Chromium, molybdenum and tungsten carbonyl derivatives of distibinomethane ligands

Article abstract of DOI:10.1039/a707798j

Substituted Group 6 carbonyl complexes of the distibinomethane ligands Ph₂SbCH₂SbPh₂ (dpsm) and Me₂SbCH₂SbMe₂ (dmsm) of types [M(CO)₅(η¹-dpsm)] (M = Cr, Mo or W), [(OC)₅M(μ-dpsm)M(CO)₅] (M ≠ Mo), [(OC)₅M(μ-dmsm)M(CO)₅], [(OC)₄M(μ-dpsm)₂M(CO)₄], [(OC)₄M(μ-dmsm)₂M(CO)₄] and fac-[M(CO)₃(η¹-dpsm)₃] have been isolated and characterised by chemical analysis, IR, NMR (¹H, ¹³C-{¹H}, ⁹⁵Mo) spectroscopy and FAB mass spectrometry. The crystal structures of [W(CO)₅(dpsm)], [{W(CO)₅}₂(dpsm)], [{W(CO)₄(dpsm)}₂] and [{W(CO)₄(dmsm)}₂] have been determined. Complexes of η¹-dmsm have been observed but are too unstable to isolate in a pure state. Both the ligands function as monodentate or bridging bidentates in the complexes characterised, but no examples with chelated distibinomethanes have been prepared. Comparisons are drawn with complexes of related diphosphine ligands.

Full text of DOI:10.1039/a707798j

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Chromium, molybdenum and tungsten carbonyl derivatives of
distibinomethane ligands†
Angela M. Hill, Nicholas J. Holmes, Anthony R. J. Genge, William Levason,* Michael Webster
and Synke Rutschow
Department of Chemistry, University of Southampton, Southampton, UK SO17 1BJ
Substituted Group 6 carbonyl complexes of the distibinomethane ligands Ph2SbCH2SbPh2 (dpsm) and
Me2SbCH2SbMe2 (dmsm) of types [M(CO)5(η1-dpsm)] (M = Cr, Mo or W), [(OC)5M(µ-dpsm)M(CO)5] (M ≠ Mo),
[(OC)5M(µ-dmsm)M(CO)5], [(OC)4M(µ-dpsm)2M(CO)4], [(OC)4M(µ-dmsm)2M(CO)4] and fac-[M(CO)3(η1-
dpsm)3] have been isolated and characterised by chemical analysis, IR, NMR (1H, 13C-{1H}, 95Mo) spectroscopy
and FAB mass spectrometry. The crystal structures of [W(CO)5(dpsm)], [{W(CO)5}2(dpsm)], [{W(CO)4(dpsm)}2]
and [{W(CO)4(dmsm)}2] have been determined. Complexes of η1-dmsm have been observed but are too unstable
to isolate in a pure state. Both the ligands function as monodentate or bridging bidentates in the complexes
characterised, but no examples with chelated distibinomethanes have been prepared. Comparisons are drawn
with complexes of related diphosphine ligands.
In marked contrast to extensive work on the phosphorus and
arsenic analogues, systematic studies of ligands containing two
or more antimony donor atoms are rare.2 In Part 1 we reported1
complexes of the distibinomethane ligands bis(diphenylstib-
ino)methane Ph2SbCH2SbPh2 (dpsm) and bis(dimethylstibino)-
methane Me2SbCH2SbMe2 (dmsm), with iron, cobalt, mang-
anese and nickel carbonyls and carbonyl halides. The present
manuscript describes detailed studies of complexes with Group
6 carbonyls. Some of these complexes have been reported
previously3–6 but with very limited spectroscopic (and no struc-
tural) characterisation and with relatively poor agreement in
the data reported by different workers. As detailed below, this
almost certainly results from the fact that many syntheses lead
to mixtures of products unless carefully controlled, and the
complexes once formed have limited stabilities and rearrange
easily. Group 6 carbonyl complexes of Ph2SbESbPh2 (E = O or
S) have been reported recently.7 The much studied diphosphine
analogues Ph2PCH2PPh2 (dppm) and Me2PCH2PMe2 (dmpm)
function as chelating, bridging bidentate or monodentate lig-
ands.8,9 The diarsine Ph2AsCH2AsPh2 also exhibits all three co-
ordination modes,10 but for the distibinomethane ligands only
monodentate (η1) or bridging bidentate (either across an M᎐M
bond, or linking otherwise unconnected metal centres)1 are def-
initely established. The claims3 in the literature for chelation,
viz. [Mo(CO)3(dpsm)2] and [M(CO)4(dpsm)], are based upon
limited spectroscopic data, and are reinvestigated below.
[Cr(CO)6] the products were a mixture of [Cr(CO)5(η1-dpsm)]
and [{Cr(CO)4(dpsm)}2], with [W(CO)6] mainly [W(CO)5(η1-
dpsm)] with a little [{W(CO)4(dpsm)}2], and unexpectedly for
[Mo(CO)6] predominantly [Mo(CO)3(η1-dpsm)3]. Substitution
of other ligands also proved to be unpredictable and very
dependent upon the conditions. For example, [Mo(CO)4(pip)2]
(pip = piperidine) and dpsm in CH2Cl2 gave [Mo(CO)3(η1-
dpsm)3] rather than the expected tetracarbonyl complex, whilst
[Mo(CO)4(cod)] (cod = cycloocta-1,5-diene) and dpsm in
benzene gave
a
mixture including [Mo(CO)5(η1-dpsm)],
[{Mo(CO)4(dpsm)}2] and [Mo(CO)6]. In addition to the weak
nucleophilicity of dpsm, a second problem is the limited stabil-
ity of the distibine complexes in solution and their tendency to
rearrange or disproportionate into other complexes. The latter
tendency was particularly noticeable during attempts to grow
crystals for X-ray studies when a mixture of crystals of visually
different habits was often obtained, some identified as free
dpsm1 or [M(CO)6]. The Me2SbCH2SbMe2 as expected was a
better donor and its reactions are often cleaner, but the air
sensitivity of the ‘free’ SbMe2 groups (the ligand is spon-
taneously inflammable in air) made it difficult to prepare
complexes with η1-co-ordinated dmsm. Despite these problems,
syntheses for a range of complexes of both dpsm and dmsm in
the pure state were developed and are now described. Small
changes in the reaction conditions can lead to different or
highly impure products.
[M(CO)5(ç1-dpsm)] (M ؍ Cr, Mo or W)
Results and Discussion
Thermal substitution of dpsm into [M(CO)6] is an unsatisfac-
tory route to these complexes; mixtures were always produced
in poor overall yield which were not readily separated. This
almost certainly accounts for the poor agreement in the spec-
troscopic data reported previously by different workers.3,4 The
complexes can be made by photolysis of [M(CO)6] in thf to
yield [M(CO)5(thf)] in situ, followed by addition of dpsm,
whilst a clean chemical route is reaction of [NEt4][M(CO)5Br]13
with dpsm in a 1:1 mol ratio in ethanol. The spectroscopic data
(Experimental section), especially the three ν(CO) modes in the
IR spectra (theory 2A1 ϩ E) and the two δ(CO) resonances (ca.
1:4 ratio) in the 13C-{1H} NMR spectra, are consistent with
the expected C4v structure I, confirmed by the X-ray study
of [W(CO)5(dpsm)] (below). The FAB mass spectrum of
[Cr(CO)5(η1-dpsm)] contains a parent ion with the correct
Substituted Group 6 carbonyl complexes have been extensively
investigated and a variety of synthetic routes developed ranging
from direct thermal or photochemical substitution of the
hexacarbonyls through to displacement of the weakly bound
ligands from complexes such as [M(CO)4(diene)] or [M(CO)3-
(η6-arene)].11 Bis(diphenylstibino)methane is a weak donor1
and reaction with [M(CO)6] in a variety of refluxing solvents
including n-hexane, n-heptane, ethanol, toluene and diglyme
(2,5,8-trioxanonane) gave poor yields (<10%) of [M(CO)5(η1-
dpsm)] and traces (<2%) of higher substitution products, along
with unchanged reagents. The reaction of [M(CO)6] with dpsm
in ethanol using NaBH4 as a catalyst12 increased the yields. For
† Complexes of distibinomethane ligands. Part 2.1
J. Chem. Soc., Dalton Trans., 1998, Pages 825–832
825

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Table 1 Selected IR spectra (cmϪ1
)
Complex
ν(CO), Nujol mull
ν(CO), CH2Cl2 solution
[Cr(CO)5(dpsm)]
[Mo(CO)5(dpsm)]
[W(CO)5(dpsm)]
2056m, 1982m, 1922s
2068m, 1991m, 1935s
2066m, 1983m, 1918s
2058m, 1980w, 1962 (sh), 1915s
2068m, 1958s, 1913s
2058m, 1971w, 1939s, 1900 (sh)
2071m, 1988m, 1955s
2067m, 2014w, 1937s, 1908s
1999m, 1911s, 1900 (sh)
2016m, 1920 (sh), 1901s, 1880s
2014m, 1913s, 1898s, 1862s
1993s, 1920 (sh), 1890s (br)
2014s, 1920 (sh), 1880s (br)
2007s, 1905 (sh), 1880s (br)
1910s, 1822s
2060m, 1983w, 1941s
2072m, 1993w, 1949s
2070m, 1982w, 1943s
2060m, 1982 (sh), 1944s
2070m, 1985 (sh), 1946s
2058m, 1967w, 1933s
2070m, 2023m, 1988 (sh), 1953s
2068m, 2014w, 1980 (sh), 1939s
2013m, 1923s, 1910 (sh), 1897s
2021m, 1926s, 1915s, 1889 (sh)
2020m, 1914s, 1903s, 1880 (sh)
2000s, 1908 (sh), 1894s, 1875 (sh)
2018m, 1919s, 1910 (sh), 1889m
2013s, 1902s (br), 1878 (sh)
1924s, 1836s
[Cr2(CO)10(dpsm)]
[W2(CO)10(dpsm)]
[Cr2(CO)10(dmsm)]
[Mo2(CO)10(dmsm)]
[W2(CO)10(dmsm)]
[Cr2(CO)8(dpsm)2]
[Mo2(CO)8(dpsm)2]
[W2(CO)8(dpsm)2]
[Cr2(CO)8(dmsm)2]
[Mo2(CO)8(dmsm)2]
[W2(CO)8(dmsm)2]
[Cr(CO)3(dpsm)3]
[Mo(CO)3(dpsm)3]
[W(CO)3(dpsm)3]
1926s, 1835s
1924s, 1809s
1944s, 1854s
1929s, 1834m (br)
Intensities: strong (s), medium (m), weak (w), shoulder (sh), broad (br).
Table 2 Selected NMR spectroscopic data
1H NMRa
13C-{1H} NMRb
Complex
δ(CH2)
δ(CH3)
δ(Ph)
δ(CH2)
δ(CH3)
δ(Ph)
δ(CO)
95Mo NMRc
[Cr(CO)5(dpsm)]
[Mo(CO)5(dpsm)]
[W(CO)5(dpsm)]
2.35
2.4
2.5
2.65
2.8
2.05
1.8
2.0
2.6
2.0
2.6
1.45
1.6
1.55
1.9
1.9
2.0
7.2–7.5
7.2–7.5
7.2–7.5
7.1–7.4
7.2–7.5
4.6
5.3
5.3
2.2
3.0
0.8
0.9
0.6
5.7
4.9
4.6
2.5
2.4
2.8
7.2
7.1
6.5
128–136
128–141
128–138
129–135
128–136
217.6, 223.0
206.5, 210.5
Ϫ1856
e
196.7 (126), 199.0 (162)d
217.2, 228.8
[Cr2(CO)10(dpsm)]
[W2(CO)10(dpsm)]
[Cr2(CO)10(dmsm)]
[Mo2(CO)10(dmsm)]
[W2(CO)10(dmsm)]
[Cr2(CO)8(dpsm)2]
[Mo2(CO)8(dpsm)2]
[W2(CO)8(dpsm)2]
[Cr2(CO)8(dmsm)2]
[Mo2(CO)8(dmsm)2]
[W2(CO)8(dmsm)2]
[Cr(CO)3(dpsm)3]
[Mo(CO)3(dpsm)3]
[W(CO)3(dpsm)3]
196.5 (123), 198.2 (156)d
218.5, 223.9
1.5
1.3
1.5
1.6
1.3
1.3
206.2, 210.1
Ϫ1830
Ϫ1760
Ϫ1730
Ϫ1519
197.1 (127), 199.0 (164)d
226.6, 228.4
7.0–7.7
7.0–7.7
7.0–7.7
129–139
127–138
129–140
210.0, 214.6
200.7 (121), 203.5 (156)d
222.8, 228.0
1.3
1.3
1.4
2.1
1.9
2.2
210.6, 216.0
202.5 (130), 206.0 (158)
232.8
6.8–7.4
6.9–7.4
7.0–7.4
128–139
128–135
127–140
220.3
210.8 (164)d
a In CDCl3. b In 10% CDCl3–CH2Cl2. c Relative to aqueous Na2MoO4, δ 0; [Mo(CO)6] has δ Ϫ1859. d 1J(183W᎐13C)/Hz. e The low sensitivity and very
long relaxation times of 183W in carbonyl complexes, coupled with solution instability in some cases, prevented convincing 183W resonances being
observed.
O
C
only in recovery of [Mo(CO)5(η1-dpsm)]. The formulation of
these complexes as [(OC)5M(µ-dpsm)M(CO)5] II follows from
the very similar IR spectra (Table 1) to those of [M(CO)5(η1-
dpsm)], and shows that the two M(CO)5 groups are essentially
isolated by the ligand bridge. Confirmation of the structure was
obtained by the X-ray study of the tungsten complex (below).
The chromium complex shows a parent ion [Cr2(CO)10-
(dpsm)]ϩ in the FAB mass spectrum, but the highest significant
feature for the tungsten complex is [P Ϫ 3(CO)]ϩ, although both
are good confirmation of the dimer formulation.
O
C
O
C
O
O
O
O
C
C
O
O
O
O
C
C
C
C
C
C
C
M
M
M
Sb
Sb
Sb
Sb
O
C
O
C
O
C
O
I
II
isotope pattern, and ions resulting from CO loss down to
[Cr(dpsm)]ϩ; the molybdenum and tungsten complexes show
[P Ϫ CO]ϩ as the highest mass ions but similar fragments.
[(OC)5M(ì-dmsm)M(CO)5] (M ؍ Cr, Mo or W)
[(OC)5M(ì-dpsm)M(CO)5] (M ؍ Cr or W)
In marked contrast to the dpsm complexes, these dmsm com-
pounds are readily made by reaction of [M(CO)6] with dmsm in
a 2:1 mol ratio in a high-boiling solvent. The spectroscopic
properties (Tables 1 and 2) are very similar to those of
[(OC)5M(µ-dpsm)M(CO)5] and an analogous structure is
proposed.
Thermal reactions of [M(CO)5(η1-dpsm)] with [M(CO)6] do not
occur to a significant extent. The reaction of [M(CO)5Br]Ϫ with
dpsm in a 2:1 mol ratio gave only [M(CO)5(η1-dpsm)] for
M = Mo or W, and a mixture of [Cr(CO)5(η1-dpsm)] and
[{Cr(CO)5}2(dpsm)] for chromium. This suggests that co-
ordination of one stibine group reduces the reactivity of the
second, but steric effects may also be important since
[M(CO)5(η1-dpsm)] is a bulky ligand towards a second metal
centre. The pure [{M(CO)5}2(dpsm)] (M = Cr or W) are best
obtained from [M(CO)5(η1-dpsm)] and [M(CO)5(thf)]. Curi-
ously, all attempts to prepare [{Mo(CO)5}2(dpsm)] resulted
cis-[{M(CO)4(L᎐L)}2] (M ؍ Cr, Mo or W; L᎐L ؍ dpsm or
dmsm)
These complexes were prepared in relatively poor yields by dis-
placement of the neutral ligands from [M(CO)4(nbd)] {M = Cr
826
J. Chem. Soc., Dalton Trans., 1998, Pages 825–832

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or Mo; nbd = norbornadiene (bicyclo[2.2.1]hepta-2,5-diene)}
or [W(CO)4(Me2NCH2CH2CH2NMe2)]. Unless carefully con-
trolled these reactions yield intractable mixtures of penta-,
tetra- and tri-carbonyl complexes. The cis tetracarbonyl
arrangement follows from the two 13C NMR carbonyl reson-
ances (1:1 intensities) and the typical ν(CO) IR modes (theory
2A1 ϩ B1 ϩ B2) (Tables 1 and 2). The formulation as dimers
[(OC)4M(µ-L᎐L)2M(CO)4] III rather than monomers
[M(CO)4(L᎐L)] is based upon the FAB mass spectra which
show parent ions for the dmsm complexes (Experimental
section), and dimetal fragments for the dpsm complexes of
Mo and W, and was confirmed by single-crystal X-ray studies
of [{W(CO)4(L᎐L)}2] (L᎐L = dpsm or dmsm) (below). Very
small yields [5% (Mo), traces (Cr, W)] of monomer species
[M(CO)4(dpsm)] containing chelated dpsm reportedly3 formed
on prolonged photolysis (several days) of [M(CO)6] and
ligand in hexane. We have been unable to confirm this. In our
hands prolonged photolysis of [Mo(CO)6] ϩ dpsm (1:1 mol
ratio) in hexane gave [Mo(CO)5(η1-dpsm)], [{Mo(CO)4-
(dpsm)}2], unchanged reagents and a large amount of grey
insoluble carbonyl-free material. If complexes with a strained
four-membered chelate ring were formed one would expect rela-
1
tively large shifts in the CH2 resonances in the H or 13C-{1H}
NMR spectra,9,10 but we have not observed examples of this.
The pure [{M(CO)4(dmsm)}2] complexes appear air stable in
the solid state, but in CH2Cl2 solution they decompose quite
rapidly.
Fig. 1 The structure of [W(CO)5(dpsm)] showing the atom labelling
scheme. Ellipsoids are drawn at the 50% probability level
O
C
bonded only via one antimony. For example addition of dmsm
to a solution of [M(CO)5(thf)] (M = Mo or W) in thf (1:1 mol
ratio), and removal of the solvent in vacuum, gave air-sensitive
oils. The tungsten product had a 13C-{1H} NMR spectrum show-
ing δ(CO) 200.1 and 197.5 in the expected ratio for a penta-
carbonyl and weaker features at 199.0 and 197.0 assignable to
[W2(CO)10(µ-dmsm)]. The range δ ϩ5 to Ϫ5 showed seven main
resonances attributable to the ditungsten complex, free dmsm1
and [W(CO)5(η1-dmsm)]. Under an inert atmosphere the spec-
trum changed over a period of a few hours and on exposure to
air a white solid deposited, no doubt due to oxidation at the free
Me2Sb groups.‡ Similar data were obtained from the molyb-
denum system and in addition the 95Mo NMR spectrum
showed resonances at δ Ϫ1859.0 {[Mo(CO)6]}, Ϫ1856.0
{[Mo2(CO)10(dmsm)]} and Ϫ1856.5 {[Mo(CO)5(η1-dmsm)]}.
The reaction of [Mo(CO)6] with an excess of dmsm in ethanol
with added NaBH4 gave after work-up a grey powder, which
was poorly soluble in chlorocarbons. It had major features in
the 13C-{1H} NMR spectrum at δ 227.0, 3.4, 2.2 and 0.7 and IR
bands at 1933 and 1840 cmϪ1 (CH2Cl2) which are consistent
with the presence of fac-[Mo(CO)3(η1-dmsm)3]. An analytically
pure sample could not be obtained, and the CH2Cl2 solution
decomposed completely in a few hours. These results show that
complexes of η1-co-ordinated dmsm can be formed, but are
unstable both to air oxidation and rearrangement into other
complexes; the latter effectively prevents isolation of pure
samples.
O
Sb
Sb
Sb
Sb
C
C
O
C
O
C
M
O
O
O
Sb
Sb
Sb
Sb
O
C
C
C
C
M
M
Sb
O
C
O
C
O
III
Sb
IV
fac-[M(CO)3(ç1-dpsm)3] (M ؍ Cr, Mo or W)
The reaction of [Mo(CO)6] with dpsm in ethanol with NaBH4
as catalyst results in good yields of fac-[Mo(CO)3(η1-dpsm)3],
although the chromium and tungsten complexes do not form in
this way. The fac-[Cr(CO)3(dpsm)3] was made in low yield by
heating [Cr(CO)4(nbd)] with an excess of dpsm in ethanol or
more slowly in methylcyclohexane, and fac-[W(CO)3(dpsm)3]
from [W(CO)3(MeCN)3] and dpsm. The single δ(CO) reson-
ance in the 13C-{1H} NMR spectrum of each complex and
the two ν(CO) bands in the IR spectra are typical of
fac-M(CO)3Sb3 compounds IV, cf. fac-[Mo(CO)3{MeC(CH2-
SbPh2)3}].14 The FAB mass spectra exhibit very weak parent
ions with the correct isotope structure confirming the formu-
lations. Unfortunately we have been unable to grow crystals of
these complexes; the chromium and tungsten complexes
decompose slowly in solution, and whilst the molybdenum
complex is stable, repeated attempts to obtain crystals have
produced only very thin needles which diffract too weakly. The
complex formulated3 as [Mo(CO)3(dpsm)2] and suggested to
contain one chelated and one monodentate dpsm ligand, des-
Crystal structures of [W(CO)5(dpsm)], [{W(CO)5}2(dpsm)],
[{W(CO)4(dpsm)}2] and [{W(CO)4(dmsm)}2]
The molecules are shown in Figs. 1, 2, 3 and 4 respectively and
selected bond lengths and angles presented in Table 3. The
results confirm the structures and bonding modes of the di-
stibines proposed above on the basis of spectroscopic data,
and also reveal some unexpected trends in comparison to
data on phosphine and arsine analogues. The first two examples
can usefully be discussed together as they show co-ordination
1
pite showing only a single δ(CH2) resonance in the H NMR
spectrum, is one of the few claimed examples containing che-
lated dpsm. Comparison of the data reported for this complex
with those obtained from [Mo(CO)3(dpsm)3] shows excellent
agreement, and we conclude that the report of [Mo(CO)3-
(dpsm)2] is in error.
ç1-dmsm Complexes
‡ Unlike phosphines and arsines, stibines do not oxidise cleanly to the
ligand oxide, but are converted into intractable polymeric materials.
A number of attempts were made to isolate complexes of dmsm
J. Chem. Soc., Dalton Trans., 1998, Pages 825–832
827

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Fig. 4 The structure of [{W(CO)4(dmsm)}2]. Details as in Fig. 1
the case of dppm upon co-ordination to a metal there is no
significant effect upon the C᎐P᎐C angles and although the data
on complexes of Ph2AsCH2AsPh2 (dpam) are more restricted
and of lower quality, the same seems to hold for the C᎐As᎐C
angles. In marked contrast, in the stibines the C᎐Sb᎐C angles
increase on co-ordination, most evident in comparing the
angles at bound and free antimony centres in the η1-dpsm
complexes. A similar increase in the C᎐Bi᎐C angles was
observed21,22 on co-ordination of BiPh3 in [M(CO)5(BiPh3)]. On
a simple hybridisation model these results suggest that on co-
ordination more s character enters into the C᎐Sb bonds (con-
versely the donor ‘lone pair’ is now in an orbital with increased
p character). A more detailed understanding of this effect must
await high level MO calculations which are presently rare in
organoantimony chemistry.23
Fig. 2 The structure of [{W(CO)5}2(dpsm)]. Details as in Fig. 1
The second effect, the changes in the E᎐CH2᎐E angles on co-
ordination, also varies with the identity of E. η1 Co-ordination
of dppm as in [Fe(CO)4(dppm)] or [Cr(CO)3(dppm)2] (the latter
contains one chelating and one monodentate dppm ligand)
results in an increase in this angle, whereas in the η1-dpsm
complexes the angle decreases. The ‘free’ SbPh2 group has no
close contacts to other groups or to the metal and hence the
decrease in the Sb᎐C᎐Sb angle does not result from any direct
interaction. Co-ordination of a second metal centre to form a µ-
dpsm ligand results in Sb᎐C᎐Sb angles similar to or greater
(р10Њ) than that in free dpsm (Table 4). The case of the inter-
mediate dpam is less clear due to limited data, but in the seven-
co-ordinated carbonyl halides it appears that the As᎐C᎐As
angle of η1-dpam is not significantly different from that in free
dpam.
Fig. 3 The structure of [{W(CO)4(dpsm)}2]. Details as in Fig. 1
at one or two Sb atoms to unconnected square pyramidal
W(CO)5 residues. The η1 derivative shows a smaller Sb᎐C᎐Sb
angle [106.8(5)Њ] than free dpsm1 [117.3(2)Њ] and the C᎐Sb᎐C
angles at the co-ordinated Sb are larger than the free C᎐Sb᎐C
angles. Co-ordination to Sb(2) in the second compound results
in an increase in the Sb᎐C᎐Sb angles by some 15Њ and the by
now expected opening up of the C᎐Sb(2)᎐C angles. The com-
plex [W(CO)5(dpsm)] is isostructural with [Cr(CO)5(Ph2Sb-
SSbPh2)],7 although in the latter the angle Sb᎐S᎐Sb is more
acute (96.7Њ).
Some comparisons
Bis(diphenylphosphino)methane forms complexes with the
Group 6 carbonyls of types [M(CO)5(η1-dppm)], [{M(CO)5}2(µ-
dppm)], mer- and fac-[M(CO)3(dppm)2], [M(CO)4(dppm)] and
[M(CO)2(dppm)2],8,18,24–26 chelation being present in the last
three types. The more nucleophilic dmpm appears more
reluctant to form η1 complexes {although fac-[M(CO)3-
(dmpm)3] are known}, but chelates readily as in [M(CO)4-
(dmpm)], and in fac-[M2(CO)6(dmpm)3] both bridging and
chelating dmpm are present.9 Bis(diphenylarsino)methane
forms η1 complexes readily, viz. [M(CO)5(dpam)], cis-
[M(CO)4(dpam)2], fac-[M(CO)3(dpam)3], but also chelates in
[M(CO)4(dpam)],10 and both chelate and η1 forms are present in
the carbonyl halides [Mo(CO)2X2(dpam)2] (X = Cl or Br).27 The
crystal structures of the latter complexes reveal very strained
non-planar four-membered rings formed by the chelated
dpam.20 The behaviour of the distibinomethanes described
above extends these trends in that η1 and bridging behaviours
are found, but we have no evidence for chelation, apparently the
strain in a four-membered chelate ring containing two large
antimony donors is too great.
The two tetracarbonyl derivatives (Figs. 3 and 4) are centro-
symmetric dimeric species with the Sb atoms bonded to
different
[{W(CO)4(dpsm)}2] is
W
atoms. The Sb᎐C᎐Sb angle [125.4(5)Њ] in
little larger (3Њ) than that in
a
[{W(CO)5}2(dpsm)] and the C᎐Sb᎐C angles are as expected for
a bonded Sb. A similar structure was found7 for [{Cr(CO)4-
(Ph2SbOSbPh2)}2] with a wider Sb᎐O᎐Sb angle of 136.9(1)Њ.
[{W(CO)4(dmsm)}2] is only the second structurally character-
ised example of a dmsm complex, the other being1 [Co2(CO)4-
(µ-CO)2(µ-dmsm)]. In both structures the C᎐Sb᎐C angles lie in
the range ca. 98 to 103Њ, but the Sb᎐C᎐Sb angle is smaller in
the cobalt complex [114.5(7)Њ] than in the present tungsten
example [119.7(8)Њ].
Comparable structural data on the distibinomethane com-
plexes and some phosphorus and arsenic analogues are col-
lected in Table 4. Most notable are the effects of co-ordination
upon the bond angles E᎐C᎐E and C᎐E᎐C (E = P, As or Sb). In
828
J. Chem. Soc., Dalton Trans., 1998, Pages 825–832

View Article Online
Table 3 Selected bond lengths (Å) and angles (Њ)
(a) [W(CO)5(dpsm)]
Sb(1)᎐W
W᎐C
Sb(1)᎐C
C᎐C
2.743(1)
Sb(1) ؒ ؒ ؒ Sb(2)
C᎐O
Sb(2)᎐C
3.497(1)
1.14(2)–1.17(2)
2.16(1)–2.19(1)
1.96(2)–2.05(2)
2.10(1)–2.16(1)
1.35(3)–1.44(2)
W᎐Sb(1)᎐C
C᎐Sb(1)᎐C
C᎐C᎐C
113.7(3)–118.4(4)
99.4(5)–104.9(5)
116(1)–123(1)
Sb(1)᎐C(50)᎐Sb(2)
C᎐Sb(2)᎐C
W᎐C᎐O
106.8(5)
96.4(5)–97.4(5)
174(1)–179(2)
(b) [{W(CO)5}2(dpsm)]
Sb(1)᎐W(1)
W᎐C
Sb(1)᎐C
C᎐C
2.756(2)
Sb(2)᎐W(2)
C᎐O
Sb(2)᎐C
2.753(2)
1.96(3)–2.12(3)
2.11(3)–2.16(2)
1.34(4)–1.46(4)
1.09(3)–1.18(3)
2.12(2)–2.17(2)
3.723(2)
Sb(1) ؒ ؒ ؒ Sb(2)
W(1)᎐Sb(1)᎐C
C᎐Sb(1)᎐C
C᎐C᎐C
111.5(5)–120.3(8)
99.3(9)–104.5(9)
116(3)–123(2)
W(2)᎐Sb(2)᎐C
C᎐Sb(2)᎐C
Sb(1)᎐C(50)᎐Sb(2)
W(2)᎐C᎐O
111.3(6)–122.5(8)
98.1(9)–102.2(9)
122(1)
W(1)᎐C᎐O
176(3)–179(2)
172(2)–179(2)
(c) [{W(CO)4(dpsm)}2]
Sb(1)᎐W(1)
W(1)᎐C
Sb(1)᎐C
C᎐C
2.7574(8)
Sb(2)᎐W(1i)
C᎐O
Sb(2)᎐C
2.7420(8)
1.96(1)–2.05(1)
2.15(1)–2,18(1)
1.35(2)–1.46(2)
1.12(1)–1.17(1)
2.12(1)–2.15(1)
3.847(1)
Sb(1) ؒ ؒ ؒ Sb(2)
W(1)᎐Sb(1)᎐C
C᎐Sb(1)᎐C
C᎐C᎐C
113.5(3)–122.8(3)
97.4(4)–100.1(4)
117(1)–122(1)
W(1i)᎐Sb(2)᎐C
C᎐Sb(2)᎐C
Sb(1)᎐C(50)᎐Sb(2)
111.2(3)–119.9(3)
97.4(5)–110.5(4)
125.4(5)
W(1)᎐C᎐O
175(1)–179(1)
(d) [{W(CO)4(dmsm)}2]
Sb(1)᎐W(1)
W(1)᎐C
Sb(1)᎐C
2.754(1)
Sb(2)᎐W(1i)
C᎐O
Sb(2)᎐C
2.752(1)
1.13(2)–1.16(2)
2.14(2)–2.18(2)
1.96(2)–2.04(2)
2.13(2)–2,17(2)
3.710(2)
Sb(1) ؒ ؒ ؒ Sb(2)
W(1)᎐Sb(1)᎐C
C᎐Sb(1)᎐C
Sb(1)᎐C(9)᎐Sb(2)
114.6(4)–123.0(5)
98.5(7)–102.8(7)
119.7(8)
W(1i)᎐Sb(2)᎐C
C᎐Sb(2)᎐C
W(1)᎐C᎐O
114.0(4)–125.3(5)
96.3(7)–102.8(6)
178(1)–179(2)
Symmetry operation: i Ϫx, Ϫy, Ϫz.
Table 4 Comparable structural data (E = P, As or Sb)
Compound
E᎐C᎐E/Њ
C᎐E᎐C/Њ (bonded)
C᎐E᎐C/Њ (free)
Sb ؒ ؒ ؒ Sb/Å
Ref.
dpsm
117.3(2)
107.9(3)
106.8(5)
122(1)
125.4(5)
115.0(2)
114.5(7)
119.7(8)
106.2(3)
112.6(4)
115.3(6)
113(2)
94.4(1)–98.7(1)
96.5(3)–97.7(3)
96.4(5)–97.4(5)
3.692(1)
3.4806(9)
3.497(1)
3.723(2)
3.847(1)
1
1
[Fe(CO)4(η1-dpsm)]
[W(CO)5(η1-dpsm)]
[{W(CO)5}2(µ-dpsm)]
[{W(CO)4(µ-dpsm)}2]
[{Pd(Ph)Cl(µ-dpsm)}2]
[Co2(CO)6(µ-dmsm)]
[{W(CO)4(µ-dmsm)}2]
dppm
100.8(3)–106.8(3)
99.4(5)–104.9(5)
98.1(9)–104.5(9)
97.4(4)–110.5(4)
95.7(2)–103.8(2)
99.0(7)–102.4(7)
96.3(7)–102.8(6)
This work
This work
This work
15
3.572(2)
3.710(2)
1
This work
99.9(2)–103.2(2)
101.7(4)–101.8(5)
99.5(5)–102.5(6)
96(2)–104(2)
90(2)–103(2)
98(1)–101(1)
16
17
18
19
20
20
[Fe(CO)4(η1-dppm)]
[Cr(CO)3(dppm)2]*
dpam
[Mo(CO)2Br2(dpam)2]*
[Mo(CO)2Cl2(dpam)2]*
102.4(4)–103.8(5)
99.3(5)–104.1(5)
113(2)
113(2)
104(1)–105(1)
101(1)–106(1)
* Data refer to the η1-co-ordinated ligand.
Evidence of the trends in electronic properties of the
R2ECH2ER2 ligands comes from the ν(CO) frequencies (in a
common medium CH2Cl2) in these substituted carbonyl com-
plexes. Examination of Table 1 shows that for analogous com-
plexes the ν(CO) frequencies are lower in dmsm than in dpsm
compounds, indicative of the expected greater σ-donor power
of dmsm. If however one compares the ν(CO) frequencies of
isostructural complexes of dppm, dpam20,24,25 and dpsm, only
small and erratic variations are observed. This probably reflects
decreasing σ donation and π acceptance as Group 15 is des-
cended which overall leads to small electron-density changes at
the metal centre.
A further probe for the ligand electronic effects is the magni-
1
tude of the J(13C᎐183W) coupling constants observed on the
COtrans-E as the donor is varied. Buchner and Schenk28 have
reported such coupling constants for a wide range of ligands in
[W(CO)5L] complexes, and the values for the distibinomethanes
(Table 2) ca. 163 Hz indicate that the ligands are relatively low
in the trans influence series. The origin of this effect may lie in
the weak σ donation from antimony.
J. Chem. Soc., Dalton Trans., 1998, Pages 825–832
829

View Article Online
[Cr2(CO)8(dpsm)2]. The complex [Cr(CO)4(nbd)]30 (0.39 g,
Experimental
1.5 mmol) and dpsm (0.86 g, 1.5 mmol) were stirred together in
warm (38 ЊC) methylcyclohexane (100 cm3) for 8 d. The solvent
was removed under reduced pressure, and the residue recrystal-
lised from CHCl3–n-hexane to give a yellow powder (yield 0.28
g, 26%) (Found: C, 48.0; H, 3.2. Calc. for C29H22CrO4Sb2:
C, 47.7; H, 3.0%). FAB mass spectrum m/z 1268, 1184 and
618; Calc. for [52Cr(CO)3(Ph2121SbCH2121SbPh2)2] 1264,
[52Cr(Ph2121SbCH2121SbPh2)2] 1180 and [52Cr(Ph2121SbCH2-
121SbPh2)] 616.
Physical measurements were made as described elsewhere.1
The 95Mo NMR spectra were recorded from CH2Cl2 solutions
on a Bruker AM360 spectrometer at 23.5 MHz and referenced
to external aqueous [MoO4]2Ϫ. The ligands were prepared as
described.1 All complex preparations were carried out in dry
solvents under a dinitrogen atmosphere.
Preparations
[M(CO)5(dpsm)] (M ؍ Cr, Mo or W). A solution of
[NEt4][M(CO)5Br]13 (1.0 mmol) in ethanol (50 cm3) was added
dropwise with stirring to a solution of dpsm (0.57 g, 1.0 mmol)
in ethanol (50 cm3) and the mixture stirred at room temperature
for 24 h. The pale coloured precipitate was filtered off, washed
with water (3 × 5 cm3), dried, and then recrystallised from
CH2Cl2–n-hexane. The resulting solid was dried in vacuo. Yield
ca. 75%.
[Cr(CO)5(dpsm)] (Found: C, 48.0; H, 3.1. Calc. for
C30H22CrO5Sb2: C, 47.5; H, 2.9%): FAB mass spectrum (3-
nitrobenzyl alcohol) m/z 758, 730, 674 and 618; Calc. for
[52Cr(CO)5(Ph2121SbCH2121SbPh2)] 756, [52Cr(CO)4(Ph2121Sb-
CH2121SbPh2)] 728, [52Cr(CO)2(Ph2121SbCH2121SbPh2)] 672 and
[52Cr(Ph2121SbCH2121SbPh2)] 616.
[Mo(CO)5(dpsm)] (Found: C, 44.4; H, 2.6. Calc. for
C30H22MoO5Sb2: C, 44.8; H, 2.7%): FAB mass spectrum m/z
774, 718 and 662; Calc. for [92Mo(CO)4(Ph2121SbCH2121SbPh2)]
768, [92Mo(CO)2(Ph2121SbCH2121SbPh2)] 712 and [92Mo(Ph2-
121SbCH2121SbPh2)] 656.
[W(CO)5(dpsm)] (Found: C, 40.1; H, 2.3. Calc. for
C30H22O5Sb2W: C, 40.4; H, 2.5%): FAB mass spectrum m/z
862, 806 and 750; Calc. for [182W(CO)4(Ph2121SbCH2121SbPh2)]
858, [182W(CO)2(Ph2121SbCH2121SbPh2)] 802 and [182W(Ph2-
121SbCH2121SbPh2)] 746.
[Mo2(CO)8(dpsm)2]. The complex [Mo(CO)4(nbd)]30 (0.45 g,
1.5 mmol) and dpsm (0.84 g, 1.5 mmol) were stirred in methyl-
cyclohexane (250 cm3) at room temperature for 24 h. The solu-
tion was concentrated to ca. 20 cm3 under reduced pressure, and
the resulting precipitate filtered off. The solid was recrystallised
from CHCl3–n-hexane and dried in vacuo. Yield 0.33 g, 28%
(Found: C, 44.7; H, 3.3. Calc. for C29H22MoO4Sb2: C, 45.0; H,
2.9%). FAB mass spectrum m/z 870, 774, 718 and 664; Calc.
for [92Mo2(CO)4(Ph2121SbCH2121SbPh2)] 860, [92Mo(CO)4(Ph2-
121SbCH2121SbPh2)] 768, [92Mo(CO)2(Ph2121SbCH2121SbPh2)]
712 and [92Mo(Ph2121SbCH2121SbPh2)] 656.
[W2(CO)8(dpsm)2]. The complex [W(CO)4(Me2NCH2CH2-
CH2NMe2)]31 (0.21 g, 0.5 mmol) and dpsm (0.28 g, 0.5 mmol)
were refluxed together in ethanol (30 cm3) for 25 min. A pale
orange solid separated from the orange filtrate and was filtered
off, washed with diethyl ether (2 × 10 cm3) and dried in vacuo.
Yield 0.055 g, 13% (Found: C, 40.0; H, 2.5. Calc. for
C29H22O4Sb2W: C, 40.4; H, 2.6%). FAB mass spectrum m/z
1130, 862, 806 and 750; Calc. for [182W2(CO)7(Ph2121Sb-
CH2121SbPh2)] 1124, [182W(CO)4(Ph2121SbCH2121SbPh2)] 858,
[
182W(CO)2(Ph2121SbCH2121SbPh2)] 802 and
CH2121SbPh2)] 746.
[
182W(Ph2121Sb-
[M2(CO)10(dpsm)] (M ؍ Cr or W). A solution of [M(CO)5-
(thf)] (thf = tetrahydrofuran) in thf, made by photolysis of
[M(CO)6] (0.25 mmol) in thf (20 cm3),29 was added to a solution
of [M(CO)5(dpsm)] (0.2 mmol) in thf (10 cm3), and the mixture
stirred for 24 h. It was then evaporated to dryness, and the
residue recrystallised from CH2Cl2–n-hexane. Yield ca. 40%.
[W2(CO)10(dpsm)] (Found: C, 34.3; H, 1.8. Calc. for
C35H22O10Sb2W2: C, 34.6; H, 1.8%): FAB mass spectrum m/z
[Cr2(CO)8(dmsm)2]. The complex [Cr(CO)4(nbd)]30 (0.19 g,
0.74 mmol) and dmsm (0.24 g, 0.75 mmol) were refluxed
together in methylcyclohexane (25 cm3) for 1 min. The mixture
was then immediately cooled to room temperature. The sticky
yellow solid formed was separated by decanting the liquor off,
dissolved in dichloromethane (20 cm3), filtered and the filtrate
taken to dryness and triturated in n-pentane to give a yellow
solid which was dried in vacuo. Yield 0.1 g, 28% (Found: C,
22.7; H, 3.1. Calc. for C9H14CrO4Sb2: C, 22.4; H, 2.9%). FAB
mass spectrum m/z 963, 879, 851, 821 and 483; Calc. for
[52Cr2(CO)8(Me2121SbCH2121SbMe2)2] 960, [52Cr2(CO)5(Me2-
1130, 862 and 806; Calc. for
[
182W2(CO)7(Ph2121SbCH2-
121SbPh2)] 1124, [182W(CO)4(Ph2121SbCH2121SbPh2)] 858 and
[
182W(CO)2(Ph2121SbCH2121SbPh2)] 802.
[Cr2(CO)10(dpsm)] (Found: C, 44.2; H, 2.3. Calc. for
121SbCH2121SbMe2)2]
876,
[52Cr2(CO)4(Me2121SbCH2121Sb-
C35H22Cr2O10Sb2: C, 44.2; H, 2.3%): FAB mass spectrum m/z
950, 866, 810 and 758; Calc. for [52Cr2(CO)10(Ph2121Sb-
CH2121SbPh2)] 948, [52Cr2(CO)7(Ph2121SbCH2121SbPh2)] 864,
[52Cr2(CO)5(Ph2121SbCH2121SbPh2)] 808 and [52Cr(CO)5(Ph2-
121SbCH2121SbPh2)] 756.
Me2)2] 848, [52Cr2(CO)3(Me2121SbCH2121SbMe2)2] 820 and
[52Cr(CO)4(Me2121SbCH2121SbMe2)] 480.
The complex [Mo2(CO)8(dmsm)2] was made similarly from
[Mo(CO)4(nbd)]30 (0.22 g, 0.73 mmol) and dmsm (0.24 g, 0.75
mmol). Yield 0.07 g, 18% (Found: C, 20.6; H, 2.8. Calc. for
C9H14MoO4Sb2: C, 20.5; H, 2.7%). FAB mass spectrum m/z
993, 965, 911, 883, 855 and 527; Calc. for [92Mo2(CO)6(Me2-
121SbCH2121SbMe2)2] 984, [92Mo2(CO)5(Me2121SbCH2121Sb-
Me2)2] 956, [92Mo2(CO)3(Me2121SbCH2121SbMe2)2] 900, [92Mo2-
(CO)2(Me2121SbCH2121SbMe2)2] 872, [92Mo2(CO)(Me2121Sb-
CH2121SbMe2)2] 844 and [92Mo(CO)4(Me2121SbCH2121SbMe2)]
520.
[W2(CO)10(dmsm)]. The compound [W(CO)6] (1.6 g, 4.4
mmol) and dmsm (0.7 g, 2.2 mmol) were refluxed in diglyme
(30 cm3) for 3 h, until evolution of CO had ceased. The solvent
was removed by distillation under reduced pressure, and the
residue recrystallised from CH2Cl2–n-hexane. Yield 0.68 g, 32%
(Found: C, 18.5, H, 1.4. Calc. for C15H14O10Sb2W2: C, 18.7;
H, 1.5%). FAB mass spectrum m/z 966, 938, 910, 854 and
614; Calc. for
[
182W2(CO)10(Me2121SbCH2121SbMe2)] 960,
[W2(CO)8(dmsm)2]. The complex [W(CO)4(Me2NCH2CH2-
CH2NMe2)]31 (0.39 g, 0.93 mmol) and dmsm (0.30 g, 0.94
mmol) were refluxed together in ethanol (25 cm3) for 1 min. The
mixture was then immediately cooled to room temperature and
the pale yellow precipitate formed filtered off, washed with
ethanol (2 × 10 cm3) and diethyl ether (2 × 10 cm3) and dried in
vacuo. Yield 0.15 g, 26% (Found: C, 18.1; H, 2.4. Calc. for
C9H14O4Sb2W: C, 17.6; H, 2.3%). FAB mass spectrum m/z 1227,
1170, 1117, 1090 and 614; Calc. for [182W2(CO)8(Me2121Sb-
[
182W2(CO)9(Me2121SbCH2121SbMe2)] 932,
[
182W2(CO)8(Me2-
121SbCH2121SbMe2)] 904, [182W2(CO)6(Me2121SbCH2121SbMe2)]
848 and [182W(CO)4(Me2121SbCH2121SbMe2)] 610.
The complex [Mo2(CO)10(dmsm)] was made similarly to the
tungsten complex using n-heptane as solvent. Yield 36%
(Found: C, 22.7; H, 1.7. Calc. for C15H14Mo2O10Sb2: C, 22.8; H,
1.7%). The complex [Cr2(CO)10(dmsm)] was made similarly
from [Cr(CO)6]. Yield 40% (Found: C, 25.9; H, 2.1. Calc. for
C15H14Cr2O10Sb2: C, 25.7; H, 2.1%).
CH2121SbMe2)2] 1220,
[
182W2(CO)6(Me2121SbCH2121SbMe2)2]
830
J. Chem. Soc., Dalton Trans., 1998, Pages 825–832

View Article Online
Table 5 Crystallographic details*
[W(CO)5(dpsm)]
[{W(CO)5}2(dpsm)]
[{W(CO)4(dpsm)}2]
[{W(CO)4(dmsm)}2]
Formula
Mr
C30H22O5Sb2W
889.85
C35H22O10Sb2W2
1213.75
C58H44O8Sb4W2
1723.68
C18H28O8Sb4W2
1227.11
Crystal system
Space group
a/Å
b/Å
c/Å
α/Њ
β/Њ
Monoclinic
P21/c (no. 14)
9.160(5)
28.903(8)
11.394(7)
Triclinic
P1 (no. 2)
Monoclinic
P21/n (no. 14)
12.657(1)
13.874(2)
16.544(1)
Monoclinic
P21/n (no. 14)
8.913(2)
16.163(2)
10.405(3)
¯
13.062(6)
14.665(10)
12.758(7)
115.36(5)
115.03(4)
63.99(4)
1899.6 (2.1)
19.0–22.5
150
98.21(5)
101.934(8)
101.46(2)
γ/Њ
U/Å3
2985.5(2.6)
14.2–16.2
300
1.980
2842.4(5)
13.9–17.9
150
2.014
2
1469.0(7)
14.2–24.5
150
2.774
2θ Range for cell/Њ
T/K
Dc/g cmϪ3
Z
2.122
2
4
2
F(000)
1672
0.50 × 0.27 × 0.10
ω
5727
1124
0.50 × 0.10 × 0.05
ω–2θ
1616
0.30 × 0.10 × 0.10
ω–2θ
1104
0.30 × 0.10 × 0.10
ω–2θ
Crystal size/mm
Scan mode
Total no. observations
7009
5494
2877
No. unique observations (Rint
hkl Ranges
Maximum, minimum transmission
)
5378 (0.067)
0–10, 0–34, Ϫ13 to 13
1.000, 0.411
3115 [I > 3σ(I)]
343
6690 (0.191)
5244 (0.048)
2699 (0.053)
0–10, 0–19, Ϫ12 to 12
1.000, 0.696
1705 [I > 2.5σ(I)]
145
0–15, Ϫ15 to 17, Ϫ15 to 13 0–15, 0–16, Ϫ19 to 19
1.000, 0.342
4015 [I > 3σ(I)]
412
1.000, 0.598
3479 [I > 2.5σ(I)]
325
No. data in refinement
No. parameters
µ/cmϪ1
57.70
74.99
60.54
116.6
S
1.76
0.02
1.91 to Ϫ1.15
0.044
2.49
0.05
2.48 to Ϫ3.37
0.069
1.31
0.001
1.16 to Ϫ1.91
0.040
1.23
0.00
1.81 to Ϫ1.58
0.040
Maximum shift/e.s.d.
Residual electron density/e ÅϪ3
R
RЈ
0.047
0.079
0.046
0.047
¹
2
2
2
* In common: wϪ1 = σ (Fo); ψ-scan absorption correction; maximum 2θ = 50Њ; R = Σ Fo| Ϫ |Fc /Σ|Fo|; RЈ = [Σw(Fo Ϫ Fc) /ΣwFo ] .
²
1164, [182W2(CO)4(Me2121SbCH2121SbMe2)2] 1108, [182W2(CO)3-
then taken to dryness, dissolved in dichloromethane (2 cm3) and
(Me2121SbCH2121SbMe2)2] 1080 and
CH2121SbMe2)] 610.
[
182W(CO)4(Me2121Sb-
added dropwise to a stirred solution of hexane (50 cm3) to give
an orange-brown solid which was filtered off, washed with hex-
ane (2 × 10 cm3) and dried in vacuo. Yield 0.19 g, 18% (Found:
C, 47.4; H, 3.2. Calc. for C78H66O3Sb6W: C, 47.6; H, 2.6%).
FAB mass spectrum m/z 1967, 806 and 750; Calc. for
[Cr(CO)3(dpsm)3]. The complex [Cr(CO)4(nbd)]30 (0.19 g,
0.74 mmol) and dpsm (1.26 g, 2.23 mmol) were refluxed
together in ethanol (50 cm3) for 30 min when a yellow solid
precipitated. The mixture was cooled and stirred at room tem-
perature for 30 min. The solid was filtered off, washed with
diethyl ether (2 × 10 cm3) and dried in vacuo. Yield 0.03 g,
2%. The same reaction occurred over several days in warm
(40 ЊC) methylcyclohexane solution (32%) (Found: C, 51.3;
H, 3.7. Calc. for C78H66CrO3Sb6: C, 51.0; H, 3.6%). FAB
mass spectrum m/z 1834, 1268, 1184 and 618; Calc. for
[52Cr(CO)3(Ph2121SbCH2121SbPh2)3] 1828, [52Cr(CO)3(Ph2121Sb-
CH2121SbPh2)2] 1264, [52Cr(Ph2121SbCH2121SbPh2)2] 1180 and
[52Cr(Ph2121SbCH2121SbPh2)] 616.
[
182W(CO)3(Ph2121SbCH2121SbPh2)3] 1958, [182W(CO)2(Ph2121Sb-
CH2121SbPh2)] 802 and [182W(Ph2121SbCH2121SbPh2)] 746.
Crystallography
Details of the crystallographic studies are presented in Table 5.
Data were collected on a Rigaku AFC7S diffractometer
equipped with Mo-Kα radiation (λ = 0.710 69 Å) and graphite
monochromator. Selected crystals were mounted on glass fibres
following oil immersion and held at 150 K using an Oxford
Cryosystems low-temperature device or glued to a glass fibre for
the room-temperature data (300 K). The Lorentz-polarisation
corrections and any correction for the small amount of decay
were applied during data reduction. Structure solution was by
means of SHELXS 8633 and full-matrix least-squares refine-
ment on F was carried out to convergence with the TEXSAN
package.34 Hydrogen atoms were not included in the models
and all atoms except as noted below were treated as anisotropic.
Crystals were grown by the liquid-diffusion technique where
ethanol was layered onto a CH2Cl2 solution of the compound.
Five C atoms of carbonyl groups mainly associated with W(2)
in [{W(CO)5}2(dpsm)] gave rise to a non-positive definite condi-
tion and were treated as isotropic in the refinement.
[Mo(CO)3(dpsm)3]. The compound [Mo(CO)6] (0.11 g, 0.4
mmol), dpsm (0.45 g, 0.8 mmol) and NaBH4 (0.15 g, 4.0 mmol)
were refluxed together in ethanol (30 cm3) for 6 h. The mixture
was cooled, the solid which precipitated filtered off, washed
with water (3 × 5 cm3), and dried in vacuo. Yield 0.18 g, 35%
(Found: C, 50.0; H, 3.5. Calc. for C78H66MoO3Sb6: C, 50.0; H,
3.2%). FAB mass spectrum m/z 1876, 1312, 718 and 662; Calc.
for [92Mo(CO)3(Ph2121SbCH2121SbPh2)3] 1868, [92Mo(CO)3(Ph2-
121SbCH2121SbPh2)2] 1304, [92Mo(CO)2(Ph2121SbCH2121SbPh2)]
712 and [92Mo(Ph2121SbCH2121SbPh2)] 656.
CCDC reference number 186/848.
[W(CO)3(dpsm)3]. A mixture of [W(CO)6] (0.196 g, 0.55
mmol) and acetonitrile (50 cm3) were refluxed under argon for 4
d to generate fac-[W(CO)3(MeCN)3].32 The solution was cooled
and dpsm (1.0 g, 1.74 mmol) in dichloromethane (10 cm3) was
added and the mixture stirred at room temperature for 3.5 d.
The orange-brown solution was filtered and the filtrate reduced
in volume to ca. 5 cm3 and refiltered. The orange filtrate was
Acknowledgements
We thank the EPSRC (A. M. H. and N. J. H.) and the University
of Southampton (A. R. J. G.) for support and the EPSRC for
funds to purchase the X-ray diffractometer.
J. Chem. Soc., Dalton Trans., 1998, Pages 825–832
831

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18 R. Colton, B. F. Hoskins and K. McGregor, Aust. J. Chem., 1987, 40,
References
1471.
1 Part 1, A. M. Hill, W. Levason, M. Webster and I. Albers,
Organometallics, 1997, 16, 5641.
2 N. R. Champness and W. Levason, Coord. Chem. Rev., 1994, 133,
115.
3 T. W. Beall and L. W. Houk, J. Organomet. Chem., 1973, 56, 261.
4 T. Fukumoto, Y. Matsumura and R. Okawara, J. Organomet.
Chem., 1972, 37, 113.
5 H. J. Breunig, W. Fichtner and T. P. Knobloch, Z. Anorg. Allg.
Chem., 1978, 445, 215.
19 A. J. Canty and B. M. Gatehouse, J. Chem. Soc., Dalton Trans.,
1972, 511.
20 M. G. B. Drew, J. Chem. Soc., Dalton Trans., 1972, 626; M. G. B.
Drew, A. P. Wolters and L. B. Tomkins, J. Chem. Soc., Dalton
Trans., 1977, 974.
21 N. J. Holmes, W. Levason and M. Webster, J. Organomet. Chem.,
1997, 445–446, 111.
22 A. J. Carty, N. J. Taylor, A. W. Coleman and M. F. Lappert,
J. Chem. Soc., Chem. Commun., 1979, 639.
23 S. Nagase, in The Chemistry of Organic Arsenic, Antimony and
Bismuth Compounds, ed. S. Patai, Wiley, New York, 1994, ch. 1.
24 Z. Ozer, S. Ozkar and H. O. Pamuk, Z. Naturforsch., Teil B, 1993,
48, 37.
25 M. K. Rottink and R. J. Angelici, Inorg. Chem., 1993, 32, 2421.
26 K. K. Cheung, T. F. Lai and K. S. Mok, J. Chem. Soc. A, 1971, 1644.
27 R. Colton, Coord. Chem. Rev., 1971, 6, 269.
28 W. Buchner and W. A. Schenk, Inorg. Chem., 1984, 23, 132.
29 W. Strohmeier, Angew. Chem., 1964, 76, 873.
30 R. B. King, Organometallic Synthesis, Academic Press, New York,
1965, pp. 122–124.
6 T. Fukumoto, Y. Matsumura and R. Okawara, Inorg. Nucl. Chem.
Lett., 1973, 9, 711; 1974, 10, 257.
7 M. Wieber and N. Graf, Z. Anorg. Allg. Chem., 1993, 619, 1991.
8 R. J. Puddephatt, Chem. Soc. Rev., 1983, 12, 99.
9 R. B. King and K. S. RaghuVeer, Inorg. Chem., 1984, 23, 2482.
10 R. Colton and C. J. Rix, Aust. J. Chem., 1971, 24, 2461.
11 Comprehensive Organometallic Chemistry, eds. E. W. Abel, F. G. A.
Stone and G. Wilkinson, Pergamon, Oxford, Series 1, 1982, Series 2,
1995.
12 J. Chatt, G. J. Leigh and N. Thankarajan, J. Organomet. Chem.,
1971, 29, 105.
13 E. W. Abel, I. S. Butler and J. G. Reid, J. Chem. Soc., 1963, 2068.
14 A. F. Chiffey, J. Evans, W. Levason and M. Webster,
Organometallics, 1996, 15, 1280.
15 A. F. Chiffey, J. Evans, W. Levason and M. Webster,
Organometallics, 1995, 14, 1522.
16 H. Schmidbaur, G. Reber, A. Schier, F. E. Wagner and G. Müller,
Inorg. Chim. Acta, 1988, 147, 143.
31 G. R. Dobson and G. C. Faber, Inorg. Chim. Acta, 1970, 4, 87.
32 D. P. Tate, J. M. Augl and W. R. Knipple, Inorg. Chem., 1962, 1, 433.
33 G. M. Sheldrick, SHELXS 86, Program for crystal structure
solution, Acta Crystallogr., Sect. A, 1990, 46, 467.
34 TEXSAN, Single crystal structure analysis software, version 1.7–1,
Molecular Structure Corporation, The Woodlands, TX, 1995.
17 A. M. G. Dias Rodrigues, J. R. Lechat and R. H. P. Francisco, Acta
Crystallogr., Sect. C, 1992, 48, 159.
Received 29th October 1997; Paper 7/07798J
832
J. Chem. Soc., Dalton Trans., 1998, Pages 825–832