Dehydrogenation of a Coordinated Alkylphosphine as a method to Prepare Cyclopentadienyl-α-alkenylphosphine-osmium Complexes

Article abstract of DOI:10.1021/om034378s

The π-alkyne complex Os(η⁵-C₅H ₅)Cl(η²-PhC≡CPh)(PⁱPr₃) (2) has been prepared by a two-step procedure involving the oxidative addition of H₂ to Os(η⁵-C₅H₅)Cl(P ⁱPr₃)₂ (1) and the subsequent reaction of the resulting dihydride with diphenylacetylene. In methanol, complex 2 evolves to give the isopropenyldi(isopropyl)phosphine derivative Os(η ⁵-C₅H₅)Cl{[η²-CH ₂=C(CH₃)]PⁱPr₂} (4) and Z-stilbene, by hydrogen transfer from one isopropyl group of the triisopropylphosphine to diphenylacetylene. When the hydrogen transfer reaction is carried out in the presence of KPF₆, the cationic Z-stilbene compound [Os(η ⁵-C₅H₅){η ²-(Z)-PhCH=CHPh}{[η²-CH₂=C(CH ₃)]PⁱPr₂}]PF₆ (5) is formed. The isopropenyldi(isopropyl)-phosphine ligand of 4 and 5 shows hemilabile properties. The hemilabile character of the isopropenyl substituent of the phosphine of 4 is revealed by the reaction of this complex with H₂, which yields an equilibrium mixture of the starting compound and the transoiddihydride OsH₂(η⁵-C₅H ₅)Cl{PⁱPr₂[C(CH₃)=CH₂]} (6). The hemilabile character of the phosphine of 5 is shown in the reaction of this compound with MeLi, which affords OsH(η⁵-C₅H ₄CH₃){η²-(Z)-PhCH=CHPh}{P ⁱPr₂[C(CH₃)=CH₂]} (7). In the solid state and in solution the Z-stilbene ligand of 7 isomerizes to give OsH(η⁵-C₅H₄CH₃){η ²-(E)-PhCH=CHPh}{PⁱPr₂-[C(CH ₃)=CH₂]} (8). Complexes 5 and 8 have been characterized by X-ray diffraction analysis.

Full text of DOI:10.1021/om034378s

1416
Organometallics 2004, 23, 1416-1423
Deh yd r ogen a tion of a Coor d in a ted Alk ylp h osp h in e a s a
Meth od to P r ep a r e Cyclop en ta d ien yl-r-
a lk en ylp h osp h in e-osm iu m Com p lexes
Miguel Baya, Mar´ıa L. Buil, Miguel A. Esteruelas,* and Enrique On˜ate
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received December 17, 2003
The π-alkyne complex Os(η5-C5H5)Cl(η2-PhCtCPh)(PiPr3) (2) has been prepared by a two-
step procedure involving the oxidative addition of H2 to Os(η5-C5H5)Cl(PiPr3)2 (1) and the
subsequent reaction of the resulting dihydride with diphenylacetylene. In methanol, complex
2 evolves to give the isopropenyldi(isopropyl)phosphine derivative Os(η5-C5H5)Cl{[η2-
CH2dC(CH3)]PiPr2} (4) and Z-stilbene, by hydrogen transfer from one isopropyl group of
the triisopropylphosphine to diphenylacetylene. When the hydrogen transfer reaction is
carried out in the presence of KPF6, the cationic Z-stilbene compound [Os(η5-C5H5){η2-(Z)-
PhCHdCHPh}{[η2-CH2dC(CH3)]PiPr2}]PF6 (5) is formed. The isopropenyldi(isopropyl)-
phosphine ligand of 4 and 5 shows hemilabile properties. The hemilabile character of the
isopropenyl substituent of the phosphine of 4 is revealed by the reaction of this complex
with H2, which yields an equilibrium mixture of the starting compound and the transoid-
dihydride OsH2(η5-C5H5)Cl{PiPr2[C(CH3)dCH2]} (6). The hemilabile character of the phos-
phine of 5 is shown in the reaction of this compound with MeLi, which affords OsH(η5-
C5H4CH3){η2-(Z)-PhCHdCHPh}{PiPr2[C(CH3)dCH2]} (7). In the solid state and in solution
the Z-stilbene ligand of 7 isomerizes to give OsH(η5-C5H4CH3){η2-(E)-PhCHdCHPh}{PiPr2-
[C(CH3)dCH2]} (8). Complexes 5 and 8 have been characterized by X-ray diffraction analysis.
In tr od u ction
The formation of transition metal complexes contain-
ing cycloalkenylphosphine ligands by dehydrogenation
of coordinated cycloalkylphosphines is a well-known
process.1,6 However, the dehydrogenation of coordinated
acyclic alkylphosphines to afford the corresponding
transition metal R-alkenylphosphine complexes is
scarcely documented. Complex OsH2Cl2(PiPr3)2 reacts
with 2.0 equiv of 1,5-cyclooctadiene or 2,5-norbornadiene
to give 1.0 equiv of monoolefin and the isopropenyldi-
(isopropyl)phosphine derivatives OsCl2(η4-diolefin){[η2-
CH2dC(CH3)]PiPr2} (diolefin ) COD, NBD).7 At room
temperature, the reactions of the elongated dihydrogen
The activation of C-H bonds by transition metal
compounds is a type of reaction of general interest due
to its connection with the functionalization of nonacti-
vated molecules. An example is the dehydrogenation of
alkanes or alkyl groups to produce olefins. The equilib-
rium is shifted to the right by adding a hydrogen
acceptor, such as an olefin or carbonyl compound.1
R-Alkenylphosphines are a type of ligand that is
attracting increased attention in the chemistry of the
metals. They can act as monodentated ligands,2 can
bridge to two metal centers,3 and can act as chelating
ligands.4
(3) See for example: Wilson, W. L. Nelson, J . H.; Alcock, N. W.
Organometallics 1990, 9, 1699. (b) Hogarth, G. J . Organomet. Chem.
1991, 407, 91. (c) Doyle, M. J .; Duckworth, T. J .; Manojlovic´-Muir, L.;
Mays, M. J .; Raithby, P. R.; Robertson, F. J . J . Chem Soc., Dalton
Trans. 1992, 2703. (d) Acum, G. A.; Mays, M. J .; Raithby, P. R.; Solan,
G. A. J . Organomet. Chem. 1996, 508, 137. (e) Hogart, G.; Shukri, K.;
Dohertys, S.; Carty, A. J .; Enright, G. D. Inorg. Chim. Acta 1999, 178.
(4) See for example: Mercier, F.; Hugel-Le Goff, C.; Ricard, L.;
Mathey, F. J . Organomet. Chem. Chem. 1990, 389, 389. (b) Mathey,
F. J . Organomet. Chem. 1990, 400, 149. (c) J i, H.; Nelson, J . H.; DeCian,
A.; Fisher, J .; Slujic´, L.; Milosavljevic´, E. B. Organometallics 1992, 11,
401.
In addition, the reversible coordination-decoordina-
tion of the olefinic group gives them hemilabile proper-
ties. As a result, under appropriate conditions, they can
stabilize highly reactive intermediates.5
* Corresponding author. E-mail: maester@posta.unizar.es.
(1) Shilov, A. E.; Shul’pin, G. B. Chem. Rev. 1997, 97, 2879.
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Inorg. Chem. 1986, 25, 2288. (b) Rahn, J . A.; Holt, M. S.; O’Neil-
J ohnson, M.; Nelson, J . H. Inorg. Chem. 1988, 27, 1316. (c) Rahn, J .
A.; Delian, A.; Nelson, J . H. Inorg. Chem. 1989, 28, 215. (d) Rahn, J .
A.; Holt, M. S.; Gray, G. A.; Alcock, N. W.; Nelson, J . H. Inorg. Chem.
1989, 28, 217. (e) Bhaduri, D.; Nelson, J . H.; Day, C. L.; J acobson, R.
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Adams, H.; Bailey, N. A.; Blenkiron, P.; Morris, M. J . J . Organomet.
Chem. 1993, 460, 73. (g) Knox, S. A. R.; Morton, D. A. V.; Orpen, A.
G.; Turner, M. L. Inorg. Chim. Acta 1994, 220, 201. (h) Maitra, K.;
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Hursthouse, M. B.; Kelly, D. G.; Toner, A. J . Polyhedron 2000, 19, 1271.
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nometallics 1997, 16, 1714.
(6) See for example: (a) Hietkamp, S.; Stufkens, D. J .; Vrieze, K. J .
Organomet. Chem. 1978, 152, 347. (b) Arliguie, T.; Chaudret, B.; J alon,
F.; Lahoz, F. J . J . Chem. Soc., Chem. Commun. 1998, 998. (c) Campion,
B. K.; Heyn, R. H.; Tilley, T. D.; Rheingold, A. L. J . Am. Chem. Soc.
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10.1021/om034378s CCC: $27.50 © 2004 American Chemical Society
Publication on Web 02/14/2004

Cyclopentadienyl-R-alkenylphosphine Os Complexes
Organometallics, Vol. 23, No. 6, 2004 1417
Os(η5-C5H5)L3 systems, in solution, this complex dis-
sociates a phosphine to form an unsaturated species
that is allowing the development of new cyclopentadi-
enylosmium chemistry.17 It is now shown that the
dehydrogenation of an isopropyl group of one of the
phosphines of Os(η5-C5H5)Cl(PiPr3)2 is an effective
method to prepare cyclopentadienylosmium compounds
containing an R-alkenylphosphine ligand.
complexes [Os{C6X4C(O)CH3}(η2-H2)(H2O)(PiPr3)2]BF4
(X ) H, F) with phenylacetylene lead to a mixture
of compounds containing the 1,4-diphenylbutadiene
derivative [OsH(η4-C4H4Ph2){[η2-CH2dC(CH3)]PiPr2}-
(PiPr2nPr)]BF4. The diene of this compound is the result
of the reductive condensation of two alkyne molecules.
The reductor is one of the triisopropylphosphines, which
undergoes dehydrogenation of one of the isopropyl
groups, to afford the monoisopropenylphosphine.8 Treat-
ment of the tetrahydride OsH4Cl(SnPh3)(PiPr3)2 with
diphenylacetylene gives rise to the trihydride-isoprope-
nyldi(isopropyl)phosphine derivative OsH3(SnClPh2)-
{[η2-CH2dC(CH3)]PiPr2}(PiPr3) in a one-pot synthesis
via multiple complex reactions, including the dehydro-
genation of one isopropyl group of one phosphine.9 This
trihydride activates an ortho-CH bond of aromatic
compounds to afford reminiscent species of the inter-
mediates proposed by Murai for the insertion of olefins
into aromatic ortho-CH bonds of ketones and imines.10
The chemistry of the half-sandwich pentamethylcy-
clopentadienyl-11 and cyclopentadienylosmium12 com-
plexes has attracted much less attention than that of
the related half-sandwich ruthenium complexes,13 in
particular, the chemistry of the Os(η5-C5H5) unit. Thus,
cyclopentadienylosmium complexes containing R-alk-
enylphosphine ligands are unknown. This is in part due
to the lack of convenient Os(η5-C5H5) starting com-
plexes12a,b,14 and the higher kinetic inertia of the Os-
(η5-C5H5)L3 species in comparison with the related
ruthenium derivatives.15
Resu lts a n d Discu ssion
1. P r ep a r a tion of a n Os(h yd r ogen a ccep tor )-
(P iP r 3) P r ecu r sor . As it has been previously men-
tioned, the equilibrium for the dehydrogenation of
alkanes and alkyl groups is shifted to the right in the
presence of a hydrogen acceptor. Furthermore, diphe-
nylacetylene has shown to be a useful hydrogen acceptor
to the dehydrogenation of one of the triisopropylphos-
phine ligands of the complex OsH4Cl(SnPh3)(PiPr3)2.9
So, we decided to prepare a diphenylacetylene derivative
as the first step of our strategy to carry out the
dehydrogenation of a phosphine of Os(η5-C5H5)Cl(PiPr3)2
(1).
One of the phosphine ligands of 1 can be easily
displaced by methyl vinyl ketone and dimethyl acety-
lenedicarboxylate. The reactions lead to the derivatives
Os(η5-C5H5)Cl{η2-CH2dCHC(O)CH3}(PiPr3) and Os(η5-
C5H5)Cl{η2-CH3CO2CtCCO2CH3}(PiPr3), respectively,
which can be isolated as pure solids.16 However, the
treatment of toluene solutions of 1 with diphenylacety-
lene gives rise to a equilibrium mixture of 1, the
π-alkyne complex Os(η5-C5H5)Cl{η2-PhCtCPh)(PiPr3)
(2), triisopropylphosphine, and diphenylacetylene. Even
at 65 °C and in the presence of an excess of alkyne, the
quantitative formation of 2 does not take place. This
indicates that the direct reaction between 1 and diphe-
nylacetylene is not a useful method to obtain 2.
In light of this difficulty, we design an alternative
pathway (Scheme 1). Bubbling molecular hydrogen
through a pentane solution of 1 produces the displace-
ment of a coordinated triisopropylphosphine and the
formation of the osmium(IV)-dihydride OsH2(η5-C5H5)-
Cl(PiPr3) (3), which is isolated as a white solid in 67%
We have previously reported the synthesis of the
cyclopentadienyl compound Os(η5-C5H5)Cl(PiPr3)2 by
reaction of the six-coordinate complex OsH2Cl2(PiPr3)2
with Tl(C5H5).16 Despite the high kinetic inertia of the
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1418 Organometallics, Vol. 23, No. 6, 2004
Baya et al.
Sch em e 1
Sch em e 2
13.8 Hz. The 31P{1H} NMR spectrum shows a singlet
at -2.9 ppm.
yield. The solid is an equilibrium mixture of the isomers
3a and 3b.17c
The formation of 4 truly involves the hydrogen
transfer from an isopropyl group of triisopropylphos-
phine to the carbon-carbon triple bond of the coordi-
nated alkyne, in 2. When the reaction is carried out in
methanol-d4 as solvent, neither the isopropenyldi(iso-
propyl)phosphine of 4 nor the obtained stilbene contain
any deuterium atom. This clearly indicates that the
solvent of the reaction does not play any direct role
during the reduction. The role of the methanol is to
promote the dissociation of chloride from 2 (Scheme 2).
Thus, the C-H activation of a methyl group of an
isopropyl substituent of the phosphine, in a cationic
unsaturated intermediate, followed by the migratory
insertion of the alkyne into the Os-H bond of the
resulting hydride affords an unsaturated alkenyl spe-
cies, containing a metalated phosphine. The â-hydrogen
elimination on the metalated group of the phosphine
should give a monoisopropenylphosphine-hydride-alk-
enyl intermediate, which could evolve into 4 by reduc-
tive elimination of Z-stilbene, and coordination of the
chloride anion dissociated in the first step.
In diethyl ether under reflux and in the presence of
2.7 equiv of diphenylacetylene, the dihydride compounds
of the isomeric mixture lose molecular hydrogen and the
resulting metallic fragment coordinates an alkyne mol-
ecule to afford 2, which was isolated as a pure dark red
solid in 81% yield. The formation of stilbene was not
observed during the reaction.
The π-coordination of the alkyne in 2 is strongly
supported by the IR spectrum of the compound, in which
the CtC stretching frequency is found at 1821 cm-1
,
thus shifted 399 cm-1 to lower wavenumbers if com-
pared with the free alkyne. In agreement with the
chirality of the osmium atom, the 1H NMR spectrum
shows two double doublets at 1.04 and 0.83 ppm due to
the methyl protons of the phosphine, whereas the 13C-
{1H} NMR spectrum contains two resonances for the
C(sp) carbon atoms of the coordinated alkyne: a broad
singlet at 92.3 ppm and a doublet with a C-P coupling
constant of 3.5 Hz at 71.1 ppm. The 31P{1H} NMR
spectrum shows a singlet at 13.2 ppm.
2. Deh yd r ogen a tion of th e P h osp h in e of 2. At
room temperature in toluene or benzene, complex 2 is
stable. However in methanol, it evolves into the isopro-
penyldi(isopropyl)phosphine derivative Os(η5-C5H5)Cl-
{[η2-CH2dC(CH3)]PiPr2} (4) and Z-stilbene (eq 1). After
24 h the formation of 4 is quantitative, according to the
1H and 31P{1H} spectra of the residue obtained from
removing the solvent of the reaction under reduced
pressure. The extraction of this residue with diethyl
ether affords 4 as a pure yellow solid in 70% yield.
The role of methanol is in fact to promote the
dissociation of chloride from 2. In tetrahydrofuran and
in the presence of KPF6, the hydrogen transfer reaction
leads to the Z-stilbene derivative [Os(η5-C5H5){η2-(Z)-
PhCHdCHPh)}{[η2-CH2dC(CH3)]PiPr3}]PF6 (5), which
was isolated as a white solid in 85% yield (eq 2).
Complex 5 is a rare example of an organometallic
compound containing two different Os-olefin bonds.
Figure 1 shows a view of the structure of this derivative.
Selected bond distances and angles are listed in Table
1. The geometry around the osmium center can be
described as a very distorted octahedron, with the
cyclopentadienyl ligand occupying the three sites of a
face, whereas the phosphorus atom P(1) and the mid-
points of the olefinic C(15)-C(17) and C(1)-C(8) bonds
(M(1) and M(2), respectively) are situated in the sites
of the opposite face. The distortion is mainly due to the
ring constraint imposed by the bidentate phosphine,
which acts with a bite angle P(1)-Os-M(1) of 57.64-
(11)°. The P(1)-Os-M(2) angle is 103.64(12)°.
The dehydrogenation of an isopropyl group of the
phosphine and the formation of the corresponding
isopropenyl substituent are strongly supported by the
1H and 13C{1H} NMR spectra of 4. In the 1H NMR
spectrum, the olefinic CH2 protons give rise to double
doublets at 4.10 (trans to P) and 2.87 (cis to P) ppm,
with a H-H coupling constant of 2.4 Hz and H-P
coupling constants of 31.2 and 7.2 Hz, respectively. In
the 13C{1H} NMR spectrum, the C(sp2) carbon atoms
of the phosphine display doublets at 36.1 (CP) and 32.6
(CH2) ppm, with C-P coupling constants of 19.7 and

Cyclopentadienyl-R-alkenylphosphine Os Complexes
Organometallics, Vol. 23, No. 6, 2004 1419
isopropenyl interaction is weaker than the Os-stilbene
interaction and suggests that the isopropenyl substitu-
ent of the phosphine is a more labile group than the
Z-stilbene ligand. This is also consistent with the C(15)-
C(17) bond length (1.403(6) Å), which is about 0.04 Å
shorter than the C(1)-C(8) distance. In accordance with
the sp2 hybridization for C(15), the angles P(1)-C(15)-
C(16) and C(17)-C(15)-C(16) are 124.9(3)° and 121.4-
(4)°, respectively. The P(1)-C(15) distance (1.765(4) Å)
is about 0.06 Å shorter than the P(1)-C(21) (1.826(4)
Å) and P(1)-C(18) (1.830(4) Å) bond lengths.
1
The H and 13C{1H} NMR spectra of 5 are consistent
1
with the asymmetry of the cation. Thus, the H NMR
spectrum contains two resonances for the olefinic pro-
tons of the coordinated Z-stilbene ligand, at 3.71 and
2.66 ppm. The first of them appears as a double doublet
with both H-H and H-P coupling constants of 9.0 Hz,
while the second one is observed as a doublet. The
olefinic CH2 protons of the isopropenyl group of the
phosphine display double doublets at 4.02 (cis to P) and
3.63 (trans to P) ppm, with a H-H coupling constant of
2.1 Hz and H-P coupling constants of 8.4 and 32.1 Hz,
respectively. In the 13C{1H} NMR spectrum the reso-
nances corresponding to the olefinic carbon atoms of
Z-stilbene appear at 25.6 and 20.6 ppm, as doublets with
the same C-P coupling constant of 7.0 Hz for both,
whereas the resonances due to the olefinic carbon atoms
of the isopropenyl group of the phosphine are observed
at 63.8 (CP) and 31.4 (CH2), also as doublets but with
C-P coupling constants of 21.2 and 6.9 Hz, respectively.
The 31P{1H} NMR spectrum shows a singlet at -4.8
ppm.
3. Hem ila bile Ch a r a cter of th e Isop r op en yl Su b-
stitu en t of th e P h osp h in e of 4. Despite the kinetic
inertia of the saturated Os(η5-C5H5)L3 complexes, the
isopropenyl substituent of the isopropenyldi(isopropyl)-
phosphine of 4 has hemilabile character. This property
is revealed in the presence of molecular hydrogen.
Under an atmosphere of this gas, complex 4 is in
equilibrium with the dihydride derivative OsH2(η5-
C5H5)Cl{PiPr2[C(CH3)dCH2]} (6), which contains a
monodentate-phosphorus isopropenyldi(isopropyl)phos-
phine ligand (eq 3).
F igu r e 1. Molecular diagram of the cation of complex [Os-
(η5-C5H5)Cl{η2-(Z)-PhCHdCHPh}{[η2-CH2dC(CH3)]PiPr2}]-
PF6 (5).
Ta ble 1. Selected Bon d Dista n ces (Å) a n d
An gles (d eg) for th e Com p lex
[Os(η5-C5H5){η2-(Z)-P h CHdCHP h }-
{[η2-CH2dC(CH3)]P iP r 3}]P F 6 (5)
Os-P(1)
2.3093(10)
2.189(4)
2.177(4)
2.264(4)
2.211(4)
2.201(4)
2.256(4)
2.310(4)
Os-C(27)
2.261(4)
2.195(4)
1.439(6)
1.403(6)
1.765(4)
1.830(4)
1.826(4)
Os-C(1)
Os-C(8)
Os-C(15)
Os-C(17)
Os-C(24)
Os-C(25)
Os-C(26)
Os-C(28)
C(1)-C(8)
C(15)-C(17)
P(1)-C(15)
P(1)-C(18)
P(1)-C(21)
P(1)-Os-Ga
124.74(13) Os-C(1)-C(2)
57.64(11) Os-C(8)-C(9)
103.64(12) P-C(15)-C(17)
130.37(17) P(1)-C(15)-C(16)
124.89(17) C(2)-C(1)-C(8)
95.77(16) C(1)-C(8)-C(9)
117.8(3)
124.4(3)
113.6(3)
124.9(3)
129.3(4)
126.4(4)
P(1)-Os-M(1)b
P(1)-Os-M(2)c
Ga-Os-M(1)b
Ga-Os-M(2)c
M(1)b-Os-M(2)c
C(1)-Os-C(8)
Os-C(1)-C(8)
Os-C(8)-C(1)
38.48(15) C(17)-C(15)-C(16) 121.4(4)
70.3(2)
71.2(2)
a
G represents the centroid of the cyclopentadienyl ligand
b
[C(24)-C(28)]. M(1) represents the midpoint of the C(15)-C(17)
double bond. c M(2) represents the midpoint of the C(1)-C(8)
double bond.
The structure proves the Z-stereochemistry of
the stilbene. The osmium-stilbene coordination ex-
hibits Os-C distances of 2.189(4) (Os-C(1)) and 2.177-
(4) (Os-C(8)) Å, which agree well with those found in
other osmium-olefin complexes (between 2.13 and
2.28 Å).7-9,17l,m,18 Similarly, the olefinic bond distance
C(1)-C(8) (1.439(6) Å) is within the range reported for
transition metal olefin complexes (between 1.340 and
1.445 Å).19
The presence of a free isopropenyl substituent in the
phosphine of 6 is strongly supported by the 13C{1H}, 1H,
and 31P{1H} NMR spectra of the complex. In the 13C-
{1H} NMR spectrum, the C(sp2) carbon atoms of the
phosphine display doublets at 140.8 (CP) and 130.9
(CH2) ppm with C-P coupling constants of 40.6 and 12.8
Hz, respectively. These resonances appear shifted 104.7
(CP) and 98.3 (CH2) ppm to lower field with regard to
those of 4. In addition, it should be noted that the CP
resonance has increased significantly the C-P coupling
constant as a consequence of the decoordination (from
19.7 to 40.6 Hz). In the 1H NMR spectrum, the reso-
nances corresponding to the CH2 protons of the isopro-
penyl group are observed at 5.61 (cis to P) and 5.44
(trans to P) ppm, as doublets with H-P coupling
The olefinic group of the isopropenyldi(isopropyl)-
phosphine ligand coordinates to the osmium atom in an
asymmetrical fashion, with Os-C distances of 2.264(1)
(Os-C(15)) and 2.211(4) (Os-C(17)) Å. These bond
lengths are between 0.03 and 0.09 Å longer than the
Os-stilbene distances, which indicates that the Os-
(18) (a) J ohnson, T. J .; Albinati, A.; Koetzle; T. F.; Ricci, J .;
Eisenstein, O.; Huffman, J . C.; Caulton, K. G. Inorg. Chem. 1994, 33,
4966. (b) Edwards, A. J .; Elipe, S.; Esteruelas, M. A.; Lahoz, F. J .; Oro,
L. A.; Valero, C. Organometallics 1997, 16, 3828. (c) Buil, M. L.;
Esteruelas, M. A.; Garc´ıa-Yebra, C.; Gutie´rrez-Puebla, E.; Oliva´n, M.
Organometallics 2000, 19, 2184. (d) Esteruelas, M. A.; Garc´ıa-Yebra,
C.; Oliva´n, M.; On˜ate, E. Organometallics 2000, 19, 3260.
(19) Allen, F. H.; Davis, J . E.; Gallay, J . J .; J ohnson, 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.

1420 Organometallics, Vol. 23, No. 6, 2004
Baya et al.
Sch em e 3
constants of 17.0 and 35.7 Hz, respectively. These
resonances are shifted 2.74 (cis to P) and 1.34 (trans to
P) ppm toward lower field with regard to the ones found
in the spectrum of 4. The H-P coupling constants also
increase as a consequence of the decoordination, in
particular that of the resonance due to the proton
disposed cis to the phosphorus atom (from 7.2 to 17.0
nances due to the olefinic protons of the coordinated
Z-stilbene agree well with those of 5. These protons
display a doublet at 4.25 ppm and a double doublet at
3.32 ppm. Both the H-H and H-P coupling constants
are 9.6 Hz. In the 13C{1H} NMR spectrum the C(sp2)P
carbon atom of the phosphine gives rise to a doublet at
139.7 ppm, with a C-P coupling constant of 31.3 Hz,
whereas the resonance due to the CH2 carbon atom is
observed at 128.6 ppm, partially masked by the solvent
(C6D6) signal. The olefinic carbon atoms of the coordi-
nated Z-stilbene display doublets at 33.6 and 26.3 ppm,
with C-P coupling constants of 2.7 and 3.2 Hz, respec-
tively. The 31P{1H} NMR spectrum contains a singlet
at 38.5 ppm.
1
Hz). The H NMR spectrum also supports the transoid
disposition of the hydride ligands, showing at -10.19
ppm only one doublet with a H-P coupling constant of
33.9 Hz for both hydrides. The 31P{1H} NMR spectrum
contains a singlet at 45.2 ppm, shifted 48.2 ppm to lower
field if it is compared with the observed one in the
spectrum of 4.
4. Isom er iza tion of Z-Stilben e. Another illustrative
example of the hemilabile properties of the isoprope-
nyldi(isopropyl)phosphine ligand in this type of system
is the reaction of 5 with MeLi, which finally produces
the isomerization of Z-stilbene to E-stilbene.
Treatment of tetrahydrofuran solutions of 5 with
1.5 equiv of MeLi leads initially to the hydride-meth-
ylcyclopentadienyl derivative OsH(η5-C5H4CH3){η2-(Z)-
PhCHdCHPh)}{PiPr2[C(CH3)dCH2]} (7), which was
isolated as a white solid in 55% yield (eq 4).
At first glance two reaction pathways are possible for
the formation of 7 (Scheme 3): the direct addition of
the methyl group to the cyclopentadienyl ligand of 5 (a),
or alternatively, the initial attack of the methyl group
to the metallic center of 5 and the subsequent Me(Os)/
H(C5H5) exchange (b). The formation of substituted
cyclopentadienyl derivatives by initial exo-addition of
nucleophiles to the cyclopentadienyl ring has been
proposed for several iron20 and cobalt21 systems, while
the Nu(Os)/H(C5H5) exchange has been invoked for the
formation of functionally substituted cyclopentadienyl
osmium(IV) compounds, starting from OsH(η5-C5H5)-
Cl(EPh3)(PiPr3) (E ) Si, Ge) complexes,17g,i and recently
for the formation of disubstituted cyclopentadienyl
cobalt derivatives.22
The direct addition of the methyl group to the cyclo-
pentadienyl ligand should give a saturated methylcy-
clopentadiene-osmium(0) intermediate a 1, with the
hydrogen bonded to the C(sp3) carbon atom of the diene
in endo-position. Thus, the decoordination of the iso-
propenyl substituent of the phosphine, followed by the
migration of this endo-hydrogen atom from the diene
to the metallic center of the resulting unsaturated
intermediate a 2, should lead to 7.
The presence of a hydride ligand in 7 is strongly
supported by the IR and 1H NMR spectra of the
complex. Thus, the IR spectrum in Nujol shows a ν(Os-
1
H) band at 2083 cm-1, whereas the H NMR spectrum
contains at -14.97 ppm a doublet with a H-P coupling
constant of 31.5 Hz. The 1H NMR spectrum is also
consistent with the presence of a methylcyclopentadi-
enyl group and a monodentate-phosphorus isopropenyl-
di(isopropyl)phosphine ligand. The methylcyclopenta-
dienyl group displays a singlet at 1.96 ppm for the
methyl protons, and between 5.10 and 3.70 ppm the
expected ABCD spin system for the ring protons. In
According to the pathway b, the hemilabile character
of the isopropenyl substituent of the phosphine of 5
(20) (a) Reger, D. L.; Belmore, K. A.; Atwood, J . L.; Hunter, W. E.
J . Am. Chem. Soc. 1983, 105, 5701. (b) Reger, D. L.; Belmore, K. A.
Organometallics 1985, 4, 305. (c) Reger, D. L.; Klaeren, S. A.; Lebioda,
L. Organometallics 1986, 5, 1072. (d) Reger, D. L. Acc. Chem. Res. 1988,
21, 229.
1
agreement with the H NMR spectrum of 6, the reso-
nances corresponding to the olefinic CH2 protons of the
isopropenyl substituent appear at 5.52 (cis to P) and
5.46 (trans to P) ppm as doublets with H-P coupling
constants of 10.5 and 32.2 Hz, respectively. The reso-
(21) (a) Sternberg, E. D.; Wollhardt, K. P. C. J . Org. Chem. 1984,
49, 1564. (b) von der Gruen, M.; Schaefer, C.; Gleiter, R. Organome-
tallics 2003, 22, 2370.
(22) Nomura, M.; Takayama, C.; J anairo, G. C.; Sugiyama, T.;
Yokoyama, Y.; Kajitani, M. Organometallics 2003, 22, 195.

Cyclopentadienyl-R-alkenylphosphine Os Complexes
Organometallics, Vol. 23, No. 6, 2004 1421
Sch em e 4
F igu r e 2. Molecular diagram of complex OsH(η5-C5H4-
CH3){η2-(E)-PhCHdCHPh}{PiPr2[C(CH3)dCH2]} (8).
could afford an unsaturated cyclopentadienyl intermedi-
ate b1. Thus, the metallic center of this intermediate
could undergo nucleophilic attack of the methyl group,
to give a saturated methyl intermediate b2. The spon-
taneous migration of the methyl group from the osmium
atom to the cyclopentadienyl ligand should lead to a
methylcyclopentadiene-osmium(0) intermediate b3, with
the hydrogen bonded to the C(sp3) carbon atom of the
diene in exo-position. Subsequently, this intermediate
should evolve by exo-1,5-hydride shift within the diene
to place the HC(sp3) hydrogen atom in endo-position,
affording b4. Finally the migration of this endo-hydrogen
atom from the diene to the osmium atom should give 7.
In the context of Scheme 3, one should take into
account that in accordance with the Davis-Green-
Mingos rules23 the nucleophilic addition to an “even”
ligand is kinetically favored with regard to the nucleo-
philic attack to an “odd” ligand. Thus, pathway a,
involving the methyl attack to an “odd” group in the
presence of “even” ligands, does not appear to be a
reasonable proposal, and therefore, we assume that the
formation of 7 takes place via the pathway b.
Complex 7 is unstable and evolves into the E-stil-
bene derivative OsH(η5-C5H4CH3){η2-(E)-PhCHdCHPh}-
{PiPr2[C(CH3)dCH2]} (8), even in the solid state at -20
°C under argon atmosphere. In toluene at 80 °C, the
isomerization is quantitative after 12 h. The transfor-
mation Z-E is favored by the presence of a hydride
ligand in 7. Thus, the insertion of the Z-stilbene ligand
into the Os-H bond, followed by the rotation around
the C-C single bond of the resulting alkyl group, and
the subsequent â-elimination of hydrogen afford 8
(Scheme 4).
Ta ble 2. Selected Bon d Dista n ces (Å) a n d
An gles (d eg) for th e Com p lex
OsH(η5-C5H4CH3){η2-(E)-P h HCdCHP h }-
[P {C(CH3)dCH2}iP r 2] (8)
Os-P
2.2886(11)
2.186(4)
2.150(4)
2.220(5)
2.249(4)
Os-C(18)
Os-C(19)
Os-C(20)
Os-H(01)
C(1)-C(8)
2.283(5)
2.261(5)
2.201(5)
1.55(6)
Os-C(1)
Os-C(8)
Os-C(15)
Os-C(17)
1.434(6)
P-Os-Ga
126.32(15)
98.76(13)
70(2)
127.74(19)
121(2)
Os-C(1)-C(8)
Os-C(1)-C(2)
Os-C(8)-C(9)
C(1)-Os-C(8)
C(2)-C(1)-C(8)
C(1)-C(8)-C(9)
69.4(2)
117.9(3)
123.1(3)
38.62(15)
123.5(4)
124.2(4)
P-Os-Mb
P-Os-H(01)
Ga-Os-Mb
Ga-Os-H(01)
Mb-Os-H(01)
97(2)
a
G represents the centroid of the cyclopentadienyl ligand
b
[C(15)-C(20)]. M represents the midpoint of the C(1)-C(8)
double bond.
in an asymmetrical fashion, with Os-C distances of
2.186(4) (Os-C(1)) and 2.150(4) (Os-C(8)) Å and a
C(1)-C(8) bond length of 1.434(6) Å. These values agree
well with those found for the coordination of the
Z-stilbene olefin in 5.
The IR, 13C{1H} NMR, and 31P{1H} NMR spectra of
8 are consistent with the structure shown in Figure 2.
The IR spectrum in Nujol shows a ν(Os-H) band at
2112 cm-1. In the 1H NMR spectrum the hydride
resonance appears at -15.89 ppm as a doublet with a
H-P coupling constant of 35.4 Hz. The methylcyclo-
pentadienyl ligand gives rise to a singlet at 1.95 ppm,
due to the methyl protons, and an ABCD spin system
corresponding to the ring protons between 4.80 and 4.00
ppm. The coordinated stilbene olefin displays at 5.27
ppm a doublet (J (H-H) ) 10.2 Hz) and at 3.93 ppm a
double doublet (J (H-H) ) J (H-P) ) 10.2 Hz). The CH2
resonances of the isopropenyl group of the phosphine
are observed at 5.34 (trans to P) and 5.23 (cis to P) ppm
as doublets with H-P coupling constants of 29.1 and
14.1 Hz, respectively. In the 13C{1H} NMR spectrum,
the olefinic resonances of the coordinated E-stilbene
appear at 25.2 and 24.6 ppm as doublets with C-P
coupling constants of 4.2 and 2.0 Hz, respectively,
whereas the olefinic resonances of the isopropenyl group
of the phosphine are observed at 142.6 (PC) and 124.8
(CH2) ppm, also as doubletes but with C-P coupling
constants of 32.4 and 5.5 Hz, respectively. The 31P{1H}
NMR spectrum contains a singlet at 32.8 ppm.
Complex 8 was isolated as a white solid in 84% yield.
Figure 2 shows a view of the geometry of this compound.
Selected bond distances and angles are listed in Table
2.
The geometry around the osmium center is close to
octahedral, with the cyclopentadienyl occupying three
sites of a face. The angle formed by the isopropenyldi-
(isoprpyl)phosphine and the midpoint of the olefinic
C(1)-C(8) double bond (P-Os-M) is 98.76(13)°.
The structure proves the E-stereochemistry of the
stilbene ligand, which coordinates to the osmium atom
(23) Elschenbroich, Ch.; Salzer, A. Organometallics:
a concise
introduction; VCH Verlagsgesellschaft: Weinheim, 1989; Chapter 15,
p 293.

1422 Organometallics, Vol. 23, No. 6, 2004
Baya et al.
ClOsP: C, 53.44; H, 5.78. Found: C, 53.90; H, 6.05. IR (Nujol,
Con clu d in g Rem a r k s
1
cm-1): ν(CtC) 1821 (s). H NMR (300 MHz, C6D6, 293 K): δ
8.30-6.90 (10H, Ph); 5.22 (s, 5H, η5-C5H5); 2.47 (m, 3H, PCH);
1.04 (dd, 9H, J H-P ) 13.5, J H-H ) 7.2, PCHCH3); 0.83 (dd, 9H,
J H-P ) 13.5, J H-H ) 7.2, PCHCH3). 13C{1H} NMR (75.4 MHz,
CD3COCD3, 293 K): δ 131.6, 129.0, 127.7, 127.6 (s, Cortho,
Cmeta Ph); 131.3, 128.5 (both s, Cipso Ph); 126.1, 125.7 (s,
This paper shows the synthesis and some reactions
of cyclopentadienyl-isopropenyldi(isopropyl)phosphine-
osmium derivatives. The isopropenyl substituent of the
phosphine of these compounds is the result of the
dehydrogenation of one of the isopropyl groups of one
of the triisopropylphosphines of the complex Os(η5-
C5H5)Cl(PiPr3)2. The dehydrogenation is promoted by
diphenylacetylene, which acts as a hydrogen acceptor.
Although the direct and quantitative formation of
a triisopropylphosphine-diphenylacetylene-osmium ad-
duct is not possible, the oxidative addition of molecular
hydrogen to Os(η5-C5H5)Cl(PiPr3)2 and the subsequent
reaction of the resulting dihydride with diphenylacety-
lene afford Os(η5-C5H5)Cl(η2-PhCtCPh)(PiPr3). In metha-
nol this compound is unstable and evolves into the
isopropenyldi(isopropyl)phosphine derivative Os(η5-
C5H5)Cl{[η2-CH2dC(CH3)]PiPr2} by hydrogen trans-
fer reaction from one isopropyl group of triisopropyl-
phosphine to diphenylacetylene. In tetrahydrofuran and
in the presence of KPF6, complex Os(η5-C5H5)Cl(η2-
PhCtCPh)(PiPr3) gives [Os(η5-C5H5){[η2-(Z)-PhCHd
CHPh}{[η2-CH2dC(CH3)]PiPr2}]PF6.
Cpara Ph); 92.3 (br, tC-); 81.1 (s, η5-C5H5); 71.1 (d, J C-P
)
3.5, tC-,); 24.4 (d, J C-P ) 27.7, PCH); 19.8, 18.6 (s, PCH-
CH3). 31P{1H} NMR (121.4 MHz, C6D6, 293 K): δ 13.2 (s). MS
(FAB+): m/z 595 (M+ - Cl).
P r ep a r a tion of Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]P iP r 2}
(4). A solution of Os(η5-C5H5)Cl(η2-PhCtCPh)(PiPr3) (299 mg,
0.48 mmol) in 10 mL of methanol was left to stir for 15 h. The
resulting solution was vacuum-dried, and the residue was
extracted in diethyl ether (50 mL). The filtered solution was
again dried in vacuo and finally washed with pentane (3 × 5
mL). A yellow solid was obtained. Yield: 150 mg (70%). Anal.
Calcd for C14H24ClOsP: C, 37.45; H, 5.39. Found: C, 37.75;
1
H, 5.50. H NMR (300 MHz, C6D6, 293 K): δ 4.62 (s, 5H, η5-
C5H5); 4.10 (dd, 1H, J H-P ) 31.2, J H-H ) 2.4, PCdCHtrans to P);
2.87 (dd, 1H, J H-P ) 7.2, J H-H ) 2.4, dCHcis to P); 2.37 (m, 1H,
PCH); 1.56 (m, 1H, PCH); 1.30-1.00 (15H, CH3). 13C{1H} NMR
(75.4 MHz, C6D6, 293 K, plus APT): δ 78.0 (+, s, η5-C5H5);
36.1 (-, d, J C-P ) 19.7, P-Cd); 32.6 (-, d, J C-P ) 13.8, d
CH2); 27.9 (+, d, J C-P ) 30.9, PCH); 23.8 (+, d, J C-P ) 2.8,
CH3); 23.3 (+, d, J C-P ) 6.0, CH3,); 21.8 (+, d, J C-P ) 4.6, CH3);
20.7 (+, d, J C-P ) 4.6, CH3); 18.8 (+, d, J C-P ) 2.3, CH3); 17.0
(+, d, J C-P ) 18.0, PCH). 31P{1H} NMR (121.4 MHz, C6D6, 293
K): δ -2.9 (s). MS (FAB+): m/z 450 (M+); 415 (M+ - Cl).
P r ep a r a tion of [Os(η5-C5H5)Cl{η2-(Z)-P h CHdCHP h }-
{[η2-CH2dC(CH3)]P iP r 2}]P F 6 (5). To a solution of Os(η5-
C5H5)Cl(η-PhCtCPh)(PiPr3) (422 mg, 0.67 mmol) in 15 mL of
THF was added KPF6 (212 mg, 1.15 mmol), and the mixture
was left to stir for 3 h. The resulting solution was vacuum-
dried, and the residue was extracted in dichloromethane (15
mL). The filtered solution was again dried in vacuo and finally
washed with diethyl ether (3 × 6 mL). A white solid was
obtained. Yield: 420 mg (85%). Anal. Calcd for C28H36F6OsP2:
C, 45.52; H, 4.92. Found: C, 45.25; H, 5.33. IR (Nujol, cm-1):
ν(PF6) 840 (s). 1H NMR (300 MHz, CDCl3, 293 K): δ 7.40-
6.60 (10H, Ph); 5.06 (s, 5H, η5-C5H5); 4.02 (dd, 1H, J H-P ) 8.4,
Despite the high kinetic inertia of the Os(η5-C5H5)L3
systems, the isopropenyldi(isopropyl)phosphine displays
hemilabile properties. The hemilabile character of the
isopropenyl substituent of the phosphine is revealed by
the reaction of Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2}
with molecular hydrogen, which yields an equilibrium
mixture of the starting compound and the dihydride
OsH2(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2}. Another il-
lustrative example of the hemilabile properties of the
isopropenyldi(isopropyl)phosphine ligand in cyclopen-
tadienyl-osmium chemistry is the reaction of [Os(η5-
C5H5)Cl{[η2-(Z)-PhCHdCHPh}{[η2-CH2dC(CH3)]PiPr2}]-
PF6 with MeLi, which leads to OsH(η5-C5H4CH3){[η2-
(E)-PhCHdCHPh]{PiPr2[C(CH3)dCH2]} via OsH(η5-
C5 H 4 CH 3 ){[η2 -(Z)-P h CH dCH P h ]{P iP r 2 [C(CH 3 )d
CH2]}.
In conclusion, the dehydrogenation of one triisopro-
pylphosphine of the complex Os(η5-C5H5)Cl(PiPr3)2 is an
easy and effective method to prepare octahedral cyclo-
pentadienyl-isopropenyldi(isopropyl)phosphine-osmium-
(II) complexes. These compounds are of interest because
due to the hemilabile character of the isopropenyl
substituent of the phosphine, they will allow the devel-
opment of a new chemistry in the field of the cyclopen-
tadienyl-osmium complexes.
J H-H ) 2.1, PCdCHcis P); 3.71 (dd, 1H, J H-P ) 9.0, J H-H
)
to
9.0, dCHPh); 3.63 (dd, 1H, J H-P ) 32.1, J H-H ) 2.1, PCdCHtrans
to P); 2.72 (m, 1H, PCH); 2.66 (d, 1H, J H-H ) 9.0, dCHPh);
2.00-1.40 (16H, PCH and CH3 groups). 13C{1H} NMR (75.4
MHz, CDCl3, 293 K, plus APT): δ 145.1; 140.8 (-, s, Cipso
Ph); 131.6, 128.4, 128.3, 127.6 (+, s, Cortho, Cmeta Ph); 126.7,
125.5 (+, s, Cpara Ph); 88.3 (+, s, η5-C5H5); 63.8 (-, d, J C-P
)
21.2, P-Cd); 41.2 (+, s, CH3); 39.9 (+, d, J C-P ) 3.7, CH3);
31.4 (-, d, J C-P ) 6.9, dCH2); 30.0 (+, d, J C-P ) 29.4, PCH);
25.6 (+, d, J C-P ) 7.0, dCHPh); 23.7 (+, d, J C-P ) 29.4, PCH);
20.6 (+, d, J C-P ) 7.0, dCHPh); 20.1 (+, d, J C-P ) 2.7, CH3);
18.5 (+, s, CH3); 9.7 (+, d, J C-P ) 3.6, CH3). 31P{1H} NMR
(121.4 MHz, CDCl3, 293 K): δ -4.8 (s, PiPr2); -145.1 (sept,
J F-P ) 717.4, PF6). MS (FAB+): m/z 595 (M+ - H).
Exp er im en ta l Section
Rea ction of Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]P iP r 2} (4)
w ith H2. (a) An NMR tube containing a solution of Os(η5-
C5H5)Cl{[η2-CH2dC(CH3)]PiPr2} (4) (20 mg, 0.033 mmol) in 0.5
mL of C6D6 was sealed under hydrogen atmosphere. After 15
min the 1H NMR spectrum shows a mixture of Os(η5-C5H5)-
Cl{[η2-CH2dC(CH3)]PiPr2} (4) and OsH2(η5-C5H5)Cl{PiPr2-
[C(CH3)dCH2]} (6) in a 3:1 molar ratio.
(b) Molecular hydrogen was bubbled through a stirred
solution of Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2} (92 mg, 0.15
mmol) in 8 mL of toluene for 1 h. The solution was concen-
trated almost to dryness, and the addition of pentane caused
the formation of a yellow solid. The solid was washed with
pentane and vacuum-dried. The 1H NMR spectrum shows a
mixture of Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2} (4) and OsH2-
(η5-C5H5)Cl{PiPr2[C(CH3)dCH2]} (6) in a 1:2 molar ratio. After
All reactions were carried out with rigorous exclusion of air
using Schlenk-tube techniques. Solvents were dried by the
usual procedures and distilled under argon prior to use. The
starting material OsH2(η5-C5H5)Cl(PiPr3)2 (1) was prepared by
the published method.16
In the NMR spectra, chemical shifts are expressed in ppm
downfield from Me4Si (1H and 13C) and 85% H3PO4 (31P).
Coupling constants, J , are given in hertz.
P r ep a r a tion of Os(η5-C5H5)Cl(η2-P h CtCP h )(P iP r 3) (2).
A solution of OsH2(η5-C5H5)Cl(PiPr3) (230 mg, 0.51 mmol) in
50 mL of diethyl ether was treated with diphenylacetylene (245
mg, 1.37 mmol). The mixture was heated under reflux condi-
tions for 6 h, filtered, and then vacuum-dried. The resulting
sticky residue was washed with pentane (3 × 4 mL), leading
to a red solid. Yield: 260 mg (81%). Anal. Calcd for C28H36
-

Cyclopentadienyl-R-alkenylphosphine Os Complexes
Organometallics, Vol. 23, No. 6, 2004 1423
leaving the mixture under vacuo for 2 h, the 1H NMR spectrum
shows a mixture of Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2} (4)
and OsH2(η5-C5H5)Cl{PiPr2[C(CH3)dCH2]} (6) in a 2:1 molar
ratio.
Ta ble 3. Cr ysta l Da ta a n d Da ta Collection a n d
Refin em en t for 5 a n d 8
5
8
Crystal Data
NMR Da ta for 6. 1H NMR (300 MHz, C6D6, 293 K): δ 5.61
formula
molecular wt
color and habit
C
28H36F6OsP2
C
29H39OsP
(d, 1H, J H-P ) 17.0, PCdCHcis P); 5.44 (d, 1H, J H-P ) 35.7,
to
738.71
608.77
PCdCHtrans to P); 4.82 (s, 5H, η5-C5H5); 2.14 (m, 2H, PCH); 1.67
(d, 3H, J H-H ) 8.4, PC(CH3)); 1.12 (dd, 6H, J H-P ) 16.1, J H-H
) 6.8, PCHCH3); 0.73 (dd, 6H, J H-P ) 15.2, J H-H ) 7.0,
PCHCH3); -10.19 (d, 2H, J H-P ) 33.9, Os-H). 13C{1H} NMR
(75.4 MHz, C6DCl6, 293 K, plus APT): 140.8 (-, d, J C-P ) 40.6,
PCd); 130.9 (-, d, J C-P ) 12.8, dCH2); 79.7 (-, s, η5-C5H5);
28.4 (+, d, J C-P ) 37.4, PCH); 18.8 (+, s, PCH3); 18.6 (+, s,
PCH3 plus PC(CH3)d). 31P{1H} NMR (121.4 MHz, C6D6, 293
K): δ 45.2 (s).
orange, irregular yellow, irregular
block block
monoclinic, P21/n monoclinic, P21/n
symmetry, space group
a, Å
b, Å
c, Å
â, deg
V, Å3
Z
11.2563(9)
20.2337(16)
12.3703(10)
92.3440(10)
2815.1(4)
4
10.0637(5)
18.3653(9)
13.7078(7)
90.5290(10)
2533.4(2)
4
D
calc, g cm-3
1.743
1.596
P r ep a r a tion of OsH(η5-C5H4CH3)Cl{η2-(Z)-P h CHdCH-
P h }{P iP r 2[C(CH3)dCH2]}] (7). To a solution of [Os(η5-C5H5)-
Cl{η2-(Z)-PhCHdCHPh}{[η2-CH2dC(CH3)]PiPr2}]PF6 (120 mg,
0.16 mmol) in 10 mL of THF was added methyllithium
(solution in alkanes, 0.15 mL, 1.6 M, 0.24 mmol), and the
mixture was left to stir for 1 h. Methanol was added, the
resulting solution was vacuum-dried, and the residue was
extracted in dichloromethane (15 mL). The filtered solution
was again dried in vacuo and finally washed with methanol
(2 × 2 mL). A white solid was obtained. Yield: 54 mg (55%).
Anal. Calcd for C29H39OsP2: C, 57.21; H, 6.46. Found: C, 57.00;
H, 6.38. IR (Nujol, cm-1): ν(Os-H) 2083 (m). 1H NMR (300
MHz, C6D6, 293 K): δ 7.60-6.90 (10 H, Ph); 5.52 (d, 1H, J H-P
) 10.5, PCdCHcis to P); 5.46 (d, 1H, J H-P ) 32.2, PCdCHtrans to P);
Data Collection and Refinement
Bruker Smart APEX
diffractometer
λ(Mo KR), Å
monochromator
scan type
0.71073
graphite oriented
ω scans
5.111
µ, mm-1
4.700
2θ range, deg
temp, K
3, 56
3, 56
100
100
no. of data collected
no. of unique data
33 606
6741 (Rint
0.0397)
30 444
)
6065 (Rint
0.0453)
288/14
0.0326
0.0723
1.015
)
no. of params/restraints 351/0
R1a [F2 > 2σ(F2)]
wR2b [all data]
Sc [all data]
0.0319
0.0718
0.984
a
b
2
R1(F) ) ∑||Fo| - |Fc||/∑|Fo|. wR2(F2) ) {∑[w(Fo - Fc2)2]/
∑[w(Fo2)2]}1/2
the number of reflections, and
parameters.
.
c Goof ) S ) {∑[Fo - Fc2)2]/(n - p)}1/2, where n is
2
5.10-3.70 (ABCD system, 4H, η5-C5H4); 4.25 (d, 1H, J H-P
9.6, dCHPh); 3.32 (dd, 1H, J H-P ) 9.6, J H-H ) 9.6, dCHPh);
1.96 (s, η5-C5H4CH3); 1.81 (m, 2 H, PCH); 1.68 (d, 3H, J H-H
)
p is the number of refined
)
7.8, PC(CH3)); 1.10-0.80 (m, 12H, PCHCH3); -14.97 (d, 1H,
tube source (molybdenum radiation, λ ) 0.71073 Å) operating
at 50 kV and 35 mA (5) or 30 mA (8). Data were collected over
the complete sphere by a combination of four sets. Each frame
exposure time was 10 s covering 0.3° in ω. The cell parameters
were determined and refined by least-squares fit of 5034 (5)
or 7967 (8) collected reflections. The first 100 frames were
collected at the end of the data collection to monitor crystal
decay. Absorption correction was performed with SADABS.24
Lorentz and polarization corrections were also performed. The
structures were solved by Patterson and Fourier methods and
refined by full matrix least-squares using the Bruker SHELX-
J H-P ) 31.5, Os-H). 13C{1H} NMR (75.4 MHz, C6DCl6, 293 K,
plus APT): δ 151.6, 149.1 (-, s, Cipso Ph); 139.7 (-, d, J C-P
)
31.3, P-Cd); 133.5, 130.4, 127.9, 127.8 (+, s, Cortho, Cmeta
Ph); 128.6 (-, masked with solvent signals, dCH2); 125.0,
123.4 (+, both s, Cpara Ph); 99.9 (-, s, η5-C5H4); 90.7, 84.6,
78.1, 74.5, (+, all s, η5-C5H4); 33.6 (+, d, J C-P ) 2.7, dCHPh);
29.3 (+, d, J C-P ) 30.9 Hz, PCH); 27.6 (+, d, J C-P ) 30.0 Hz,
PCH); 26.3 (+, d, J C-P ) 3.2, dCHPh); 23.0-14.0 (+, all s,
CH3). 31P{1H} NMR (121.4 MHz, CDCl3, 293 K): δ 38.5 (s, d,
in off-resonance). MS (FAB+): m/z 610 (M+).
P r epar ation of OsH(η5-C5H4CH3){η2-(E)-P h CHdCHP h }-
{P iP r 2[C(CH3)dCH2]} (8). A solution of OsH(η5-C5H4CH3)-
Cl{η2-(Z)-PhCHdCHPh}{PiPr2[C(CH3)dCH2]}] (96 mg, 0.16
mmol) in 10 mL of toluene was heated under reflux conditions
for 16 h. The mixture was vacuum-dried, and the residue was
washed with methanol (2 × 1 mL). A white solid was obtained.
Yield: 81 mg (84%). Anal. Calcd for C29H39OsP: C, 57.21; H,
6.46. Found: C, 57.30; H, 6.31. IR (Nujol, cm-1): ν(Os-H):
2112 (m). 1H NMR (300 MHz, C6D6, 293 K): δ 7.60-6.90 (10H,
Ph); 5.34 (d, 1H, J H-P ) 29.1, PCdCHtrans to P); 5.27 (d, 1H, J H-P
) 10.2, dCHPh); 5.23 (d, 1H, J H-P ) 14.1, PCdCHcis to P); 4.80-
4.00 (ABCD system, 4H, η5-C5H4); 3.93 (dd, 1H, J H-P ) 10.2,
J H-H ) 10.2, dCHPh); 1.95 (s, 3H, η5-C5H4CH3); 1.74 (m, 2H,
PCH); 1.55 (d, 3H, J H-H ) 9.0, PC(CH3)d); 1.10-0.60 (m, 12H,
PCHCH3); -15.89 (d, 1H, J H-P ) 35.4, Os-H). 13C{1H} NMR
(75.4 MHz, C6D6, 293 K, plus APT): δ 153.7, 153.6 (-, both s,
Cipso Ph); 142.6 (-, d, J C-P ) 32.4, P-Cd); 130.4, 128.6, 128.0,
126.8 (+, s, Cortho, Cmeta Ph); 124.8 (-, d, J C-P ) 5.5, dCH2);
124.3, 123.7 (+, s, Cpara Ph); 96.7 (-, s, η5-C5H4); 89.9, 84.1,
79.4, 77.3, (+, all s, η5-C5H4); 29.8 (+, d, J C-P ) 31.0, PCH);
28.4 (+, d, J C-P ) 31.0, PCH); 25.2 (+, d, J C-P ) 4.2, dCHPh);
24.6 (+, d, J C-P ) 2.0, dCHPh); 23.0-14.0 (+, all s, CH3). 31P-
{1H} NMR (121.4 MHz, C6D6, 293 K): δ 32.8 (s, d in off-
resonance). MS (FAB+): m/z 610 (M+).
2
TL25 program package minimizing w(Fo - Fc2)2. The isopro-
penyldi(isopropyl)phosphine of complex 8 was observed with
the isopropenyl group disordered in two sites and refined with
complementary occupancy factors and restrained geometry.
The nondisordered non-hydrogen atoms of 5 and 8 were
anisotropically refined. The hydrogen atoms were observed or
calculated and refined riding on bonded carbon atoms. The
hydride ligand of 8 was observed in the difference Fourier
maps and refined freely. Weighted R factors (Rw) and goodness
of fit (S) are based on F2; conventional R factors are based on
F. Crystal data and details of the data collection and refine-
ment are given in Table 3.
Ack n ow led gm en t . Financial support from the
MCYT of Spain (Project BQU2002-00606, PPQ2000-
0488-P4-02) is acknowledged. M.L.B. thanks the Min-
isterio de Ciencia y Tecnolog´ıa (CICYT) of Spain for a
Ramo´n y Cajal project.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal-
lographic data and bond lengths and angles. This material is
available free of charge via the Internet at http://pubs.acs.org.
OM034378S
X-r a y An a lysis of 5 a n d 8. Two irregular crystals of size
0.20 × 0.12 × 0.12 mm (5) and 0.16 × 0.12 × 0.08 mm (8)
were mounted on a Bruker Smart APEX CCD diffractometer
at 100.0(2) K equipped with a normal focus, 2.4 kW sealed
(24) Blessing, R. H. Acta Crystallogr., Sect. A 1995, 51, 33. SADABS,
Area-detector absorption correction; Bruker-AXS: Madison, WI, 1996.
(25) SHELXTL Package, v. 6.1; Bruker Analytical, X-ray Systems:
Madison, WI, 2000.