Synthesis and Characterization of the W-Os Heterometallic Complex Os3(CO)10(μ-H)(μ-η 3-C(=CHPh)C≡CW(O)2(C5Me5)): Evidence of Hydride Dislocation on a Triosmium Framework by Crystal Polymorphism

Article abstract of DOI:10.1021/om980957z

The heterometallic compound Os₃(CO)₁₀(μ-H)(μ-η ³-C(=CHPh)C≡CW(O)₂(C₅Me₅)) (1), which possesses a bridging hydride and a C≡CC=CHPh ligand, is obtained on addition of the diynyl complex (C₅Me₅)W(O)₂(C≡CC≡CPh) to Os₃(μ-H)₂(CO)₁₀. ¹H NMR spectra show the occurrence of three isomers at equilibrium in solution, of which two isomers have been unambiguously characterized by an X-ray diffraction study. During subsequent tests of reactivity we isolated Os₃(CO)₁₀(μ-σ:η ²-C≡CCHCHPh)(μ-H) (2) and (C₅Me₅)W(μ-O)₂Os₃(CO) ₉(μ-σ:η²-C≡CCHCHPh) (3) through two distinct processes initiated by removal of the (C₅Me₅)W(O)₂ fragment and decarbonylation, respectively.

Full text of DOI:10.1021/om980957z

Organometallics 1999, 18, 1675-1679
1675
Syn th esis a n d Ch a r a cter iza tion of th e W-Os
Heter om eta llic Com p lex
Os3(CO)10(µ-H)(µ-η3-C(dCHP h )CtCW(O)2(C5Me5)):
Evid en ce of Hyd r id e Disloca tion on a Tr iosm iu m
F r a m ew or k by Cr ysta l P olym or p h ism
Te-Kun Huang,† Yun Chi,*,† Shie-Ming Peng,*,‡ and Gene-Hsiang Lee‡
Department of Chemistry, National Tsing Hua University, Hsinchu 30043, Taiwan, and
Department of Chemistry and Instrumentation Center, National Taiwan University,
Taipei 10764, Taiwan
Received November 30, 1998
The heterometallic compound Os3(CO)10(µ-H)(µ-η3-C(dCHPh)CtCW(O)2(C5Me5)) (1), which
possesses a bridging hydride and a CtCCdCHPh ligand, is obtained on addition of the diynyl
complex (C5Me5)W(O)2(CtCCtCPh) to Os3(µ-H)2(CO)10. 1H NMR spectra show the occurrence
of three isomers at equilibrium in solution, of which two isomers have been unambiguously
characterized by an X-ray diffraction study. During subsequent tests of reactivity we isolated
Os3(CO)10(µ-σ:η2-CtCCHCHPh)(µ-H) (2) and (C5Me5)W(µ-O)2Os3(CO)9(µ-σ:η2-CtCCHCHPh)
(3) through two distinct processes initiated by removal of the (C5Me5)W(O)2 fragment and
decarbonylation, respectively.
Examination of the bonding of ligated hydrocarbon
moieties in metal cluster compounds provides detailed
data that may be applicable to the characterization of
chemisorbed intermediates on metal surfaces.1 While
the chemistry of cluster complexes with small carbon-
rich ligands such as carbide, dicarbide, and alkynyl
ligands has been investigated,2 it is only recently that
the higher analogues of diynyl or polyynyl fragments
have received similar attention as a result of the
emerging synthetic application of materials possessing
extended carbon unsaturation.3 This new trend is
evident from several reports devoted to the syntheses
and characterization of monometallic or dimetallic di-
ynyl and polyynyl complexes.4
pattern influenced by steric effects. We report here a
related coupling reaction of (C5Me5)W(O)2(CtCCtCPh)
with the dihydride complex Os3(µ-H)2(CO)10, which
proceeds smoothly to give the product Os3(CO)10(µ-H)-
(µ-η3-C(dCHPh)CtCW(O)2(C5Me5)) (1), in which the
organic ligand CtCCdCHPh is formed by facile hydride
transfer to the diynyl unit, a result consistent with the
expected higher activity of Os3(µ-H)2(CO)10.6 Moreover,
X-ray diffraction analyses of two single crystals of 1
provide not only unambiguous structural identification
of the linear µ-η3-CtCCdCHPh ligand but also a unique
case for hydride dislocation on the triosmium framework
by crystal polymorphism.
In seeking to extend these studies, the chemistry of
diynylmetal complexes with organic substrates or with
transition-metal clusters has been investigated.5 It is
shown that the coupling occurred at the alkyne unit
farther from the metal atom, displaying a reactivity
Exp er im en ta l Section
Gen er a l In for m a tion a n d Ma ter ia ls. Infrared spectra
were recorded on a Perkin-Elmer 2000 FT-IR spectrometer.
1H and 13C NMR spectra were recorded on a Bruker AM-400
† National Tsing Hua University.
(4) (a) Lang, H. Angew. Chem., Int. Ed. Engl. 1994, 33, 547. (b)
Lagow, R. J .; Kampa, J . J .; Wei, H.-C.; Battle, S. L.; Genge, J . W.;
Laude, D. A.; Harper, C. J .; Bau, R.; Stevens, R. C.; Haw, J . F.; Munson,
E. Science 1995, 267, 362. (c) Bartik, T.; Bartik, B.; Brady, M.;
Dembinski, R.; Galdysz, J . A. Angew. Chem., Int. Ed. Engl. 1996, 35,
414. (d) Chi, Y.; Carty, A. J .; Blenkiron, P.; Delgado, E.; Enright, G.
D.; Wang, W.; Peng, S.-M.; Lee, G.-H. Organometallics 1996, 15, 5269.
(e) Bartik, B.; Dembinski, R.; Bartik, T.; Arif, A. M.; Gladysz, J . A.
New J . Chem. 1997, 21, 739.
(5) (a) Brady, M.; Weng, W.; Gladysz, J . A. J . Chem. Soc., Chem.
Commun. 1994, 2655. (b) Bruce, M. I.; Skelton, B. W.; White, A. H.;
Zaitseva, N. N. J . Chem. Soc., Dalton Trans. 1996, 3151. (c) Bruce, M.
I.; Ke, M.; Low, P. J . Chem. Commun. 1996, 2405. (d) Gevert, O.; Wolf,
J .; Werner, H. Organometallics 1996, 15, 2806. (e) Bruce, M. I.; Ke,
M.; Low, P. J .; Skelton, B. W.; White, A. H. Organometallics 1998, 17,
3539.
‡ National Taiwan University.
(1) (a) Thimmappa, B. H. S. Coord. Chem. Rev. 1995, 143, 1. (b)
Zaera, F. Chem. Rev. 1995, 95, 2651.
(2) (a) J ohn, K. D.; Geib, S. J .; Hopkins, M. D. Organometallics 1996,
15, 4357. (b) J ensen, M. P.; Phillips, D. A.; Sabat, M.; Shriver, D. F.
Organometallics 1992, 11, 1859. (c) Norton, D. M.; Eveland, R. W.;
Hutchison, J . C.; Stern, C.; Shriver, D. F. Organometallics 1996, 15,
3916. (d) Akita, M.; Moro-oka, Y. Bull. Chem. Soc. J pn. 1995, 68, 420.
(e) Carty, A. J .; Hogarth, G.; Enright, G.; Frapper, G. Chem. Commun.
1997, 1883. (f) Doherty, S.; Corrigan, J . F.; Carty, A. J .; Sappa, E. Adv.
Organomet. Chem. 1995, 37, 39. (g) J ensen, M. P.; Phillips, D. A.;
Sabat, M.; Shriver, D. F. Organometallics 1992, 11, 1859. (h) Adams,
C. J .; Bruce, M. I.; Skelton, B. W.; White, A. H. Chem. Commun. 1996,
975.
(3) (a) Blenkiron, P.; Taylor, N. J .; Carty, A. J . J . Chem. Soc., Chem.
Commun. 1995, 327. (b) Bruce, M. I.; Ke, M.; Low, P. J . Chem.
Commun. 1996, 2405. (c) Bruce, M. I.; Denisovich, L. I.; Low, P. J .;
Peregudova, S. M.; Ustynyuk, N. A. Mendeleev Commun. 1996, 200.
(d) Norton, D. M.; Stern, C. L.; Shriver, D. F.; J ensen, M. P.; Shriver,
D. F. Inorg. Chem. 1994, 33, 2701. (e) Lang, H.; Weber, C. Organo-
metallics 1995, 14, 4415.
(6) (a) Shapley, J . R.; Park, J .-T.; Churchill, M. R.; Ziller, J . W.;
Beanan, L. R. J . Am. Chem. Soc. 1984, 106, 1144. (b) Chi, Y.; Shapley,
J . R.; Churchill, M. R.; Li, Y. J . Inorg. Chem. 1986, 25, 4165. (c) Green,
M.; Orpen, A. G.; Schaverien, C. J . J . Chem. Soc., Dalton Trans. 1989,
1333. (d) Koike, M.; Hamilton, D. H.; Wilson, S. R.; Shapley, J . R.
Organometallics 1996, 15, 4930.
10.1021/om980957z CCC: $18.00 © 1999 American Chemical Society
Publication on Web 04/09/1999

1676 Organometallics, Vol. 18, No. 9, 1999
Huang et al.
Ta ble 1. X-r a y Str u ctu r a l Da ta of Com p lexes 1a
a n d 1ba
(400.13 MHz) or a Bruker AMX-300 (300.6 MHz) instrument.
Mass spectra were measured on a J EOL-HX110 instrument
operating in the fast atom bombardment mode (FAB). All
reactions were performed under a nitrogen atmosphere using
solvents dried with an appropriate reagent. Products were
separated on commercially available preparative thin-layer
chromatographic plates (Kieselgel 60 F254, E. Merck). Elemen-
tal analyses were performed at the NSC Regional Instrumen-
tation Center at National Cheng Kung University, Tainan,
Taiwan.
1a
1b
formula
mol wt
diffractometer
cryst syst
space group
a (Å)
C
30H22O12Os3W
C30H22O12Os3W
1328.95
Siemens Smart CCD
monoclinic
Cc
21.6673(3)
16.4637(2)
14.5454(1)
131.467(1)
3888.08(8)
4
1328.95
Nonius CAD-4
monoclinic
C2/c
34.79(5)
12.973(4)
14.917(4)
98.88(3)
6653(3)
8
b (Å)
c (Å)
Rea ction of Os3(µ-H)2(CO)10 w ith (C5Me5)W(O)2(CtCCt
CP h ). In a 100 mL reaction flask, a CH2Cl2 solution (60 mL)
of Os3(µ-H)2(CO)10 (180 mg, 0.21 mmol) and the diynyl complex
(C5Me5)W(O)2(CtCCtCPh) (100 mg, 0.21 mmol) was heated
at reflux for 3 h, during which period the solution changed
from red-purple to red-orange. After removal of solvent under
vacuum, the oily residue was dissolved in a minimum amount
of CH2Cl2 and this solution subjected to separation by thin-
layer chromatography. Development with a mixture of ethyl
acetate, CH2Cl2, and hexane (3:1:12) produced orange and dark
red bands, which were extracted from silica gel with CH2Cl2,
affording yellow-orange Os3(CO)10(µ-σ:η2-CtCCHCHPh)(µ-H)
(2; 40.7 mg, 0.042 mmol, 20%) and red Os3(CO)10(µ-H)(µ-η3-
C(dCHPh)CtCW(O)2(C5Me5)) (1; 110 mg, 0.083 mmol, 40%).
Single crystals of 1, suitable for X-ray diffraction, were
obtained from a mixture of CH2Cl2 and heptane or from a
solution of THF and methanol at -20 °C, respectively.
Spectral data of 1 are as follows. MS (FAB, 192Os, 184W): m/z
1334 (M+). IR (C6H12): ν(CO) 2123 (vw), 2104 (w), 2068 (vs),
2054 (vs), 2041 (w), 2034 (w), 2021 (vs), 2004 (m), 1997 (m),
1989 (w), 1986 (w, sh), 1975 (vw), 1964 (vw), 1922 (vw, br)
cm-1. 1H NMR (400 MHz, CD2Cl2, 240 K): δ 7.27-7.16 (broad,
C6H5 & CH), 6.89 (s, CH, 0.54 H), 2.10 (s, C5Me5, 0.14 H), 2.03
(s, C5Me5, 0.32 H), 1.92 (s, C5Me5, 0.54 H), -16.91 (s, µ-H, 0.54
H), -17.24 (s, µ-H, 0.14 H). Anal. Calcd for C30H22O12Os3W:
C, 27.11; H, 1.67. Found: C, 27.50; H, 1.78.
â (°)
V (Å3)
Z
Dc (g/cm3)
F(000)
2.654
4800
2.270
2400
2θ(max) (deg)
50.0
55.0
hkl ranges
-41 to +40, 0-15, -28 to +24, -21 to +21,
0-17 -13 to +18
crystal size (mm) 0.30 × 0.25 × 0.25 0.45 × 0.17 × 0.16
µ(Mo KR) (cm-1
)
150.08
127.72
0.746, 0.362
transmissn: max, 0.737, 0.693
min
no. of data in
refinement
no. of params
max µ/σ ratio
RF; Rw or
3908 with I g 2σ(I) 7055
419
416
0.001
0.02
0.037; 0.033
0.036; 0.077
2
RF; RwF
GOF
1.23
1.05
D-map, max/min 1.14/-1.81
1.57/-0.77
(e/Å-3
)
a
Features common to all determinations: λ(Mo KR) ) 0.7107
Å; function minimized ∑(w|Fo - Fc| ); weighting scheme w-1
)
2
σ2(Fo) + |g|Fo2; GOF ) [∑w|Fo - Fc| /(No - Nv)]1/2 (No ) number
2
of observations; Nv ) number of variables).
high-angle reflections. Three standard reflections were moni-
tored every 3600 s. No significant change of intensities (e2%)
was observed during the course of all data collection. Intensi-
ties of diffraction signals were corrected for Lorentz, polariza-
tion, and absorption effects (ψ scans). The structure was solved
with the NRCC-SDP-VAX package. All non-hydrogen atoms
had anisotropic temperature factors; hydrogen atoms of or-
ganic substituents were placed at calculated positions with UH
) UC + 0.1.
Spectral data of 2 are as follows. MS (FAB, 192Os): m/z 984
(M+). IR (C6H12): ν(CO) 2109 (w), 2070 (vs), 2061 (s), 2024 (vs),
2005 (s), 1990 (w), 1984 (m) cm-1 1H NMR (400 MHz, CD2-
.
Cl2, 220 K): δ 7.71 (d, J HH ) 7.2 Hz, C6H5, 2 H), 7.35-7.23
(m, C6H5, 3 H), 6.67 (d, J HH ) 12.2 Hz, CH), 5.94 (d, J HH
)
12.2 Hz, CH), -16.51 (s, µ-H). 13C NMR (100.6 MHz, CD2Cl2,
223 K): CO, δ 182.6, 182.3, 178.4 (2 C), 175.3 (2 C), 171.4 (2
C), 170.0 (2 C); δ 142.4 (CδH), 135.2 (i-C6H5), 129.6 (p-C6H5),
129.0 (m-C6H5, 2 C), 128.5 (o-C6H5, 2 C), 106.8 (CγH), 94.1 (Câ),
79.4 (CR).
Single-crystal X-ray diffraction data of 1b were measured
on a Siemens SMART CCD diffractometer. Reflections were
collected using three different æ setting angles; each setting
was scanned by 0.3 ω between frames. Each frame was
exposed for 5 s. The detector was located 4.0 cm away from
the crystal. Crystal decay was monitored by repeating the
initial 50 frames at the end of data collection and analyzing
the duplicate reflections, and no decay was observed. An
empirical absorption correction using SADABS was applied.
The structure was solved by the direct method. Hydrogen
atoms were fixed at calculated positions and refined using a
riding model. Anisotropic displacement parameters were used
for all non-H atoms, while the given isotropic displacement
parameters were used for H atoms (1.2 and 1.5 times the
equivalent isotropic displacement parameter of the atom to
which they are respectively attached for methylene H atoms
and methyl H atoms). Data collection was carried out by using
the SMART program. Cell refinement and data reduction were
performed by using the SAINT program. Structure analysis
was carried out by using the SHELXTL/PC program.
Crystallographic refinement parameters of 1a and 1b are
summarized in Table 1; selected bond distances and angles
are presented in Tables 2 and 3, respectively.
Th er m olysis of 1. A CH2Cl2 solution (40 mL) of Os3(CO)10-
(µ-H)(µ-η3-C(dCHPh)CtCW(O)2(C5Me5)) (1; 120 mg, 0.090
mmol) was heated at reflux for 40 h. After removal of the
solvent in vacuo, the residue was dissolved in CH2Cl2 and
subjected to chromatography. Development with a similar
mixture of ethyl acetate, CH2Cl2, and hexane produced two
bands, which were extracted from silica gel to afford yellow-
orange Os3(CO)10(µ-σ:η2-CtCCHCHPh)(µ-H) (2; 48 mg, 0.049
mmol, 54%) and orange-red (C5Me5)W(µ-O)2Os3(CO)9(µ-σ:η2-
CtCCHCHPh) (3; 28.5 mg, 0.022 mmol, 25%).
Spectral data of 3 are as follows. MS (FAB, 192Os, 184W): m/z
1306 (M+). IR (C6H12): ν(CO) 2088 (w), 2069 (vs), 2026 (vs),
1
2001 (s), 1989 (w), 1973 (vw, br), 1955 (w), 1937 (w) cm-1. H
NMR (400 MHz, CDCl3, 230 K): δ 7.48 (d, J HH ) 7.4 Hz, C6H5),
7.40-7.24 (m, C6H5), 6.47 (d, J HH ) 11.9 Hz, CH), 2.08 (s, C5-
Me5). 13C NMR (100.6 MHz, CDCl3, 230 K): δ 187.2 (1 CO),
185.4 (2 CO), 177.6 (2 CO), 172.4 (2 CO), 168.9 (2 CO), 138.6
(CδH), 134.8 (p-C6H5), 128.7 (m-C6H5), 128.1 (o-C6H5), 126.5
(i-C6H5), 115.4 (C5Me5), 110.1 (CγH), 95.3 (Câ), 65.0 (CR), 12.3
(C5Me5). Anal. Calcd for C29H22O11Os3W: C, 26.77; H, 1.70.
Found: C, 26.94; H, 1.75.
X-r a y Cr ysta llogr a p h y. The X-ray diffraction measure-
ments were made with a Nonius CAD-4 or a Siemens Smart
CCD diffractometer at room temperature. For complex 1a ,
lattice parameters were determined from 25 randomly selected
Resu lts a n d Discu ssion
F or m a tion a n d Ch a r a cter iza tion of 1. The reac-
tion of the hydridoosmium complex Os3(µ-H)2(CO)10 with

A W-Os Heterometallic Complex
Organometallics, Vol. 18, No. 9, 1999 1677
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) of 1a (Esd ’s in P a r en th eses)
Os(1)-Os(2)
Os(2)-Os(3)
Os(1)-C(12)
W-C(11)
2.959(1)
2.877(1)
2.53(1)
2.10(1)
1.71(1)
1.43(2)
1.81(1)
Os(1)-Os(3)
Os(1)-C(11)
Os(2)-C(13)
W-O(11)
C(11)-C(12)
C(13)-C(14)
Os(2)-H
2.915(1)
2.42(1)
2.15(1)
1.71(1)
1.23(2)
1.32(2)
1.72(1)
W-O(12)
C(12)-C(13)
Os(1)-H
Os(1)-Os(2)-Os(3)
Os(2)-Os(1)-Os(3)
59.91(3)
58.64(3)
C(11)-C(12)-C(13) 173(1)
Os(1)-Os(3)-Os(2)
W-C(11)-C(12)
61.45(3)
152(1)
C(12)-C(13)-C(14) 123(1)
C(11)-W-O(11)
O(11)-W-O(12)
103.9(5)
108.7(5)
C(11)-W-O(12) 100.6(5)
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) of 1b (Esd ’s in P a r en th eses)
Os(1)-Os(2)
Os(2)-Os(3)
Os(1)-C(12)
W-C(11)
2.8451(6)
2.8996(7)
2.46(1)
2.15(1)
1.72(1)
Os(1)-Os(3)
Os(1)-C(11)
Os(2)-C(13)
W-O(11)
C(11)-C(12)
C(13)-C(14)
3.0741(6)
2.30(1)
2.13(1)
1.71(1)
1.24(2)
1.36(2)
W-O(12)
C(12)-C(13)
1.35(2)
Os(1)-Os(2)-Os(3)
Os(2)-Os(1)-Os(3)
64.70(2)
58.51(2)
C(11)-C(12)-C(13) 177(1)
Os(1)-Os(3)-Os(2)
W-C(11)-C(12)
56.80(2)
147(1)
C(12)-C(13)-C(14) 124(1)
C(11)-W-O(11)
O(11)-W-O(12)
101.7(5)
106.4(5)
C(11)-W-O(12) 102.8(4)
F igu r e 1. Molecular structure and atomic labeling scheme
of the complex Os3(CO)10(µ-H)(µ-η3-C(dCHPh)CtCW(O)2-
(C5Me5)) (1a ) with thermal ellipsoids shown at the 30%
probability level.
the tungsten acetylide complex (C5Me5)W(O)2(CtCCt
CPh) in CH2Cl2 at reflux gives the heterometallic
compound Os3(CO)10(µ-H)(µ-η3-C(dCHPh)CtCW(O)2-
(C5Me5)) (1) as a red solid. This compounds is relatively
unstable in solution upon exposure to air; therefore,
recrystallization is carried out in a mixture of CH2Cl2
and heptane at -20 °C. FAB MS analysis of 1 shows a
parent ion M+ at m/z 1334 that is consistent with
formation of a molecular formula corresponding to a 1:1
combination of starting materials. The IR spectrum in
cyclohexane solution exhibits nearly 20 overlapping CO
stretching bands in the range 2123-1922 cm-1, indica-
tive of at least two structural isomers. This behavior is
Sch em e 1
1
confirmed by subsequent H NMR analysis. In addition
to a broad and complicated signal at δ 7.27-7.16
assigned to aromatic and olefinic hydrogens, we ob-
served three distinctive hydride signals at δ -16.91,
-17.24, and -17.73 with the relative intensity ratio 3.9:
2.3:1, demonstrating the coexistence of three isomers
(Scheme 1). To establish their molecular structures and
the interrelationships, we carried out the X-ray diffrac-
tion study of a single crystal obtained from CH2Cl2/
heptane solution.
The molecular structure of this heterometallic com-
pound labeled 1a is depicted in Figure 1; selected bond
lengths and angles appear in Table 2. The structure
contains a triangular osmium framework with 10 ter-
minal CO ligands. The arrangement of CO ligands on
this osmium triangle is similar to those of the clusters
Os3(µ-X)(µ-H)(CO)10,7 in which one Os-Os edge is
bridged by ligand X (X ) three-electron donor) and a
hydride ligand located below the osmium triangle. One
hydride ligand bridging the Os(1)-Os(2) edge is posi-
tively defined by difference Fourier synthesis. The
second hydride migrates to the terminal carbon atom
C(14) of the incoming acetylide complex (C5Me5)W(O)2-
(CtCCtCPh), giving a novel CtCCdCHPh fragment
which is confirmed by observation of a C-C double bond
with distance 1.32(2) Å between C(13) and C(14) atoms.
The resulting C4 hydrocarbon fragment is coordinated
to the triosmium framework in two axial sites; one is
filled by carbon atom C(13), forming a regular σ-bond
with distance 2.15(1) Å, whereas the second has a
π-interaction from alkyne fragment C(11)-C(12) with
Os(1)-C(11) ) 2.42(1) Å and Os(1)-C(12) ) 2.53(1) Å.
The resulting C(13)-C(12)-C(11) unit is linear with
bond angle 173(1)° and is nearly parallel to the Os(1)-
Os(1) edge. This novel µ-η3-bonding mode is in contrast
to that of a related hydrocarbyl ligand in the allyl
(7) (a) Deeming, A. J . Adv. Organomet. Chem. 1986, 26, 1. (b) Smith,
A. K. In Comprehensive Organometallic Chemistry II; Abel, E. W.,
Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: Oxford, U.K., 1982;
Vol. 7, Chapter 13.

1678 Organometallics, Vol. 18, No. 9, 1999
Huang et al.
hydride, and a coordinated (C5Me5)W(O)2(CtCCd
CHPh) unit attached to two osmium atoms at adjacent
axial sites. However, the (C5Me5)W(O)2 fragment here
undergoes a 180° rotation about the W-C bond, placing
terminal oxo ligands in positions away from the unique
Os(CO)4 fragment. Moreover, a hydride is found to
bridge the Os(1)-Os(3) edge (3.0741(6) Å), not the Os-
(1)-Os(2) edge as observed earlier, which is verified by
a slight elongation of the Os-Os vector with respect to
other Os-Os edges: Os(1)-Os(2) ) 2.845(6) Å and Os-
(2)-Os(3) ) 2.8996(7) Å. Thus, the structures of 1a and
1b are related by hydride migration between two
adjacent Os-Os edges. By further extending this de-
lineation, we assume that the last isomer (1c) would
possess a structure with the hydride ligand associated
with the third Os-Os edge (Scheme 1). This isomeriza-
tion is consistent with a well-established tendency of
hydride to migrate on a polymetallic cluster frame-
work.11
Th er m olysis of 1. Decarbonylation of 1 is achieved
on extensive thermolysis in CH2Cl2 at reflux (40 h).
Separation of the reaction mixture by thin-layer chro-
matography yields two major bands. The first fast-
eluting band is due to the yellow triosmium compound
Os3(CO)10(µ-σ:η2-CtCCHCHPh)(µ-H) (2), but this com-
F igu r e 2. Molecular structure and atomic labeling scheme
of the complex Os3(CO)10(µ-H)(µ-η3-C(dCHPh)CtCW(O)2-
(C5Me5)) (1b) with thermal ellipsoids shown at the 30%
probability level.
complex Os3(CO)10(µ-AuPEt3)(µ-η3-C3H5),8 in which the
AuPEt3 ligand is isolobal with a hydride, whereas the
allyl ligand, adapting a µ2-η3-mode and serving as a
three-electron donor, is found to coordinate to equatorial
sites on the triosmium triangle, not the axial sites.
Another notable feature is the pendant (C5Me5)W(O)2
fragment that resides above equatorial CO ligands on
the atom Os(2). The lengths of bonds between the W
atom and terminal oxo ligands (W-O(11), W-O(12) )
1.71(1) Å) are similar to the average WdO distance
observed in the anionic complex [(C5Me5)W(O)3][PPN]9
and in the parent dioxo complex (C5Me5)W(O)2(Ct
CPh).10
The structure of 1a evidently represents one isomeric
structure detected in 1H NMR spectra. The second
structure (1b) is established with X-ray diffraction study
of another single crystal obtained from a mixed solution
of THF and methanol at -20 °C. Preliminary X-ray
analysis indicates that the cell parameters of 1b are not
the same as those of 1a . For example, the unit cell
volume of 1b is substantially greater, indicating a less
efficient packing for molecules in the solid state. This
observation prompted us to undertake the next single-
crystal X-ray analysis.
plex is relatively unstable, forming some intractable
materials on dissolution in air at room temperature. As
such, its recrystallization must be carried out at -20
°C and no attempt was made to obtain microanalysis
data because of the poor thermal stability. In contrast,
the second, red-orange band is more stable and consists
of the complex (C5Me5)W(µ-O)2Os3(CO)9(µ-σ: η2-Ct
CCHCHPh) (3). Its formation is a result of competitive
loss of CO and coordination of the (C5Me5)W(O)2 unit
to the osmium framework, a sequence which is typical
for the related oxo carbonyl cluster compounds.12
Ch a r a cter iza tion of 2 a n d 3. For complex 2, the
FAB mass spectrum shows parent molecular ions as-
signed to C20H10H8Os3; the IR spectrum in the ν(CO)
region closely resembles that of the compound Os3-
(CO)10(µ-H)(µ-σ:η2-CtCPh).13 Furthermore, the 13C
NMR spectrum was then recorded at 220 K, giving eight
13C NMR signals in the region δ 142.4-79.4, attributed
to a µ-CtCCHdCHPh fragment. Six sharp 13C NMR
signals at δ 182.6, 182, 178.4, 175.3, 171.4, and 170.0
with intensity ratio 1:1:2:2:2:2 are also observed, show-
As indicated in Figure 2, the structure of 1b differs
little from that of 1a , consisting of three fundamental
building blocks: a triangular Os3(CO)10 unit, a bridging
(11) (a) Band, E.; Muetterties, E. L. Chem. Rev. 1978, 78, 639. (b)
Humphries, A. P.; Kaesz, H. D. Prog. Inorg. Chem. 1979, 25, 146. (c)
Farrugia, L. J . Adv. Organomet. Chem. 1990, 31, 301.
(12) (a) Blenkiron, P.; Carty, A. J .; Peng, S.-M.; Lee, G.-H.; Su, C.-
J .; Shiu, C.-W.; Chi, Y. Organometallics 1997, 16, 519. (b) Chao, W.-
J .; Chi, Y.; Chung, C.; Carty, A. J .; Delgado, E.; Peng, S.-M.; Lee, G.-
H. J . Organomet. Chem. 1998, 565, 3.
(13) (a) Deeming, A. J .; Hasso, S.; Underhill, M. J . Chem. Soc.,
Dalton Trans. 1975, 1614. (b) Koridze, A. A.; Kizas, O. A.; Petrovskii,
P. V.; Kolobova, N. E.; Struchkov, Yu. T.; Yanovsky, A. I. J . Organomet.
Chem. 1988, 338, 81.
(8) Housecroft, C. E.; J ohnson, B. F. G.; Lewis, J .; Lunniss, J . A.;
Owen, S. M.; Raithby, P. R. J . Organomet. Chem. 1991, 409, 271.
(9) (a) Rau, M. S.; Kertz, C. M.; Mercando, L. A.; Geoffroy, G. L.;
Rheingold, A. L. J . Am. Chem. Soc. 1991, 113, 7420. (b) Rau, M. S.;
Kretz, C. M.; Geoffroy, G. L. Organometallics 1993, 12, 3447.
(10) Shiu, C.-W.; Su, C.-J .; Pin, C.-W.; Chi, Y.; Peng, S.-M.; Lee, G.-
H. J . Organomet. Chem. 1997, 545-546, 151.

A W-Os Heterometallic Complex
Organometallics, Vol. 18, No. 9, 1999 1679
Sch em e 2
ing the acetylide ligand undergoing a facile σ f π, π f
σ rearrangement, which produces a time-averaged plane
of mirror symmetry bisecting the entire molecule. The
CO chemical shifts observed and the respective dynamic
behavior are all consistent with those of the complex
Os3(CO)10(µ-H)(µ-σ:η2-CtCPh). In addition, the 1H
NMR spectrum exhibits a signal at δ -16.51, charac-
teristic of hydride bridging a Os-Os bond, a doublet at
δ 7.71, and a multiplet centered at δ 7.29 due to the
phenyl group. Notably, a pair of doublets at δ 6.67 and
Os-Os edge to another during crystallization. A crystal
polymorphism involving the hydride ligand has been
documented for the cluster Ru6(µ-H)(µ6-B)(CO)17,16 in
which the isomeric pairs differ in the rotameric confor-
mation of Ru(CO)3 units and in the location of hydride.
Other isomerism that is relevant to the present study
is also observed in the compounds Ir6(CO)16 and Ru6-
(µ6-C)(CO)17.17 As they possess no bridging hydride
ligand, the isomerism arises entirely from the disposi-
tion of CO ligands with respect to the central cluster
framework.
3
5.94 with the coupling constant J HH ) 12.2 Hz are
observed, which pertain to olefinic protons that are cis-
disposed.
On the other hand, the structure of 3 is assigned with
reasonable certainty from FAB MS analysis and from
the analysis of the IR ν(CO) spectrum in the region
2088-1937 cm-1. Agreement between this ν(CO) pat-
tern with those observed for the structurally character-
ized complexes CpW(µ-O)2Os3(CO)9(µ-H)14 and (C5-
Me5)W(µ-O)2Os3(CO)9(µ-σ:η2-CtCPh)15 is excellent.
Thus, the cluster core geometry can be definitely as-
signed to have the symmetrical butterfly skeletal ar-
rangement of a (C5Me5)W(µ-O)2Os3(CO)9 unit. In agree-
ment with this assignment, the 13C NMR spectrum
shows a time-averaged, five-line pattern for Os-CO
signals at δ 187.2, 185.4, 177.6, 172.4, and 168.9 with
intensity ratio 1:2:2:2:2. The 1H NMR spectrum exhibits
the expected signals for the phenyl group and two
doublets at δ 6.47 and 6.14 assigned to the CHdCHPh
Furthermore, a mechanism leading to formation of 2
and 3 can be deduced according to their structures.
Complex 3 is clearly produced in a sequence involving
decarbonylation and migration of hydride to the µ-η3-
CtCCdCHPh ligand. Formation of this cis-CtCCHd
CHPh ligand favors a pathway involving direct transfer
of hydride to the CtCCdCHPh ligand of 1; otherwise,
production of a mixture of trans and cis isomers is
envisaged. In contrast, the formation of 2 seems to
involve removal of the (C5Me5)W(O)2 unit and concomi-
tant addition of a hydrogen atom. This novel process is
reminiscent of conversion from the heterometallic oxo
carbonyl complex Ru3(CO)8(µ3-NPh)(µ-η4-CH2CMeCt
CW(O)2(C5Me5)) to the triruthenium complex Ru3(CO)9-
[CH2CMeCC(CONHPh)CO] (Scheme 2).18 To under-
stand how this reaction occurs, imagine that an H2O
molecule (or an equivalent) is introduced into the
reaction system by chance or during workup. In effect,
it reacts with the (C5Me5)W(O)2 fragment, giving off the
unstable [(C5Me5)W(O)2OH] and a proton. The coproduct
[(C5Me5)W(O)2OH] adsorbs on silica gel, and the proton
remains on the cluster framework to afford the isolated
homometallic complex 2. This postulation has been
3
unit. The coupling constant J HH ) 11.9 Hz is essentially
identical with that observed in 2, demonstrating the
same cis-disposition of the CHdCHPh unit.
Su m m a r y. Complex 1 forms three isomers in solution
and maintains a constant ratio of isomers in solvents
such as CD2Cl2 and d8-THF. The structures of 1a and
1b represent an unique example of tetrametallic clus-
ters identified by X-ray diffraction to have a hydride
located on two distinct positions of the cluster frame-
work. The reason for variation of the solid-state struc-
ture is unclear but may be associated with the polarity
of solvents used for recrystallization. It is possible that
the interaction of solvent molecules with oxo ligands
perturbs packing of the (C5Me5)W(O)2 pendant within
the molecule, inducing the hydride to move from one
1
substantiated by in situ H NMR studies, which indicate
almost no formation of 2 prior to chromatographic
separation.
(14) Chi, Y.; Hwang, L.-S.; Lee, G.-H.; Peng, S.-M. J . Chem. Soc.,
Chem. Commun. 1988, 1456.
(15) (a) Shiu, C.-W.; Chi, Y.; Carty, A. J .; Peng, S.-M.; Lee, G.-H.
Organometallics 1997, 16, 5368. (b) Shiu, C.-W.; Chi, Y.; Chung, C.;
Peng, S.-M.; Lee, G.-H. Organometallics 1998, 17, 2970.
(16) (a) Draper, S. M.; Housecroft, C. E.; Keep, A. K.; Matthews, D.
M.; Song, X.; Rheingold, A. L. J . Organomet. Chem. 1992, 423, 241.
(b) Hong, F.; Coffy, T. L.; McCarthy, D. A.; Shore, S. G. Inorg. Chem.
1989, 28, 3284.
(17) (a) Garlaschelli, L.; Martinengo, S.; Bellon, P. L.; Demartin,
F.; Manassero, M.; Chiang, M. Y.; Wei, C. Y.; Bau, R. J . Am. Chem.
Soc. 1984, 106, 6664. (b) Braga, D.; Grepioni, F.; Dyson, P. J .; J ohnson,
B. F. G.; Frediani, P.; Bianchi, M.; Piacenti, F. J . Chem. Soc., Dalton
Trans. 1992, 2565.
Ack n ow led gm en t. We thank the National Sciences
Council of Taiwan (NSC Grant No. 87-2113-M007-047)
for support of this work.
Su p p or t in g In for m a t ion Ava ila b le: Tables of non-
essential crystal data, bond lengths, atomic coordinates, and
corresponding anisotropic thermal parameters for structures
1a and 1b. This material is available free of charge via the
Internet at http://pubs.acs.org.
(18) Pin, C.-W.; Chi, Y.; Chung, C.; Carty, A. J .; Peng, S.-M.; Lee,
G.-H. Organometallics 1998, 17, 4161.
OM980957Z