Preparation, X-ray structure, and reactivity of an olefin-carbene-osmium complex: A-alkenylphosphine to a-allylphosphine transformation via an osmaphosphabicyclopentane intermediate

Article abstract of DOI:10.1021/om0496075

The uses of transition-metal carbene complexes for organic and organometallic synthesis were discussed. It was observed that the organic and organometallic compounds were prepared through [2+2] cycloaddition reactions between M-C double and C-C unsaturated bonds. It was also observed that the osmium-αalkenylphosphine complexes were formed from alkylphosohine compounds by dehydrogenation of an alkyl substituent of the phosphine. The results show the development of synthetic methods for the preparation of coordinated ligands with a variable number of donor groups.

Full text of DOI:10.1021/om0496075

4858
Organometallics 2004, 23, 4858-4870
P r ep a r a tion , X-r a y Str u ctu r e, a n d Rea ctivity of a n
Olefin -Ca r ben e-Osm iu m Com p lex: r-Alk en ylp h osp h in e
to r-Allylp h osp h in e Tr a n sfor m a tion via a n
Osm a p h osp h a bicyclop en ta n e In ter m ed ia te
Miguel A. Esteruelas,* Ana I. Gonza´lez, Ana M. Lo´pez,* 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 J une 1, 2004
The isopropenyldi(isopropyl)phosphine complex Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2} (1)
reacts at room temperature with phenyldiazomethane to give the olefin-carbene derivative
Os(η5-C5H5)Cl(dCHPh){PiPr2[C(CH3)dCH2]} (2), which has been characterized by X-ray
diffraction analysis. In toluene at 70 °C, complex 2 evolves into the osmaphosphabicyclo-
pentane compound Os(η5-C5H5)Cl{PiPr2[C(CH3)CH2CHPh]} (3). Treatment of 3 with TlPF6
at room temperature leads to a 1:1 mixture of the R-allylphosphine complex [OsH(η5-C5H5)-
Cl{[η3-CHPhCHC(CH3)]PiPr2}]PF6 (4) and its R-alkenyl-γ-(η3-benzyl)phosphine isomer [OsH-
(η5-C5H5){[η3-C6H5CHCHdC(CH3)]PiPr2}]PF6 (5). The heating of the mixture in tetrahydro-
furan at 66 °C gives rise to the isomerization of 5 into 4, which has been also characterized
by X-ray diffraction analysis. The hydride ligand of 4 is fairly acidic. Its deprotonation with
NaOCH3 leads to an equilibrium mixture of the neutral osmium(II) R-allylphosphine OsH-
(η5-C5H5)Cl{[η3-CHPhCHC(CH3)]PiPr2} (6), R-alkenyl-γ-(η3-benzyl)phosphine OsH(η5-C5H5)-
Cl{[η3-CHPhCHC(CH3)]PiPr2} (7), and R-alkenyl-γ-carbenephosphine OsH(η5-C5H5){[dC(Ph)-
CHdC(CH3)]PiPr2} (8) isomers. Complex 2 also reacts with TlPF6. The reaction affords the
hydride-carbyne derivative [OsH(η5-C5H5)(tCPh){PiPr2[C(CH3)dCH2]}]PF6 (9), which evolves
into 4. The isomerization is a first-order process with activation parameters of ∆Hq ) 23 (
3 kcal‚mol-1 and ∆Sq ) -4 ( 4 cal‚K-1‚mol-1. The hydride ligand of 9 is also fairly acidic.
Its deprotonation with NaOCH3 leads to the neutral carbyne Os(η5-C5H5)(tCPh){PiPr2-
[C(CH3)dCH2]} (10), which reacts with methanol to give the hydride-alkoxycarbene derivative
OsH(η5-C5H5){dC(OMe)Ph}{PiPr2[C(CH3)dCH2]} (11). The carbene carbon atom of 2 has
amphiphilic character, reacting with electrophiles and nucleophiles. The reaction with HBF4
leads to the hydride-benzylcyclopentadienyl derivative OsH(η5-C5H4CH2Ph)Cl{[η2-
CH2dC(CH3)]PiPr2}]PF6 (14) via η1-benzyl intermediates, whereas the reaction with CH3Li
gives the hydride-styrene compound OsH(η5-C5H5)(η2-CH2dCHPh){PiPr2[C(CH3)dCH2]} (15).
In tr od u ction
and ruthenium counterparts.3 In the course of our
investigations on the chemistry of the Os(η5-C5H5) unit,4
we have recently observed that the addition of a toluene
solution of phenyldiazomethane to Os(η5-C5H5)Cl(PiPr3)2
Transition-metal carbene complexes are one of the
most useful tools in organic and organometallic synthe-
sis. Through [2+2] cycloaddition reactions between
M-C double and C-C unsaturated bonds, numerous
compounds have been prepared.1 In particular, half-
sandwich complexes of the iron triad have shown to be
useful in cyclopropanation and unusual C-C coupling
reactions from diazo compounds and terminal alkenes
or alkynes.2
(1) See for example: (a) Do¨tz, K. H. Angew. Chem., Int. Ed. Engl.
1984, 23, 587. (b) Brothers, P. J .; Roper, W. R. Chem. Rev. 1988, 88,
1293. (c) Grubbs, R. H.; Miller, S. J .; Fu, G. C. Acc. Chem. Res. 1995,
28, 446. (d) Harvey, D. F.; Sigano, D. M. Chem. Rev. 1996, 96, 271. (e)
Pariya, C.; J ayaprakash, K. N.; Sarkar, A. Coord. Chem. Rev. 1998,
168, 1. (f) Doyle, M. P.; Forbes, D. C. Chem. Rev. 1998, 98, 911. (g)
Hegedus, L. S. Transition Metals in the Synthesis of Complex Organic
Molecules, 2nd ed.; University Science Books: Sausalito, 1999; Chapter
6. (h) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18. (i)
Schrock, R. R. J . Chem. Soc., Dalton Trans. 2001, 2541. (j) Schrock,
R. R. Chem. Rev. 2002, 102, 145. (k) Connon, S. J .; Blechert, S. Angew.
Chem., Int. Ed. 2003, 42, 1900.
The osmium derivatives of this type are very scarce,
and they have been much less studied than their iron
* Corresponding authors. E-mail: maester@posta.unizar.es.
10.1021/om0496075 CCC: $27.50 © 2004 American Chemical Society
Publication on Web 09/15/2004

Olefin-Carbene-Osmium Complex
Organometallics, Vol. 23, No. 21, 2004 4859
leads to the osmium-carbene complex Os(η5-
C5H5)Cl(dCHPh)(PiPr3), which shows a Fischer-Schrock
ambivalent behavior.5
R-Alkenylphosphines are attracting increased atten-
tion in the chemistry of the metals.6 Recently, it has
been proved that osmium-R-alkenylphosphine com-
plexes can be formed from alkylphosphine compounds
by dehydrogenation of an alkyl substituent of the
phosphine.7 Despite the high kinetic inertia of the
Os(η5-C5H5)L3 systems,8 the isopropenyldi(isopropyl)-
phosphine ligand of the osmium-cyclopentadienyl com-
hemilabile character, prompted us to prepare the olefin-
carbene complex Os(η5-C5H5)Cl(dCHPh){PiPr2[C(CH3)d
CH2]}, to study the [2+2] cycloaddition between the
carbene and the olefin and the influence of the isopro-
penyl group on the Fischer-Schrock ambivalent behav-
ior of the carbene ligand.
In this paper, we report the results of these studies
and the unprecedented R-alkenylphosphine to R-allyl-
phosphine conversion via carbene and osmaphosphabi-
cyclopentane intermediates. In the context of the latter
transformation, it should be mentioned that the cata-
lytic cycles involve short-lived species with variable
coordination numbers, which are connected by equilib-
ria. Thus, the selective formation of a particular cata-
lytic product depends on the equilibrium concentration
of one or several of these short-lived intermediates. To
control their stability, the development of synthetic
methods for the preparation of coordinated ligands with
a variable number of donor groups is of great interest.
plex Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2} displays
hemilabile properties.9
It is generally accepted that cyclopropanation and
olefin metathesis reactions involve the intermediacy of
carbene-olefin species, which evolve into metallacycle
intermediates. However, these species have been rarely
isolated or detected.10 The presence of an η2-isopropenyl
ligand in Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2}, and its
Resu lts a n d Discu ssion
(2) See for example: (a) Baratta, W.; Del Zotto, A.; Rigo, P. Chem.
Commun. 1997, 2163. (b) Baratta, W.; Del Zotto, A.; Rigo, P. Organo-
metallics 1999, 18, 5091. (c) Baratta, W.; Herrmann, W. A.; Kratzer,
R. M.; Rigo, P. Organometallics 2000, 19, 3664. (d) Le Paih, J .; De´rien,
S.; O¨ zdemir, I.; Dixneuf, P. H. J . Am. Chem. Soc. 2000, 122, 7400. (e)
Guerchais, V. Eur. J . Inorg. Chem. 2002, 783. (f) Priya, S.; Balakrishna,
M. S.; Mobin, S. M.; McDonald, R. J . Organomet. Chem. 2003, 688,
227.
(3) (a) Brumaghim, J . L.; Girolami, G. S. Chem. Commun. 1999,
953. (b) Weberndo¨rfer, B.; Henig, G.; Werner, H. Organometallics 2000,
19, 4687. (c) Baya, M.; Esteruelas, M. A. Organometallics 2002, 21,
2332. (d) Baya, M.; Esteruelas, M. A.; On˜ate, E. Organometallics 2002,
21, 5681. (e) Weberndo¨rfer, B.; Henig, G.; Hockless, D. C. R.; Bennett,
M. A.; Werner, H. Organometallics 2003, 22, 744.
(4) (a) Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A. M.; Oro, L. A.
Organometallics 1996, 15, 878. (b) Esteruelas, M. A.; Lo´pez, A. M.;
Ruiz, N.; Tolosa, J . I. Organometallics 1997, 16, 4657. (c) Crochet, P.;
Esteruelas, M. A.; Gutie´rrez-Puebla, E. Organometallics 1998, 17,
3141. (d) Crochet, P.; Esteruelas, M. A.; Lo´pez, A. M.; Ruiz, N.; Tolosa,
J . I. Organometallics 1998, 17, 3479. (e) Baya, M.; Crochet, P.;
Esteruelas, M. A.; Gutie´rrez-Puebla, E.; Ruiz, N. Organometallics 1999,
18, 5034. (f) Esteruelas, M. A.; Gutie´rrez-Puebla, E.; Lo´pez, A. M.;
On˜ate, E.; Tolosa, J . I. Organometallics 2000, 19, 275. (g) Baya, M.;
Crochet, P.; Esteruelas, M. A.; Gutie´rrez-Puebla, E.; Lo´pez, A. M.;
Modrego, J .; On˜ate, E.; Vela, N. Organometallics 2000, 19, 2585. (h)
Esteruelas, M. A.; Lo´pez, A. M.; Tolosa, J . I.; Vela, N. Organometallics
2000, 19, 4650. (i) Baya, M.; Crochet, P.; Esteruelas, M. A.; On˜ate, E.
Organometallics 2001, 20, 240. (j) Baya, M.; Crochet, P.; Esteruelas,
M. A.; Lo´pez, A. M.; Modrego, J .; On˜ate, E. Organometallics 2001, 20,
4291. (k) Baya, M.; Esteruelas, M. A.; On˜ate, E.; Organometallics 2001,
20, 4875. (l) Carbo´, J . J .; Crochet, P.; Esteruelas, M. A.; J ean, Y.; Lledo´s,
A.; Lo´pez, A. M.; On˜ate, E. Organometallics 2002, 21, 305. (m)
Esteruelas, M. A.; Lo´pez, A. M.; On˜ate, E.; Royo, E. Organometallics
2004, 23, 3021.
1. P r ep a r a tion a n d Str u ctu r e of Os(η5-C5H5)Cl-
(dCHP h ){P iP r 2[C(CH3)dCH2]}. In agreement with
the hemilabile character of the R-alkenylphosphine of
Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2} (1), the treat-
ment at room temperature of a toluene solution of this
compound with 2.0 equiv of phenyldiazomethane in
toluene leads after 1 h to the olefin-carbene derivative
Os(η5-C5H5)Cl(dCHPh){PiPr2[C(CH3)dCH2]} (2), which
is the result of the displacement of the R-alkenylphos-
phine olefin group from the coordination sphere of the
metal by the carbene ligand (eq 1).
Complex 2 was isolated as a blue solid in 87% yield
and characterized by MS, elemental analysis, IR, and
1H, 13C{1H}, and 31P{1H} NMR spectroscopy as well as
by an X-ray crystallographic study. The structure has
two chemically equivalent but crystallographically in-
dependent molecules in the asymmetric unit (enanti-
omers). A drawing of the R enantiomer is shown in
Figure 1. Selected bond distances and angles for both
enantiomers are listed in Table 1.
(5) Esteruelas, M. A.; Gonza´lez, A. I.; Lo´pez, A. M.; On˜ate, E.
Organometallics 2003, 22, 414.
(6) See for example: (a) J i, H.; Nelson, J . H.; DeCian, A.; Fischer,
J .; Slujic´, L.; Milosavljevic´, E. B. Organometallics 1992, 11, 401. (b)
Barthel-Rosa, L. P.; Maitra, K.; Fischer, J .; Nelson, J . H. Organo-
metallics 1997, 16, 1714. (c) Barthel-Rosa, L. P.; Maitra, K.; Nelson,
J . H. Inorg. Chem. 1998, 37, 633. (d) Hogarth, G.; Shukri, K.; Doherty,
S.; Carty, A. J .; Enright, G. D. Inorg. Chim. Acta 1999, 178. (e) Coles,
S. J .; Faulds, P.; Hursthouse, M. B.; Kelly, D. G.; Toner, A. J .
Polyhedron 2000, 19, 1271. (f) Hansen, H. D.; Nelson, J . H. Organo-
metallics 2000, 19, 4740.
(7) (a) Edwards, A. J .; Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, A. M.;
On˜ate, E.; Oro, L. A.; Tolosa, J . I. Organometallics 1997, 16, 1316. (b)
Barrio, P.; Esteruelas, M. A.; On˜ate, E. Organometallics 2003, 22, 2472.
(c) Esteruelas, M. A.; Lledo´s, A.; Maseras, F.; Oliva´n, M.; On˜ate, E.;
Tajada, M. A.; Toma`s, J . Organometallics 2003, 22, 2087.
(8) Atwood, J . D. Inorganic and Organometallic Reaction Mecha-
nisms; VCH Publisher: New York, 1997; Chapter 3.
The geometry around the osmium center is close to
octahedral, with the cyclopentadienyl ligand occupying
a face. The C(1)-Os(1)-P(1), C(1)-Os(1)-Cl(1), and
P(1)-Os(1)-Cl(1) angles are 87.08(15)°, 102.59(15)°, and
87.49(4)° in
R and 86.73(15)°, 103.35(14)°, and
87.63(5)° in S, respectively.
The X-ray structure reveals that the obtained rotamer
contains the phenyl group disposed toward the cyclo-
pentadienyl ligand. The bond lengths of 1.895(5) Å (R)
and 1.887(5) Å (S) are consistent with an Os(1)-C(1)
double bond. They agree well with those found in the
complexes OsCl2(dCHCH2Ph)(CO)(PiPr3) (1.887(9) Å),11
(9) Baya, M.; Buil, M. L.; Esteruelas, M. A.; On˜ate, E. Organome-
tallics 2004, 23, 1416.
(10) (a) J ennings, P. W.; J ohnson, L. L. Chem. Rev. 1994, 94, 2241.
(b) Tallarico, J . A.; Bonitatebus, P. J ., J r., Snapper, M. L. J . Am. Chem.
Soc. 1997, 119, 7157. (c) AÄ lvarez, P.; Lastra, E.; Gimeno, J .; Bassetti,
M.; Falvello, L. R. J . Am. Chem. Soc. 2003, 125, 2386. (d) Mashima,
K.; Yonekura, H.; Yamagata, T.; Tani, K. Organometallics 2003, 22,
3766.
(11) Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro, L. A.; Valero,
C.; Zeier, B. J . Am. Chem. Soc. 1995, 117, 7935.

4860 Organometallics, Vol. 23, No. 21, 2004
Esteruelas et al.
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)Cl(dCHP h ){P iP r 2[C(CH3)dCH2]} (2)
R
S
R
S
Os(1)-P(1)
Os(1)-Cl(1)
Os(1)-C(1)
Os(1)-C(17)
Os(1)-C(18)
Os(1)-C(19)
2.3019(13)
2.3853(13)
1.895(5)
2.188(5)
2.332(5)
2.364(5)
2.2952(13)
2.3870(13)
1.887(5)
2.368(5)
2.326(5)
2.170(5)
Os(1)-C(20)
Os(1)-C(21)
C(1)-C(2)
P(1)-C(11)
C(11)-C(12)
C(11)-C(13)
2.299(5)
2.191(5)
1.470(6)
1.843(5)
1.331(6)
1.490(6)
2.196(5)
2.301(5)
1.491(6)
1.855(5)
1.313(6)
1.494(6)
Ma-Os(1)-P(1)
Ma-Os(1)- Cl(1)
Ma-Os(1)- C(1)
P(1)-Os(1)-Cl(1)
C(1)-Os(1)-P(1)
130.6
115.4
125.0
87.49(4)
87.08(15)
130.0
115.5
125.1
87.63(5)
86.73(15)
C(1)-Os(1)-Cl(1)
Os(1)-C(1)-C(2)
P(1)-C(11)-C(12)
P(1)-C(11)-C(13)
C(12)-C(11)-C(13)
102.59(15)
130.8(3)
123.6(4)
115.9(3)
120.4(5)
103.35(14)
130.6(4)
123.1(4)
116.0(3)
120.8(4)
a
M represents the midpoint of the Cp ring.
with regard to those of 1 (δ, 32.6 (CH2), 36.1 (CP)).9 In
addition, it should be mentioned that the CP resonance
has significantly increased the C-P coupling constant
as a consequence of the decoordination (from 19.7 to 33
1
Hz). In the H NMR spectrum, the resonances due to
the CH2 protons of the isopropenyl group are observed
at 5.67 (trans to P) and 5.34 (cis to P) ppm, as doublets
with H-P coupling constants of 28.5 and 12.0 Hz,
respectively. These resonances are shifted 1.57 (trans
to P) and 2.47 (cis to P) ppm toward lower field with
regard to those found in the spectrum of 1 (δ, 4.10 and
2.87).9 The H-P coupling constant of the resonance
corresponding to the proton disposed cis to the phos-
phorus atom also increases as a consequence of the
decoordination (from 7.2 to 12.0 Hz).
The 31P{1H} NMR spectrum of 2 contains a singlet
at 31.6 ppm, shifted 34.5 ppm to lower field compared
with the observed one in the spectrum of 1 (δ, -2.9).
2. [2+2] Cycloa d d ition betw een th e Olefin a n d
Ca r ben e Gr ou p s. In toluene the olefin-carbene com-
plex 2 very slowly evolves to give the unprecedented
F igu r e 1. Molecular diagram of the R enantiomer of
Os(η5-C5H5)Cl(dCHPh){PiPr2[C(CH3)dCH2]} (2).
[OsH(κ2-O2CCH3){dC(Ph)CH2}(PiPr3)2]BF4 (1.895(10)
and 1.882(11) Å),12 [OsH(κ2-O2CCH3){dC(Ph)CH2}-
osmaphosphabicyclopentane derivative Os(η5-C5H5)Cl-
(PiPr3)2]BF4 (1.879(6) Å),13 and [OsCl{dCHCH(Ph)Nd
CMe2}(CO)](PiPr3)2][CF3SO3] (1.890(10) Å),14 where an
Os-C double bond has also been proposed to exist. The
Os(1)-C(1)-C(2) (130.8(3)° in R and 130.6(4)° in S)
angles support the sp2 hybridization of C(1). The C(11)-
C(12) distances (1.331(6) Å in R and 1.313(6) Å in S) as
well as the angles around C(11), close to 120°, support
the presence of a double bond between these atoms of
the phosphine.
{PiPr2[C(CH3)CH2CHPh]} (3). At 70 °C in an NMR tube
the transformation is quantitative after 50 h. Under the
same conditions at Schlenk-tube scale, complex 3 was
isolated as an orange solid in 72% yield (eq 2).
In the 1H NMR spectrum of 2 in benzene-d6, the most
noticeable resonance of the carbene ligand is that
corresponding to the CR-H proton, which appears at
18.50 ppm as a doublet with a H-P coupling constant
of 16.8 Hz. In the 13C{1H} NMR spectrum, the CR atom
of the carbene displays a broad resonance at 234.2 ppm.
The 13C{1H} and 1H NMR spectra also reveal the
presence of a free isopropenyl substituent in the phos-
phine. In the 13C{1H} NMR spectrum, the C(sp2) carbon
atoms of the phosphine give rise to a doublet at 142.5
(CP) ppm, with a C-P coupling constant of 33 Hz, and
a singlet at 125.8 (CH2) ppm. These resonances appear
shifted 93.2 (CH2) and 106.4 (CP) ppm to lower field
The presence of Os-CHPh and Os-C(CH3)P single
bonds in 3 is strongly supported by its 13C{1H} NMR
spectrum, which shows doublets at -9.5 and -22.4 ppm,
with C-P coupling constants of 3 and 13 Hz, respec-
1
tively. In the H NMR spectrum, the resonance corre-
sponding to the OsCH proton of the bicycle appears at
3.99 ppm. The CH2 group displays two resonances: one
of them at 4.47 ppm, overlapped by the Cp signal, and
the other one at 3.45 ppm. The resonance due to the
methyl substituent of the bicycle is observed at 0.55
ppm. The 31P{1H} NMR spectrum contains a singlet at
-23.3 ppm, shifted 54.9 ppm to higher field compared
with the observed one in the spectrum of 2.
(12) Buil, M. L.; Eisenstein, O.; Esteruelas, M. A.; Garc´ıa-Yebra,
C.; Gutie´rrez-Puebla, E.; Oliva´n, M.; On˜ate, E.; Ruiz, N.; Tajada, M.
A. Organometallics 1999, 18, 4949.
(13) Buil, M. L.; Esteruelas, M. A.; Garc´ıa-Yebra, C.; Gutie´rrez-
Puebla, E.; Oliva´n, M. Organometallics 2000, 19, 2184.
(14) Castarlenas, R.; Esteruelas, M. A.; On˜ate, E. Organometallics
2001, 20, 2294.

Olefin-Carbene-Osmium Complex
Organometallics, Vol. 23, No. 21, 2004 4861
Sch em e 1
F igu r e 2. Molecular diagram of the cation of OsH(η5-
C5H5)Cl{[η3-CHPhCHC(CH3)]PiPr2}]PF6 (4).
The stereochemistry shown in eq 2 was inferred on
the basis of a NOE experiment; the saturation of the
CH3 resonance of the bicycle increases the intensity of
the Ph (6.4%) and Cp (7.0%) resonances, while a NOE
effect with the OsCH resonance is not observed. The
exclusive formation of this diastereomer proves that the
reaction is diastereoselective and involves a [2+2]
cycloaddition process between the C-C double bond of
the phosphine and the Os-C double bond in the rotamer
shown in Figure 1.
The extraction of the chloride ligand from 3 provokes
the destruction of the bicycle. At room temperature, the
treatment of acetone solutions of 3 with 1.0 equiv of
TlPF6 leads to a 1:1 mixture of the R-allylphosphine
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-C5H5)Cl{[η3-CHP h CHC(CH3)]P iP r 2}]P F 6(4)
Os-P(1)
Os-C(1)
Os-C(3)
Os-C(4)
Os-C(17)
Os-C(18)
Os-C(19)
Os-C(20)
2.2634(9)
2.221(3)
2.173(3)
2.209(3)
2.224(3)
2.230(3)
2.232(3)
2.214(3)
Os-C(21)
Os-H(01)
C(1)-C(2)
C(1)-C(3)
C(3)-C(4)
C(4)-C(5)
P(1)-C(1)
2.212(3)
1.33(4)
1.507(4)
1.414(4)
1.415(5)
1.484(4)
1.772(3)
Ma-Os-P(1)
Ma-Os-C(1)
Ma-Os-C(3)
Ma-Os-C(4)
Ma-Os-H(01)
P(1)-Os-C(1)
P(1)-Os-C(3)
P(1)-Os-C(4)
P(1)-Os-H(01)
138.6
130.8
130.2
137.9
C(1)-Os-C(3)
C(1)-Os-C(4)
C(3)-Os-C(4)
C(1)-C(3)-C(4)
P(1)-C(1)-C(2)
P(1)-C(1)-C(3)
C(2)-C(1)-C(3)
C(3)-C(4)-C(5)
37.52(12)
67.91(12)
37.67(12)
122.1(3)
122.9(2)
115.8(2)
120.6(3)
121.6(3)
complex OsH(η5-C5H5)Cl{[η3-CHPhCHC(CH3)]PiPr2}]-
PF6 (4) and its R-alkenyl-γ-(η3-benzyl)phosphine isomer
106.1
46.53(8)
75.11(9)
83.01(9)
85.2(15)
OsH(η5-C5H5){[η3-C6H5CHCHdC(CH3)]PiPr2}]PF6 (5).
The transformation initially affords the hydride-η1-
allylphosphine intermediate a (Scheme 1), as a result
of the Os-C(CH3)P bond cleavage and a â-hydrogen
elimination reaction on the CH2 group of the bicycle.
From a thermodynamic point of view, complex 4 is more
stable than 5. Thus, the heating of the mixture in
tetrahydrofuran at 66 °C gives rise to the isomerization
of 5 into 4, and the latter can be isolated as a pure white
solid in 70% yield.
It should be noted that a â-H elimination rather than
a metathesis process, driven by the presence of the
vacant site, is observed in the metallacyclobutane of 3.
Although intermediates have not been isolated, it has
been proposed that an intramolecular [2+2] cycloaddi-
tion reaction in olefin-carbene-metal complexes and the
subsequent transformation of the resulting metallacy-
clobutane into hydrido-η3-allyl-metal derivatives are the
key steps for the catalytic formation of Cn olefins, by
addition of diazoalkanes to Cn-1 olefins.2c,f,15 The reac-
tions shown in eqs 1 and 2 and the formation of 4
according to Scheme 1 are strong evidence in favor of
this proposal. Kirchner et al. have also postulated that
ruthenium complexes react with terminal alkynes, in
the presence of base, to yield η3-butadienyl compounds
via metallacyclobutane intermediates related to 3.16
a
M represents the midpoint of the C(23)-C(27) Cp ring.
by the phosphorus and the C(1), C(3), and C(4) carbon
atoms. The angles C(1)-Os-C(4), C(3)-Os-P(1), C(1)-
C(3)-C(4), and C(3)-C(1)-P(1) are 67.91(12)°,
75.11(9)°, 122.1(3)°, and 115.8(2)°, respectively. The
phenyl substituent is syn disposed with regard to C(3),
with a C(3)-C(4)-C(5) angle of 121.6(3)°. The allyl
moiety coordinates in an asymmetrical fashion, with the
separation between the central carbon atom, C(3), and
the metal (2.173(3) Å) shorter than the separation
between the metal and the terminal carbon atoms C(4)
(2.209(3) Å) and C(1) (2.221(3) Å). The carbon-carbon
distances are 1.414(4) Å for C(1)-C(3) and 1.415(5) Å
for C(3)-C(4). The Os-P(1) and P(1)-C(1) bond lengths
reflect the peculiarities of the R-allylphosphine. The Os-
P(1) distance (2.2634(9) Å) is about 0.09 Å shorter than
the separation between the metal and the triisoprop-
ylphosphine ligand in the hydride-η3-allyl-osmium(IV)
derivative [OsH(η5-C5H4SiPh3){η3-CH2C(Ph)CH2}(PiPr3)]-
BF4 (2.3500(11) Å),4k whereas the P(1)-C(1) distance
(1.772(3) Å) is about 0.04 and 0.07 Å shorter than the
P(1)-C(11) (1.816(3) Å) and P(1)-C(14) (1.848(3) Å)
distances, respectively. The P(1)-C(1) distance is also
about 0.07 Å shorter than the P-(Csp2) bond length in
the R-alkenylphosphine of 2, suggesting that some
electron density of the allyl unit extends toward the
phosphorus.
Figure 2 shows a view of the structure of the cation
of 4. Table 2 collects selected bond distances and angles.
The structure proves the formation of the R-allylphos-
phine ligand, which is coordinated to the metallic center

4862 Organometallics, Vol. 23, No. 21, 2004
Esteruelas et al.
Sch em e 2
In agreement with the presence of a hydride ligand
in the complex, the H NMR spectrum shows at -13.74
1
ppm a double doublet by spin coupling with the phos-
phorus (20.5 Hz) and the CHPh proton of the allyl unit
(2.4 Hz). The resonance due to the latter appears at 3.40
ppm with a H-Hmeso coupling constant of 7.8 Hz. The
resonance corresponding to the Hmeso is observed at 6.19
ppm, as a double doublet with a H-P coupling constant
of 23.5 Hz. In the 13C{1H} NMR spectrum, the most
noticeable resonances are three doublets at 79.3, 53.5,
and 41.6 ppm, with C-P coupling constants of 7, 14,
and 5 Hz, respectively. On the basis of the 1H-13C
HMQC spectrum, these resonances are assigned to the
C(3), C(1), and C(4) atoms of the allyl moiety, respec-
tively. The 31P{1H} NMR spectrum contains a singlet
at 32.6 ppm.
1
In the H NMR spectrum of 5, the hydride resonance
appears at -13.27 ppm, as a doublet with a H-P
coupling constant of 27.9 Hz. The resonance correspond-
ing to the olefinic proton of the alkenyl unit of the
phosphine is observed at 6.29 ppm, as a double multiplet
with a H-P coupling constant of 52.0 Hz, whereas the
protons of the η3-unit of the benzyl group display
multiplets at 6.03 and 4.66 ppm. In the 13C{1H} NMR
spectrum, the most noticeable feature is the presence
of singlets at 87.7, 67.1, and 47.8 ppm, due to the carbon
atoms of the η3-moiety of the benzyl group. These
spectroscopic data are in accordance with those reported
previously for other η3-benzyl complexes.5,17 The 31P-
{1H} NMR spectrum contains a singlet at 74.0 ppm.
with HR and Hâ hydrogen atoms with regard to the
σ,Os-C bond. As a consequence of the rigidity imposed
by the sp2-hybridization of the CHâ carbon atom of the
metallacycle, the Hâ hydrogen atom points in the
opposite direction of the metallic center and, therefore,
the â-hydrogen elimination is disfavored with regard to
the R-hydrogen elimination reaction. The migration of
the HR hydrogen from the CPh carbon atom to the
osmium should yield isomer 8. The formation of carbene
derivatives by R-elimination on alkyl species, which
have no accessible â-hydrogen atoms, is a well-known
process.18
The hydride ligand of 4 is fairly acidic. Thus, the
addition of 2.0 equiv of sodium methoxide to tetra-
hydrofuran solutions of this compound results in its
deprotonation to afford a white solid in 58% yield.
According to the elemental analysis, the composition of
the solid is Os(C5H5)(iPr2PC10H10).
The 1H, 13C{1H}, and 31P{1H} NMR spectra of the
solid in toluene-d8 indicate that in solution it gives rise
to an equilibrium mixture of the neutral osmium(II)
In the 1H NMR spectrum of 6, at 80 °C, the resonance
corresponding to the CHPh proton of the allyl unit
appears at 3.05 ppm, as a double doublet with H-P and
H-Hmeso coupling constants of 10.6 and 5.7 Hz, respec-
tively. The Hmeso resonance is observed at 5.59 ppm, also
as a double doublet but with a H-P coupling constant
of 23.4 Hz. In the 13C{1H} NMR spectrum the most
noticeable features are two doublets at 70.4 and 39.0
ppm, with C-P coupling constants of 13 and 15 Hz,
respectively, assigned to the Cmeso and PC(sp2) carbon
atoms, and a singlet at 29.0 ppm corresponding to the
CHPh carbon atom. The 31P{1H} NMR spectrum shows
a singlet at 0.9 ppm.
R-allylphosphine OsH(η5-C5H5)Cl{[η3-CHPhCHC(CH3)]P-
iPr2}]PF6 (6), R-alkenyl-γ-(η3-benzyl)phosphine OsH(η5-
C5H5){[η3-C6H5CHCHdC(CH3)]PiPr2}]PF6 (7), and R-alk-
enyl-γ-carbenephosphine OsH(η5-C5H5){[dC(Ph)CHd
C(CH3)]PiPr2} (8) isomers. The equilibrium is highly
dependent on the temperature. At 80 °C, isomer 6 is
favored with regard to 8, and the latter with regard to
7. Thus, at this temperature the 6:8:7 molar ratio is
20:6:1. Lowering the sample temperature produces a
decrease of the amount of 6 and an increase in the
amounts of 7 and 8. At room temperature the 6:8:7
molar ratio is 2:1:1. At -20 °C, only traces of 6 are
observed, while the 8:7 molar ratio is 1:2.
In the 1H NMR spectrum of 7 at -20 °C, the
resonance corresponding to the olefinic proton of the
alkenyl unit of the phosphine is observed at 5.95 ppm,
(15) (a) Wolf, J .; Brandt, L.; Fries, A.; Werner, H. Angew. Chem.,
Int. Ed. Engl. 1990, 29, 510. (b) Werner, H.; Mo¨hring, U. J . Organomet.
Chem. 1994, 475, 277. (c) Werner, H. J . Organomet. Chem. 1995, 500,
331.
(16) (a) Slugovc, C.; Mereiter, K.; Schmid, R.; Kirchner, K. J . Am.
Chem. Soc. 1998, 120, 6175. (b) Slugovc, C.; Mereiter, K.; Schmid, R.;
Kirchner, K. Eur. J . Inorg. Chem. 1999, 1141. (c) Slugovc, C.; Mereiter,
K.; Schmid, R.; Kirchner, K. Organometallics 1999, 18, 1011.
(17) See for example: (a) Carmona, E.; Paneque, M.; Poveda, M. L.
Polyhedron 1989, 8, 285. (b) Lee, B. Y.; Bazan, G. C.; Vela, J .; Komon,
Z. J . A.; Bu, X. J . Am. Chem. Soc. 2001, 123, 5352.
The formation of this equilibrium mixture can be
rationalized according to Scheme 2. It is reasonable to
assume that the deprotonation of 4 initially affords 6.
The η3-η1 conversion of the allyl moiety of the phos-
phine ligand of 6 should lead to intermediate b, where
the η1-allyl unit is also a η1-benzyl moiety. Thus, the
η1-η3 conversion of the benzyl group could yield the
R-alkenyl-γ-(η3-benzyl)phosphine isomer 7. Intermediate
b is an unsaturated osmaphosphacyclopentene species
(18) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 3rd ed.; Wiley-Interscience: New York, 2001; Chapter 7, p 190.

Olefin-Carbene-Osmium Complex
Organometallics, Vol. 23, No. 21, 2004 4863
Sch em e 3
F igu r e 3. Stacked 1H NMR spectra (hydride region)
illustrating the isomerization of complex 9 into 4 in
acetone-d6 at 308 K.
as a double multiplet with a H-P coupling constant of
46.2 Hz, whereas the protons of the η3-unit of the benzyl
group display a multiplet at 4.88 ppm and a double
doublet at 3.12 ppm with H-P and H-H coupling
constants of 13.8 and 5.6 Hz, respectively. In the 13C-
{1H} NMR spectrum, the carbon atoms of the η3-moiety
of the benzyl group display two singlets at 73.5 and 39.5
ppm and a doublet at 38.2 ppm with a C-P coupling
constant of 3 Hz. The 31P{1H} NMR spectrum shows a
singlet at 65.1 ppm.
In agreement with the presence of a hydride ligand
1
in 8, its H NMR spectrum at -20 °C contains at -14.03
ppm a doublet with a H-P coupling constant of 31.6
Hz. The olefinic resonance of the alkenyl group is
observed at 6.58 ppm, as a double quartet with H-P
and H-H coupling constants of 43.8 and 1.8 Hz,
respectively. The presence of an Os-C double bond in
the complex is strongly supported by the 13C{1H} NMR
spectrum, which contains a singlet at 238.4 ppm. The
olefinic resonances appear at 173.7 and 141.3 ppm, as
doublets with C-P coupling constants of 31 and 35 Hz,
respectively. The 31P{1H} NMR spectrum shows a
singlet at 73.4 ppm.
F igu r e 4. Eyring plot of the first-order rate constants (kobs
for the isomerization of 9 into 4 in acetone-d6 at 308 K.
)
Ta ble 3. Ra te Con sta n ts of Isom er iza tion of
Com p lex 9 in to 4 in Aceton e-d 6
temperature (K)
kobs (105 s-1
)
308
313
318
323
328
8.9 ( 0.1
16 ( 0.1
32 ( 0.5
58 ( 0.6
84 ( 2.6
3. Tr a n sfor m a tion of 2 in to 4 via a Hyd r id e-
Ca r byn e In ter m ed ia te. An alternative method to
prepare 4 is shown in Scheme 3. The addition of 1.0
equiv of TlPF6 to acetone solutions of 2 produces the
extraction of the chloride ligand and the migration of
the hydrogen atom of the carbene from the carbon atom
to the metallic center. As a result, the hydride-carbyne
derivative [OsH(η5-C5H5)(tCPh){PiPr2[C(CH3)dCH2]}]-
PF6 (9) is formed. This compound was isolated as a
yellow solid in 82% yield.
In agreement with the presence of a hydride ligand
in the complex, its 1H NMR spectrum in dichlo-
romethane-d2 at room temperature shows a doublet at
-12.04 ppm, with a H-P coupling constant of 22.5 Hz.
In the low-field region of the spectrum the CH2 olefinic
protons of the phosphine display two doublets at 5.95
and 5.70 ppm, with H-P coupling constants of 38.4 and
17.7 Hz, respectively. In the 13C{1H} NMR spectrum the
resonance corresponding to the CR atom of the carbyne
appears at 280.1 ppm, as a doublet with a C-P coupling
constant of 9.0 Hz. The C(sp2) atoms of the phosphine
give rise to a singlet at 135.1 (CH2) ppm and a doublet
at 134.0 (CP) ppm, with a C-P coupling constant of 8
Hz. The 31P{1H} NMR spectrum shows a singlet at 42.0
ppm.
In acetone as solvent, the hydride-carbyne complex 9
evolves selectively into 4. At first glance, one could think
that the rearrangement occurs through a hydride-
carbyne/carbene backward step, which should afford an
unsaturated osmaphosphabicyclopentane intermediate.
However, it should be pointed out that the transforma-
tion is unaffected by the presence of chloride and that
traces of 5 are not observed during the reaction.
1
The rearrangement was followed by H NMR spec-
troscopy by measuring the disappearance of the hydride
resonance of 9 as a function of time. As shown in Figure
3, the decrease of 9 (with the corresponding increase of
4) is an exponential function of time, in agreement with
a first-order process. The values obtained for the first-
order rate constant kobs in the temperature range
studied are reported in Table 3. The activation param-
eters of the reaction were obtained from the Eyring
analysis shown in Figure 4, giving values of ∆Hq ) 23
( 3 kcal‚mol-1 and ∆Sq ) -4 ( 4 cal‚K-1‚mol-1
.

4864 Organometallics, Vol. 23, No. 21, 2004
Esteruelas et al.
Sch em e 4
Sch em e 5
The above-mentioned observations are consistent with
an intramolecular [2+2] cycloaddition process between
the isopropenyl substituent of the phosphine and the
carbyne ligand. The cycloaddition leads to the short-
lived intermediate c (Scheme 3), which rapidly affords
4, by 1,2-hydrogen shift from the CH2 group to the
C(sp2) atom of the bicycle.
respectively, corresponding to the olefinic CH2 protons
of the phosphine and a singlet at 3.13 ppm due to the
methoxy group. In the 13C{1H} NMR spectrum, the
resonance due to the CR atom of the carbene is observed
at 244.6 ppm, as a doublet with a C-P coupling constant
of 9 Hz. The 31P{1H} NMR spectrum shows a singlet at
44.7 ppm.
The hydride ligand of 9 is fairly acidic, as the hydride
of 4. Thus, similarly to 4, the addition of 2.0 equiv of
sodium methoxide to tetrahydrofuran solutions of 9
produces its deprotonation, to afford the neutral carbyne
derivative Os(η5-C5H5)(tCPh){PiPr2[C(CH3)dCH2]} (10),
which was isolated as a dark brown oil in 73% yield
(Scheme 4).
4. Am p h ip h ilic Ch a r a cter of th e CR Atom of th e
Ca r ben e Liga n d of 2. The CR atom of 2 has nucleo-
philic character, adding electrophiles. Thus, at -40 °C,
the addition of 1.0 equiv of HBF4 to an NMR tube
containing a dichloromethane-d2 solution of 2 leads to
the instantaneous formation of the benzyl-osmium(IV)
derivative [Os(η5-C5H5)(CH2Ph)Cl{[η2-CH2dC(CH3)]P-
iPr2}]BF4 (12), as a result of the addition of the proton
of the acid to the CR atom of the carbene of 2, and the
coordination of the isopropenyl substituent of the phos-
phine to the osmium atom (Scheme 5).
1
In the H NMR spectrum of 10 in benzene-d6 at room
temperature, the most noticeable feature is the presence
of two doublets at 5.72 and 5.39, with H-P coupling
constants of 14.7 and 32.5 Hz respectively, correspond-
ing to the olefinic CH2 protons of the phosphine. In the
13C{1H} NMR spectrum, the resonance due to the CR
atom of the carbyne is observed at 263.1 ppm as a
doublet with a C-P coupling constant of 14, whereas
the olefinic resonances of the phosphine appear at 142.0
and 127.8 ppm, the first of them (CP) as a doublet with
a C-P coupling constant of 33 Hz, and the second one
(CH2) as a singlet. The 31P{1H} NMR spectrum contains
a singlet at 50.2 ppm.
Complex 10 is soluble in hydrocarbon solvents. Its
solutions are stable for up to several days if kept under
argon at -20 °C. In toluene at 75 °C, it decomposes to
give a complex mixture of 10 unidentified products;
according to the 31P{1H} NMR spectrum of the mixture,
none of them is 6, 7, or 8. In methanol at room
temperature complex 10 evolves into the hydride-
alkoxycarbene derivative OsH(η5-C5H5){dC(OMe)Ph}-
{PiPr2[C(CH3)dCH2]} (11), as a consequence of the
addition of the O-H bond of the alcohol to the Os-C
triple bond (Scheme 4).
The 1H and 13C{1H} NMR spectra of 12 are consistent
with the structure proposed for this compound in
1
Scheme 5. In the H NMR spectrum, the olefinic CH2
protons of the phosphine display two doublets at 4.92
and 3.51 ppm, with H-P coupling constants of 10.7 and
32.7 Hz, respectively, whereas the CH2 protons of the
benzyl group give rise to a double doublet at 4.06 ppm,
with both H-P and H-H coupling constants of 8.8 Hz,
and a doublet at 3.12 ppm. In the 13C{1H} NMR
spectrum, the olefinic resonances of the phosphine are
observed at 71.9 (CP) and 40.0 (CH2) ppm, as doublets
with C-P coupling constants of 20 and 4 Hz, respec-
tively, whereas the CH2 resonance of the benzyl group
appears at 4.1 ppm as a doublet with a C-P coupling
constant of 5 Hz. The 31P{1H} NMR spectrum shows a
singlet at -7.2 ppm.
At room temperature complex 12 isomerizes into 13.
After 5 min the transformation is quantitative. The
isomerization probably involves the decoordination of
the isopropenyl group in 12, which lies between the
phosphorus atom and the benzyl ligand, and its subse-
quent coordination between the phosphorus and chlo-
rine atoms. The driving force for the isomerization
seems to be the greater size of the benzyl group with
regard to the chlorine atom, which makes unfavorable
the isopropenyl-benzyl cisoid disposition with regard to
the isopropenyl-chlorine cisoid disposition.
Complex 11 was isolated as an orange oil in 79% yield.
The presence of a hydride ligand in the complex is
1
strongly supported by the H NMR spectrum in benzene-
d6 at room temperature, which contains at -14.98 ppm
a doublet with a H-P coupling constant of 31.5 ppm.
In the low-field region of the spectrum, the most
noticeable resonances are two doublets at 5.49 and 5.28
ppm, with H-P coupling constants of 28.2 and 12.3 Hz,

Olefin-Carbene-Osmium Complex
Organometallics, Vol. 23, No. 21, 2004 4865
Sch em e 6
There are some significant differences between the
1H and 13C{1H} NMR spectra of 12 and 13. In contrast
to 12, in the 1H NMR spectrum of 13, the low-field
resonance corresponding to the CH2 protons of the
benzyl group (δ, 3.57) does not show any H-P coupling
constant. In the 13C{1H} NMR spectrum of 13, the CH2
benzyl resonance appears at 18.8 ppm, shifted 14.7 ppm
toward low field compared with that of 12. Furthermore,
the C-P coupling constant reflects the change of the
relative position of the benzyl group with regard to the
phosphorus atom, from transoid to cisoid, increasing its
value up to 10 Hz.4k The singlet in the 31P{1H} NMR
spectrum of 13 (δ -12.2) appears shifted to higher field
than that of 12.
In dichloromethane-d2 at room temperature, the
benzyl group of 13 and one of the hydrogen atoms of
the cyclopentadienyl ligand slowly exchange their posi-
tions. As a result, the isomerization of 13 into the
isopropenyl substituent in the phosphine has a marked
influence on the nature of the resulting products of the
H
+ addition to the carbene carbon atom. In contrast to
hydride-benzylcyclopentadienyl derivative [Os(η5-
2, the addition of the acid to the carbene carbon atom
of the triisopropylphosphine complex initially leads to
a η3-benzyl derivative, which loses HCl to give the
hydride-carbyne compound [OsH(η5-C5H5)(tCPh)(P-
iPr3)]BF4. The stronger coordinating power of an iso-
propenyl group with regard to an isopropyl substituent
explains the observed difference in behavior.
The carbene-carbon atom of 2 also shows a marked
electrophilicity, characteristic of the Fischer-type de-
rivatives. Thus, the treatment at 0 °C of tetrahydro-
furan solutions of 2 with the stoichiometric amount of
methyllithium in diethyl ether affords the hydride-
styrene derivative OsH(η5-C5H5)(η2-CH2dCHPh){PiPr2-
[C(CH3)dCH2]} (15), which was isolated as an orange
oil in 60% yield (Scheme 6).
The formation of 15 can be rationalized as the
addition of the nucleophilic organic fragment to the
carbene carbon atom of 2, followed by the elimination
of chloride and subsequent â-hydrogen extraction. An
alternative pathway involving a carbene-methyl-metal
species, which evolves into the same intermediate as
that resulting from the direct attack of the organic
fragment to the carbene carbon atom, may also be
considered.20
C5H5)(CH2Ph)Cl{[η2-CH2dC(CH3)]PiPr2}]BF4 (14) is ob-
served. After 72 h, the transformation is quantitative.
When the protonation of 2 is carried out in a Schlenk
tube at room temperature, complex 14 is directly
obtained after 72 h as a yellow solid in 81% yield.
We note that the carbene-rhodium complex Rh(η5-
C5H5)(dCPh2)(PiPr3) reacts with HX to give the rhod-
ium(III) derivatives RhH(η5-C5H4CHPh2)X(PiPr3) (X )
Cl, Br, I, CF3CO2). Similarly to the formation of 14 these
reactions involve the initial addition of the proton of the
acids to the carbene carbon atom to give nondetected
alkyl intermediates, which evolve by alkyl(Rh)/H(Cp)
exchange into the observed products.19 The generation
of functionally substituted cyclopentadienyl ligands in
the osmium(IV) chemistry, by ligand(Os)/H(Cp) ex-
change, has been recently shown.4i In contrast to 2, the
protonation of Rh(η5-C5H5)(dCPh2)(PiPr3) with HBF4
affords an η3-benzylrhodium derivative.19b
The presence of a hydride ligand in 14 is strongly
1
supported by its H NMR spectrum, which contains a
doublet at -11.67 ppm. In agreement with the cisoid
disposition of the phosphorus atom and the hydride
ligand,4e the value of the H-P coupling constant is 26.7
Hz. The spectrum is also consistent with the presence
of a benzylcyclopentadienyl ligand and a coordinated
isopropenyl group. The benzylcyclopentadienyl ligand
displays an AB spin system, centered at 3.77 ppm and
defined by ∆ν ) 57 Hz and J A-B ) 16.2 Hz, for the CH2
benzyl protons, and between 6.28 and 5.36 ppm the
expected ABCD spin system for the ring protons. The
resonances corresponding to the CH2 olefinic protons of
the phosphine appear at 4.70 and 3.53 ppm with H-P
coupling constants of 10.9 and 26.6 Hz, respectively, and
a H-H coupling constant of 1.7 Hz. In the 13C{1H} NMR
spectrum the C(sp2) atoms of the phosphine give rise to
doublets at 72.1 (CP) and 43.2 (CH2) ppm, with C-P
coupling constants of 22 and 5 Hz, respectively, whereas
the CH2 benzyl resonance is observed at 34.5 ppm as a
singlet. The 31P{1H} NMR spectrum contains a singlet
at 13.6 ppm.
The stereochemistry shown in Scheme 6 for 15, with
the phenyl group disposed cisoid-anti with regard to the
phosphorus atom, is strongly supported by the 1H NMR
spectrum of this compound. In this context, it should
be mentioned that X-ray diffraction analysis together
with spectroscopic studies have proved for this type of
system that hydrogen atoms of coordinated olefins
disposed cisoid-syn with regard to hydride and phos-
phine ligands undergo spin coupling with the respective
active nuclei ofthese ligands, in the 1H NMR spectrum.3d,5
1
According to this, in the H NMR spectrum of 15, the
resonance corresponding to the olefinic CHPh proton,
which is cisoid-syn disposed to the phosphorus atom,
appears at 3.24 ppm as a double doublet of doublets,
by spin coupling with the phosphorus of the phosphine
(8.1 Hz) and the CH2 hydrogens of the styrene (J trans
)
The behavior of 2 agrees well with that previously
observed for the triisopropylphosphine complex Os(η5-
C5H5)Cl(dCHPh)(PiPr3).5 However, it must be noted
that the replacement of an isopropyl group by an
(19) (a) Herber, U.; Bleuel, E.; Gevert, O.; Laubender, M.; Werner,
H. Organometallics 1998, 17, 10. (b) Bleuel, E.; Schwab, P.; Laubender,
M.; Werner, H. J . Chem. Soc., Dalton Trans. 2001, 266.
(20) Braun, T.; Gevert, O.; Werner, H. J . Am. Chem. Soc. 1995, 117,
7291.

4866 Organometallics, Vol. 23, No. 21, 2004
Esteruelas et al.
7.5 Hz, J cis ) 6.6 Hz). The resonance due to the CH2
proton disposed trans to the phenyl group, which is
cisoid-syn disposed with regard to the hydride ligand,
is observed at 2.30 ppm with a H-H coupling constant
with the hydride of 3.6 Hz. The other CH2 resonance
appears at 2.93 ppm with a gem H-H coupling constant
of 3.6 Hz. The hydride ligand gives rise to a double
doublet at -15.96 ppm with a H-P coupling constant
of 34.2 Hz. In the 13C{1H} NMR spectrum, the styrene
resonances appear at 23.2 (CHPh) and 3.4 (CH2) ppm,
as singlets, while the olefinic resonances of the isopro-
penyl substituent of the phosphine are observed at 140.9
(CP) and 128.9 (CH2) ppm as doublets with C-P
coupling constants of 32 and 11 Hz, respectively. The
31P{1H} NMR spectrum shows a singlet at 39.1 ppm.
Con clu d in g Rem a r k s
This paper reveals that coordinated R-alkenylphos-
phines can be transformed into R-allylphosphines by
reaction with diazoalkanes via [2+2] cycloaddition
processes. As a result of the hemilabile character of the
R-alkenylphosphine of the complex Os(η5-C5H5)Cl{[η2-
H2CdC(CH3)]PiPr2}, the treatment of this compound
with phenyldiazomethane affords the olefin-carbene-
osmium(II) derivative Os(η5-C5H5)Cl(dCHPh){PiPr2-
[C(CH3)dCH2]}, which is converted into the R-allylphos-
phine OsH(η5-C5H5)Cl{[η3-CHPhCHC(CH3)]PiPr2}]PF6
compound by two alternative pathways.
In toluene at 70 °C,the complexOs(η5-C5H5)Cl(dCHPh)-
{PiPr2[C(CH3)dCH2]} isomerizes into the unprecedented
In benzene-d6 at 80 °C complex 15 isomerizes into 16
(Scheme 6), containing the phenyl group of the styrene
ligand cisoid-anti with regard to the hydride ligand.
osmaphosphabicyclopentane derivative Os(η5-C5H5)Cl{P-
1
According to this, in the H NMR spectrum of 16, the
iPr2[C(CH3)CH2CHPh]}, by a [2+2] cycloaddition reac-
olefinic CHPh resonance (δ 3.78) shows spin coupling
with the hydride (2.4 Hz) and does not show spin
coupling with the phosphorus atom, whereas the reso-
nance corresponding to the CH2 proton of styrene,
disposed cis (7.3 Hz) to the CHPh proton and trans to
the phenyl group (δ 1.21), shows a H-P coupling
constant of 10.5 Hz. The other CH2 resonance appears
at 2.98 ppm, with H-P and gem H-H coupling con-
stants of 2.9 and 3.0 Hz, respectively. The hydride
ligand is observed at -15.23 with a H-P coupling
constant of 32.8 Hz. In the 13C{1H} NMR spectrum, the
styrene resonances appear at 24.8 (CHPh) and 2.2 (CH2)
ppm, the first of them as a singlet and the second one
as a doublet with a C-P coupling constant of 5 Hz. The
olefinic resonances of the isopropenyl substituent of the
phosphine are observed at 140.3 (CP) and 128.6 (CH2)
ppm as doublets with C-P coupling constants of 33 and
10 Hz, respectively. The 31P{1H} NMR spectrum con-
tains a singlet at 40.0 ppm.
tion between the C-C double bond of the phosphine and
the Os-C double bond. The extraction of the chloride
ligand from this complex provokes the destruction of the
bicycle and the formation of OsH(η5-C5H5)Cl{[η3-
CHPhCHC(CH3)]PiPr2}]PF6. The alternative pathway
involves the initial extraction of the chloride ligand of
Os(η5-C5H5)Cl(dCHPh){PiPr2[C(CH3)dCH2]} to give the
hydride-carbyne-olefin intermediate [OsH(η5-C5H5)-
(tCPh){PiPr2[C(CH3)dCH2]}]PF6, which also evolves
into the R-alkenylphosphine complex. The osmaphos-
phabicyclopentane-allylphosphine transformation indi-
cates that a â-H elimination rather than a metathesis
process, driven by the presence of a vacant site, is favored
in the metallacyclobutane of the osmaphosphabicyclo-
pentane.
The carbene carbon atom of the complexes Os(η5-
C5H5)Cl(dCHPh)(PR3) has amphiphilic character, react-
ing with both nucleophiles and electrophiles. However,
there are marked differences in the nature of the result-
ing products of the H+ addition, which depend on the
substituent R of the phosphine. Thus, while the reaction
of the triisopropylphosphine complex Os(η5-C5H5)Cl-
(dCHPh)(PiPr3) with H+ affords a η3-benzyl derivative,
which loses HCl to give [OsH(η5-C5H5)(tCPh)(PiPr3)]+,
the addition of H+ to the isopropenyldi(isopropyl)-
phosphine compound Os(η5-C5H5)Cl(dCHPh){PiPr2-
[C(CH3)dCH2]} leads to the hydride-benzylcyclopenta-
The chemical shifts of the styrene resonances in the
13C{1H} NMR spectra of both isomers are typical for
C(sp3) atoms. This suggests that the acceptor component
of the osmium-styrene bond has a very important
contribution to the structure of both 15 and 16.
Complexes 15 and 16 are diastereoisomers resulting
from the chirality of the osmium atom and the prochiral-
ity of the olefin. The conversion of 15 into 16 involves
the decoordination of the styrene ligand and its subse-
quent coordination by the other face. The process
probably takes place via a short-lived hydride-isopro-
penyldi(isopropyl)phosphine intermediate stabilized by
coordination of the isopropenyl substituent of the phos-
phine. The driving force for the isomerization could be
the steric hindrance experienced by the phosphine and
the phenyl group, which makes unfavorable the cisoid
phosphine-CHPh disposition with regard to the cisoid
phosphine-CH2 disposition observed in 16.
dienyl derivative [OsH(η5-C5H4CH2Ph)Cl{[η2-CH2d
C(CH3)]PiPr2}]BF4.
In conclusion, this paper reports the preparation,
X-ray structure, and reactivity of the olefin-carbene
complex Os(η5-C5H5)Cl(dCHPh){PiPr2[C(CH3)dCH2]},
which shows Fischer-Schrock ambivalent behavior.
This complex can be transformed into the R-allylphos-
phine compound OsH(η5-C5H5)Cl{[η3-CHPhCHC(CH3)]P-
iPr2}]PF6 by a [2+2] cycloaddition process via the
Complex 2 shows a Fischer-Schrock ambivalent
behavior, which is supported by the amphiphilic char-
acter of its carbene carbon atom. Complexes Ru(dCF2)-
(CO)2(PPh3)2, Re(η5-C5H5)(dCHCH2CH2CMe3)(CO)2, and
Re{dC(CH3)C(CH3)2CH2(η5-C5H4)}(CO)2 also show am-
phiphilic reactivity at the carbene carbon atom.21
(21) (a) Clark, G. R.; Hoskins, S. V.; J ones, T. C.; Roper, W. R. J .
Chem. Soc., Chem. Commun. 1983, 719. (b) Casey, C. P.; Vosejpka, P.
C.; Askham, F. R. J . Am. Chem. Soc. 1990, 112, 3713. (c) Casey, C. P.;
Czerwinski, C. J .; Powell, D. R.; Hayashi, R. K. J . Am. Chem. Soc.
1997, 119, 5750.

Olefin-Carbene-Osmium Complex
Organometallics, Vol. 23, No. 21, 2004 4867
) 14.5, J H-H ) 9.0, 1H, CH2), 2.79 (m, 1H, PCH), 1.60 (dd,
J H-P ) 18.0, J H-H ) 7.2, 3H, PCHCH3), 1.26 (dd, J H-P ) 18.0,
J H-H ) 6.0, 3H, PCHCH3), 1.21 (dd, J H-P ) 14.7, J H-H ) 6.3,
4H, PCHCH3 + PCH), 1.00 (dd, J H-P ) 14.2, J H-H ) 6.4, 3H,
PCHCH3), 0.55 (d, J H-P ) 8.1, 3H, PC(CH3)). 31P{1H} NMR
(121.42 MHz, C6D6, 293 K): δ - 23.3 (s). 13C{1H} NMR (75.42
unprecendented osmaphosphabicyclopentane Os(η5-
C5H5)Cl{PiPr2[C(CH3)CH2CHPh]}, which is isolated and
characterized.
MHz, C6D6, 293 K, plus APT, plus HSQC): δ 157.3 (s, Cipso
Ph), 128.3, 125.1, and 122.5 (all s, Ph), 87.8 (s, Cp), 48.7 (s,
CH2), 26.9 (d, J C-P ) 28, PCH), 24.9 (s, CH3), 22.8 (d, J C-P
-
Exp er im en ta l Section
)
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
24, PCH), 22.3 (d, J C-P ) 8, CH3), 21.5 (d, J C-P ) 5, CH3), 20.8
(s, CH3), 20.4 (d, J C-P ) 3, CH3), -9.5 (d, J C-P ) 3, CHPh),
- 22.4 (d, J C-P ) 13, PC(CH3)). MS (FAB+): m/z 540 (M+).
starting materials Os(η5-C5H5)Cl{[η2-CH2dC(CH3)]PiPr2}9 (1)
and N2dCHPh22 were prepared by the published methods.
1H, 31P{1H}, and 13C{1H} NMR spectra were recorded on
either a Varian UNITY 300, a Varian Gemini 2000, a Bruker
AXR 300, or a Bruker Avance 400 MHz instrument. Chemical
shifts (expressed in parts per million) are referenced to
residual solvent peaks (1H, 13C{1H}) or external H3PO4 (31P-
{1H}). Coupling constants, J , are given in hertz. Infrared
spectra were run on a Perkin-Elmer 1730 spectrometer (Nujol
mulls on polyethylene sheets). C, H, and N analyses were
carried out in a Perkin-Elmer 2400 CHNS/O analyzer. Mass
spectral analyses were performed with a VG Austospec instru-
ment. In FAB+ mode, ions were produced with the standard
Cs+ gun at ca. 30 kV, and 3-nitrobenzyl alcohol (NBA) was
used in the matrix.
Rea ction of Os(η5-C5H5)Cl{P iP r 2[C(CH3)CH2CHP h ]} (3)
with TlP F6: For m ation of OsH(η5-C5H5)Cl{[η3-CHP h CHC-
(CH3)]P iP r 2}]P F 6 (4) a n d OsH(η5-C5H5){[η3-C6H5CHCHd
C(CH3)]P iP r 2}]P F 6 (5). An orange solution of 3 (192 mg, 0.36
mmol) in 10 mL of acetone was treated with thallium(I)
hexafluorophosphate (124 mg, 0.36 mmol). The resulting
mixture was stirred for 15 min in the absence of light and
filtered through Kieselguhr. The resultant dark orange solu-
tion was concentrated to ca. 1 mL and cooled to - 50 °C.
Diethyl ether was added (5 mL), and 20 min later, a yellow
solid appeared, which was separated by decantation, washed
with 2 mL of diethyl ether, and dried in vacuo. The NMR
spectra at room temperature in CD2Cl2 showed the presence
of 4 and 5 in a 1:1 molar ratio. Yield of the mixture: 167 mg
P r ep a r a tion of Os(η5-C5H5)Cl(dCHP h ){P iP r 2[C(CH3)d
CH2]} (2). A yellow solution of 1 (146 mg, 0.32 mmol) in 3 mL
of toluene was treated with 5 mL of a red solution of N2dCHPh
in toluene (0.128 M, 0.64 mmol). The reaction mixture was
allowed to react at room temperature for 1 h, it was filtered
through Kieselguhr, and the solvent was removed in vacuo.
The resultant green oil was washed with cold pentane (5 × 3
mL), and a blue solid was obtained. The solid was separated
by decantation and dried in vacuo. Yield: 152 mg (87%). Anal.
1
(72%). Spectroscopic data for 5: H NMR (300 MHz, CD2Cl2,
293 K, plus COSY): δ 7.43-7.11 (m, 4H, H2-H5), 6.29 (dm,
J H-P ) 52.0, 1H, H8), 6.03 (m, 1H, H7), 4.98 (s, 5H, C5H5), 4.66
(m, 1H, H1), 2.64 (m, 1H, PCH), 2.00 (m, 1H, PCH), 1.90 (ddd,
J H-P ) 8.4, J H-H7 ) J H-H8 ) 1.3, 3H, PC(CH3)d), 1.37 (dd, J H-P
) 16.9, J H-H ) 6.7, 3H, PCHCH3), 1.31-1.20 (6H, PCHCH3),
1.12 (dd, J H-P ) 16.8, J H-H ) 6.9, 3H, PCHCH3), -13.27 (d,
J H-P ) 27.9, 1H, Os-H). 31P{1H} NMR (121.42 MHz, CD2Cl2,
293 K): δ 74.0 (s, PiPr2), -144.2 (sept, J F-P ) 714, PF6). 13C-
{1H} NMR (75.42 MHz, CD2Cl2, 293 K, plus APT, plus
HSQC): δ 146.0 (s, C8), 138.2 (d, J C-P ) 39, PCd), 135.9, 132.5,
130.6, and 127.3 (all s, C2-C5), 87.7 (s, C6), 85.5 (s, Cp), 67.1
Calcd for C21H30ClOsP: C, 46.78; H, 5.61. Found: C, 46.71;
1
H, 5.46. H NMR (300 MHz, C6D6, 293 K): δ 18.50 (d, J H-P
)
16.8, 1H, OsdCH), 7.91-7.11 (m, 5H, Ph), 5.67 (d, J H-P ) 28.5,
1H, dCHHtrans to P), 5.34 (d, J H-P ) 12.0, 1H, dCHHcis to P), 5.00
(s, 5H, C5H5), 2.66 (m, 1H, PCH), 2.27 (m, 1H, PCH), 1.91 (d,
J H-P ) 9.3, 3H, PC(CH3)d), 1.20 (dd, J H-P ) 15.1, J H-H ) 7.2,
3H, PCHCH3), 1.09 (dd, J H-P ) 12.3, J H-H ) 7.3, 3H, PCHCH3),
0.83 (dd, J H-P ) 14.2, J H-H ) 7.3, 3H, PCHCH3), 0.80 (dd, J H-P
) 14.7, J H-H ) 7.3, 3H, PCHCH3). 31P{1H} NMR (121.42 MHz,
C6D6, 293 K): δ 31.6 (s). 13C{1H} NMR (75.42 MHz, C6D6, 293
K, plus APT): δ 234.2 (br, OsdC), 167.1 (d, J C-P ) 5, CipsoPh),
142.5 (d, J C-P ) 33, PCd), 129.8 and 125.9 (both s, Ph), 125.8
(s, dCH2), 125.2 (s, Ph), 86.0 (s, Cp), 25.5 (d, J C-P ) 32, PCH),
23.6 (d, J C-P ) 32, PCH), 21.1 (d, J C-P ) 9, CH3), 20.5 (d, J C-P
) 2, CH3), 19.5 (d, J C-P ) 3, CH3), 18.3 (s, CH3), 16.8 (d, J C-P
) 3, CH3). MS (FAB+): m/z 506 (M+ - Cl + H).
(s, C1), 47.8 (s, C7), 30.2 (d, J C-P ) 33, PCH), 24.0 (d, J C-P
)
36, PCH), 18.1 (d, J C-P ) 3, CH3), 18.1, 17.9, and 17.8 (all s,
CH3), 15.4 (d, J C-P ) 4, CH3).
P r ep a r a tion of Os(η5-C5H5)Cl{P iP r 2[C(CH3)CH2CHP h ]}
A suspension of the obtained 1:1 mixture of 4 and 5 (167
mg) in 10 mL of tetrahydrofuran was stirred at reflux
temperature for 30 h. The solvent was removed under vacuum,
and the yellow residue was solved in ca. 1 mL of acetone and
cooled to 0 °C. Addition of diethyl ether caused the precipita-
tion of 4 as a white solid. Yield: 162 mg (70%). Anal. Calcd
for C21H30F6OsP2: C, 38.89; H, 4.66. Found: C, 38.80; H, 4.44.
IR (Nujol, cm-1): ν(Ph) 1597 (m), ν(PF6) 836 (vs). 1H NMR (300
MHz, CD2Cl2, 293 K): δ 7.33-7.18 (m, 5H, Ph), 6.19 (dd, J H-P
) 23.5, J H-H ) 7.8, 1H, Hmeso), 5.38 (s, 5H, C5H5), 3.40 (dd,
J H-Hmeso ) 7.8, J H-Hhyd ) 2.4, 1H, CHPh), 2.46 (m, 1H, PCH),
2.34 (d, J H-P ) 7.8, 3H, PC(CH3)), 2.24 (m, 1H, PCH), 1.54
(3). A bluish green solution of 2 (125 mg, 0.23 mmol) in 10
mL of toluene was allowed to react at 70 °C for 50 h. The
resultant orange solution was concentrated to dryness, and
the product was extracted from the dark orange oil with 10
mL of diethyl ether and was filtered through Kieselguhr. The
orange solution was concentrated to about 1 mL and stored
at - 78 °C for 15 min, and cold pentane was added (2 mL).
After 5 min, an orange solid appeared. The solid was separated
by decantation, washed with cold pentane, and dried in vacuo.
Yield: 90 mg (72%). Anal. Calcd for C21H30ClOsP: C, 46.78;
H, 5.61. Found: C, 46.60; H, 5.23. IR (Nujol, cm-1): ν(Ph) 1593
(m). 1H NMR (300 MHz, C6D6, 293 K, plus COSY): δ 7.66-
7.05 (m, 5H, Ph), 4.47 (s, 6H, C5H5 + 1H of CH2), 3.99 (dd,
J H-H ) J H-H ) 9.0, 1H, CHPh), 3.45 (ddd, J H-P ) 23.2, J H-H
(dd, J H-P ) 15.9, J H-H ) 6.9, 3H, PCHCH3), 1.39 (dd, J H-P
20.5, J H-H ) 7.3, 3H, PCHCH3), 1.28 (dd, J H-P ) 17.1, J H-H
)
)
7.5, 3H, PCHCH3), 1.27 (dd, J H-P ) 22.5, J H-H ) 7.5, 3H,
PCHCH3), -13.74 (dd, J H-P ) 20.5, J H-H ) 2.4, 1H, Os-H).
31P{1H} NMR (121.42 MHz, CD2Cl2, 293 K): δ 32.6 (s, PiPr2),
-144.3 (sept, J F-P ) 712, PF6). 13C{1H} NMR (75.42 MHz, CD2-
(22) J ime´nez, A. I.; Lo´pez, P.; Oliveros, L.; Cativiela, C. Tetrahedron
2001, 57, 6019.

4868 Organometallics, Vol. 23, No. 21, 2004
Esteruelas et al.
Cl2, 293 K, plus APT, plus HSQC): δ 141.7 (s, CipsoPh), 129.2,
127.2, and 126.0 (all s, Ph), 84.1 (s, Cp), 79.3 (d, J C-P ) 7,
CHmeso), 53.5 (d, J C-P ) 14, PC(CH3)), 41.6 (d, J C-P ) 5, CHPh),
31.9 (d, J C-P ) 39, PCH), 23.5 (d, J C-P ) 6, CH3), 20.4 (d, J C-P
) 36, PCH), 19.1 (d, J C-P ) 7, CH3), 17.9 (d, J C-P ) 4, CH3),
17.2 and 16.8 (both s, CH3). MS (FAB+): m/z 505 (M+).
P r ep a r a tion of [OsH(η5-C5H5)(tCP h ){P iP r 2[C(CH3)d
CH2]}]P F 6 (9). A bluish green solution of 2 (160 mg, 0.30
mmol) in 10 mL of acetone was treated with thallium(I)
hexafluorophosphate (104 mg, 0.30 mmol). The slurry was
allowed to react for 5 min in the absence of light at room
temperature. After that, it was filtered through Kieselguhr.
The resultant light orange solution was concentrated to ca. 1
mL and cooled to 0 °C. Diethyl ether was added (5 mL), and 2
min later, a yellow solid appeared, which was separated by
decantation and dried in vacuo. Yield: 157 mg (82%). Anal.
Calcd for C21H30F6OsP2: C, 38.89; H, 4.66. Found: C, 39.06;
H, 4.66. IR (Nujol, cm-1): ν(OsH) 2128 (w), ν(Ph) 1586 (m),
ν(PF6) 908 (s). 1H NMR (300 MHz, CD2Cl2, 293 K): δ 7.86-
7.47 (m, 5H, Ph), 5.95 (d, J H-P ) 38.4, 1H, dCHHtrans to P), 5.84
(s, 5H, C5H5), 5.70 (d, J H-P ) 17.7, 1H, dCHHcis to P), 2.31 (m,
3H, PCH), 2.15 (m, 3H, PCH), 2.03 (d, J H-P ) 10.2, 3H, PC-
(CH3)d), 1.23 (dd, J H-P ) 17.4, J H-H ) 6.9, 3H, PCHCH3), 1.17
Dep r oton a tion
of OsH(η5-C5H5)Cl{[η3-CHP h CHC-
(CH3)]P iP r 2}]P F 6 w ith Na OCH3. A yellowish solution of 4
(165 mg, 0.25 mmol) in 10 mL of tetrahydrofuran was treated
with sodium methoxide (27 mg, 0.51 mmol). The slurry was
allowed to react for 15 h at room temperature. The solvent
was removed. The product was extracted with 15 mL of
pentane, and the slurry was filtered through Kieselguhr. The
resultant dark orange solution was concentrated to 2 mL and
cooled to -40 °C. Immediately, a light orange solid appeared.
The solid was separated by decantation, washed with 1 mL of
cold pentane, and dried in vacuo. The NMR spectra at room
temperature showed the presence of 6, 7, and 8 in a molar
ratio 2:1:1. Yield of the mixture: 75 mg (58%). Anal. Calcd for
C21H29OsP: C, 50.18; H, 5.81. Found: C, 49.92; H, 5.95. MS
(FAB+): m/z 503 (M+). Spectroscopic data for 6: 1H NMR (300
MHz, toluene-d8, 353 K): δ 7.32-7.02 (m, 5H, Ph), 5.59 (dd,
J H-P ) 23.4, J H-H ) 5.7, 1H, Hmeso), 4.52 (s, 5H, C5H5), 3.05
(dd, J H-P ) 10.6, J H-H ) 5.7, 1H, CHPh), 1.85 (d, J H-P ) 6.0,
3H, PC(CH3)), 1.74 (m, 2H, PCH), 1.13 (dd, J H-P ) 13.8, J H-H
) 6.9, 3H, CH3), 1.11 (dd, J H-P ) 11.7, J H-H ) 7.2, 3H, CH3),
(dd, J H-P ) 17.4, J H-H ) 6.9, 3H, PCHCH3), 1.16 (dd, J H-P
12.0, J H-H ) 6.9, 3H, PCHCH3), 1.10 (dd, J H-P ) 10.8, J H-H
)
)
6.9, 3H, PCHCH3), -12.04 (d, J H-P ) 22.5, 1H, Os-H). 31P-
{1H} NMR (121.42 MHz, CD2Cl2, 293 K): δ 42.0 (s, PiPr2),
-144.2 (sept, J F-P ) 712, PF6). 13C{1H} NMR (75.42 MHz, CD2-
Cl2, 233 K, plus APT): δ 280.1 (d, J C-P ) 9.0, OstC), 144.6 (s,
C
ipsoPh), 135.1 (s, dCH2), 134.6 (s, Ph), 134.0 (d, J C-P ) 8,
PCd), 131.8 and 129.1 (both s, Ph), 88.6 (s, Cp), 28.8 (d, J C-P
) 37, PCH), 26.8 (d, J C-P ) 35, PCH), 23.6 (d, J C-P ) 8, CH3),
18.4, 18.4, 18.2, and 18.0 (all s, CH3). MS (FAB+): m/z 505
(M+).
1.02 (dd, J H-P ) 23.1, J H-H ) 7.5, 3H, CH3), 1.02 (dd, J H-P
)
Isom er iza tion of [OsH(η5-C5H5)(tCP h ){P iP r 2[C(CH3)d
18.1, J H-H ) 7.3, 3H, CH3). 31P{1H} NMR (121.42 MHz,
toluene-d8, 353 K): δ 0.9 (s). 13C{1H} NMR (75.42 MHz,
CH2]}]P F 6 (9) in to OsH(η5-C5H5)Cl{[η3-CHP h CHC-
toluene-d8, 353 K, plus APT, plus HSQC): δ 137.5 (s, Cipso
Ph), 128.1, 124.9, and 122.5 (all s, Ph), 70.4 (s, Cp), 70.4 (d,
J C-P ) 13, Cmeso), 39.0 (d, J C-P ) 15, PC(CH3)), 32.6 (d, J C-P
-
(CH3)]P iP r 2}]P F 6 (4). A yellowish solution of 9 (150 mg, 0.23
mmol) in 8 mL of dichloromethane was stirred for 40 h at room
temperature. The resulting yellowish solution was filtered
through Kieselguhr and concentrated to ca. 1 mL. Diethyl
ether was added (5 mL) and, immediately, a white solid
appeared, which was separated by decantation, washed with
2 mL of diethyl ether, and dried in vacuo. The solid was
characterized by 1H, 31P{1H}, and 13C{1H} as compound 4.
Yield: 134 mg (89%).
)
42, PCH), 29.0 (s, CHPh), 24.7 (d, J C-P ) 3, PCHCH3), 22.1 (s,
PC(CH3)), 20.4 (d, J C-P ) 7, PCH(CH3)), 19.3 (d, J C-P ) 6,
PCH(CH3)), 18.3 (s, PCH(CH3)), 12.5 (d, J C-P ) 12, PCH).
Spectroscopic data for 7: 1H NMR (400 MHz, toluene-d8, 253
K, plus COSY): δ 7.12-6.95 (m, 2H, H2 and H5), 6.40 and 6.29
(both m, each 1H, H3 and H4), 5.95 (dm, J H-P ) 46.2, 1H, H8),
4.88 (m, 1H, H7), 4.05 (s, 5H, C5H5), 3.12 (dd, J H-P ) 13.8,
J H-H ) 5.6, 1H, H1), 2.01 and 1.51 (both m, each 1H, PCH),
2
P r epar ation of Os(η5-C5H5)(tCP h ){P iP r 2[C(CH3)dCH2]}
(10). A slurry of 9 (175 mg, 0.27 mmol) in 10 mL of tetrahy-
drofuran was treated with 30 mg (0.55 mmol) of sodium
methoxide. The mixture was allowed to react for 1 h at room
temperature. Then, the solvent was removed and a brown oil
was obtained. The product was extracted with 15 mL of
pentane, and the slurry was filtered through Kieselguhr. The
solution was concentrated to dryness, and the product was
isolated as a dark brown oil. Yield: 99 mg (73%). IR (Nujol,
cm-1): ν(Ph) 1583 (w). 1H NMR (300 MHz, C6D6, 293 K): δ
7.77-6.90 (m, 5H, Ph), 5.72 (d, J H-P ) 14.7, 1H, dCHHcis to P),
7
8
1.51 (ddd, J H-P ) 6.6, J H-H ) J H-H ) 1.5, 3H, PC(CH3)d),
1.09 (dd, J H-P ) 14.2, J H-H ) 7.2, 3H, PCHCH3), 1.07 (dd, J H-P
) 14.2, J H-H ) 7.2, 3H, PCHCH3), 0.98 (dd, J H-P ) 15.2, J H-H
) 6.8, 3H, PCHCH3), 0.95-0.89 (3H, PCHCH3). 31P{1H} NMR
(161.89 MHz, toluene-d8, 253 K): δ 65.1 (s). 13C{1H} NMR
(100.56 MHz, toluene-d8, 253K, plus APT, plus HMQC): δ
149.4 (d, J C-P ) 34, C8), 142.1 (s, C2 or C5), 133.3 (d, J C-P
)
35, PCd), 127.9 (s, C5 or C2), 123.3 and 116.7 (both s, C3 and
C4), 74.6 (s, Cp), 73.5 (s, C6), 39.5 (s, C7), 38.2 (d, J C-P ) 3, C1),
30.5 (d, J C-P ) 31, PCH), 25.1 (d, J C-P ) 27, PCH), 20.7-18.1
(CH3 of the PiPr2 fragment), 16.0 (d, J C-P ) 2, PC(CH3)d).
Spectroscopic data for 8: 1H NMR (400 MHz, toluene-d8, 253
K, plus COSY): δ 7.42-6.95 (m, 5H, Ph), 6.58 (dq, J H-P ) 43.8,
J H-H ) 1.8, 1H, Csp2-H), 4.97 (s, 5H, C5H5), 1.87 and 1.61 (both
m, each 1H, PCH), 0.95-0.89 (9H, PC(CH3)d + PCHCH3), 0.79
5.39 (d, J H-P ) 32.5, 1H, dCHHtrans P), 4.82 (s, 5H, C5H5),
to
1.86 (d, J H-H ) 8.7, 3H, PC(CH3)d), 1.73 (m, 2H, PCH), 1.19
(dd, J H-P ) 16.2, J H-H ) 7.0, 6H, PCHCH3), 0.90 (dd, J H-P
)
14.5, J H-H ) 6.7, 6H, PCHCH3). 31P{1H} NMR (121.42 MHz,
C6D6, 293 K): δ 50.2 (s). 13C{1H} NMR (75.42 MHz, C6D6, 293
K, plus APT): δ 263.1 (d, J C-P ) 14, OstC), 150.5 (s, CipsoPh),
142.0 (d, J C-P ) 33, PCd), 128.5 and 128.3 (both s, Ph), 127.8
(s, dCH2), 126.8 (s, Ph), 76.4 (s, Cp), 28.1 (d, J C-P ) 34, PCH),
23.9 (d, J C-P ) 10, CH3), 19.6 (d, J C-P ) 4, CH3), 18.7 (s, CH3).
MS (FAB+): m/z 504 (M+ + H).
(dd, J H-P ) 13.0, J H-H ) 6.6, 3H, PCHCH3), 0.74 (dd, J H-P
)
15.0, J H-H ) 6.6, 3H, PCHCH3), -14.03 (d, J H-P ) 31.6, 1H,
Os-H). 31P{1H} NMR (161.89 MHz, toluene-d8, 253 K): δ 73.4
(s). 13C{1H} NMR (100.56 MHz, toluene-d8, 253 K, plus APT,
plus HMQC): δ 238.4 (s, OsdC), 173.7 (d, J C-P ) 31, Csp2-H),
169.9 (s, CipsoPh), 141.3 (d, J C-P ) 35, PCd), 132.6, 124.5, and
120.7 (all s, Ph), 82.9 (s, Cp), 23.3 (d, J C-P ) 32, PCH), 22.3
(d, J C-P ) 33, PCH), 20.7-18.1 (all CH3 groups).
P r ep a r a tion of OsH(η5-C5H5){dC(OCH3)P h }{P iP r 2-
[C(CH3)dCH2]} (11). An orange solution of 10 (125 mg, 0.25
mmol) in 5 mL of methanol was stirred for 2 h at room
temperature. The solvent was removed, and the product was
1
isolated as an orange oil. Yield: 105 mg (79%). H NMR (300
MHz, C6D6, 293 K): δ 7.21-6.96 (m, 5H, Ph), 5.49 (d, J H-P
28.2, 1H, dCHHtrans to P), 5.28 (d, J H-P ) 12.3, 1H, dCHHcis
)
to
P), 4.79 (s, 5H, C5H5), 3.13 (s, 3H, OCH3), 2.01 (d, J H-P ) 8.7,
4H, PC(CH3)d + PCH), 1.73 (m, 1H, PCH), 1.10-0.95 (12H,
CH3), - 14.98 (d, J H-P ) 31.5, 1H, Os-H). 31P{1H} NMR (121.42

Olefin-Carbene-Osmium Complex
Organometallics, Vol. 23, No. 21, 2004 4869
MHz, C6D6, 293 K): δ 44.7 (s). 13C{1H} NMR (75.42 MHz, C6D6,
0.39 mmol) in 10 mL of dichloromethane was treated with
HBF4‚Et2O (53 µL, 0.39 mmol). The resulting yellowish solu-
tion was stirred for 72 h at room temperature and then was
concentrated almost to dryness. The addition of diethyl ether
(7 mL) caused the formation of a yellow solid. The solid was
washed with diethyl ether and dried in vacuo. Yield: 197 mg
(81%). Anal. Calcd for C21H31BClF4OsP: C, 40.23; H, 4.98.
Found: C, 39.91; H, 4.68. IR (Nujol, cm-1): ν(BF4) 1062 (s).
1H NMR (300 MHz, CD2Cl2, 293 K): δ 7.43-7.23 (m, 5H, Ph),
293 K, plus APT): δ 244.6 (d, J C-P ) 9, OsdC), 160.5 (s, Cipso
-
Ph), 143.0 (d, J C-P ) 32, PCd), 126.8, 125.6, and 122.7 (all s,
Ph), 122.0 (d, J C-P ) 4, dCH2), 83.3 (s, Cp), 58.0 (s, OCH3),
28.5 (d, J C-P ) 32, PCH), 26.4 (d, J C-P ) 31, PCH), 19.5, 19.5,
18.8, 18.2, and 18.2 (all s, CH3). MS (FAB+): m/z 535 (M+
H).
-
R ea ct ion of Os(η5-C5H 5)Cl(dCH P h ){P iP r 2[C(CH 3)d
CH2]} (2) w ith HBF 4. An NMR tube containing a bluish green
solution of 2 (44 mg, 0.08 mmol) in 0.4 mL of CD2Cl2, at - 40
°C, was treated with HBF4‚Et2O (11 µL, 0.08 mmol). The
solution color changed immediately from green to dark red,
and the NMR spectra showed the presence of the species 12.
Spectroscopic data for 12: 1H NMR (300 MHz, CD2Cl2, 233
K): δ 7.30-7.09 (m, 5H, Ph), 5.62 (s, 5H, C5H5), 4.92 (d, J H-P
) 10.7, 1H, dCHHcis to P), 4.06 (dd, J H-P ) 8.8, J gem ) 8.8, 1H,
CH2Ph), 3.51 (d, J H-P ) 32.7, 1H, dCHHtrans to P), 3.12 (d, J gem
) 8.8, 1H, CH2Ph), 2.90 (m, 1H, PCH), 2.50 (d, J H-P ) 9.8,
3H, PC(CH3)d), 1.95 (m, 1H, PCH), 1.79-1.62 (9H, PCHCH3),
1.48 (dd, J H-P ) 20.8, J H-H ) 6.3, 3H, PCHCH3). 31P{1H} NMR
(121.42 MHz, CD2Cl2, 233 K): δ - 7.2 (s). 13C{1H} NMR (75.42
6.28-5.36 (ABCD spin system, 4H, C5H4), 4.70 (dd, J H-P
)
10.9, J H-H ) 1.7, 1H, dCHHcis to P), 3.77 (AB spin system, ∆ν
) 57.0, J A-B ) 16.2, 2H, CH2Ph), 3.53 (dd, J H-P ) 26.6, J H-H
) 1.7, 1H, dCHHtrans to P), 2.80 (m, 1H, PCH), 2.57 (d, J H-P
)
9.9, 3H, PC(CH3)d), 2.05 (m, 1H, PCH), 1.69-1.21 (12H,
PCHCH3), -11.67 (d, J H-P ) 26.7, 1H, Os-H). 31P{1H} NMR
(121.42 MHz, CD2Cl2, 293 K): δ 13.6 (s). 13C{1H} NMR (75.42
MHz, CD2Cl2, 293 K, plus APT, plus HSQC): δ 136.6 (s, Cipso
-
Ph), 129.8, 129.4, and 127.8 (all s, Ph), 126.7 (s, CipsoCp), 102.4,
84.3, 81.5, and 74.6 (all s, Cp), 72.1 (d, J C-P ) 22, PCd), 43.2
(d, J C-P ) 5, dCH2), 34.5 (s, CH2Ph), 32.3 (d, J C-P ) 37, PCH),
29.1 (d, J C-P ) 24, PCH), 22.2 (d, J C-P ) 3, CH3), 18.8 and
17.8 (both s, CH3), 16.3 (d, J C-P ) 2, CH3). MS (FAB+): m/z
540 (M+ - H); 541 (M+).
MHz, CD2Cl2, 233 K, plus APT, plus HSQC): δ 149.0 (s, Cipso
-
Ph), 128.5, 127.8, and 125.3 (all s, Ph), 94.7 (s, Cp), 71.9 (d,
J C-P ) 20, PCd), 40.0 (d, J C-P ) 4, dCH2), 33.5 (d, J C-P ) 28,
PCH), 26.7 (d, J C-P ) 7, CH3), 20.2 (d, J C-P ) 4, CH3), 19.7 (d,
J C-P ) 29, PCH), 17.4 and 17.1 (both s, CH3), 10.3 (d, J C-P
2, CH3), 4.1 (d, J C-P ) 5, CH2Ph).
)
P r ep a r a tion of [OsH(η5-C5H5)(η2-CH2dCHP h ){P iP r 2-
[C(CH3)dCH2]}] (15). A bluish green solution of 2 (261 mg,
0.48 mmol) in 10 mL of tetrahydrofuran at 0 °C was treated
with methyllithium (0.45 mL, 0.72 mmol) 1.6 M in diethyl
ether. Immediately, the reaction mixture became orange. It
was allowed to react at 0 °C for 30 min. Then, the solvent was
removed, and the resultant oil was extracted with pentane (15
mL) and filtered through Kieselguhr. The pentane solution was
concentrated to dryness, and 15 was obtained as an orange
Isom er iza tion of 12 in to 13. The sample used to measure
spectroscopic data for 12 was warmed to room temperature
for 5 min. The entire transformation of 12 into 13 was
observed. Spectroscopic data for 13: 1H NMR (300 MHz, CD2-
Cl2, 233 K): δ 7.30-7.14 (m, 5H, Ph), 5.62 (s, 5H, C5H5), 4.72
(d, J H-P ) 12.3, 1H, dCHHcis to P), 3.57 (d, J gem ) 8.4, 1H, CH2-
1
oil. Yield: 150.7 mg (60%). H NMR (300 MHz, C6D6, 293 K):
Ph), 3.56 (d, J H-P ) 34.2, 1H, dCHHtrans P), 3.21 (d, J gem
)
to
δ 7.27-6.95 (m, 5H, Ph), 5.65 (dd, J H-P ) 14.7, J H-H ) 1.8,
8.4, 2H, CH2Ph + PCH), 2.54 (d, J H-P ) 9.6, 3H, PC(CH3)d),
1.95 (m, 1H, PCH), 1.70 (dd, J H-P ) 17.0, J H-H ) 7.4, 3H,
PCHCH3), 1.65 (dd, J H-P ) 17.0, J H-H ) 7.4, 3H, PCHCH3),
1.52 (dd, J H-P ) 13.1, J H-H ) 7.0, 3H, PCHCH3), 1.46 (dd, J H-P
) 20.4, J H-H ) 7.0, 3H, PCHCH3). 31P{1H} NMR (121.42 MHz,
CD2Cl2, 233 K): δ - 12.2 (s). 13C{1H} NMR (75.42 MHz, CD2-
Cl2, 233 K, plus APT, plus HSQC): δ 149.4 (s, CipsoPh), 128.6,
128.4, and 125.9 (all s, Ph), 92.5 (s, Cp), 69.7 (d, J C-P ) 19,
PCd), 44.1 (s, dCH2), 29.0 (d, J C-P ) 25, PCH), 26.6 (d, J C-P
) 8, CH3), 21.6 (d, J C-P ) 29, PCH), 19.8 (d, J C-P ) 5, CH3),
18.8 (d, J C-P ) 10, CH2Ph), 18.4, 17.7, and 10.9 (all s, CH3).
The sample used to measure spectroscopic data for 13 was kept
at room temperature for 72 h. After that period of time, the
1H, dCHHcis P), 5.55 (dd, J H-P ) 32.5, J H-H ) 1.8, 1H, d
to
CHHtrans to P), 4.51 (s, 5H, C5H5), 3.24 (ddd, J H-P ) 8.1, J trans
)
7.5, J cis ) 6.6, 1H, dCHPh), 2.93 (dd, J trans ) 7.5, J gem ) 3.6,
1H, dCHHcis Ph), 2.30 (ddd, J cis ) 6.6, J gem ) J H-Hhyd ) 3.6,
to
1H, dCHHtrans Ph), 1.99 (m, 1H, PCH), 1.84 (m, 1H, PCH),
to
1.75 (d, J H-P ) 7.8, 3H, PC(CH3)d), 1.07 (dd, J H-P ) 13.8, J H-H
) 6.9, 3H, PCHCH3), 0.95-0.84 (9H, PCHCH3), -15.96 (dd,
J H-P ) 34.2, J H-H ) 3.6, 1H, Os-H). 31P{1H} NMR (121.42
MHz, C6D6, 293 K): δ 39.1 (s). 13C{1H} NMR (75.42 MHz, C6D6,
293 K, plus APT, plus HSQC): δ 153.6 (s, CipsoPh), 140.9 (d,
J C-P ) 32, PCd), 128.9 (d, J C-P ) 11, PCdCH2), 128.1, 125.4,
and 122.9 (all s, Ph), 80.4 (s, Cp), 30.0 (d, J C-P ) 31, PCH),
28.5 (d, J C-P ) 32, PCH), 23.2 (s, dCHPh), 21.2 (d, J C-P ) 6,
CH3), 20.4, 20.1, 19.9, and 19.7 (all s, CH3), 3.4 (s, dCH2). MS
(FAB+): m/z 520 (M+).
quantitative formation of [Os(η5-C5H5)(CH2Ph)Cl{[η2-CH2d
C(CH3)]PiPr2}]BF4 (14) was observed.
Isom er iza tion of 15 in to 16. An orange solution of 15 (40
mg, 0.08 mmol) in 0.4 mL of benzene-d6 was heated to 80 °C
for 24 h. The NMR spectra showed the presence of 15 and 16
in a molar ratio 3:8. Spectroscopic data for 16: 1H NMR (300
P r ep a r a tion of [Os(η5-C5H5)(CH2P h )Cl{[η2-CH2dC-
(CH3)]P iP r 2}]BF 4 (14). A bluish green solution of 2 (210 mg,
MHz, C6D6, 293 K): δ 7.35-6.93 (m, 5H, Ph), 5.56 (dd, J H-P
)

4870 Organometallics, Vol. 23, No. 21, 2004
Esteruelas et al.
Ta ble 4. Cr ysta l Da ta a n d Da ta Collection a n d
Refin em en t for 2 a n d 4
14.8, J H-H ) 2.2, 1H, dCHHcis to P), 5.45 (dd, J H-P ) 33.0, J H-H
) 2.2, 1H, dCHHtrans to P), 4.49 (s, 5H, C5H5), 3.78 (ddd, J H-Hhyd
) 2.4, J trans ) 9.4, J cis ) 7.3, 1H, dCHPh), 2.98 (ddd, J H-P
)
2
4
2.9, J trans ) 9.4, J gem ) 3.0, 1H, dCHHcis Ph), 1.83 (m, 1H,
to
Crystal Data
21H30ClOsP
539.07
dark red, irregular
block
PCH), 1.70 (d, J H-P ) 7.8, 4H, PC(CH3)d + PCH), 1.21 (ddd,
formula
molecular wt
color and habit
C
C21H30F6OsP2
648.59
yellow, irregular
prism
J H-P ) 10.5, J cis ) 7.3, J gem ) 3.0, 1H, dCHHtrans Ph), 1.07
to
(dd, J H-P ) 13.8, J H-H ) 6.9, 3H, PCHCH3), 0.89 (dd, J H-P
14.1, J H-H ) 7.2, 3H, PCHCH3), 0.86 (dd, J H-P ) 13.2, J H-H
)
)
7.2, 3H, PCHCH3), 0.76 (dd, J H-P ) 13.8, J H-H ) 7.2, 3H,
PCHCH3), -15.23 (dd, J H-P ) 32.8, J H-H ) 2.4, 1H, Os-H).
31P{1H} NMR (121.42 MHz, C6D6, 293 K): δ 40.0 (s). 13C{1H}
NMR (75.42 MHz, C6D6, 293 K, plus APT, plus HSQC): δ 152.6
(s, CipsoPh), 140.3 (d, J C-P ) 33, PCd), 128.6 (d, J C-P ) 10,
PCdCH2), 127.7, 126.4, and 122.7 (all s, Ph), 80.3 (s, Cp), 29.4
(d, J C-P ) 32, PCH), 25.6 (d, J C-P ) 31, PCH), 24.8 (s, dCHPh),
21.7 (d, J C-P ) 6, CH3), 19.8 (d, J C-P ) 2, CH3), 19.4 (d, J C-P
) 2, CH3), 19.3 and 19.1 (both s, CH3), 2.2 (d, J C-P ) 5, d
CH2). MS (FAB+): m/z 431 (M+ - C7H6 + H).
size, mm
symmetry, space
group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
0.14, 0.12, 0.04
triclinic, P1h
0.18, 0.08, 0.02
monoclinic, P21/n
12.189(3)
13.368(4)
13.614(4)
101.590(5)
102.886(5)
102.962(5)
2032.7(10)
4
8.3356(13)
16.209(3)
17.149(3)
101.913(3)
2267.2(6)
4
1.900
Z
D
calc, g cm-3
1.761
Data Collection and Refinement
Bruker Smart APEX
0.71073
diffractometer
λ(Mo KR), Å
monochromator
scan type
graphite oriented
ω scans
µ, mm-1
6.483
5.82
2θ, range, deg
temp, K
3, 57
3, 57
Kin etic An a lysis. The isomerization of complex 6 into 4
was followed quantitatively by 1H NMR spectroscopy in
acetone-d6. The decrease of the intensity of the hydride ligand
of 6 was measured automatically at intervals in a Varian
Gemini 2000 spectrometer. The rate constants and the errors
were obtained by fitting the data to an exponential decay
function, using the routine programs of the spectrometer.
Activation parameters ∆Hq and ∆Sq were obtained by least-
squares fit of the Eyring plot. Error analysis assumed a 3.1%
error in the rate constants (the maximum value found in the
experimental determinations) and 1 K in the temperature.
Errors were computed by published methods.23
100.0(2)
24 928
100.0(2)
27 240
no. of data collect
no. of unique data
no. of params/
restraints
9454 (Rint ) 0.0396) 5460 (Rint ) 0.0406)
449/0
289/0
R1a [F2 > 2σ(F2)]
0.0299
0.0523
0.840
0.0236
0.0419
0.884
b
wR2 [all data]
Sc [all data]
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
p is the number of refined
Str u ctu r a l An a lysis of Com p lexes 2 a n d 4. Crystals
suitable for the X-ray diffraction were obtained by cooling at
4 °C a solution of 2 in pentane and by slow diffusion of diethyl
ether into a concentrated solution of 4 in dichloromethane.
X-ray data were collected for both complexes at low temper-
ature on a Bruker Smart Apex CCD diffractometer with
graphite-monochromated Mo KR radiation (λ ) 0.71073 Å)
using ω scans. Data were corrected for absorption by using a
multiscan method applied with the SADABS program.24 The
structures for the two compounds were solved by direct
methods. Refinement, by full-matrix least squares on F2 with
SHELXL97,25 was similar for both complexes, including iso-
tropic and subsequently anisotropic displacement parameters
for all non-hydrogen atoms. The hydride ligand of 4 was
located and refined freely. The rest of the hydrogen atoms were
observed or calculated and refined freely or using a restricted
riding mode in the last cycles of refinement. All the highest
electronic residuals were observed in close proximity of the
Os centers and make no chemical sense.
A summary of crystal data and data collection and refine-
ment details is reported in Table 4.
Ack n ow led gm en t . Financial support from the
MCYT of Spain (Proyects BQU2002-00606 and PPQ2000-
0488-P4-02) is acknowledged.
(23) Morse, P. M.; Spencer, M. O.; Wilson, S. R.; Girolami; G. S.
Organometallics 1994, 13, 1646.
(24) Blessing, R. H. Acta Crystallogr. 1995, A51, 33-38. SADABS:
Area-detector absorption correction; Bruker-AXS: Madison, WI, 1996.
(25) SHELXTL Package v. 6.10; Bruker-AXS: Madison, WI, 2000.
Sheldrick, G. M. SHELXS-86 and SHELXL-97; University of Go¨ttin-
gen: Go¨ttingen, Germany, 1997.
Su p p or tin g In for m a tion Ava ila ble: Crystal structure
determinations, including bond lengths and angles of com-
pounds 2 and 4. This material is available free of charge via
the Internet at http://pubs.acs.org.
OM0496075