Coupling Reaction of Phenylacetylene with OsHn(PPh 3)(2,6-(PPh2CH2)2C6H 3) (n = 1, 3)

Article abstract of DOI:10.1021/om034141w

Treatment of OsCl(=C=CHPh)(PPh₃)(PCP) with thallium acetate produces the vinylidene complex Os(O₂CCH₃)(=C=CHPh)(PCP). Treatment of OsCl(PPh₃)(PCP) with NaH in wet THF produces a mixture of the monohydride OsH(PPh₃)(PCP) and the trihyhride OsH ₃(PPh₃)(PCP). The latter complexes react with phenylacetylene to give Os(C≡CPh)(=C= CHPh)(PPh₃)(l-(CHPh=C)-2, 6-(PPh₂CH₂)₂C₆H₃).

Full text of DOI:10.1021/om034141w

Organometallics 2003, 22, 4947-4951
4947
Cou p lin g Rea ction of P h en yla cetylen e w ith
OsHn (P P h 3)(2,6-(P P h 2CH2)2C6H3) (n ) 1, 3)
Ting Bin Wen,† Zhong Yuan Zhou,‡ and Guochen J ia*,†
Department of Chemistry, The Hong Kong University of Science and Technology,
Clear Water Bay, Kowloon, Hong Kong, and Department of Applied Biology and
Chemical Technology, Hong Kong Polytechnic University, Kowloon, Hong Kong
Received August 29, 2003
Treatment of OsCl(dCdCHPh)(PPh3)(PCP) with thallium acetate produces the vinylidene
complex Os(O2CCH3)(dCdCHPh)(PCP). Treatment of OsCl(PPh3)(PCP) with NaH in wet
THF produces a mixture of the monohydride OsH(PPh3)(PCP) and the trihyhride OsH3-
(PPh3)(PCP). The latter complexes react with phenylacetylene to give Os(CtCPh)(dCd
CHPh)(PPh3)(1-(CHPhdC)-2,6-(PPh2CH2)2C6H3).
In tr od u ction
ligands in the reactions of terminal acetylenes with
transition metal complexes are known.
It has been established that vinylidene complexes Ln-
MR′(dCdCHR) can undergo migratory insertion reac-
tions of R′ to the R-carbon of the vinylidene ligands to
give LnM(CR′dCHR).1,2 As reactions of terminal acety-
lenes HCtCR with coordinatively unsaturated com-
pounds could often lead to vinylidene complexes, one
might expect that reactions of terminal acetylenes
HCtCR with transition metal complexes LnM-R′ may
go through vinylidene intermediates LnM-R′(dCd
CHR) to give coupling complexes LnM-R′CdCHR.
Indeed, there are many examples of coupling reactions
between acetylide and vinylidene ligands, especially in
the reactions of HCtCR with certain complexes to give
RC3HR complexes and in catalytic dimerization or
oligomerization of terminal acetylenes.3-5 In contrast,
only a few coupling reactions between vinylidene and
other ligands such as hydride,6 vinyl,7-10 and aryl11a,b
In our efforts to investigate the coupling reactions
between vinylidene and aryl ligands, we have studied
the reactions of terminal acetylenes with MCl(PPh3)-
(PCP) (M ) Ru, Os; PCP ) 2,6-(PPh2CH2)2C6H3).11a,b It
is found that reactions of RuCl(PPh3)(PCP) with
HCtCR lead to the formation of the coupling products
RuCl(PPh3)(1-(RCHdC)-2,6-(PPh2CH2)2C6H3)11a,b through
the vinylidene intermediates RuCl(dCdCHR)(PPh3)-
(PCP). In contrast, the analogous osmium complex OsCl-
(PPh3)(PCP) reacts with HCtCR (R ) Ph, But, C(OH)-
Ph2) to give the vinylidene complexes OsCl(dCd
CHR)(PPh3)(PCP), which do not undergo coupling
reactions similar to those of their ruthenium ana-
logues.12 In a related study, Gusev et al. have shown
t
that the reaction of HCtCBut with RuHCl(1,3-(PBu2 -
CH2)2C6H4) gives the coupling product RuCl(dCd
CHBut)(1-(CHButdC)-2,6-(PBut CH2)2C6H3), while the
2
reaction of HCtCBut with OsH2Cl(2,6-(PBut CH2)2C6H3)
2
† The Hong Kong University of Science and Technology.
‡ Hong Kong Polytechnic University.
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(PBut CH2)2C6H3).13 These results suggest that metals
2
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10.1021/om034141w CCC: $25.00 © 2003 American Chemical Society
Publication on Web 10/24/2003

4948 Organometallics, Vol. 22, No. 24, 2003
Wen et al.
Sch em e 1
can have drastic effects on the coupling reactions
between vinylidene and hydrocarbyl ligands. One might
also expect that the ligand environment may also
influence the course of coupling reactions of vinylidene
ligands. To this end, we have investigated the reaction
of OsCl(dCdCHPh)(PPh3)(PCP) with thallium acetate
and the reactions of the hydride complexes OsHn(PPh3)-
(PCP) (n ) 1, 3) with HCtCPh. It should be noted that
PCP and related ligands are receiving increasing at-
tention in organometallic chemistry and catalysis.14
Several other reports have appeared in the literature
on the chemistry and catalytic properties of ruth-
enium15-17 and osmium18 complexes with PCP or related
ligands.
the geometry, the 13C{1H} NMR spectrum (in CD2Cl2)
showed a virtual triplet 13C signal for the methylene
carbons at 44.5 ppm. The presence of the vinylidene
ligand is supported by the 13C{1H} NMR spectrum (in
CD2Cl2), which exhibited the OsdC signal at 300.4 ppm
and the OsdCdCH signal at 109.2 ppm, and the 1H
NMR spectrum (in C6D6), which showed the vinylidene
proton signal at 2.60 ppm. The presence of the acetate
Resu lts a n d Discu ssion
Syn th esis a n d Ch a r a cter iza tion of Os(O2CCH3)-
(dCdCHP h )(P CP ). In an attempt to induce aryl-
vinylidene coupling, we have treated the vinylidene
complex OsCl(dCdCHPh)(PPh3)(PCP) (1)12 with thal-
lium acetate, hoping that the acetate ligand will replace
the chloride and function as a bidentate ligand to push
the aryl group to migrate to the R-carbon of the
vinylidene ligand. In reality, reaction of 1 with thallium
acetate produces the vinylidene complex Os(O2CCH3)-
(dCdCHPh)(PCP) (2) and the PPh3 ligand is liberated
(eq 1).
1
ligand is indicated by the H and 13C{1H} NMR data.
1
In particular, the H NMR spectrum (in C6D6) showed
the CH3 signal at 1.44 ppm, and the 13C{1H} NMR
spectrum (in CD2Cl2) showed the carbonyl and CH3
signals at 185.1 and 25.6 ppm, respectively.
Syn th esis a n d Ch a r a cter iza tion of OsH(P P h 3)-
(P CP ) a n d OsH3(P P h 3)(P CP ). Treatment of OsCl-
(PPh3)(PCP) (3) with NaH in THF under an argon
atmosphere produced a mixture of the monohydride
OsH(PPh3)(PCP) (4) and the trihyhride OsH3(PPh3)-
(PCP) (5) (Scheme 1). The H2 needed for the formation
of 5 in the reaction is presumably generated in situ from
the reaction of NaH with trace water present in the
solution. When the reaction was performed under a H2
atmosphere, the trihydride complex 5 was obtained
quantitatively. However, both 4 and 5 cannot be isolated
in pure form because of their air-sensitivity, and there-
fore they were characterized in situ and used im-
mediately once generated.
The structure of 2 can be readily assigned on the basis
of elemental analysis and NMR and MS spectroscopy.
The 31P{1H} NMR spectrum in C6D6 displayed only a
1
singlet at 27.3 ppm. The H NMR spectrum (in C6D6)
displayed two sets of virtual doublets of triplet 1H
signals at 4.37 and 4.23 ppm for the methylene protons
of the PCP ligand, indicating that the two PPh2 groups
are trans to each other and that the PCP ligand is
coordinated in a meridional fashion.19 Consistent with
The structure of 4 can be assigned on the basis of its
NMR spectroscopic data. In particular, the 31P{1H}
NMR spectrum in THF-d8 showed a doublet at 25.2 ppm
for the PPh2 groups and a triplet at 11.7 ppm for the
PPh3 ligand with a J (PP) of 9.9 Hz. The 31P NMR data
are very similar to those of the chloride complex OsCl-
(PPh3)(PCP) (3),12 implying that the two compounds
have similar structures, i.e., square pyramid with the
bulky PPh3 ligand occupying the apical site. Consistent
with the structure, the 1H NMR spectrum in THF-d8
displayed a hydride signal at -11.84 ppm (dt, J (PH) )
18.0, 19.5 Hz).
(14) (a) Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. 2001,
40, 3750. (b) Van der Boom, M. E.; Milstein, D. Chem. Rev. 2003, 103,
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40, 3750. (c) Dani, P., Richter, B.; van Klink, G. P. M.; van Koten, G.
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M.; Antipin, M. Y.; Organometallics 2001, 20, 1001. (c) Gauvin, R. M.;
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Y.; Lau, C. P.; J ia, G. Inorg. Chim. Acta 2002, 334, 122.
The 31P{1H} NMR spectrum of 5 in THF-d8 showed a
doublet at 25.1 ppm for the PPh2 groups and a triplet
at 19.8 ppm for the PPh3 ligand with a J (PP) of 12.6
1
Hz. The room-temperature H NMR spectrum in THF-
d8 showed two hydride signals at -4.79 ppm (dt, J (PH)
) 24.9, 14.1 Hz) and -6.98 ppm (br s) with relative
intensities of 1:2. The magnitude of the J (PH) constants
for the OsH resonance suggests that the hydride is cis
1
to all three phosphorus atoms. The H NMR in THF-d8
did not change appreciably when the temperature is
lowered to -70 °C. The structure of 5 could be assigned
(19) Wilkes, L. M.; Nelson, J . H.; McCusker, L. B.; Seff, K.; Mathey,
F. Inorg. Chem. 1983, 22, 2476, and references therein.

Coupling Reaction of Phenylacetylene
Organometallics, Vol. 22, No. 24, 2003 4949
as either a trihydride complex OsH3(PPh3)(PCP) with
two of the hydrides exchanging rapidly or a hydrido-
dihydrogen complex OsH(H2)(PPh3)(PCP). To distin-
guish the two possibilities, we have measured the T1
values of the OsH2 resonance at -6.98 ppm. The
minimum T1 value for the hydride signal was found to
be 89.6 ms at 270 K (300 MHz). The long T1(min) value
indicates that the H‚‚‚H interaction is very weak if it
exists at all.20 We also failed to detect J (HD) coupling
for the partially deuterated samples of OsHxD3-x
-
(PPh3)(PCP). On the basis of the spectroscopic data, we
tentatively assign the complex as a seven-coordinated
pentagonal bipyramidal trihydride complex. Consistent
with this structure, the 13C{1H} NMR spectrum in THF-
d8 showed the Os-Cipso signal at 154.8 ppm as a doublet
with a 2J (PC) coupling of 36.2 Hz. The magnitude of
the 2J (PC) coupling constant is much smaller than those
observed for other osmium-PCP complexes, in which the
PPh3 is trans to the orthometalated carbon. For ex-
ample, the 2J (PC) is 60.4 Hz for the structurally
characterized complex OsCl(H2)(PPh3)(PCP).18e Many
seven-coordinated osmium trihydride complexes have
been reported.18a,21
Rea ction of OsH(P P h 3)(P CP ) a n d OsH3(P P h 3)-
(P CP ) w ith P h CtCH. Treatment of a freshly prepared
benzene solution of 5 with excess PhCtCH produced
the coupling product Os(CtCPh)(dCdCHPh)(PPh3)(1-
(CHPhdC)-2,6-(PPh2CH2)2C6H3) (6). As indicated by in
situ NMR experiments, the reaction also produced ca.
1.7 equiv of styrene and some oligomers of phenylacety-
lene (Scheme 1). 6 is also produced when a mixture of
4 and 5 was treated with phenylacetylene. Although 6
is the only metal-containing product, the presence of
oligomeric phenylacetylene makes its purification dif-
ficult and limits the isolated yield. An analytically pure
sample of 6 was obtained in 56% yield by column
chromatography on neutral alumina.
F igu r e 1. Molecular structure of Os(CtCPh)(dCdCHPh)-
(PPh3)(1-(CHPhdC)-2,6-(PPh2CH2)2C6H3) (6).
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for Os(CtCP h )(dCdCHP h )(P P h 3)-
(1-(CHP h dC)-2,6-(P P h 2CH2)2C6H3)‚3C6H6
empirical formula
fw
C74H59OsP3‚3C6H6
1465.65
temperature
wavelength
cryst syst
294(2) K
0.71073 Å
triclinic
space group
unit cell dimens
P1h (No. 2)
a ) 11.897(3) Å, R ) 93.799(6)°
b ) 12.121(3) Å, â ) 101.487(7)°
c ) 26.035(6) Å, γ ) 97.342(6)°
3632.9(14) Å3
2
volume
Z
density(calcd)
abs coeff
1.340 g/cm3
1.868 mm-1
θ range for data collection
no. of reflns collected
no. of indep reflns
no. of obsd reflns [I>2σ(I)]
max. and min. transmn
1.70-23.31°
16 931
10440 (Rint ) 0.0837)
5144
1.0000 and 0.8352
The structure of 6 could not be assigned confidently
on the basis of the spectroscopic data. Thus a single-
crystal X-ray diffraction study was carried out. The
molecular structure of 6 is depicted in Figure 1. The
crystallographic details and selected bond distance and
angles are given in Tables 1 and 2, respectively.
The crystal structure reveals that three molecules of
phenylacetylene have been incorporated into the os-
mium center: one in the form of vinylidene, one in the
form of acetylide, and the other one linked to the central
aromatic ring of PCP and osmium as a vinyl substituent
CdCHPh. The coordination geometry around osmium
can be described as a distorted octahedron with the
PPh3 trans to the vinyl ligand. The bite angle P(1)-Os-
(1)-P(2) (147.97(6)°) is close to that of OsCl(PPh3)(PCP)
(149.9(1)°)12 and significantly smaller than those in
no. of data/restraints/params 10 440/27/865
goodness-of-fit on F2
0.821
final R indices [I>2σ(I)]
largest diff peak and hole
R1 ) 0.0697, wR2 ) 0.1297
1.287 and -1.458 e‚Å-3
Ta ble 2. Selected Bon d Len gth s a n d An gles for
Os(CtCP h )(dCdCHP h )(P P h 3)(1-(CHP h dC)-
2,6-(P P h 2CH2)2C6H3)‚3C6H6 (6‚3C6H6)
Bond Distances (Å)
Os(1)-P(1)
Os(1)-P(3)
Os(1)-C(17)
C(1)-C(9)
2.3883(15)
2.4108(17)
1.869(6)
1.483(8)
1.273(8)
Os(1)-P(2)
Os(1)-C(9)
Os(1)-C(25)
C(9)-C(10)
C(25)-C(26)
2.4075(14)
2.155(6)
2.109(6)
1.316(8)
1.169(8)
C(17)-C(18)
Bond Angles (deg)
P(1)-Os(1)-P(2)
P(1)-Os(1)-P(3)
147.97(6) P(2)-Os(1)-P(3)
100.76(5)
163.03(17)
77.52(14)
97.74(14)
85.2(2)
108.67(5) C(9)-Os(1)-P(3)
C(17)-Os(1)-C(25) 174.9(2)
C(9)-Os(1)-P(1)
83.21(16) C(25)-Os(1)-P(1)
99.9(2) C(25)-Os(1)-C(9)
C(17)-Os(1)-P(1)
C(17)-Os(1)-C(9)
C(17)-Os(1)-P(2)
C(9)-Os(1)-P(2)
C(25)-Os(1)-P(3)
C(10)-C(9)-Os(1) 129.8(5)
C(9)-C(10)-C(11) 127.8(6)
C(17)-C(18)-C(19) 138.3(6)
(20) (a) Crabtree, R. H. Angew. Chem., Int. Ed. Engl. 1993, 32, 789.
(b) Heinekey, D. M.; Oldham, W. J ., J r. Chem. Rev. 1993, 93, 913. (c)
J essop, P. G.; Morris, R. H. Coord. Chem. Rev. 1992, 121, 155. (d)
Esteruelas, M. A.; Oro, L. A. Chem. Rev. 1998, 98, 577. (e) G. J . Kubas,
Dihydrogen and σ-bond Complexes, Kluwer Academic/Plenum Press:
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M. A.; Lledo´s, A.; Maseras, F.; On˜ate, E.; Toma´s, J . Organometallics
2001, 20, 442. (b) Barea, G.; Esteruelas, M. A.; Lledo´s, A.; Lopez, A.
M.; On˜ate, E.; Tolosa, J . I. Organometallics 1998, 17, 4065. (c) Gusev,
D. G.; Hu¨bener, R.; Burger, P.; Orama, O.; Berke, H. J . Am. Chem.
Soc. 1997, 119, 3716. (d) Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, A. M.;
On˜ate, E.; Oro, L. A.; Ruiz, N.; Sola, E.; Tolosa, J . I. Inorg. Chem. 1996,
35, 7811.
81.12(15) C(25)-Os(1)-P(2) 100.34(14)
77.90(13) C(17)-Os(1)-P(3)
78.38(17) C(1)-C(9)-Os(1)
96.57(19)
104.8(4)
125.3(5)
C(10)-C(9)-C(1)
C(18)-C(17)-Os(1) 175.5(5)
C(26)-C(25)-Os(1) 172.5(5)
OsCl(dCdCHPh)(PPh3)(PCP) (157.13(5)°),12 RuCl(P-
Ph3)(1-(PhCHdC)-2,6-(PPh2CH2)2C6H3) (159.17(6)°),11a,b
and RuCl(dCdCHBut)(1-(ButCHdC)-2,6-(CH2PBut ) -
2 2
C6H3) (163.53(3)°).13 The Os-C(vinyl) (2.155(6) Å),

4950 Organometallics, Vol. 22, No. 24, 2003
Wen et al.
Sch em e 2
Os-C (alkynyl) (2.109(6) Å), and OsdC (vinylidene)
(1.869(6) Å) as well as the corresponding Os-C-C bond
angles are normal compared to those reported for
osmium alkenyl,2c,22 alkynyl,23 or vinylidene8,24 com-
plexes.
deposition of the vinyl and PPh3 ligands. The â-carbon
signal of the vinyl group was observed at 132.8 ppm (t,
J (PC) ) 6.2 Hz). The presence of the acetylide ligand is
also supported by the infrared spectrum, which showed
the characteristic absorption of CtC stretching at
2080.9 cm-1. Complex 6 is interesting because it rep-
resents a rare example of mononuclear complexes with
acetylide, vinyl, and vinylidene ligands.
Consistent with the solid-state structure, the 31P{1H}
NMR spectrum in CD2Cl2 showed a doublet at 5.8 ppm
for the PPh2 groups and a triplet at -4.2 ppm for the
PPh3 ligand (J (PP) ) 4.5 Hz). The presence of the
vinylidene ligand is supported by the 13C{1H} NMR
spectrum (in CD2Cl2), which exhibited the OsdC signal
at 306.6 ppm and the OsdCdCH signal at 110.1 ppm,
Scheme 2 shows a plausible mechanism for the
formation of 6. Complex 5 may lose an H2 molecule first
to give the 16e monohydride 4, which then undergoes
an insertion reaction with PhCtCH to give the vinyl
intermediate A. The vinyl complex A can then react with
the H2 to liberate styrene and regenerate the monohy-
dride 4. Similar reactions are well documented for
hydrogenation of alkynes by metal hydride complexes.
Complex 4 can again react with an additional molecule
of PhCtCH to give the vinyl intermediate A, which now
can react with another molecule of PhCtCH to give
styrene and acetylide intermediate B. Reactions of vinyl
complexes with terminal alkynes to give acetylide
complexes and olefins are well-established reactions.25
Reaction of B with PhCtCH could then give vinylidene
complex C, which can then undergo coupling reactions
to give the coordinatively unsaturated intermediate D.
Reaction of intermediate D with PhCtCH would give
complex 6. To gain information on the reaction mech-
anism, the reaction of 5 with excess phenylacetylene has
been monitored by NMR. Unfortunately, no intermedi-
ates can be identified.
1
and the H NMR spectrum (in CD2Cl2), which showed
the vinylidene proton signal at -0.37 ppm. The vinyl
proton signal appeared as a quartet at 7.95 ppm (J (PH)
1
) 3.5 Hz) in the H NMR spectrum or a singlet in the
1H{31P} NMR spectrum. In the 13C{1H} NMR spectrum,
the signal of the R-carbon of the vinyl group appeared
at 144.7 ppm (dt, J (PC) ) 41.7, 17.8 Hz). The magnitude
of the coupling constants agrees well with the trans
(22) (a) Castarlenas, R.; Esteruelas, M. A.; On˜ate, E. Organometal-
lics 2001, 20, 2294. (b) Liu, S. H, Lo, S. T.; Wen, T. B.; Zhou, Z. Y.;
Lau, C. P.; J ia, G. Organometallics 2001, 20, 667. (c) Wen, T. B.; Yang,
S. Y.; Zhou, Z. Y.; Lin, Z.; Lau, C. P.; J ia, G. Organimetallics 2000, 19,
3757. (d) Bohanna, C.; Callejas, B.; Edwards, A. J .; Esteruelas, M. A.;
Lahoz, F. J .; Oro, L. A.; Ruiz, N.; Valero, C. Organometallics 1998,
17, 373.
(23) (a) Wong, W. Y.; Wong, C. K.; Lu, G. L. J . Organomet. Chem.
2003, 671, 27. (b) Rickard, C. E. F.; Roper, W. R.; Woodgate, S. D.;
Wright, L. J . J . Organomet. Chem. 2001, 623, 109. (c) Baya, M.;
Crochet, P.; Esteruelas, M. A.; Gutie´rrez-Puebla, E.; Lopez, A. M.;
Modrego, J .; On˜ate, E.; Vela, N. Organometallics 2000, 19, 2585.
(24) (a) Barrio, P.; Esteruelas, M. A.; On˜ate, E. Organometallics
2003, 22, 2472. (b) Barrio, Esteruelas, M. A.; On˜ate, E. Organometallics
2002, 21, 2491. (c) Baya, M.; Crochet, P.; Esteruelas, M. A.; Lo´pez, A.
M.; Modrego, J .; On˜ate, E. Organometallics 2001, 20, 4291. (d)
Castarlenas, E.; Esteruelas, M. A.; Gutie´rrez-Puebla, E.; On˜ate, E.
Organometallics 2001, 20, 1545. (e) Castarlenas, E.; Esteruelas, M.
A.; On˜ate, E. Organometallics 2000, 19, 5454. (e) Esteruelas, M. A.;
Oliva´n, M.; On˜ate, E.; Ruiz, N.; Tajada, M. A. Organometallics 1999,
18, 2953. (f) Weber, B.; Steinert, P.; Windmu¨ller, B.; Wolf, J .; Werner,
H. J . Chem. Soc., Chem. Commun. 1994, 2595.
(25) See for example: (a) Bassetti, M.; Marini, S.; Dı´az, J .; Gamasa,
M. P.; Gimeno, J .; Rodr´ıguez-AÄ lvarez, Y.; Garc´ıa-Granda, S. Organo-
metallics 2002, 21, 4815. (b) Hill, A. F.; White, A. J . P.; Williams, D.
J .; Wilton-Ely, J . D. E. T. Organometallics 1998, 17, 4249. (c) Santo,
A.; Lo´pez, J .; Gala´n, A.; Gonza´lez, J . J .; Tinoco, P.; Echavarren, A. M.
Organometallics 1997, 16, 3482. (d) Santos, A.; Lo´pez, J .; Montoya,
J .; Noheda, P.; Romero, A.; Echavarren, A. M. Organometallics 1994,
13, 3605.

Coupling Reaction of Phenylacetylene
Organometallics, Vol. 22, No. 24, 2003 4951
6.70 (m, 38 H, PPh3, PPh2, C6H3). 13C{1H} NMR (75.5 MHz,
THF-d8): δ 154.8 (d, J (PC) ) 36.2 Hz, Os-C(aryl)), 149.0-121.8
(m, other aromatic carbons), 50.4 (td, J (PC) ) 19.4, 3.0 Hz,
CH2). T1 [ms, OsH2, 300.13 MHz, THF-d8]: 121.2 (298 K), 89.8
(273 K), 89.6 (270 K), 89.8 (265 K), 98.6 (253 K), 117.9 (235
K).
It is noted that reaction of OsCl(PPh3)(PCP) with
RCtCH produces the vinylidene complexes OsCl(dCd
CHR)(PPh3)(PCP), which do not undergo coupling reac-
tions. In contrast, reactions of OsHn(PPh3)(PCP) (n )
1, 3) with PhCtCH produce the unusual coupling
product Os(CtCPh)(dCdCHPh)(PPh3)(1-(CHPhdC)-
2,6-(PPh2CH2)2C6H3). Probably, the presence of strong
σ-donor ligand (e.g., the acetylide ligand in the inter-
mediate C) weakens the OsdC and Os-C bonds,
therefore facilitating the coupling reaction.
Os(CtCP h )(dCdCHP h )(P P h 3)(1-(CHP h dC)-2,6-(P P h 2-
CH2)2C6H3) (6). A mixture of OsCl(PPh3)(PCP) (0.50 g, 0.52
mmol) and NaH (0.12 g, 5.0 mmol) in THF (15 mL) was stirred
under a H2 atmosphere at RT for 1 h to give a light brown
solution. The solvent was removed under vacuum. The residue
was extracted with benzene (30 mL) under a H2 atmosphere
and then filtered under an argon atmosphere to give a pink
solution. Phenylacetylene (0.58 mL, 5.2 mmol) was added to
the pink solution. The mixture was stirred under an argon
atmosphere for 1 h to give a brown solution. The volume of
the reaction mixture was reduced to ca. 1 mL under vacuum.
Then hexane (40 mL) was added slowly with stirring to give a
pale brown solid, which was collected by filtration, washed
with hexane (2 × 30 mL), and dried under vacuum. The crude
product was redissolved in 2 mL of CH2Cl2 and passed through
a neutral alumina column using benzene as the eluting
solvent. The pink band was collected, and the solvent was
removed completely to give a pink solid. Yield: 0.36 g, 56%.
31P{1H} NMR (121.5 MHz, CD2Cl2): δ 5.8 (d, J (PP) ) 4.5 Hz),
-4.2 (t, J (PP) ) 4.5 Hz). 1H NMR (300.13 MHz, CD2Cl2): δ
-0.37 (t, J (PH) ) 4.1 Hz, 1 H, OsdCdCH), 3.45 (dt, J (HH) )
14.2 Hz, J (PH) ) 4.5 Hz, 2 H, CH2), 4.08 (dt, J (HH) ) 14.2
Hz, J (PH) ) 4.1 Hz, 2 H, CH2), 7.95 (q, J (PH) ) 3.5 Hz, 1 H,
PCP-CdCHPh), 4.81-8.31 (m, 53 H, PPh3, PPh2, C6H3, C6H5).
13C{1H} NMR (100.4 MHz, CD2Cl2): δ 306.6 (td, J (PC) ) 16.7,
9.0 Hz, OsdC), 167.6 (td, J (PC) ) 8.9, 3.0 Hz, ipso-C of PCP
aryl), 144.7 (dt, J (PH) ) 41.7, 17.8 Hz, PCP-CdCHPh), 132.8
(t, J (PC) ) 6.7 Hz, PCP-CdCHPh), 140.4-121.4 (m, other
aromatic carbons), 119.0 (dt, J (PH) ) 25.3, 9.7 Hz, Os-CtCPh),
126.1 (br s, tCPh), 110.1 (t, J (PH) ) 8.9 Hz, OsdCdCH), 43.3
(t, J (PC) ) 19.4 Hz, CH2 of PCP). The 13C assignments were
supported by DEPT, 1H-13C COSY, and 1H-13C COLOC
spectra. IR (KBr): 2080.9 cm-1 [ν(CtC)]. Anal. Calcd for
Exp er im en ta l Section
All manipulations were carried out at room temperature
under a nitrogen atmosphere using standard Schlenk tech-
niques, unless otherwise stated. Solvents were distilled under
nitrogen from sodium-benzophenone (hexane, diethyl ether,
THF, benzene) or calcium hydride (dichloromethane, CHCl3).
The starting materials OsCl(PPh3)(PCP) and OsCl(dCdCHPh)-
(PPh3)(PCP) were prepared according to literature methods.12
Microanalyses were performed by M-H-W Laboratories (Phoe-
nix, AZ). 1H, 13C{1H}, and 31P{1H} NMR spectra were collected
on a Bruker ARX-300 spectrometer (300 MHz). 1H and 13C
NMR chemical shifts are relative to TMS, and 31P NMR
chemical shifts are relative to 85% H3PO4.
Os(O2CCH3)(dCdCHP h )(P CP ) (2). A mixture of OsCl-
(CdCHPh)(PPh3)(PCP) (0.60 g, 0.56 mmol) and TlOAc (0.22
g, 0.85 mmol) in THF (60 mL) was stirred at room temperature
for 24 h to give a brownish-red solution along with a pale
precipitate. The solvent was removed under vacuum to give a
pale brown solid, which was extracted with benzene (30 mL).
The insoluble TlCl was removed by filtration. After the filtrate
was concentrated to ca. 5 mL, hexane (30 mL) was added
slowly to give a pink solid. The solid was collected by filtration,
washed with hexane (2 × 30 mL), and dried under vacuum
overnight. Yield: 0.29 g, 63%. 31P{1H} NMR (121.5 MHz,
C6D6): δ 27.3 (s). 1H NMR (300.13 MHz, C6D6): δ 1.44 (s, 3 H,
O2CCH3), 2.60 (t, J (PH) ) 3.1 Hz, 1 H, OsdCdCH), 4.23 (dt,
J (HH) ) 15.7 Hz, J (PH) ) 4.7 Hz, 2 H, CH2), 4.37 (dt, J (HH)
) 15.7 Hz, J (PH) ) 4.4 Hz, 2 H, CH2), 7.88-6.87 (m, 28 H,
PPh2, C6H3, C6H5). 13C{1H} NMR (75.47 MHz, CD2Cl2): δ 300.4
(t, J (PC) ) 11.0 Hz, OsdC), 185.1 (s, O2CCH3), 151.8 (s, Os-
C(aryl)), 149.7-122.6 (m, other aromatic carbons), 109.2 (t,
J (PC) ) 3.7 Hz, OsdCdCH), 44.50 (t, J (PC) ) 17.9 Hz, CH2),
25.6 (s, O2CCH3). Anal. Calcd for C42H36O2P2Os: C, 61.16; H,
4.40. Found: C, 61.19; H, 4.60. FAB-MS (NBA, M/z): 825 (M+).
OsH(P P h 3)(P CP ) (4). Due to its low stability, this com-
pound was not isolated but was prepared and characterized
in situ. To an NMR tube charged with OsCl(PPh3)(PCP) (30
mg) and excess NaH was added degassed THF-d8 (0.5 mL)
under an argon atmosphere. After the mixture was shaken
for 2 min, the NMR tube was put in an ultrasonic bath for 5
min. to give a brown solution. The NMR spectrum of the brown
solution indicates that it is a mixture of 4 and 5 in ca. 1:2
ratio. Characterization data for 4: 31P{1H} NMR (121.5 MHz,
THF-d8): δ 25.2 (d, J (PP) ) 9.9 Hz), 11.7 (t, J (PP) ) 9.9 Hz).
1H NMR (300.13 MHz, THF-d8): δ -11.84 (dt, J (PH) ) 18.0,
19.5 Hz, 1 H, OsH), 3.73 (dt (br), J (HH) ) 15.2 Hz, J (PH) )
4.4 Hz, 2 H, CH2), 4.46 (dt (br), J (HH) ) 15.2 Hz, J (PH) ) 3.5
Hz, 2 H, CH2), 6.76-7.68 (m, PPh3, PPh2, C6H3).
C
74H59P3Os: C, 72.18; H, 4.83. Found: C, 72.25; H, 5.02. FAB-
MS (NBA, m/z): 1232 (M+), 970 ([M - PPh3]+).
Cr ysta llogr a p h ic An a lysis. Crystals suitable for X-ray
diffraction were grown from a saturated solution of 6 in
benzene. Intensity data were collected on a Bruker SMART
CCD area detector and corrected for SADABS (Siemens Area
Detector Absorption).26 The structure was solved by direct
methods, expanded by difference Fourier syntheses, and
refined by full matrix least-squares on F2 using the Bruker
SHELXTL (Version 5.10)27 program package. All non-hydrogen
atoms were refined anisotropically. Three benzene solvent
molecules were cocrystallized in the packing. The benzene
solvent molecules and the phenyl ring of the vinylidene ligand
were refined with fixed C-C bond distances restraints.
Hydrogen atoms were placed in the ideal positions and refined
as riding atoms. Further details on crystal data and data
collection are summarized in Table 1.
Ack n ow led gm en t. The authors acknowledge finan-
cial support from the Hong Kong Research Grants
Council.
Su p p or tin g In for m a tion Ava ila ble: Tables of bond
distances and angles, atomic coordinates and equivalent
isotropic displacement coefficients, and anisotropic displace-
ment coefficients for Os(CtCPh)(dCdCHPh)(PPh3)(1-(CH-
PhdC)-2,6-(PPh2CH2)2C6H3) (6). This material is available free
of charge via the Internet at http://pubs.acs.org.
OM034141W
OsH3(P P h 3)(P CP ) (5). Due to its low stability, this com-
pound was not isolated but was prepared and characterized
in situ. The NMR sample containing a mixture of 4 and 5
prepared above was refilled with dihydrogen gas to give a pink
solution. The NMR spectra of the resulting solution were
collected. 31P{1H} NMR (121.5 MHz, THF-d8): δ 25.1 (d, J (PP)
1
) 12.6 Hz), 19.8 (t, J (PP) ) 12.6 Hz). H NMR (300.13 MHz,
(26) Sheldrick G. M. SADABS, Empirical Absorption Correction
Program; University of Go¨ttingen: Germany, 1996.
(27) Bruker, SHELXTL Reference Manual (Version 5.1); Bruker
Analytical X-Ray Systems Inc.: Madison, WI, 1997.
THF-d8): δ -6.98 (br s, W1/2 ) 23.1 Hz, 2 H, OsH2), -4.79 (dt,
J (PH) ) 24.9, 14.1 Hz, 1 H, OsH), 3.89 (br d, J (HH) ) 16.0
Hz, 2 H, CH2), 4.12 (br d, J (HH) ) 16.0 Hz, 2 H, CH2), 7.97-