 H, PCHCH3) and Ϫ7.13 (td, JP᎐H = 22.0,
JH ᎐H = 5.0, 1 H, OsH); 13C-{1H}, δ 190.4 (t, JP᎐C = 5.5, CO),
185.5 (t, JP᎐C = 7.8, CO), 144.5 (t, JP᎐C = 1.9, ipso-C of Ph), 142.5
(t, JP᎐C = 3.7, OsCH᎐CHPh), 135.2 (t, JP᎐C = 12.9, OsCH-
᎐
᎐CHPh), 128.8 (s, o-C of Ph), 124.9 (s, m-C of Ph), 124.5 (s,
᎐
p-C of Ph), 26.2 (vt, N = 27.6, JP᎐C = 2.3 Hz, PCHCH3) and
19.0 (s, PCHCH3); 31P-{1H}, δ 19.0 (s).
1900s, νasym(OCO) 1560s, ν(C᎐C) 1540m, νsym(OCO) 1300s.
᎐
1
NMR (C6D6, 20 ЊC): H, δ 9.09 (d, JH ᎐H = 15.6, 1 H, OsCH-
[OsH{C H (CD᎐CHH)}(CO)(PPri ) ] 2a. The complex was
᎐CHPh), 8.63 (t, J
᎐
= 1.9, 1 H, O2CH), 7.38 (d, JH ᎐H = 7.4 Hz,
᎐
6
4
3 2
P᎐H
prepared using the procedure described for 2 (100 mg, 0.15
2 H, o-H of Ph), 7.24 (t, JH ᎐H = 7.4, 2 H, m-H of Ph), 6.93 (t,
JH ᎐H = 7.4, 1 H, p-H of Ph), 6.46 (dt, JH ᎐H = 15.6, JP᎐H < 1, 1 H,
mmol), starting for [Os{(E )-CH᎐CDPh}Cl(CO)(PPri ) ].
᎐
3
2
NMR: 1H (C6D6, 20 ЊC), δ 7.26 (d, JH ᎐H = 7.1, 1 H, HPh), 7.03 (t,
JH ᎐H = 7.1, 1 H, HPh), 6.90 (t, JH ᎐H = 7.1, 1 H, HPh), 6.56 (d,
JH ᎐H = 7.1, 1 H, HPh), 3.71 (t, JP᎐H = 5.7, 1 H, ᎐CH ), 2.74 (s,
OsCH᎐CHPh), 2.44 (m, 6 H, PCHCH ), 1.24 (dvt, N = 13.5,
᎐
3
JH ᎐H = 7.1, 18 H, PCHCH3) and 1.17 (dvt, N = 13.2, JH ᎐H = 7.1,
18 H, PCHCH3). 13C-{1H}, δ 185.9 (t, JP᎐C = 9.2, CO), 174.4 (t,
JP᎐C = 1.4, O2CH), 142.6 (t, JP᎐C = 1.2, ipso-C of Ph), 137.0 (t,
᎐
2
᎐CH ), 2.15 (m, 6 H, PCHCH ), 1.05 (dvt, N = 13.5, J
= 6.3,
᎐
2
3
H ᎐H
2
36 H, PCHCH3) and Ϫ8.01 (t, JP᎐H = 27.3 Hz, 1 H, OsH); H
JP᎐C = 9.7, OsCH᎐CHPh), 132.8 (t, J = 2.7, OsCH᎐CHPh),
᎐
᎐
P᎐C
(C H , 20 ЊC), δ 5.03 (s, CD᎐); 31P-{1H} (C6D6, 20 ЊC), δ 17.1
128.8 (s, o-CH of Ph), 124.1 (s, m-CH of Ph), 123.7 (s, p-CH
of Ph), 24.8 (vt, N = 24.0 Hz, PCHCH3), 19.7 (s, PCHCH3) and
19.6 (s, PCHCH3); 31P-{1H}, δ 15.6 (s).
᎐
6
6
(s).
[OsH{(E )-CH᎐CDPh}(CO){P(OMe) }(PPri ) ] 3a. The
᎐
3
3 2
[Os{(E )-CH᎐CHPh}{ç1-OC(O)H}(CO) (PPri ) ] 9. A slow
complex was prepared using the procedure described for 3 (100
᎐
2
3 2
mg, 0.15 mmol), starting for [Os{(E )-CH᎐CDPh}Cl(CO)-
᎐
stream of carbon monoxide was bubbled through a hexane
solution of complex 8 (100 mg, 0.15 mmol) during 5 min. The
white solid obtained was decanted, washed with hexane and
dried in vacuo. Yield 89.0 mg (83%) (Found: C, 48.75; H, 6.95.
Calc. for C29H50O4OsP2: C, 48.75; H, 7.0%). IR (Nujol, cmϪ1):
1
(PPri3)2]. NMR: H (C6D6, 20 ЊC), δ 8.78 (d, JP᎐H = 18.3, 1 H,
OsCH᎐CHPh), 7.46 (d, J
= 7.3, 2 H, o-H of Ph), 7.23 (t,
᎐
H ᎐H
JH ᎐H = 7.3, 2 H, m-H of Ph), 6.96 (t, JH ᎐H = 7.3, 1 H, p-H of Ph),
3.39 (d, JP᎐H = 10.1, 9 H, POMe), 2.47 (m, 6 H, PCHCH3), 1.27
(dvt, N = 14.0, JH ᎐H = 7.1, 18 H, PCHCH3), 1.20 (dvt, N = 11.9,
ν(CO) 2020s, 1940s, νasym(OCO) 1625s, ν(C᎐C) 1590m, ν
-
᎐
sym
1
JH ᎐H = 7.1, 18 H, PCHCH3) and Ϫ8.94 (dt, JP᎐H = 134.4, 24.5, 1
(OCO) 1295s. NMR (C6D6, 20 ЊC): δ H, 8.68 (dt, JH ᎐H = 17.0,
2
H, OsH); H (C H , 20 ЊC), δ 7.01 (s, OsCH᎐CDPh); 31P-{1H}
᎐
6
6
JP᎐H < 1, 1 H, OsCH᎐CHPh), 8.11 [s, 1 H, OC(O)H)], 7.44 (d,
᎐
(C6D6, 20 ЊC), δ 103.0 (t, JP᎐P = 18.6 POMe), 17.5 (d, JP᎐P = 18.6
JH ᎐H = 7.7, 2 H, o-H of Ph), 7.44 (t, JH ᎐H = 7.7, 2 H, m-H of Ph)
Hz, PPri3).
(the OsCH᎐CHPh signal is masked by the C D signal), 6.69 (t,
᎐
6
6
JH ᎐H = 7.7, 1 H, p-H of Ph), 2.38 (m, 6 H, PCHCH3), 1.08 (dvt,
N = 12.9, JH ᎐H = 6.7, 18 H, PCHCH3) and 1.04 (dvt, N = 12.1,
JH ᎐H = 6.9, 18 H, PCHCH3); 13C-{1H}, δ 186.8 (t, JP᎐C = 6.9,
CO), 184.4 (t, JP᎐C = 7.8, CO), 168.4 [s, OC(O)H], 149.1 (t,
[OsH{C H D(CH᎐CHH)}(CO)(PPri ) ] 2b,
᎐
6
3
3 2
[OsH{C H (CH᎐CDH)}(CO)(PPri ) ] 2c,
᎐
6
4
3 2
[OsH{C H (CH᎐CHD)}(CO)(PPri ) ] 2d and
᎐
6
4
3 2
JP᎐C = 12.9, ipso-C of Ph), 143.2 (t, JP᎐C = 2.3, OsCH᎐CHPh),
᎐
[OsD{C H (CH᎐CHH)}(CO)(PPri ) ] 2e. The complexes were
140.0 (t, JP᎐C = 4.6, OsCH᎐CHPh), 128.9 (s, CH of Ph), 125.4
᎐
6
4
3
2
᎐
o
prepared using the procedure described for 2 (100 mg, 0.15
(s, CHm of Ph), 124.8 (s, p-CH of Ph), 25.3 (vt, N = 25.3 Hz,
PCHCH3), 19.6 (s, PCHCH3) and 19.4 (s, PCHCH3); 31P-{1H},
δ 9.3 (s).
mmol), starting from [Os{(E )-CD᎐CHPh}Cl(CO)(PPri ) ].
᎐
3
2
1
NMR: H (C6D6, 20 ЊC), δ 7.26 (d, JH ᎐H = 7.1, 1 H, HPh), 7.03
(t, JH ᎐H = 7.1, 1 H, HPh), 6.90 (t, JH ᎐H = 7.1, 1 H, HPh), 6.56
[OsH(ç2-O2CH)(CO)(PPri3)2] 10. A slow stream of carbon
(d, JH ᎐H = 7.1, HPh), 4.95 (br dd, JH ᎐H = 9.0, J = 7.7, CH᎐), 3.71
᎐
dioxide was bubbled through a solution of [OsH (η2-CH ᎐
(br dt, JH ᎐H = 9.0, JP᎐H = 5.7, ᎐CH ), 2.74 (br d, J
= 7.7,
᎐
2
H ᎐H
᎐
2
2
CHEt)(CO)(PPri3)2] 11 (93 mg, 0.16 mmol) in hexane (5 cm3)
at room temperature. After ca. 20 min a yellow solid was
formed. The solid was decanted, washed with hexane and dried
1 H, ᎐CH ), 2.15 (m, 6 H, PCHCH ), 1.05 (dvt, N = 13.5,
᎐
2
3
JH ᎐H = 6.3, 36 H, PCHCH3) and Ϫ8.01 (br t, JP᎐H = 27.3 Hz,
2
1 H, OsH); H (C6H6, 20 ЊC), δ 6.52 (s, DPh), 3.68 (s, ᎐CHD),
᎐
190
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192

View Article Online
in vacuo. Yield 74.8 mg (82%) (Found: C, 41.6; H, 8.1. Calc. for
C20H44O3OsP2: C, 41.1; H, 7.6%). IR (Nujol, cmϪ1): ν(Os᎐H)
2180m, ν(CO) 1900s, νasym(OCO) 1565s, νsym(OCO) 1385m.
with NEt2H (5 µl, 0.05 mmol). The tube was sealed under Ar and
heated at 60 ЊC for 1 h. Under these conditions complex 15 was
the only detectable product. IR (CH2Cl2, cmϪ1): ν(CO) 1870s,
1
1
NMR (CDCl3, 20 ЊC): H, δ 8.81 (s, O2CH), 2.42 (m, 6 H,
ν(OCO) 1525s. NMR (C6D6, 20 ЊC): H, δ 3.14, 3.02 (both q,
PCHCH3), 1.30 (dvt, N = 13.6, JH ᎐H = 7.4, 18 H, PCHCH3),
1.26 (dvt, N = 13.0, JH ᎐H = 7.2, 18 H, PCHCH3) and Ϫ21.58
(t, JP᎐H = 15.7, 1 H, OsH). 13C-{1H}, δ 182.9 (t, JP᎐C = 9.1,
CO), 173.3 (t, JP᎐C = 1.5, O2CH), 25.6 (vt, N = 24.8 Hz,
PCHCH3), 20.1 (s, PCHCH3) and 19.4 (s, PCHCH3); 31P-{1H},
δ 39.6 (s).
JH ᎐H = 7.2, 2 H, NCH2), 2.37 (m, 6 H, PCHCH3), 1.38 (dvt,
N = 13.5, JH ᎐H = 6.9, 18 H, PCHCH3), 1.25 (dvt, N = 13.5,
JH ᎐H = 6.9, 18 H, PCHCH3), 0.95, 0.91 (both t, JH ᎐H = 7.0, 3 H,
NCH2CH2) and Ϫ20.37 (t, JP᎐H = 16.2, 1 H, Os᎐H); 13C-{1H}, δ
184.5 (t, JP᎐C = 9.2, CO), 165.4 (s, O2C), 39.3, 39.0 (s, NCH2),
25.7 (vt, N = 24.8 Hz, PCHCH3), 20.4 (s, PCHCH3), 19.5 (s,
PCHCH3), 14.2 (s, NCH2CH3); 31P-{1H}, δ 38.4 (s).
Reaction of complex 8 with H2. A solution of complex 8 (25
mg, 0.04 mmol) in C6D6 placed in a NMR tube was saturated
with H2 at room temperature and the tube sealed. The reaction
Reaction of complex 8 with NEt2H: preparation of [Os{(E )-
CH᎐CHPh}(ç2-O CNEt )(CO)(PPri ) ] 16.
A solution of
᎐
2
2
3 2
1
was monitored by H and 31P-{1H} NMR spectroscopy. After
complex 8 (25 mg, 0.04 mmol) in C6D6 placed in a NMR tube
was treated with NEt2H (4 µl, 0.04 mmol). After 3 h at room
temperature the 1H and 31P-{1H} NMR spectra of the solution
showed a mixture of 8 (41), 10 (10), 15 (12) and 16 (37%). After
24 h at room temperature a mixture of complexes 15 (60) and
16 (40%) was obtained. NMR data for 16 (C6D6, 20 ЊC): 1H, δ
72 h the spectra showed signals corresponding to 10 and
styrene.
[OsH{ç1-OC(O)H}(CO)2(PPr3)2] 12. A slow stream of car-
bon monoxide was bubbled through a suspension of complex
10 (90 mg, 0.156 mmol) in dichroromethane (5 cm3) during 5
min. The solution was dried under vacuum, and the residue
treated with hexane causing the precipitation of a white solid.
The solid was washed with hexane and dried in vacuo. Yield
77.4 mg (82%) (Found: C, 41.15; H, 7.25. Calc. for
C21H44O4OsP2: C, 40.6; H, 7.85%). IR (Nujol, cmϪ1): ν(Os᎐H)
2050m, ν(CO) 1975s, 1915s, νasym(OCO) 1643s, νsym(OCO)
9.37 (d, JH ᎐H = 15.6, 1 H, OsCH᎐CHPh), 7.43 (d, J
= 6.8 Hz,
᎐
H ᎐H
2 H, o-H of Ph), 7.28 (t, JH ᎐H = 6.8 Hz, 2 H, m-H of Ph, 7.09 (t,
JH ᎐H = 6.8 Hz, 1 H, p-H of Ph), 6.57 (dt, JH ᎐H = 15.6 Hz, JP᎐H < 1
Hz, 1 H, OsCH᎐CHPh), 3.14, 3.04 (q, J
= 7.0, 2 H, NCH2),
᎐
2.40 (m, 6 H, PCHCH3), 1.27 (dvt, N =H1᎐2H.0, JH ᎐H = 6.9, 18 H,
PCHCH3), 1.17 (dvt, N = 12.0, JH ᎐H = 6.9, 18 H, PCHCH3),
0.93, 0.91 (t, JH ᎐H = 7.0, 3 H, NCH2CH3); 13C-{1H}, δ 184.3 (t,
JP᎐C = 9.1, CO), 165.0 (s, O2C), 143.2 (s, ipso-C of Ph), 138.7 (t,
JP᎐C = 7.7, OsCH᎐CHPh), 132.3 (br, OsCH᎐CHPh), 128.6 (s,
1
1370m. NMR (C6D6, 20 ЊC): H, δ 7.88 [s, 1 H, OC(O)H],
2.10 (m, 6 H, PCHCH3), 1.14 (dvt, N = 14.1, JH ᎐H = 7.5, 18 H,
PCHCH3), 1.17 (dvt, N = 14.1, JH ᎐H = 7.5, 18 H, PCHCH3) and
Ϫ4.29 (t, JP᎐H = 21.0 Hz, 1 H, OsH); 31P-{1H}, δ 29.1 (s).
᎐
᎐
o-CH of Ph), 124.0 (s, m-CH of Ph), 123.2 (s, p-CH of Ph),
39.1, 38.7 (s, NCH2), 24.5 (vt, N = 23.7 Hz, PCHCH3), 19.8
(s, PCHCH3), 19.7 (s, PCHCH3), 16.7, 16.6 (s, NCH2CH3); 31P-
{1H}, 16.1 (s).
[OsH{ç1-OC(O)H}(CO){P(OMe)3}(PPri3)2] 13. A suspen-
sion of complex 10 (65 mg, 0.11 mmol) in hexane (7 cm3) was
treated with P(OMe)3 (19 µl, 0.16 mmol). After ca. 15 min at
room temperature a white solid was formed. The solid was
decanted, washed with hexane and dried in vacuo. Yield 60.7
mg (80%) (Found: C, 38.95; H, 7.55. Calc. for C23H53O6OsP3:
C, 39.55; H, 8.45%). IR (Nujol, cmϪ1): ν(Os᎐H) 2030w, ν(CO)
1920s, νasym(OCO) 1650s, νsym(OCO) 1380m. NMR (C6D6,
[Os{(E )-CH᎐CHPh}(CO)(MeCN) (PPri ) ]BF 17. A solu-
᎐
2
3
2
4
tion of complex 8 (100 mg, 0.15 mmol) was treated with
HBF4ؒOEt2 (16 µl, 0.15 mmol) in diethyl ether. Addition of
MeCN (8 µl, 0.15 mmol) caused the precipitatiion of a white
solid, which was washed with ether and hexane and dried in
vacuo. Yield 97.3 mg (80%) (Found: C, 45.4; H, 7.05; N, 3.15.
Calc. for C31H55BF4N2OOsP2: C, 45.95; H, 6.8; N, 3.45%). IR
1
20 ЊC): δ H, 8.37 [s, 1 H, OC(O)H], 3.43 (d, JP᎐H = 10.1, 9 H,
(Nujol, cmϪ1): ν(C᎐N) 2330w, 2300w, ν(CO) 1930s, ν(C᎐C)
᎐
POMe), 2.29 (m, 6 H, PCHCH3), 1.30 (dvt, N = 12.3,
JH ᎐H = 6.8, 18 H, PCHCH3), 1.10 (dvt, N = 12.3, JH ᎐H = 6.8, 18
H, PCHCH3) and Ϫ6.30 (dt, JP᎐H = 149.0, 23.8, 1 H, OsH);
31P-{1H}, δ 102.9 (t, JP᎐P = 17.9, POMe) and 20.8 (d, JP᎐P = 17.9
Hz, PPri3).
᎐
᎐
1550m, ν([BF4]Ϫ) 1060 (br). NMR (CDCl3, 20 ЊC); H, δ 8.28
1
(d, JH ᎐H = 17.3, 1 H, OsCH᎐CHPh), 7.20 (t, J
= 7.7, 2 H, m-H
᎐
H ᎐H
of Ph), 7.07(d, JH ᎐H = 7.7, 2H, o-H of Ph), 6.99(t, JH ᎐H = 7.7, 1H,
p-H of Ph), 6.42 (d, JH ᎐H = 17.3, 1 H, OsCH᎐CHPh), 2.68 (s, 3 H,
᎐
NCCH3), 2.58 (m, 6 H, PCHCH3), 2.57 (s, 3 H, NCCH3), 1.31
(dvt, N = 13.5, JH ᎐H = 7.2, 18 H, PCHCH3) and 1.29 (dvt,
N = 13.5, JH ᎐H = 7.2, 18 H, PCHCH3); 13C-{1H}, δ 185.0 (t,
JP᎐C = 9.4, CO), 142.5 (br, ipso-C of Ph), 136.2 (t, JP᎐C = 3.0,
OsCH᎐CHPh), 132.7 (t, J = 8.9, OsCH᎐CHPh), 128.2 (br,
1
2
i
᎐
[OsH{ç -OC(O)H}(ç -MeO CC᎐CCO Me)(CO)(PPr ) ]
᎐
2
2
3 2
14. A suspension of complex 10 (65 mg, 0.11 mmol) in hexane (6
cm ) was treated with MeO CC᎐CCO Me (14 µl, 0.11 mmol).
3
᎐
᎐
2
2
After ca. 5 min at room temperature a white solid was formed.
The solid was decanted, washed with hexane and dried in vacuo.
Yield 60.7 mg (80%) (Found: C, 42.95; H, 6.95. Calc. for
᎐
᎐
P᎐C
o-CH of Ph), 126.0, 125.5 (both s, NCCH3), 124.0 (br, CHPh
,
m-CH of Ph), 24.4 (vt, N = 24.7 Hz, PCHCH3), 19.4 (s,
PCHCH3), 19.0 (s, PCHCH3), 4.4, 3.7 (both s, NCCH3);
31P-{1H}, δ 3.1 (s).
C26H50O7OsP2: C, 42.55; H, 7.2%). IR (Nujol, cmϪ1): ν(Os᎐H)
᎐
2040w, ν(CO) 1955s, ν(C᎐C) 1880m, ν(C᎐O) 1710s, νasym(OCO)
᎐
᎐
1620s, νsym(OCO) 1375m. The H and 31P-{1H} NMR spectra
1
[Os(ç2-O CH)(᎐CHCH Ph)(CO)(PPri ) ]BF 18. A solution
of a solution of 14 (32 mg, 0.03 mmol) in C6D6 at room tem-
᎐
2
2
3
2
4
of complex 8 (100 mg, 0.15 mmol) in chloroform was treated
with HBF4ؒOEt2 (16 µl, 0.15 mmol). The solution was dried in
vacuo, yielding a green oil. IR (CH2Cl2, cmϪ1): ν(CO) 1980s,
νasym(O2CH) 1560s, νsym(O2CH) 1355m. NMR (CDCl3, 20 ЊC):
1H, δ 17.63 (t, JH ᎐H = 6.1, 1 H, Os᎐CH), 9.19 (s, O CH), 7.35–
perature showed signals corresponding to 14, 10 and MeO2-
᎐
CC᎐CCO Me in ca. 1:1:1 molar ratio. Data for 14 (CDCl ,
᎐
2
1
3
᎐
20 ЊC): δ H, 7.63 [s, 1 H, OC(O)H], 3.74 (s, 6 H, ᎐CCO Me),
᎐
2
2.64 (m, 6 H, PCHCH3), 1.27 (dvt, N = 12.7, JH ᎐H = 6.7, 18 H,
PCHCH3), 1.15 (dvt, N = 14.9, JH ᎐H = 6.6, 18 H, PCHCH3)
᎐
2
and Ϫ2.28 (dt, JP᎐H = 28.3, 1 H, OsH); 13C-{1H}, δ 179.8
7.22 (m, 5 H, Ph), 3.52 (d, JH ᎐H = 6.1, 2 H, ᎐CHCH Ph), 2.45
᎐
2
᎐
(m, 6 H, PCHCH3), 1.34 (dvt, N = 14.2, JH ᎐H = 7.1, 18 H,
(t, JP᎐C = 9.1, CO), 167.4 (s, ᎐CCO Me), 166.2 [t, JP᎐C = 5.3,
᎐
2
᎐
᎐
PCHCH3) and 1.19 (dvt, N = 13.8, JH ᎐H = 7.5, 18 H, PCHCH3);
OC(O)H], 107.3 (t, JP᎐C = 3.3, ᎐CCO Me), 52.4 (s, ᎐CCO Me),
᎐
᎐
2
2
13C, δ 290.8 (br, Os᎐C), 179.6 (t, JP᎐C = 8.3, CO), 168.7 (s,
25.5 (vt, N = 28.0 Hz, PCHCH3), 20.8 (s, PCHCH3) and 18.8 (s,
PCHCH3); 31P-{1H}, δ 30.8 (s).
᎐
O2CH), 134.2 (s, ipso-C of Ph), 129.1 (s, o-CH of Ph), 127.8 (s,
p-CH of Ph), 127.8 (s, m-CH of Ph), 65.3 (s, CH2Ph), 25.8 (vt,
N = 25.9 Hz, PCHCH3), 19.3 (s, PCHCH3) and 19.1 (s,
PCHCH3); 31P-{1H}, δ 38.3 (s).
[OsH(ç2-O2CNEt2)(CO)(PPri3)2] 15. A solution of complex 9
(28 mg, 0.05 mmol) in C6D6 placed in a NMR tube was treated
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192
191

View Article Online
[OsH(CO)(MeCN)2(PPri3)2]BF4 19. A solution of complex 10
(65 mg, 0.11 mmol) in ether was treated with HBF4ؒOEt2 (11 µl,
0.11 mmol). The resulting suspension was treated with MeCN
(6 µl, 0.11 mmol) causing the precipitation of a white solid. The
solid was washed with ether and dried in vacuo. Yield 49.1 mg
(75%) (Found: C, 39.3; H, 7.45; N, 3.8. Calc. for C23H49BF4-
financial support. E. O. thanks the DGA (Diputación General
de Aragón) for a grant.
References
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N2OOsP2: C, 39.0; H, 6.95; N, 3.95%). IR (Nujol, cmϪ1): ν(C᎐N)
᎐
᎐
2330w, 2290w, ν(Os᎐H) 2140w, ν(CO) 2140s. NMR (CDCl3,
20 ЊC): 1H, δ 2.53 (s, 3 H, NCCH3), 2.50 (s, 3 H, NCCH3), 2.40
(m, 6 H, PCHCH3), 1.30 (dvt, N = 13.5, JH ᎐H = 7.0, 36 H,
PCHCH3) and Ϫ14.87 (t, JP᎐H = 17.0 Hz, 1 H, OsH); 31P-{1H},
δ 24.94 (s).
Reaction of complex 10 with HBF4. A CDCl3 solution of
complex 10 (8 mg, 0.01 mmol) placed in a NMR tube was
treated with HBF4 (1.9 µl, 0.01 mmol) and the tube sealed under
argon. After 5 min four products were mainly formed (Fig. 1).
Significant NMR signals (CDCl3, 20 ЊC) are: A 1H, δ 7.98 (br, 1
H, O2CH) and Ϫ6.80 (br, 2 H, η2-H2); 31P, δ 25.6 (s); T1/ms
[Os(η2-H2), 300 MHz, CDCl3] = 38 (293), 21 (253), 17 (233), 17
1
(218 K); B, H, δ 8.14 [br, 1 H, OC(O)H] and Ϫ6.94 (br, 2 H,
η2-H2); 31P, δ 41.8 (s); T1/ms [Os(η2-H2), 300 MHz, CDCl3] = 36
1
(293), 21 (253 K); C, H, δ 9.26 [br, 1 H, OC(O)H] and Ϫ9.04
(dd, JP᎐H = 28.6, 15.7 Hz, OsH); T1/ms (OsH, 300 MHz,
CDCl3) = 740 (293), 305 (253), 290 (233), 260 (218 K); D, 1H, δ
9.16 [br, 1 H, OC(O)H] and Ϫ9.70 (br, OsH); 31P, δ 35.6 (br).
Computation
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All calculations were performed with an ab initio molecular
orbital method with introduction of correlation energy through
the Møller–Plesset perturbational approach,24 excluding excita-
tions concerning the lowest-energy electrons (frozen-core
approach). Effective core potentials were used to represent the
60 innermost electrons (up to the 4d shell) of the osmium
atom,25 as well as the 10-electron core of the phosphorus
atoms.26 The basis set used for the osmium atom is that associ-
ated with the pseudo-potential,25 with a (541/41/111) contrac-
tion,27 which is triple ζ for the 5d shell, double ζ for the 6s and
single ζ for the 6p. For the phosphorus atoms a valence double
ζ basis set 26 with a (21/21) contraction was used, while the
standard 6-31G basis set was used for all the other atoms.28
Geometry optimizations were carried out at the second level
of the Møller–Plesset theory (MP2). All geometrical param-
eters were optimized except the dihedral angle of one of the
hydrogen atoms of each phosphine, which was fixed to be
oriented towards the carbon of the carbonyl ligand, in order to
avoid chemically meaningless rotations around the M᎐P axis.
Single-point energy-only calculations were made at a higher
computational level with the MP2 optimized geometries. This
is the fourth level of the same perturbational theory (MP4),
with consideration of single, double, triple and quadruple
excitations.
24 C. Møller and M. S. Plesset, Phys. Rev., 1934, 46, 618.
25 P. J. Hay and W. R. Wadt, J. Chem. Phys., 1985, 82, 299.
26 P. J. Hay and W. R. Wadt, J. Chem. Phys., 1985, 82, 284.
27 Z. Lin and M. B. Hall, J. Am. Chem. Soc., 1992, 114, 2928.
28 W. J. Hehre and R. Ditchfield, J. Chem. Phys., 1972, 56, 2257.
Acknowledgements
We thank the Dirección General de Investigación Gentificay
Técnica (Projects PB 92–0092 and PB 92–0621, Programa de
Promoción General del Conocimiento) and EU (Project, Select-
ive Processes and Catalysis Involving Small Molecules) for
Received 27th June 1996; Paper 6/04486G
192
J. Chem. Soc., Dalton Trans., 1997, Pages 181–192