Synthesis, structures and reactivity of bis(diphenylphosphino)-methane (dppm)-substituted selenido osmium carbonyl clusters

Article abstract of DOI:10.1016/S0022-328X(03)00627-2

The unsaturated cluster [(μ-H)Os₃(CO)₈ {Ph₂PCH₂P(Ph)C₆H₄}] (2) reacts with elemental selenium at 110 °C to give two triosmium clusters [Os₃(CO)₇(μ₃-Se)₂ (μ-dppm)] (3), [Os₃(CO)₇(μ₃-CO) (μ₃-Se)(μ-dppm)] (4) and the tetraosmium cubane-like cage cluster [Os₄(CO)₁₀(μ₃-Se) ₄(μ-dppm)] (5) in 20, 47 and 5% yields, respectively. Treatment of the labile cluster [Os₃(CO)₁₀(MeCN) ₂] with dppmSe at ambient temperature gives the dinuclear compound [Os₂(CO)₆(μ-Se)(μ-dppm)] (6) along with 3 and 4 in 13, 24 and 4% yields, respectively, while with dppmSe₂ at 80 °C it yields 3 and 5 in 27 and 7% yields, respectively, by oxidative transfer of selenium atoms to the metal center. The reaction of 3 with Me₃NO at 80 °C leads to loss of 1 mol of CO and formation of the condensation derivative [Os₆(CO)₁₂(μ₃-Se)₄ (μ-dppm)₂] (7), containing a central 64-electron butterfly core, in 75% yield. Compound 7 reacts with CO at 98 °C to regenerate 4 by cleavage of the three unsupported metal-metal bonds. In the disubstituted square-pyramidal selenido cluster, 3, the dppm ligand bridges two bonded osmium atoms whereas in 7 both the dppm ligands bridge the open osmium-osmium edges. Treatment of 3 with PPh₃ in the presence of Me₃NO at room temperature gives the phosphine-substituted compound [Os₃(CO)₆ (μ₃-Se)₂(μ-dppm)(PPh₃)] (8) and the dimer 6 in 26 and 20% yields, respectively. The structure of 8 is comparable with that of 3 from which it is derived by replacing one equatorial carbonyl group with the PPh₃ ligand. The molecular structures of the complexes 3, 4, 6, 7 and 8 have been fully elucidated by single-crystal X-ray diffraction studies.

Full text of DOI:10.1016/S0022-328X(03)00627-2

Journal of Organometallic Chemistry 681 (2003) 237Á249
/
www.elsevier.com/locate/jorganchem
Synthesis, structures and reactivity of bis(diphenylphosphino)-
methane (dppm)-substituted selenido osmium carbonyl clusters
Shariff E. Kabir, * a, Salina Pervin a, Nitai C. Sarker a, Afroza Yesmin a,
Ayesha Sharmin a, Tasneem A. Siddiquee b, Daniel T. Haworth b,
Dennis W. Bennett b,*, K.M. Abdul Malik c
a Department of Chemistry, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh
b Department of Chemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA
c Department of Chemistry, Cardiff University, P.O. Box 912, Park Place, Cardiff CF10, UK
Received 17 January 2003; received in revised form 30 May 2003; accepted 16 June 2003
Abstract
The unsaturated cluster [(m-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] (2) reacts with elemental selenium at 110 8C to give two
triosmium clusters [Os3(CO)7(m3-Se)2(m-dppm)] (3), [Os3(CO)7(m3-CO)(m3-Se)(m-dppm)] (4) and the tetraosmium cubane-like cage
cluster [Os4(CO)10(m3-Se)4(m-dppm)] (5) in 20, 47 and 5% yields, respectively. Treatment of the labile cluster [Os3(CO)10(MeCN)2]
with dppmSe at ambient temperature gives the dinuclear compound [Os2(CO)6(m-Se)(m-dppm)] (6) along with 3 and 4 in 13, 24 and
4% yields, respectively, while with dppmSe2 at 80 8C it yields 3 and 5 in 27 and 7% yields, respectively, by oxidative transfer of
selenium atoms to the metal center. The reaction of 3 with Me3NO at 80 8C leads to loss of 1 mol of CO and formation of the
condensation derivative [Os6(CO)12(m3-Se)4(m-dppm)2] (7), containing a central 64-electron butterfly core, in 75% yield. Compound
7 reacts with CO at 98 8C to regenerate 4 by cleavage of the three unsupported metalꢀ
pyramidal selenido cluster, 3, the dppm ligand bridges two bonded osmium atoms whereas in 7 both the dppm ligands bridge the
open osmiumÁosmium edges. Treatment of 3 with PPh3 in the presence of Me3NO at room temperature gives the phosphine-
/
metal bonds. In the disubstituted square-
/
substituted compound [Os3(CO)6(m3-Se)2(m-dppm)(PPh3)] (8) and the dimer 6 in 26 and 20% yields, respectively. The structure of 8 is
comparable with that of 3 from which it is derived by replacing one equatorial carbonyl group with the PPh3 ligand. The molecular
structures of the complexes 3, 4, 6, 7 and 8 have been fully elucidated by single-crystal X-ray diffraction studies.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Selenium ligands; Triosmium clusters; Tetraosmium clusters; Crystal structure
1. Introduction
plays a key role in stabilizing the cluster bonding
network and frequently introduces novel structural
and reactivity features [2,3]. There are numerous exam-
ples of the synthesis and reactivity of simple trinuclear
clusters of iron, ruthenium and osmium and their
monophosphine derivatives containing capping chalco-
Transition metal clusters containing chalcogenido
ligands have important chemical and structural signifi-
cance, since they can be regarded as discrete molecular
models of extended inorganic solids with novel electro-
nic, magnetic and optical properties and can be used in
cluster growth reactions [1,2]. Furthermore, the combi-
nation of chalcogen elements and transition metals often
genido ligands [4Á6]. In contrast, there are few reports
/
concerning the synthesis and reactivity of diphosphine-
substit uted chalcogenido trimetallic carbonyl clusters.
A simple one-step synthetic methodology for the
monophosphine and diphosphine-substituted selenido
trimetallic compounds of iron and ruthenium has been
* Corresponding authors. Tel.: ꢀ
5530.
E-mail
dwbent@uwm.edu (D.W. Bennett).
/
1-414-229-5276; fax: ꢀ
/
1-414-229-
Kabir),
developed by exploiting the lability of the Pꢁ
/E bond of
the tertiary phosphine chalcogenides, which allows for
the facile formation of phosphine-substituted chalco-
addresses:
skabir_ju@yahoo.com (S.E.
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00627-2

238
S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á249
/
genido clusters through oxidative transfer of chalcogen
atoms to low valent metal centers [5Á7]. Despite the
unless specified otherwise. Reagent grade solvents were
dried and distilled prior to use by standard methods.
Black selenium, triphenylphosphine and dppm were
purchased from Aldrich and used as received. Infrared
spectra were recorded on a Shimadzu FTIR 8101
spectrophotometer. 1H- and 31P{1H}-NMR spectra
were recorded on a Bruker DPX 400 spectrometer.
The elemental analysis was performed at the Micro-
analytical Laboratory of the Chemistry Department at
the University College London. The compounds [(m-
/
synthetic potential of the diphosphine selenides, their
reactions with osmium carbonyl clusters have not thus
far been explored. The simple triosmium selenido
compounds [Os3(CO)9(m3-Se)2], obtained from the ther-
molysis
of
[Os3(CO)10(m-SePh)2]
and
[(m-
H)2Os3(CO)9(m3-Se)], synthesized from the reaction of
[Os3(CO)12] with elemental selenium at 128 8C were
described in the literature a number of years ago [4d].
Other selenido osmium carbonyl cluster compounds,
such as Os4(CO)12(m3-Se)2 have been prepared by the
reaction of substituted osmium carbonyl cluster com-
pounds with PhSeH, followed by the thermal elimina-
tion of benzene [4e]. However, to our knowledge, little is
known about the phosphine and diphosphine-substi-
tuted derivatives of these selenido osmium carbonyl
cluster compounds.
H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}]
[14]
(2),
[Os3(CO)10(MeCN)2] [21], dppmSe [22] and dppmSe2
[22] were prepared according to literature procedures.
2.1. Reaction of [(m-
H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] (2) with
elemental selenium
The chemistry of the bridging dppm triosmium cluster
[Os3(CO)10(m-dppm)] (1) and its orthometallated deri-
vative [(m-H)Os3(CO)8{Ph2PCH2P(Ph)C6H4}] (2) has
To a toluene solution (20 ml) of 2 (0.102 g, 0.087
mmol) was added elemental black selenium (0.015 g,
0.190 mmol) and the reaction mixture was heated to
reflux for 1.5 h during which time analytical TLC
indicated complete consumption of 2. The solvent was
removed under reduced pressure and the residue was
chromatographed by TLC on silica gel. Elution with
hexane/CH2Cl2 (3:1, v/v) produced three bands. The
faster-moving band afforded [Os3(CO)7(m3-Se)2(m-
dppm)] (3) (0.023 g, 20%) as orange crystals after
recrystallization from hexane/CH2Cl2 at 20 8C. IR
(nCO, CH2Cl2): 2067 vs, 2000 vs, 1985 sh, 1944 s
been studied by several groups [8Á19] and continues to
/
be the focus of considerable attention. The interest in
these complexes is due not only to the special ability of
the diphosphine ligand to maintain the structural
integrity of the metal cluster framework during chemical
reactions, but also because of the unsaturated nature of
2, which allows it to react with various small inorganic
and organic molecules such as CO [9], H2 [10], PPh3 [11],
P(OMe)3 [11], PPh2H [12], PhCꢂ/CPh [13],
[Au(PPh3)]PF6 [14], HBF4 [14], [Sn{CH(SiMe3)2}2]
[15], EtSH [16], PhSH [16], pySH [17], pymSH [17],
HSCH2CH2SH [18], HSCH2CH2CH2SH [18] and
CH2N2 [19] to give many interesting and potentially
useful compounds. We have recently reported [20] the
cmꢁ1 1H-NMR (CDCl3): d 7.80 (m, 2H), 7.41 (m,
;
13H), 7.13 (m, 1H), 7.05 (m, 2H), 6.74 (m, 2H), 5.93 (m,
1H), 3.93 (m, 1H) ppm; 31P{1H}-NMR (CDCl3): d
ꢁ
/
7.6 (d, Jꢂ
/
92.4 Hz), ꢁ
/
23.1 (d, Jꢂ92.4 Hz) ppm;
/
synthesis
and
structural
characterization
of
mass spectrum: m/z 1310. Anal. Calc. for
C32H22O7Os3P2Se2: C, 29.36; H, 1.70; P, 4.73. Found:
C, 29.48; H, 1.82; P, 4.91%.
[Os3(CO)7(m3-S)2(m-dppm)] as two separable isomeric
forms from the reaction of [Os3(CO)10(m-dppm)] with
tetramethylthiourea at 110 8C.
The second band gave [Os3(CO)7(m3-CO)(m3-Se)(m-
We report here the results of our investigation on the
reactivity of the unsaturated triosmium cluster 2 with
elemental selenium and the labile triosmium cluster
[Os3(CO)10(MeCN)2] with dppmSe and dppmSe2. Of
particular interest is the establishment of the viability of
the synthesis of triply bridging selenido triosmium
clusters containing the bridging dppm ligand and the
exploration of their derivative chemistry. These com-
pounds are believed to be the first examples of osmium
clusters containing bridging dppm and selenium ligands
to be structurally characterized.
dppm)] (4)×
/
CH2Cl2 (0.055 g, 47%) as yellow crystals
from hexane/CH2Cl2 at ꢁ
/
4 8C by slow evaporation of
the solvents. IR (nCO, CH2Cl2): 2071 s, 2016 vs, 1995 s,
1
1960 m cmꢁ1; IR (nCO, KBr): 1734 s cmꢁ1; H-NMR
(CDCl3): d 7.63 (m, 4H), 7.41 (m, 4H), 7.26 (m, 4H),
7.18 (m, 4H), 5.27 (m, 1H), 3.41 (m, 1H) ppm; 31P{1H}-
NMR (CDCl3): d ꢁ21.2(s) ppm; mass spectrum: m/z
/
1258. Anal. Calc. for C34H24Cl2O8Os3P2Se: C, 30.41; H,
1.80; P, 4.61. Found: C, 30.58; H, 1.93; P, 4.85%. The
third band afforded [Os4(CO)10(m3-Se)4(m-dppm)] (5)
(0.008 g, 5%) as yellow crystals from hexane/CH2Cl2
at ꢁ
1992 vs, 1948 m cmꢁ1; H-NMR (CD2Cl2): d 7.36 (m,
20H), 4.07 (t, 2H, Jꢂ
11.6 Hz) ppm; 31P{1H}-NMR
(CD2Cl2): d ꢁ7.4(s) ppm; mass spectrum: m/z 1740.
/
4 8C. IR (nCO, CH2Cl2): 2091 m, 2075 s, 2017 s,
1
2. Experimental
/
/
All reactions were routinely performed under a
nitrogen atmosphere using standard Schlenk techniques
Anal. Calc. for C35H22O10Os4P2Se4: C, 24.14; H, 1.28; P,
3.56. Found: C, 24.32; H, 1.45; P, 3.72%.

S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á
/249
239
2.2. Reaction of [Os3(CO)10(MeCN)2] with dppmSe
To dichloromethane solution (30 ml) of
2562. Anal. Calc. for C62H44O12Os6P4Se4: C, 29.06; H,
1.73; P, 4.84. Found: C, 29.35; H, 1.27, P, 4.96%.
a
[Os3(CO)10(MeCN)2] (0.225 g, 0.241 mmol) was added
dppmSe (0.168 g, 0.363 mmol) and the reaction mixture
was stirred at room temperature for 48 h. The solvent
was removed under reduced pressure and the residue
was chromatographed by TLC on silica gel. Elution
with hexane/acetone (3:2, v/v) developed three major
and several very minor bands. The faster moving yellow
band gave [Os2(CO)6(m-Se)(m-dppm)] (6) (0.032 g, 13%)
as yellow crystals after recrystallization from hexane/
CH2Cl2 at room temperature. IR (nCO, CH2Cl2): 2098
w, 2073 vs, 2035 vs, 1998 m, 1977 w, 1963 m cmꢁ1; 1H-
NMR (CDCl3): d 7.43 (m, 20H), 4.95 (m, 1H), 3.36 (m,
1H) ppm; methylene signals are ‘‘apparent quartets’’ due
to overlapping triplets. 31P{1H}-NMR (CDCl3): d
2.5. Reaction of 3 with PPh3 in presence of Me3NO
To a dichloromethane solution of 3 (0.045 g, 0.034
mmol) and PPh3 (0.018 g, 0.068 mmol) was added
dropwise a solution of anhydrous Me3NO (0.005 g,
0.067 mmol) in the same solvent (10 ml) over a period of
10 min. The reaction mixture was stirred at room
temperature for 3 h during which time analytical TLC
indicated complete consumption of 3. Work-up fol-
lowed by chromatographic separation as above devel-
oped two bands. The yellow band yielded [Os3(CO)6(m3-
Se)2(m-dppm)(PPh3)] (8) (0.014 g, 26%) as yellow
crystals after recrystallization from hexane/CH2Cl2 at
4 8C. IR (nCO, CH2Cl2) 2014 s, 1989 vs, 1941 vs, 1928 m
cmꢁ1; 1H-NMR (CD2Cl2): d 7.31 (m, 20H), 5.36 (q, 1H,
ꢁ23.6(s) ppm; mass spectrum: m/z 1012. Anal. Calc.
/
for C31H22O6Os2P2Se: C, 36.80; H, 2.20; P, 6.12. Found:
C, 36.92; H, 2.35; P, 6.12%. The second band gave 3
(0.0075 g, 24%) while the third band yielded 4 (0.013 g,
4%). Each of the minor bands gave a small amount of
unidentified product.
Jꢂ
NMR (CD2Cl2): d 13.1(s), ꢁ
(d, Jꢂ40.0 Hz) ppm; mass spectrum: m/z 1542. Anal.
/
11.4 Hz), 3.81 (q, 1H, Jꢂ
/
11.2 Hz) ppm; 31P{1H}-
40.0 Hz), ꢁ19.1
/
6.8 (d, Jꢂ
/
/
/
Calc. for C49H37O6Os3P3Se2: C, 38.13; H, 2.42; P, 6.02.
Found: C, 38.27; H, 2.52; P, 6.15%. The green band
afforded 7 (0.009 g, 20%).
2.3. Reaction of [Os3(CO)10(MeCN)2] with dppmSe2
2.6. Reaction of 7 with CO
A benzene solution (100 ml) of [Os3(CO)10(MeCN)2]
(0.205 g, 0.220 mmol) and dppmSe2 (0.196 g, 0.361
mmol) was heated to reflux for 2 h. The solvent was
removed under reduced pressure and the residue was
chromatographed by TLC on silica gel. Elution with
hexane/CH2Cl2 (7:3, v/v) developed two bands. The first
band yielded 3 (0.079 g, 27%), while the second band
afforded 5 (0.016 g, 7%) as orange crystals after
recrystallization from hexane/CH2Cl2 at room tempera-
ture.
Carbon monoxide gas was bubbled through a reflux-
ing heptane solution (30 ml) of 7 (0.015 g, 0.006 mmol)
for 3 h. The color changed from green to yellow. The
solvent was removed under reduced pressure and the
residue was chromatographed by TLC on silica gel.
Elution with hexane/CH2Cl2 (3:1, v/v) gave a single
band which afforded 3 (0.012 g, 80%).
2.7. Attempted reaction of 1 with elemental selenium
To a toluene solution of 1 (0.0026 g, 0.021 mmol) was
added black selenium (0.004 g, 0.051 mmol) and the
reaction mixture was heated to reflux for 3 h. Usual
work-up followed by chromatographic separation af-
forded several very minor bands each of which afforded
very small amount of intractable material.
2.4. Reaction of 3 with Me3NO
A toluene solution (30 ml) of 3 (0.126 g, 0.096 mmol)
and anhydrous Me3NO (0.011 g, 0.146 mmol) was
heated at 80 8C for 20 min during which time the color
changed from orange to green. The reaction solution
was filtered through a short silica gel column to remove
excess anhydrous Me3NO. The solvent was removed
under reduced pressure and the residue was chromato-
graphed by TLC on silica gel. Elution with hexane/
CH2Cl2 (3:2, v/v) developed a green band which
afforded [Os6(CO)12(m3-Se)4(m-dppm)2] (7) (0.093 g,
75%), as green crystals after recrystallization from
heptane/CH2Cl2 at room temperature. IR (nCO,
CH2Cl2) 2031 w, 2015 vs, 1981 s, 1950 s, 1894 w
2.8. X-ray structural determination of 4 and 6
Crystallographic and other experimental data are
summarized in Table 1. Crystallographic data were
collected at 120 K, using a Bruker-Nonius CCD area
detector diffractometer and MoÁ
/
Ka radiation (lꢂ
/
˚
0.71073 A). Data collection and processing were carried
out using the programs COLLECT [23] and DENZO [24].
Empirical absorption corrections were applied to the
data sets using multiple and symmetry-related data
measurements via the program SORTAV [25,26]. The
unit cells were indexed from all observed reflections in a
cmꢁ1
4H) ppm; 31P{1H}-NMR (CD2Cl2): d ꢁ
15.6), ꢁ11.11 (d, Jꢂ17.2) ppm; mass spectrum: m/z
;
1H-NMR (CDCl3): d 7.29 (m, 40H), 4.28 (t,
/
10.92 (d, Jꢂ
/
/
/

240
S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á249
/
Table 1
Crystallographic data for 3, 4, 6, 7 and 8
3
4×
/
CH2Cl2
6
7
8
Empirical formula
Formula weight
Temperature (K)
C
32H22O7Os3P2Se2
C33H22O8Os3P2Se
1342.93
120(2)
C31H22O6Os2P2Se
1011.79
150(2)
C62H44C10O12Os6P4Se3
2482.93
293(2)
C48H35O6Os3P3Se2
1529.19
293(2)
1308.96
293(2)
0.71073
˚
Wavelength (A)
0.71073
Triclinic
¯
P1
0.71073
Monoclinic
C2/c
0.71073
Monoclinic
P21/c
0.71073
Monoclinic
P21/n
Crystal system
Space group
Unit cell
Triclinic
¯
P1
/
/
dimensions
˚
a (A)
˚
10.1870(10)
11.1430(10)
17.873(2)
74.580(10)
84.660(10)
64.400(10)
1763.2(3)
2
9.07250(10)
10.70790(10)
19.0488(3)
86.4630(10)
86.5990(10)
81.5570(10)
1824.63(4)
2
22.6088(2)
12.44590(10)
24.2228(3)
90
18.234(8)
19.37(2)
20.396(10)
90.01(7)
75.21(3)
90.03(5)
6964(9)
4
14.736(3)
12.301(4)
26.897(7)
90
b (A)
˚
c (A)
a (8)
b (8)
115.7778(6)
90
98.61(2)
90
g (8)
3
V (A )
˚
6137.70(11)
8
9.606
4821(2)
4
9.544
Z
Absorption coeffi- 12.982
cient (cmꢁ1
Crystal size (mm3) 0.20ꢃ
11.701
12.619
)
/0.25ꢃ
/0.30
0.45ꢃ/0.16ꢃ
/0.16
0.25ꢃ
/
0.08ꢃ
/
0.06
0.163ꢃ/0.09ꢃ
/0.06
0.34ꢃ/0.17ꢃ0.13
/
Reflections
collected
4014
22402
42205
3604
3174
Independent
reflections
Refinement
method
3270 [Rint
ꢂ
/
0.0240]
6399 [Rint
ꢂ
/
0.1223]
7013 [Rint
ꢂ
/
0.0472]
2807 [Rint
ꢂ
/
0.0822]
2295 [Rint
ꢂ0.0659]
/
Full-matrix least-
squares on F2
Full-matrix least-
squares on F2
0.957
Full-matrix least-
squares on F2
1.072
Full-matrix least-squares Full-matrix least-
on F2
1.065
squares on F2
1.104
Goodness-of-fit on 1.089
F2
Final R indices
[I ꢀ2s(I)]
R indices (all data) R1ꢂ
wR2ꢂ
R1ꢂ
wR2ꢂ
0.0382,
0.936
/
0.0353,
R1ꢂ
wR2ꢂ
R1ꢂ0.0782,
wR2ꢂ0.1669
/
0.0742,
R1ꢂ
wR2ꢂ
R1ꢂ0.0315,
wR2ꢂ0.0575
/
0.0252,
R1ꢂ
wR2ꢂ
R1ꢂ0.1093,
wR2ꢂ0.1844
/
0.0677,
R1ꢂ
wR2ꢂ
R1ꢂ0.0766,
wR2ꢂ0.1762
/
0.0621,
/
/
0.0909
/0.1634
/0.0550
/0.1601
/
0.1575
/
/
/
/
/
/
/
/
/
/
1=2
/
R1 ꢂa½½Fo½ꢁ½Fc½½=a½Fo½; wR2 ꢂ½a[w(Fo2 ꢁFc2)=a[w(Fo2)2]ꢀ
;
wꢂ1=[s2(Fo2)ꢀ(a1P)2 ꢀa2P] where Pꢂ(Fo2 ꢀFc2)=3:
/
u-range of 108 and refined using the entire data sets. The
structures were solved by direct methods (SHELXS-97
[27] and refined on F2 by full-matrix least-squares
SHELXL-97) [28] using all unique data. All non-hydrogen
atoms were refined anisotropically. Hydrogen atoms
were included in calculated positions (riding model) with
Uiso set at 1.2 times the Ueq of the parent atom. Selected
bond lengths and angles for 4 and 6 are given in Tables 3
and 4, respectively.
hydrogen atoms for 3 were refined anisotropically.
Carbon atoms for 7 and 8 were refined isotropically,
with all other atoms refined anisotropically. Hydrogen
atoms were included in calculated positions (riding
model) with Uiso set at 1.2 times the Ueq of the parent
atom. Selected bond lengths and angles for 3 and 7 and
8 are given in Tables 2, 5 and 6, respectively.
)
(
3. Results and discussion
2.9. X-ray structural determination of 3, 7 and 8
The 46 electron cluster [(m-H)Os3(CO)8{Ph2PCH2-
P(Ph)C6H4}] (2) reacts with elemental selenium at
80 8C to give, after chromatographic separation, two
triosmium clusters and one tetraosmium cluster,
[Os3(CO)7(m3-Se)2(m-dppm)] (3), [Os3(CO)7(m3-CO)(m3-
Se)(m- dppm)] (4) and [Os4(CO)10(m3-Se)4(m-dppm)] (5)
in 20, 47 and 5% yields, respectively (Scheme 1).
Compound 3 has been characterized by a combination
of infrared, 1H- and 31P{1H}-NMR spectroscopies,
FAB mass spectrometry, elemental analysis and a
single-crystal X-ray diffraction study. The molecular
structure of 3 is shown in Fig. 1, and selected bond
Crystallographic and other experimental data are
summarized in Table 1. Crystallographic data were
collected at 296 K, using a Bruker P4 diffractometer
˚
with MoÁ
/
Ka radiation (lꢂ
/
0.71073 A). Data collection
and processing were carried out using XSCANS [29]. The
unit cells were indexed on low angle reflections and
refined from 25 reflections in a u-range of 128Á
structures were solved by direct methods (SHELXS-97
[27] and refined on F2 by full-matrix least-squares
SHELXL-97) [28], utilized as incorporated in the WINGX
[30] program package using all unique data. All non-
/
138. The
)
(

S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á
/249
241
Table 2
˚
Selected interatomic distances (A) and angles (8) for 3
Interatomic distances
s(1)ꢀ
Os(1)ꢀ
Os(1)ꢀ
Os(1)ꢀ
Os(2)ꢀ
Os(2)ꢀ
Os(3)ꢀ
Os(3)ꢀ
Os(1)ꢀ
Os2ꢀP(1)
Os(2)ꢀOs(3)
Se(1)ꢀSe(2)
OsꢀC(CO) (average)
CꢀO (average)
PꢀC (average)
/
Os(2)
2.8742(7)
2.8330(7)
2.5404(13)
2.5757(13)
2.4773(13)
2.5277(12)
2.4987(14)
2.5264(12)
2.313(3)
2.356(3)
3.812
/
Os(3)
Se(1)
Se(2)
Se(1)
Se(2)
Se(1)
Se(2)
P(2)
/
/
/
/
/
/
/
/
/
/
3.246
/
1.89(2)
/
1.13(2)
/
1.84(2)
Scheme 1.
Interatomic angles
Se(1)ꢀ
Se(1)ꢀ
Se(2)ꢀ
P(2)ꢀOs(1)ꢀ
Se(1)ꢀOs(1)ꢀ
Se(2)ꢀOs(1)ꢀ
Os(3)ꢀOs(1)ꢀ
P(1)ꢀOs(2)ꢀ
P(1)ꢀOs(2)ꢀ
Se(1)ꢀ
P(1)ꢀOs(2)ꢀ
Se(1)ꢀOs(2)ꢀ
Se(2)ꢀOs(2)ꢀ
Se(1)ꢀOs(3)ꢀ
Se(1)ꢀOs(3)ꢀ
Se(2)ꢀOs(3)ꢀ
Os(3)ꢀSe(2)ꢀ
Os(3)ꢀSe(2)ꢀ
Os(2)ꢀSe(2)ꢀ
Os(2)ꢀSe(1)ꢀ
Os(3)ꢀSe(1)ꢀ
/
Os(1)ꢀ
Os(1)ꢀ
Os(1)ꢀ
/
Se(2)
Se(3)
Se(3)
74.75(4)
55.10(3)
55.45(3)
81.35(7)
54.03(3)
54.93(3)
83.80(2)
153.96(8)
85.65(8)
80.85(4)
97.92(7)
56.09(3)
56.09(3)
80.46(4)
56.49(3)
57.11(3)
97.90(4)
67.45(3)
68.55(3)
69.88(3)
68.41(3)
/
/
/
/
/
/
Os(2)
/
/
Os(2)
/
/
Os(2)
/
/
Os(2)
/
/Se(1)
/
/Se(2)
/
Os(2)ꢀ
/
Se(2)
/
/Os(1)
/
/
Os(1)
Os(1)
Se(2)
Os(1)
Os(1)
Os(2)
Os(1)
Os(1)
Os(1)
Os(1)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Fig. 1. Molecular structure of [Os3(CO)7(m3-Se)2(m-dppm)] (3).
ligands results in an increase in electron density at the
metal centers increasing electronÁelectron repulsion
between the non-bonded osmium atoms [34,35]. Alter-
natively, the expansion of the cluster could be explained
on the basis of steric interactions. In this case, the
substitution of a bulky ligand for a less bulky one would
/
distances and angles are collected in Table 2. The
molecule consists of an open cluster of three metal
atoms with two metalꢀ/metal bonds and seven linear
terminal carbonyl ligands. Two osmium atoms, Os(1)
and Os(2), are each bound to two terminal carbonyls
and to a phosphorus atom from the dppm ligand; Os(3)
also result in an increase in the non-bonded Osꢀ
/Os
distance [36]. In this cluster, there are two triply bridging
(non-bonded) selenium atoms (the separation between
˚
these atoms is 3.246 A) and one doubly bridging dppm
is bound to three terminal carbonyls. The osmiumꢀ
osmium bonding distances in 3 are Os(1)ꢀOs(3)ꢂ
2.8742(7) A, similar to
Os distances observed in [Os3(CO)12]
˚
{2.877(3) A} [31]. The corresponding distances in 1 are
˚
2.7910(11) and 2.8412(12) A [20]. The non-bonding
/
/
/
˚
˚
2.8330(7) A and Os(1)ꢀ
/
Os2ꢂ
/
ligand. In contrast, in [Fe3(CO)7(m3-Se)2(m-dppm)] [7b],
[Fe3(CO)7(m3-Se)2(m-dppe)] [7b], [Fe3(CO)7(m3-Se)2(m-
the average Osꢀ
/
dppfc)]
[7b],
[Ru3(CO)7(m3-Se)2(m-dppm)]
[7c],
˚
3.812 A} is
[Ru3(CO)7(m3-Se)2(m-dppa)] [3a] and [Ru3(CO)7(m3-
Se)2(m-dppe)] [7d] the bidentate phosphine ligand
bridges the two basal metal atoms in the axial positions;
the dppm ligand in 3 bridges one of the bonded pair of
osmiumÁ
/
osmium distance {Os(2)ꢀ
/
Os(3)ꢂ
/
significantly longer than that observed in [Os3(CO)9(m3-
˚
˚
S)2] {3.662(1) A} [32], [Os3(CO)9(m3-Se)2] {3.718 A} [33]
˚
and [Os3(CO)8(m3-S)2(CS)] {3.644 A} [32]. This observa-
tion is consistent with the argument that the substitution
osmium atoms, Os(1) and Os(3). The Os(2)ꢀ
/
P(1)
˚
distance {2.356(3) A, equatorial, transoid to Se} is
of carbonyls with more weakly p-acidic phosphine

242
S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á249
/
significantly longer than the Os(1)ꢀ
/
P(2) distance
˚
{2.313(3) A, axial, transoid to Os}. This observation is
consistent with that suggested by Tiripicchio et al. in
which the MÁP interaction in the 50-electron M3S2
/
nido-clusters experiences a trans stabilizing effect [7d].
The structure can be envisaged as a square-pyramidal
Os3Se2 core with two Os atoms and the Se atoms
alternating in the basal positions and third osmium
atom at the apex of the pyramid. The Osꢀ
/
Se distances to
the central seven coordinated metal atom Os(1), {Os(1)ꢀ
/
˚
˚
2.5707(13) A}
Se(1)ꢂ
are significantly longer than those to the external six-
coordinate metal atoms Os(2) and Os(3) {Os(2)ꢀ
Se(1)ꢂ2.4773(13), Os(2)ꢀSe(2)ꢂ2.5277(12), Os(3)ꢀ
(1)ꢂ2.4987(14), Os(3)ꢀSe(2)ꢂ2.5264(12) A}. A similar
structural feature has also been observed for the
unsubstituted selenium and sulfur analogs
/
2.5404(13) A and Os(1)ꢀ
/
Se(2)ꢂ
/
/
/
/
/
/
˚
/
/
/
[Os3(CO)9(m3-S)2] [32] and [Os3(CO)9(m3-Se)2] [33].
The spectroscopic data of 3 are consistent with the
solid-state structure. The mass spectrum of 3 confirms
the formula [Os3(CO)7(m3-Se)2(m-dppm)], exhibiting the
molecular ion peak at m/z 1308 and peaks due to the
sequential loss of seven carbonyl groups. The infrared
spectrum of 3 exhibits peaks at 2067 vs, 2000 vs, 1985 sh,
1944 s and 1869 w cmꢁ1, indicating the presence of only
terminally bonded carbonyls. The 31P{1H}-NMR spec-
Fig. 2. Molecular structure of [Os3(CO)7(m3-CO)(m3-Se)(m-dppm)] (4).
Os(3) edges are of comparable length {2.8442(7) and
˚
2.8556(8) A, respectively} whereas Os(2)ꢀ
/
Os(3)
Os
distances are shorter than that in the parent carbonyl
˚
{2.8274(8) A} is slightly shorter. All three Osꢀ
/
˚
complex [Os3(CO)12] {2.877(3) A} [31]. The triply
trum of 3 in CDCl3 shows two doublets at d ꢁ
/
7.6 (d,
bridging selenido and the carbonyl ligands lie on
opposite sides of the Os3 triangle resulting in a trigonal
bipyramidal geometry for the Os3(Se)(CO) core. The
Jꢂ 92.4 Hz) and ꢁ23.1 (d, Jꢂ 92.4 Hz) ppm. This
/
/
/
implies the presence of only one isomer with the
phosphorus nuclei in inequivalent environments. The
1H-NMR spectrum shows two multiplets at d 3.93 and
5.93 ppm for the methylene protons and a series of well-
separated multiplets centered at d 6.74, 7.05, 7.13, 7.41
and 7.80 ppm with a relative intensity ratio of 2:2:1:13:2,
respectively, for the phenyl protons of the dppm ligand.
dppm ligand bridges the shortest Os(2)ꢀ
/
Os(3) edge of
the triangle. Of the seven terminal carbonyl ligands two
bonded to each of Os(2) and Os(3) and three to Os(1).
˚
P(1)ꢂ2.342(3) A
The Osꢀ
/
P bond distances in 4 {Os(2)ꢀ
/
/
˚
P(2)ꢂ2.326(3) A} are comparable with the
and Os(3)ꢀ
/
/
1
˚
corresponding distances in 1 {2.332(3) and 2.312(3) A}
[37]. The compound contains 48 valence electrons,
The cluster 4 has been characterized from IR, H-,
31P{1H}-NMR and mass spectroscopic data as well as
by single-crystal X-ray diffraction studies. The infrared
spectrum in the carbonyl stretching region consists of
bands typical of terminal carbonyls, and one strong
band at 1734 cmꢁ1 consistent with the triply bridging
carbonyl ligand. The molecular structure of 4 is shown
in Fig. 2 and selected bond distances and angles are
listed in Table 3. Compound 4 consists of a triangular
cluster of three mutually bonded osmium atoms with
seven terminal carbonyls and a triply bridging carbonyl
ligand, a triply bridging selenido ligand and a bridging
dppm ligand. The geometry of the Os3Se core in which
consistent with three metalꢀ/metal bonds. Overall, the
structure of 4 is similar to that of the sulfur analog
[Os3(CO)7(m3-CO)(m3-S)(m-dppm)], synthesized from the
reaction of 1 with thiourea [20].
The tetranuclear cluster 5 is probably formed either
by the self-assembly of two dinuclear Os2Se2 groups,
derived from 3 by loss of a mononuclear metal fragment
or by addition of an Os(CO)n fragment to 3 along with
addition of two further Se atoms. The latter scenario is
consistent with the observation that there is only a single
diphosphine ligand in the complex. The structural
assignment for 5 is based primarily on infrared spectro-
scopic data. The infrared spectrum of 5 exhibits bands at
2091 s, 2075 s, 2017 vs, 1992 w and 1948 w cmꢁ1, which
are characteristic of terminal carbonyl ligands. No
an isosceles triangle of osmium atoms is symmetrically
˚
Se(1)ꢂ2.5221(13) A,
capped by the Se atom {Os(2)ꢀ
/
/
˚
A
Os(1)ꢀ
/
Se(1)ꢂ
/
2.5123(14)
and
2.5302(15) A} can be described as tetrahedral. In
Os(3)ꢀ
/
Se(1)ꢂ
/
˚
bands are observed in the 1700Á
1900 cmꢁ1 region,
/
contrast, the triply bridging carbonyl ligand is bonded
asymmetrically to the Os3 triangle {Os(1)ꢀ
/
C(1)ꢂ
2.160(14) A and Os(2)ꢀ
2.190(13) A}. The Os(1)ꢀOs(2) and Os(1)ꢀ
/
indicating that no bridging carbonyls are present in the
complex. This structural assignment is supported by
comparison with n(CO) the frequencies observed for the
˚
˚
2.221(15) A, Os(3)ꢀ
/
C(1)ꢂ
/
/
˚
C(1)ꢂ
/
/
/

S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á
/249
243
Table 3
spectrum of 5 in the aliphatic region contains a triplet at
d 4.07 ppm indicating that the two phosphorus atoms
and the two methylene hydrogen atoms of the bridging
dppm ligand are equivalent. All of the spectroscopic
data for 5 are very similar to those of the corresponding
ruthenium analog [Ru4(CO)10(m3-Se)4(m-dppm)2] [7a],
indicating that they are isostructural. Compound 5
could not be characterized structurally by X-ray diffrac-
tion due to the lack of X-ray quality crystals.
Treatment of [Os3(CO)10(MeCN)2] with dppmSe at
room temperature leads to the formation of the di-
nuclear compound [Os2(CO)6(m-Se)(m-dppm)] [8] and
the trinuclear compounds 3 and 4 (Scheme 2) in 13, 24
and 4% yields, respectively. Minor uncharacterized
products were also obtained. The dinuclear compound
is probably produced by decomposition of the Os3Se
˚
Selected interatomic distances (A) and angles (8) for 4
Interatomic distances
Os(1)ꢀ
Os(2)ꢀ
Os(1)ꢀ
Os(2)ꢀ
Os(1)ꢀ
Os(3)ꢀ
Os(1)ꢀ
Os(3)ꢀ
Os(2)ꢀ
Os(2)ꢀ
Os(3)ꢀ
Osꢀ
CꢀO (average)
PꢀC (average)
/
Os(2)
Os(3)
Os(3)
Se(1)
Se(1)
Se(1)
C(1)
C(1)
C(1)
P(1)
2.8442(7)
2.8274(8)
2.8556(8)
2.5221(13)
2.5123(14)
2.5302(15)
2.221(15)
2.160(14)
2.190(13)
2.342(3)
2.326(3)
1.91(2)
/
/
/
/
/
/
/
/
/
/P(2)
/
C(terminal) (average)
/
1.14(2)
/
1.82(2)
Interatomic angles
Os(1)ꢀ
Os(1)ꢀ
Os(2)ꢀ
O(1)ꢀC(1)ꢀ
O(1)ꢀC(1)ꢀ
O(1)ꢀC(1)ꢀ
O(1)ꢀC(1)ꢀ
Os(3)ꢀC(1)ꢀ
Os(3)ꢀC(1)ꢀ
C(2)ꢀOs(1)ꢀ
C(3)ꢀOs(1)ꢀ
C(7)ꢀOs(2)ꢀ
P(1)ꢀOs(2)ꢀ
C(5)ꢀOs(3)ꢀ
C(1)ꢀOs(3)ꢀ
C(4)ꢀOs(1)ꢀ
C(1)ꢀOs(1)ꢀ
C(8)ꢀOs(2)ꢀ
C(1)ꢀOs(2)ꢀ
C(6)ꢀOs(3)ꢀ
P(2)ꢀOs(3)ꢀ
Os(2)ꢀOs(1)ꢀ
Os(3)ꢀOs(2)ꢀ
Os(2)ꢀOs(3)ꢀ
Se(1)ꢀOs(1)ꢀ
Se(1)ꢀOs(1)ꢀ
Se(1)ꢀOs(3)ꢀ
Se(1)ꢀOs(1)ꢀ
Se(1)ꢀOs(2)ꢀ
Se(1)ꢀOs(3)ꢀ
P(1)ꢀOs(2)ꢀ
P(2)ꢀOs(3)ꢀ
/
Se(1)ꢀ
Se(1)ꢀ
Se(1)ꢀ
/
Os(3)
Os(2)
Os(3)
69.07(3)
68.88(3)
68.16(3)
133.0(9)
129.2(9)
80.5(4)
core in 4 through an inner reductionÁoxidation process.
/
/
/
Compound 6 was initially characterized by elemental
1
/
/
analysis, IR, H-NMR, 31P{1H}-NMR and mass spec-
/
/
Os(2)
Os(1)
Os(1)
Os(3)
troscopic data. The infrared spectrum of 6 exhibits
bands at 2073 vs, 2035 vs, 1998 m, 1977 w and 1963 m
cmꢁ1, indicating that all the CO groups are terminally
bonded. The mass spectrum contains a parent ion at m/
z 1012 and in addition stepwise loss of six carbonyl
groups has been observed. The 1H-NMR spectrum
contains two multiplets centered at d 4.95 and 3.36
ppm due to the methylene protons and a multiplet
centered at d 7.43 ppm for phenyl protons of the dppm
/
/
/
/
/
/
131.9(9)
81.3(4)
/
/
Os(2)
Os(1)
Se(1)
Se(1)
Se(1)
/
/
81.4(4)
/
/
94.6(4)
/
/
94.8(4)
/
/
166.4(4)
87.80(8)
172.4(4)
91.1(3)
/
/Se(1)
/
/
Se(1)
Se(1)
Se(1)
Se(1)
Se(1)
Se(1)
Se(1)
/
/
ligand. The 31P{1H}-NMR shows a singlet at d ꢁ
19.7
/
/
/
170.7(4)
90.2(3)
ppm, indicating that the 31P nuclei are equivalent. In
spite of this apparent equivalency, the number of
carbonyl stretching frequencies observed in CH2Cl2
presents the possibility of isomers in solution in which
the dppm ligand adopts ‘‘up’’ and ‘‘down’’ conforma-
tions. It is likely that the isomers interconvert more
rapidly than can be detected on the NMR time scale.
The structure of 6 has been confirmed by single-crystal
X-ray diffraction studies; its molecular structure is
shown in Fig. 3 and selected bond distances and bond
angles are presented in Table 4. The compound consists
of two osmium atoms with six linear terminal carbonyl
ligands, three bonded to each osmium atom, one doubly
/
/
/
/
101.3(4)
90.9(3)
/
/
/
/
91.3(4)
/
/Se(1)
94.01(8)
59.490(16)
60.460(16)
60.050(16)
55.72(3)
55.40(3)
55.78(3)
55.76(3)
56.06(3)
55.17(3)
95.57(8)
89.77(8)
/
/
Os(3)
/
/
Os(1)
Os(1)
/
/
/
/
Os(2)
Os(1)
Os(2)
Os(3)
Os(3)
Os(2)
/
/
/
/
/
/
/
/
/
/
/
/Os(3)
/
/Os(2)
bridging selenido ligand and a bridging dppm ligand.
˚
Os(2) bond length is 2.8933(2) A, which is
The Os(1)ꢀ
/
slightly longer than that found in [Os3(CO)12] {2.877(3)
˚
ruthenium analog, [Ru4(CO)10(m3-Se)4(m-dppm)] which
was synthesized by Predieri et al., from the reaction of
[Ru3(CO)12] with dppmSe in the presence of Me3NO at
110 8C and unambiguously characterized by single-
crystal X-ray diffraction studies [7a]. The FAB mass
spectrum of 5 exhibits the molecular ion peak at m/z
1740 followed by sequential loss of 10 carbonyl ligands.
This typical fragmentation pattern suggests that 5 is a
decacarbonyl tetraosmium complex. The 31P{1H}-NMR
A} [31]. The Os(1)ꢀ
/
Se(1) and Os(2)ꢀ
/
Se(1) bond dis-
˚
tances of 2.5471(4) and 2.518(4) A are comparable to the
Osꢀ/Se bond distances in 3, 4 and other triosmium
spectrum contains a singlet at d ꢁ
/
7.4 ppm indicating
equivalent 31P nuclei. Consistent with this, the 1H-NMR
Scheme 2.

244
S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á249
/
of [Os3(CO)10(MeCN)2] with dppmSe2 at 80 8C is quite
selective giving 3 and 5 in 27 and 7% yields, respectively.
The triply bridging chalcogenido ligands with lone
pairs of electrons have been considered to be ideal
species for cluster growth reactions. These ligands
facilitate the formation of higher nuclearity clusters by
using the lone pair of electrons to form coordinative
interactions to electron-deficient metal groupings. Of
the chalcogen elements, the triply bridging sulfido ligand
has been extensively used for the purpose of cluster
growth reactions [2]. The much larger tellurido ligand
has also been shown to stabilize triangular and square
arrays of metal atoms [3b,39]. In comparison, few
studies have been performed using the capping selenido
ligand for cluster growth reactions [7c]. By analogy with
the formation of [Os6(CO)16(m3-S)4] [30] by photolysis of
[Os3(CO)9(m3-S)2] and [Ru6(CO)12(m3-Se)4(m-dppm)2]
[7c] by the reaction of [Ru3(CO)7(m-Se)2(m-dppm)] with
Me3NO at 110 8C, it was considered that the reaction of
3 with Me3NO might give the corresponding hexa-
nuclear compound [Os6(CO)12(m3-Se)4(m-dppm)2]. As
expected, treatment of 3 with Me3NO in toluene at
80 8C affords the novel cluster [Os3(CO)6(m3-Se)2(m-
dppm)]2 [9] (Scheme 3) as green crystals in 50% yield.
Compound 7 has been characterized both spectroscopi-
cally and by single-crystal X-ray diffraction studies. The
solid-state structure of 7 is shown in Fig. 4 and selected
bond distances and angles are collected in Table 5. The
compound is believed to be formed by condensation of
two [Os3(CO)6(m3-Se)2(m-dppm)] units formed by the
loss of a carbonyl ligand from 3. An intriguing
structural feature of 7 is that, in contrast to 3 in which
Fig. 3. Molecular structure of [Os2(CO)6(m-Se)(m-dppm)] (6).
Table 4
˚
Selected interatomic distances (A) and angles (8) for 6
Interatomic distances
Os(1)ꢀ
Os(1)ꢀ
Os(2)ꢀ
Os(2)ꢀ
Os(1)ꢀ
Os(1)ꢀ
Os(1)ꢀ
Os(2)ꢀ
Os(2)ꢀ
Os(2)ꢀ
Os(1)ꢀ
Cꢀ
PꢀC (average)
/
Os(2)
Se(1)
Se(1)
P(1)
2.8933(2)
2.5471(4)
2.5418(4)
2.4041(9)
1.4004(9)
1.906(4)
1.932(4)
1.899(4)
1.908(4)
1.933(4)
1.917(5)
1.13(2)
/
/
/
/P(2)
/
C(1)
C(3)
C(6)
C(5)
C(4)
C(2)
/
/
/
the dppm ligand bridges one of the bonding Osꢀ
/
Os
/
edges, both the dppm ligands span the open osmiumꢀ
/
/
/
O (average)
osmium edges with two phosphorus atoms occupying
equatorial sites on two metal atoms. The molecule may
be viewed as an extended array of six osmium atoms
with four triply bridging selenido ligands, two bridging
dppm ligands and twelve terminal carbonyl ligands, two
terminally coordinated to each osmium atom. The
internuclear separations in the core of the cluster span
/
1.83(1)
Interatomic angles
Se(1)ꢀOs(1)ꢀOs(2)
P(1)ꢀOs(2)ꢀOs(1)
Se(2)ꢀOs(2)ꢀ
Os(2)ꢀSe(1)ꢀ
P(2)ꢀOs(1)ꢀ
P(2)ꢀOs(1)ꢀ
Se(1)ꢀ
/
/
55.265(9)
69.297(10)
55.438(9)
69.297(10)
90.51(2)
/
/
/
/Os(1)
/
/Os(1)
/
/
Se(1)
/
/
Os(2)
88.90(2)
a range and suggest the existence of seven metalꢀ
/
metal
/
Os(2)ꢀ
/Os(1)
55.438(9)
bonds. The new metalꢀmetal bonds join the two
/
triosmium diselenido fragments. The central portion of
the molecule adopts the form of a butterfly tetrahedron
compounds containing bridging selenido ligands 38. The
dppm ligand bridges two osmium atoms in the axial
position and the Osꢀ
/
P bond distances {Os(1)ꢀ
/
P(2)ꢂ
2.4041(9) A} are signifi-
cantly longer than those found in [Os3(CO)7(m3-S)2(m-
/
˚
˚
2.4004(9) A and Os(2)ꢀ
/
P(1)ꢂ
/
˚
dppm)] (3), {Os(1)ꢀ
/
P(1)ꢂ
/
2.286(3) A and Os(2)ꢀ
/
P(2)ꢂ
/
˚
2.302(3) A}. The doubly bridging selenido ligand
donates two electrons and the bridging dppm ligand
donates four electrons to make 6 a 34 electron valence-
saturated bimetallic compound. In contrast, the reaction
Scheme 3.

S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á
/249
245
Fig. 4. Molecular structure of [Os6(CO)12(m3-Se)4(m-dppm)2] (7).
of four metal atoms, illustrated by Os(2), Os(3), Os(5)
and Os(6). The dihedral angle between the planes
defined by Os(3), Os(5), Os(6) and Os(3), Os(6) and
Os(2) is 140.58. This value is comparable to the
corresponding dihedral angles in [Os6(CO)16(m3-S)4],
{136.38} [40] and [Ru6(CO)12(m3-Se)4(m-dppm)2],
{141.18} [7c]. The two remaining metal atoms are linked
to the central cluster at the ‘‘hinge’’ atoms one to each,
the number which formally satisfy the 18 electron rule.
These extra electrons occupy low lying anti-bonding
orbitals of the central Os4 core, which correlates well
with the lengthening of the four Osꢀ
/Os bonds around
periphery of the central cluster.
Spectroscopic data for 7 are consistent with the solid-
state structure. The infrared spectrum of 7 exhibits
bands at 2031 w, 2015 vs, 1981 s, 1950 s and 1894 w
cmꢁ1, indicating that all of the CO groups are terminal.
via a metalꢀ
ligands. The shortest metalꢀ
involving the external metal atoms, Os(3)ꢀ
/
metal bond and the bridging selenido
metal bonds are those
Os(4)ꢂ
2.851(4) A. and the hinge
1
/
The H-NMR spectrum of 7 in CD2Cl2 shows a triplet
/
/
at d 4.29 ppm due to equivalent methylene protons, and
a multiplet centered at d 7.29 ppm due to the phenyl
protons of the dppm ligand. The 31P{1H} spectrum
˚
˚
2.841(4) A and Os(1)ꢀ
bond, Os(3)ꢀOs(6)ꢂ
bonds around the periphery of the central cluster
{Os(2)ꢀOs(6)ꢂ3.042(5), Os(2)ꢀOs(3)ꢂ2.982(4),
Os(3)ꢀOs(5)ꢂ 3.022(5), Os(5)ꢀOs(6)ꢂ2.988(4) A},
are significantly longer. The latter distances are compar-
able to the corresponding osmiumꢀosmium distances in
[Os6(CO)16(m3-S)4] [40], ranging from 2.941(1) to
/
Os(6)ꢂ
/
˚
/
/
2.848(4) A. The metalꢀ
/metal
contains two doublets at singlet at d ꢁ
/
10.9 and ꢁ11.1
/
/
/
/
/
ppm, indicating that the 31P nuclei are not equivalent.
The methylene protons appear equivalent at 298 K, but
resolve into two resonances at d 4.56 and 3.88 ppm at
183 K, indicating that the methylene group is fluxional
at ambient temperature. The FAB mass spectrum of 7
exhibits the molecular ion peak at m/z 2562 [Mꢀ].
Compound 7 is unusually reactive as exemplified by
its reaction with 1 atm of carbon monoxide at 98 8C to
regenerate 3 by the cleavage of three unsupported
˚
/
/
/
/
/
˚
2.973(1) A, whereas the former are longer than the
external metalꢀmetal bond distances in [Os6(CO)16(m3-
/
˚
S)4], which range from 2.789(1) to 2.792(1) A. The triply
bridging selenido ligands are arranged in pairs along
diametrically opposed edges of the central cluster and
metalꢀ
/
metal bonds.
extend to each of the external metal atoms. The Osꢀ
/
Se
˚
2.551(8) A} are similar to the
Treatment of 3 with PPh3 in presence of Me3NO as
reaction initiator at ambient temperature afforded the
substitution product [Os3(CO)6(m3-Se)2(m-dppm)(PPh3)]
(8) (Scheme 4) in 26% yield along with the dimer 7 in
20% yield.
distances in 7 {2.472(8)Á
/
˚
2.5757(3) A}. The
OsꢀSe distances in 3 {2.4773(13)Á
/
/
short bite of the dppm ligands, with an average Pꢀ
/
P
˚
distance of 3.1973 A and an average Pꢀ
/
Cꢀ
/
P angle of
1188, results in the reduction of the non-bonding Osꢀ
/Os
Compound 8 has been characterized by elemental
1
analysis, infrared spectroscopy, H-NMR and 31P{1H}-
˚
˚
separation from 3.812 A in 3 to 3.724 and 3.735 A in 7.
˚
Se distances increase from 3.246 A in
In parallel, the Seꢀ
/
NMR, as well as by a single-crystal X-ray diffraction
study. The infrared spectrum of 8 shows, by comparison
with that of 3, an expected shift of the n(CO) bands to
lower frequencies consistent with greater back-donation
into the p* frontier orbitals on CO, due to the increased
electron density on the metal atoms from the PPh3
˚
3 to 3.323 and 3.319 A in 7. The Osꢀ
/P bond distances
are comparable to the corresponding distances in 3. As
has been suggested for [Os6(CO)16(m3-S)4] [40] and
[Ru6(CO)12(m3-Se)4(m-dppm)2] [7c], cluster 7, with seven
OsÁOs interactions, contains two electrons in excess of
/

246
S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á
/249
Table 5 (Continued)
Table 5
˚
Selected interatomic distances (A) and angles (8) for 7
Os(4)ꢀ
Os(6)ꢀ
Se(4)ꢀOs(3)ꢀ
Se(2)ꢀOs(3)ꢀ
Os(4)ꢀOs(3)ꢀ
Os(6)ꢀOs(3)ꢀ
Os(2)ꢀOs(3)ꢀ
P(4)ꢀOs(4)ꢀ
P(4)ꢀOs(4)ꢀ
Se(4)ꢀ
P(4)ꢀOs(4)ꢀ
Se(4)ꢀOs(4)ꢀ
Se(2)ꢀOs(4)ꢀ
P(3)ꢀOs(5)ꢀ
P(3)ꢀC(32)ꢀ
P(1)ꢀC(1)ꢀP(2)
P(1)ꢀOs(2)ꢀOs(6)
Se(3)ꢀOs(2)ꢀOs(6)
P(3)ꢀOs(5)ꢀSe(2)
Se(4)ꢀOs(5)ꢀSe(2)
P(3)ꢀOs(5)ꢀOs(6)
Se(4)ꢀOs(5)ꢀ
Se(2)ꢀOs(5)ꢀ
P(3)ꢀOs(5)ꢀ
Se(4)ꢀOs(5)ꢀ
Se(2)ꢀOs(5)ꢀ
Os(6)ꢀOs(5)ꢀ
Se(3)ꢀOs(6)ꢀ
Se(3)ꢀOs(6)ꢀ
Se(1)ꢀOs(6)ꢀ
Se(3)ꢀOs(6)ꢀ
Se(1)ꢀOs(6)ꢀ
Os(3)ꢀOs(6)ꢀ
Se(3)ꢀOs(6)ꢀ
Se(1)ꢀOs(6)ꢀ
Os(3)ꢀOs(6)ꢀ
Os(1)ꢀOs(6)ꢀ
Se(3)ꢀOs(6)ꢀ
Se(1)ꢀOs(6)ꢀ
Os(3)ꢀOs(6)ꢀ
Os(1)ꢀOs(6)ꢀ
Os(5)ꢀOs(6)ꢀ
/
Os(3)ꢀ
/
Os(2)
131.48(14)
62.85(11)
53.56(18)
53.28(18)
78.79(12)
61.34(10)
112.00(13)
95.6(5)
/
Os(3)ꢀ
/
Os(2)
Interatomic distances
/
/Os(5)
Se(1)ꢀ
Se(1)ꢀ
Se(1)ꢀ
Se(2)ꢀ
Se(2)ꢀ
Se(2)ꢀ
Se(3)ꢀ
Se(3)ꢀ
Se(3)ꢀ
Se(4)ꢀ
Se(4)ꢀ
Se(4)ꢀ
P(1)ꢀ
P(2)ꢀ
P(3)ꢀ
P(4)ꢀ
Os(1)ꢀ
Os(2)ꢀ
Os(2)ꢀ
Os(3)ꢀ
Os(3)ꢀ
Os(3)ꢀ
Os(5)ꢀ
Se(2)ꢀ
Se(1)ꢀ
Os(5)ꢀ
Os(2)ꢀ
/
Os(1)
Os(6)
Os(2)
Os(5)
Os(4)
Os(3)
Os(6)
Os(1)
Os(2)
Os(3)
Os(4)
Os(5)
2.532(7)
2.539(8)
2.548(8)
2.534(8)
2.531(7)
2.551(8)
2.483(8)
2.516(8)
2.524(7)
2.472(8)
2.509(8)
2.524(7)
2.31(2)
2.31(2)
2.32(2)
2.31(2)
2.851(4)
2.982(4)
3.042(5)
2.841(4)
2.848(4)
3.022(5)
2.998(4)
3.323
/
/Os(5)
/
/
/
Os(5)
Os(5)
Os(5)
/
/
/
/
/
/
/
/
/Se(4)
/
/
/Se(2)
97.2(5)
/
/
Os(4)ꢀ
/Se(2)
82.5(2)
/
/
/Os(3)
139.5(5)
54.61(18)
56.36(18)
91.6(5)
/
/
/Os(3)
/
/
/Os(3)
/
/
/Se(4)
/
/
/P(4)
119.0(4)
117.0(4)
128.7(4)
51.97(19)
91.2(5)
/
Os(2)
Os(1)
Os(5)
Os(4)
/
/
/
/
/
/
/
/
/
/
/
/
Os(6)
Os(3)
Os(6)
Os(4)
Os(6)
Os(5)
Os(6)
/
/
82.1(2)
/
/
/
170.5(5)
97.3(2)
/
/
/Os(6)
/
/
/Os(6)
86.80(19)
128.7(5)
51.99(19)
53.80(19)
56.47(10)
82.7(2)
/
/
/Os(3)
/
/
/Os(3)
/
/
/Os(3)
/Se(4)
/
/
Os(3)
/Se(3)
3.319
/
/
Se(1)
Os(3)
Os(3)
Os(1)
Os(1)
/Os(4)
3.724
/
/
99.9(2)
/Os(1)
3.735
/
/
91.74(18)
55.77(19)
55.68(16)
138.75(15)
161.8(2)
94.32(19)
62.20(11)
135.73(14)
53.20(19)
53.40(19)
60.73(10)
78.60(12)
111.01(12)
Interatomic angles
/
/
Os(1)ꢀ
Os(1)ꢀ
Os(6)ꢀ
Os(5)ꢀ
Os(5)ꢀ
Os(4)ꢀ
Os(6)ꢀ
Os(6)ꢀ
Os(1)ꢀ
Os(3)ꢀ
Os(3)ꢀ
P(2)ꢀOs(1)ꢀ
Se(3)ꢀOs(1)ꢀ
P(2)ꢀOs(1)ꢀOs(6)
Se(3)ꢀOs(1)ꢀ
Se(1)ꢀOs(1)ꢀ
P(1)ꢀOs(2)ꢀ
P(1)ꢀOs(2)ꢀ
Se(3)ꢀ
P(1)ꢀOs(2)ꢀ
Se(3)ꢀOs(2)ꢀ
Se(1)ꢀOs(2)ꢀ
Os(4)ꢀSe(4)ꢀ
P(2)ꢀOs(1)ꢀ
Se(1)ꢀOs(2)ꢀ
Os(3)ꢀOs(2)ꢀ
Se(4)ꢀOs(3)ꢀ
Se(4)ꢀOs(3)ꢀ
Se(2)ꢀOs(3)ꢀ
Se(4)ꢀOs(3)ꢀ
Se(2)ꢀOs(3)ꢀ
Os(4)ꢀOs(3)ꢀ
Se(4)ꢀOs(3)ꢀ
Se(2)ꢀOs(3)ꢀ
/
Se(1)ꢀ
Se(1)ꢀ
Se(1)ꢀ
Se(2)ꢀ
Se(2)ꢀ
Se(2)ꢀ
Se(3)ꢀ
Se(3)ꢀ
Se(3)ꢀ
Se(4)ꢀ
Se(4)ꢀ
/
Os(6)
Os(2)
Os(2)
Os(4)
Os(3)
Os(3)
Os(2)
Os(1)
Os(2)
Os(4)
Os(5)
68.40(19)
94.7(2)
73.5(2)
/
/
/
/
/
/
Os(1)
/
/
/
/Os(5)
/
/
94.6(2)
/
/Os(5)
/
/
72.9(2)
/
/
Os(5)
Os(5)
/
/
68.0(2)
/
/
/
/
74.8(2)
/
/Os(2)
/
/
69.5(2)
/
/Os(2)
/
/
95.7(3)
/
/
Os(2)
Os(2)
Os(2)
/
/
69.5(2)
/
/
/
/
74.4(2)
/
/
/
/
Se(1)
97.5(5)
/
/Se(1)
82.2(2)
/
/
139.1(5)
54.69(18)
55.92(18)
91.8(5)
/
/Os(6)
/
/Os(6)
/
/
Se(3)
/
/
Se(1)
91.5(5)
/
Os(2)ꢀ
/Se(1)
81.8(2)
172.6(5)
95.5(2)
/
/
Os(3)
/
/
Os(3)
Os(3)
Os(5)
/
/
88.55(19)
95.4(3)
Scheme 4.
/
/
/
/
Se(3)
Os(6)
Os(6)
94.9(6)
ligand, a better s-donor than CO. The 1H-NMR
spectrum of 8 contains two pseudo-quartets centered
at d 5.36 and 3.81 ppm and a multiplet centered at d
7.31 ppm with a relative intensity ratio of 1:1:35. The
31P{1H}-NMR spectrum contains three resonances of
/
/
53.15(19)
56.41(10)
82.8(3)
/
/
/
/
Se(2)
Os(4)
Os(4)
Os(6)
Os(6)
/
/
55.84(18)
55.67(16)
102.6(2)
89.76(18)
138.73(15)
164.6(2)
91.89(19)
/
/
/
/
/
/
equal intensity, two doublets at d ꢁ
/
6.8 and ꢁ
/
19.1 (Jꢂ
/
/
/
Os(6)
40.0 Hz) ppm and a singlet at d 13.1 ppm. The doublets
are due to the non-equivalent 31P nuclei of the dppm
ligand, while the singlet is due to the PPh3 ligand. These
/
/Os(2)
/
/Os(2)

S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á
/249
247
NMR data provide strong evidence for the formulation
of 8 as [Os3(CO)6(m3-Se)2(m-dppm)(PPh3)]. This formu-
lation of 8 is also clear from its FAB mass spectrum,
which exhibits the molecular ion peak at m/z 1542 as
well ions for formulas corresponding to the sequential
loss of six carbonyl ligands.
The solid-state structure of 8 is shown in Fig. 5 and
selected bond distances and angles are collected in Table
6. The structure consists of an Os3 triangle involving two
Table 6
˚
Selected interatomic distances (A) and angles (8) for 8
Interatomic distances
Se(1)ꢀ
Se(1)ꢀ
Se(1)ꢀ
Se(2)ꢀ
Se(2)ꢀ
Se(2)ꢀ
/
Os(1)
Os(2)
Os(3)
Os(2)
Os(1)
Os(3)
2.474(5)
2.501(3)
2.526(3)
2.529(5)
2.545(3)
2.564(4)
2.320(9)
2.351(10)
2.318(8)
2.864(2)
2.842(2)
3.835
/
/
/
/
/
P(1)ꢀ
P(2)ꢀ
P(3)ꢀ
/
Os(3)
Os(1)
Os(2)
/
˚
2.864(2) A and
metalꢀ
Os(2)ꢀ
metal separation {Os(1)ꢀ
/
metal bonds {Os(1)ꢀ
/
Os(3)ꢂ
/
/
˚
/
Os(3)ꢂ
/
2.842(2) A} and a non-bonding metalꢀ
/
Os(1)ꢀ
Os(2)ꢀ
Os(1)ꢀ
Se(1)ꢀ
PꢀC (average)
OsꢀC(CO) (average)
CꢀO (average)
/
Os(3)
Os(3)
Os(2)
˚
Os(2)ꢂ3.835 A}. There are six
/
/
/
/
linear terminal carbonyl ligands, two bonded to each
/
Se(2)
3.232
osmium atom, two triply bridging selenido ligands, a
/
1.81(4)
1.84(4)
1.19(3)
bridging dppm ligand and a PPh3 ligand. The Os(1)ꢀ
/
/
Os(3) edge containing the bridging dppm ligand is
slightly longer than the edge which is not bridged. The
/
Interatomic angles
Osꢀ
/
P bond distances of the dppm ligand in 8 {Os(3)ꢀ
/
Os(1)ꢀ
Os(1)ꢀ
Os(2)ꢀ
Os(2)ꢀ
Os(2)ꢀ
Os(1)ꢀ
P(2)ꢀOs(1)ꢀ
P(2)ꢀOs(1)ꢀ
Se(1)ꢀ
P(2)ꢀOs(2)ꢀ
Se(1)ꢀOs(1)ꢀ
Se(2)ꢀOs(1)ꢀ
P(3)ꢀOs(2)ꢀ
P(3)ꢀOs(2)ꢀ
Se(1)ꢀ
P(3)ꢀOs(2)ꢀ
Se(1)ꢀOs(2)ꢀ
Se(2)ꢀOs(2)ꢀ
P(1)ꢀOs(3)ꢀ
Se(1)ꢀOs(3)ꢀ
P(1)ꢀOs(3)ꢀOs(2)
Se(1)ꢀOs(3)ꢀ
Se(2)ꢀOs(3)ꢀ
P(1)ꢀOs(3)ꢀ
Se(1)ꢀOs(3)ꢀ
Se(2)ꢀOs(3)ꢀ
Os(2)ꢀOs(3)ꢀ
/
Se(1)ꢀ
Se(1)ꢀ
Se(1)ꢀ
Se(2)ꢀ
Se(2)ꢀ
Se(2)ꢀ
/
Os(2)
Os(3)
Os(3)
Os(1)
Os(3)
Os(3)
100.84(15)
69.91(11)
68.85(9)
98.18(13)
67.83(11)
68.19(9)
153.8(2)
90.7(2)
˚
˚
P(1)ꢂ P(2)ꢂ2.351(10) A} are
close to those observed in 3. The PPh3 ligand is
/
/
/
2.320(9) A and Os(1)ꢀ
/
/
/
/
/
/
coordinated to the unbridged osmium atom Os(2) and
˚
P(3) distance at 2.318(8) A is comparable to
/
/
the Os(2)ꢀ
/
/
/
/
/
Se(1)
that observed in the related open cluster [Os3(CO)8(m3-
Se)2(PMe2Ph)] {2.298(3) A} [4b]. The osmiumꢀ
/
/Se(2)
˚
/selenium
/
Os(1)ꢀ
/
Se(2)
80.19(13)
98.7(2)
distances to the triply bridging selenido ligands {Os(1)/
˚
A and
/
/Os(3)
Os(2)/Os(3)ꢀ
/
Se(1)ꢂ
/
2.474(5)/2.501(3)/2.526(3)
/
/
Os(3)
55.88(8)
56.22(9)
107.8(2)
98.4(3)
˚
2.545(3)/2.529(5)/2.564(4) A}
/
/
Os(3)
Os(1)/Os(2)/Os(3)ꢀ
/
Se(2)ꢂ
/
/
/Se(1)
are very similar to those in 3. The overall structure of 8
is essentially the same as that of 3, differing only by the
substitution of one of the equatorially positioned
carbonyl ligands by a triphenylphosphine ligand.
/
/Se(2)
/
Os(2)ꢀ
/
Se(2)
79.99(13)
150.2(3)
55.97(8)
56.69(9)
95.4(3)
/
/Os(3)
/
/
Os(3)
/
/
Os(3)
/
/Se(2)
/
/
Se(2)
78.87(12)
149.9(2)
55.18(8)
55.49(11)
84.1(2)
/
/
/
/
Os(2)
/
/
Os(2)
/
/Os(1)
/
/
Os(1)
54.20(11)
55.59(8)
84.44(6)
/
/
Os(1)
/
/
Os(1)
4. Conclusions
The unsaturated cluster 2 is clearly a versatile reagent
for the synthesis of open triangular nido-cluster 3, the
closo-triangular cluster 4 and the cubane-like cage
cluster 5. In contrast, the reaction of 1 with elemental
selenium at 110 8C affords only intractable material.
When treated with Me3NO at 80 8C, compound 3
undergoes a self-condensation and forms the green
dimer 7. The formation of the dimer can be viewed as
a back-to-back coupling of two [Os3(CO)6(m3-Se)2(m-
dppm)] units derived from 3 by loss of one CO-ligand.
The two triosmium units are then joined through the
Fig. 5. Molecular structure of [Os3(CO)6(m3-Se)2(m-dppm)(PPh3)] (8).

248
S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á249
/
2351;
(c) Y. Mizobe, M. Hosomizu, J. Kawabato, M. Hidai, J. Chem.
Soc. Chem. Commun. (1991) 1226.;
formation of three new osmiumꢀ
pound 7 reacts with CO by cleavage of the three
unsupported metalꢀmetal bonds to regenerate 3 in
/
osmium bonds. Com-
/
(d) R.D. Adams, J.E. Babin, P. Mathur, K. Natarajan, J.W.
Wang, Inorg. Chem. 26 (1989) 1440;
high yield. Compound 3 reacts with PPh3 in the presence
of Me3NO to afford the substitution product 8 along
with the hexanuclear cluster 7. The substitution of a
carbonyl with PPh3 does not cause significant structural
alterations to the cluster framework, with all the
important distances remaining effectively unchanged
with respect to 3. The reactions of dppmSe and dppmSe2
with [Os3(CO)10(MeCN)] provides a simple one-step
synthetic procedure for the dppm-substituted selenido
clusters 3, 4, 5 and 6 by oxidative addition and transfer
of selenium atoms to the low-valent osmium centers. We
anticipate further advances will be made in this area of
research.
(e) R.D. Adams, J.E. Babin, J. Estrada, J.-G. Wang, M.B. Hall,
A.A. Low, Polyhedron 8 (1989) 1885.
[3] (a) T.M. Layer, J. Lewis, A. Martin, P.R. Raithby, W.-T. Wong,
J. Chem. Soc. Dalton Trans. (1992) 3411.;
(b) P. Mathur, B.H.S. Thimmappa, A.L. Rheingold, Inorg.
Chem. 29 (1990) 4658.
[4] (a) R.D. Adams, L.-W. Yang, J. Am. Chem. Soc. 104 (1982) 4115;
(b) R.D. Adams, I.T. Horvath, B.E. Segmuller, L.-W. Yang,
Organometallics 2 (1983) 144, 1301.;
(c) R.D. Adams, G. Chen, S. Sun, T.A. Wolfe, J. Am. Chem. Soc.
112 (1990) 868;
(d) B.F.G. Johnson, J. Lewis, P.G. Lodge, P.R. Raithby, Acta
Crystallogr. B 37 (1981) 1731;
(e) R.D. Adams, I.T. Horvath, Inorg. Chem. 23 (1984) 4718;
(f) P. Mathur, D. Chakrabarty, J. Organomet. Chem. 373 (1989)
129;
(g) P. Mathur, I.J. Mavunkal, V. Rugmini, Inorg. Chem. 28
(1989) 3616;
5. Supplementary material
(h) P. Mathur, Adv. Organomet. Chem. 41 (1997) 243.
[5] (a) G. Hogarth, N.J. Taylor, A.J. Carty, A. Meyer, J. Chem. Soc.
Chem. Commun. (1988) 834.;
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 201321 for compound 3,
201322 for compound 4, 201323 for compound 6,
201324 for compound 7, and 201325 for compound 8.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road
(b) S.M. Stuczynski, Y.-U. Kwon, M.L. Steigerwald, J. Organo-
met. Chem. 449 (1993) 167;
(c) W. Imhof, G. Huttner, J. Organomet. Chem. 448 (1993) 247.
[6] (a) P. Baistrocchi, D. Cauzzi, M. Lanfranchi, G. Predieri, A.
Tiripicchio, M.T. Camellini, Inorg. Chim. Acta 235 (1995) 173;
(b) P. Baistrocchi, M. Carezi, D. Cauzzi, C. Graiff, M. Lanfran-
chi, P. Manini, G. Predieri, A. Tiripicchio, Inorg. Chim. Acta 252
(1996) 367.
Cambridge, CB2 1EZ, UK (Fax: ꢀ44-1223-336033; e-
/
mail:deposit@ccdc.cam.ac.uk
www.ccdc.cam.ac.uk).
or www: http://
[7] (a) D. Cauzzi, C. Graiff, M. Lanfranchi, G. Predieri, A.
Tiripicchio, J. Chem. Soc. Dalton Trans. (1995) 2321.;
(b) D. Cauzzi, C. Graiff, M. Lanfranchi, G. Predieri, A.
Tiripicchio, J. Organomet. Chem. 536Á537 (1997) 497;
/
(c) D. Cauzzi, C. Graiff, G. Predieri, A. Tiripicchio, C. Vignali, J.
Chem. Soc. Dalton Trans. (1999) 237.;
Acknowledgements
(d) D. Cauzzi, C. Graiff, C. Massera, G. Predieri, A. Tiripicchio,
D. Acquotti, J. Chem. Soc. Dalton Trans. (1999) 3515.
[8] (a) J.A. Akter, K.A. Azam, S.E. Kabir, K.M.A. Malik, Md.A.
Mottalib, Inorg. Chem. Commun. 3 (2000) 553;
We gratefully acknowledge the Ministry of Science
and Technology, Government of the Peoples’ Republic
of Bangladesh for financial assistance. KMAM ac-
knowledges the EPSRC for the X-ray service at Cardiff.
(b) A.J. Deeming, S.E. Kabir, J. Organomet. Chem. 340 (1988)
359;
(c) S.E. Kabir, A. Miah, L. Nesa, K. Uddin, K.I. Hardcastle, E.
Rosenberg, A.J. Deeming, J. Organomet. Chem. 492 (1995) 41;
(d) S.R. Hodge, B.F.G. Johnson, J. Lewis, P.R. Raithby, J. Chem.
Soc. Dalton Trans. (1987) 931.;
References
(e) B.F.G. Johnson, J. Lewis, M. Manari, D. Braga, F. Grepioni,
C. Gradella, J. Chem. Soc. Dalton Trans. (1990) 2863.;
(f) D.F. Foster, J.H. Harrison, B.S. Nicholls, A.K. Smith, J.
Organomet. Chem. 295 (1985) 99;
[1] (a) M.I. Steigerwald, Polyhedron 13 (1994) 1245;
(b) G. Longoni, M.C. Iapalucci, In Clusters and Colloids, VCH,
Weiheim, 1994, p. 132;
(g) K.-L. Lu, H.J. Chen, P.-Y. Lu, S.-Y. Li, S.-M. Hong, S.-M.
Peng, G.-H. Lee, Organometallics 13 (1994) 585;
(c) L.C. Roof, J.W. Kolis, Chem. Rev. 93 (1993) 1037;
(d) J.G. Brennan, T. Siegrist, P.J. Carrol, S.M. Stuczynski, L.E.
Brus, M.L. Steigerwald, J. Am. Chem. Soc. 111 (1989) 4141;
(e) Z. Nomikou, B. Schubert, R. Hoffmann, M.L. Steigerwald,
Inorg. Chem. 31 (1992) 2201;
(h) S. Cartwright, J.A. Clucas, R.H. Dawson, D.F. Foster, M.M.
Harding, A.K. Smith, J. Organomet. Chem. 302 (1986) 403.
[9] J.A. Clucas, D.F. Foster, M.M. Harding, A.K. Smith, J. Chem.
Soc. Chem. Commun. (1984) 949.
(f) D. Fenske, J. Ohmer, J. Hachgenci, Angew. Chem. Int. Ed.
Engl. 24 (1985) 993;
[10] J.A. Clucas, M.M. Harding, A.K. Smith, J. Chem. Soc. Chem.
Commun. (1985) 2080.
(g) D. Fenske, H. Krautscheid, M. Muller, Angew. Chem. Int. Ed.
Engl. 31 (1992) 321;
[11] M.P. Brown, P.A. Dolby, M.M. Harding, A.J. Mathews, A.K.
Smith, J. Chem. Soc. Dalton Trans. (1993) 1671.
(h) D. Fenske, in: G. Schmid (Ed.), In Clusters and Colloids,
VCH, Weinheim, 1994, p. 212.
[12] K.A. Azam, M.B. Hursthouse, Md.R. Islam, S.E. Kabir, K.M.A.
Malik, R. Miah, C. Sudbrake, H. Vahrenkamp, J. Chem. Soc.
Dalton Trans. (1998) 1097.
[2] (a) R.D. Adams, Polyhedron 4 (1985) 2003;
(b) R.D. Adams, J.E. Babin, J.G. Wang, Polyhedron 8 (1989)

S.E. Kabir et al. / Journal of Organometallic Chemistry 681 (2003) 237Á
/249
249
[13] (a) J.A. Clucas, P.A. Dolby, M.M. Harding, A.K. Smith, J.
Chem. Soc. Chem. Commun. (1987) 1829.;
[25] R.H. Blessing, Acta Crystallogr. A 51 (1995) 33.
[26] R.H. Blessing, J. Appl. Crystallogr. A 51 (1995) 33.
[27] G.M. Sheldrick, Acta Crystallogr. A 46 (1990) 467.
(b) M.P. Brown, P.A. Dolby, M.M. Harding, A.J. Mathews, A.K.
Smith, D. Osella, M. Arbrun, R. Gobetto, P.R. Raithby, P.
Zanello, J. Chem. Soc. Dalton Trans. (1993) 827.
[28] G.M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement, University of Gottingen, Germany, 1997.
¨
[14] M.M. Harding, B. Kariuki, A.J. Mathews, A.K. Smith, P.
Braunstein, J. Chem. Soc. Dalton Trans. (1994) 33.
[15] R.A. Bartlett, C.J. Cardin, D.J. Cardin, G.A. Lawless, M.J.
Power, P.P. Power, J. Chem. Soc. Chem. Commun. (1988) 312.
[16] S.M.T. Abedin, K.A. Azam, M.B. Hursthouse, S.E. Kabir,
K.M.A. Malik, Md.A. Mottalib, E. Rosenberg, J. Cluster Sci.
12 (2001) 5.
[29] XSCANS Data Collection Software, Release 2.10b. Bruker AXS,
Inc., Madison, WI, 1994.
[30] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
[31] M.R. Churchill, B.G. DeBoer, Inorg. Chem. 16 (1977)
878.
[32] R.D. Adams, I.T. Horvath, H.-S. Kim, Organometallics 3 (1984)
548.
[17] S.E. Kabir, K.M.A. Malik, E. Mollah, Md.A. Mottalib, J.
Organomet. Chem. 616 (2000) 157.
[33] B.F.G. Johnson, J. Lewis, P.G. Lodge, P.R. Raithby, Acta
Crystallogr. B 37 (1981) 1731.
[18] S.E. Kabir, C.A. Johns, K.M.A. Malik, Md.A. Mottalib, E.
Rosenberg, J. Organomet. Chem. 625 (2001) 112.
[34] D.J. Dahm, R.A. Jacobson, J. Am. Chem. Soc. 90 (1968) 5106.
[35] E.J. Forbes, N. Goodhand, D.L. Jones, T.A. Hamor, J. Organo-
met. Chem. 182 (1979) 143.
[19] S.M.T. Abedin, K.I. Hardcastle, S.E. Kabir, K.M.A. Malik,
Md.A. Mottalib, E. Rosenberg, M.J. Abedin, Organometallics 19
(2000) 5623.
[36] R.E. Benfield, B.F.G Johnson, G.M. Sheldrick, Acta Crystallogr.
B 34 (1978) 666.
[20] K.A. Azam, G.M.G. Hossain, S.E. Kabir, K.M.A. Malik, Md.A.
Mottalib, S. Pervin, N.C. Sarker, Polyhedron 21 (2002) 381.
[21] (a) B.F.G. Johnson, J. Lewis, D.A. Pippard, J. Chem. Soc. Dalton
Trans. (1981) 407.;
[37] S.E. Kabir, K.M.A. Malik, M.A. Mottalib, J. Chem. Crystallogr.
29 (1999) 7.
[38] (a) A.J. Arce, P. Arrojo, Y.De. Sanctis, A.J. Deeming, D.J. West,
Polyhedron 11 (1992) 1013;
(b) J.N. Nicholls, M.D. Vargas, Inorg. Synth. 26 (1989) 289.
[22] (a) A.M. Bond, R. Cotton, P. Panagiotidou, Organometallics 7
(1988) 1767;
(b) B.F.G. Johnson, J. Lewis, P.G. Lodge, P.R. Raithby, K.
Henrick, M. McPartlin, J. Chem. Soc. Chem. Commun. (1979)
719.
(b) S.O. Grim, E.D. Walton, Inorg. Chem. 19 (1980) 1982.
[23] R. Hooft, COLLECT Data Collection Software, Nonius B.V.,
Delft, The Netherlands, 1998.
[39] (a) P. Mathur, I.J. Mavunkal, J. Organomet. Chem. 350 (1988)
251;
(b) P. Mathur, I.J. Mavunkal, V. Rugmini, J. Organomet. Chem.
367 (1989) 243.
[24] Z Otwinowski, W. Minor, in: C.W. Carter, Jr., R.M. Sweet (Eds.),
In Macromolecular Crystallography, Academic Press, New York,
[40] R.D. Adams, I.T. Horvath, J. Am. Chem. Soc. 106 (1984)
1869.
1997, pp. 307Á326.
/