Multiply bridged organodiantimony(V) compounds; crystal structures of [(SbR2)2(μ-O)2(μ-O2AsMe 2)2] (R = Ph or p-tolyl) and [(SbR3)2(μ-O)(μ-O2MR′ 2)2] (R = Ph, M = P, R′ = Me; R = Ph, M = As, R′ = Me or Ph; R = p-tolyl, M = P, R′ = Me)

Article abstract of DOI:10.1039/a702244a

A number of quadruply and triply bridged organodiantimony(V) compounds have been synthesized by reactions of [(SbR₂BrO)₂] (R = Ph or p-tolyl) and [(SbR₃X)₂O] (R = Ph or p-tolyl, X = Br or Cl) with Na(O₂AsMe₂), Na(O₂AsPh₂) or Na(O₂AsMe₂). The compounds have been characterised by a range of spectroscopic methods and crystal structures are reported for two quadruply bridged, [(SbPh₂)₂(μ-O)₂(μ-O₂AsMe ₂)₂] and [{Sb(p-MeC₆H₄)₂}₂(μ-O) ₂(μ-O₂AsMe₂)₂], and four triply bridged compounds, [(SbPh₃)₂(μ-O)(μ-O₂PMe₂) ₂], [(SbPh₃)₂-(μ-O)(μ-O₂AsMe ₂)₂], [(SbPh₃)₂(μ-O)(μ-O₂AsPh ₂)]₂ and [{Sb(p-MeC₆H₄)₃} ₂(μ-O)(μ-O₂PMe₂)₂]. Related trimethylantimony(V) compounds, i.e. [{SbMe₃(O₂PMe₂)}₂O] and [{SbMe₃(O₂AsPh₂)}₂O], which are highly moisture sensitive, have also been obtained.

Full text of DOI:10.1039/a702244a

View Article Online / Journal Homepage / Table of Contents for this issue
Multiply bridged organodiantimony(V) compounds; crystal structures
of [(SbR2)2(ì-O)2(ì-O2AsMe2)2] (R = Ph or p-tolyl) and [(SbR3)2(ì-
O)(ì-O2MRЈ2)2] (R = Ph, M = P, RЈ = Me; R = Ph, M = As, RЈ = Me
or Ph; R = p-tolyl, M = P, RЈ = Me)
Martin N. Gibbons and D. Bryan Sowerby*
Department of Chemistry, University of Nottingham, Nottingham, UK NG7 2RD
A number of quadruply and triply bridged organodiantimony() compounds have been synthesized by reactions
of [(SbR2BrO)2] (R = Ph or p-tolyl) and [(SbR3X)2O] (R = Ph or p-tolyl, X = Br or Cl) with Na(O2AsMe2),
Na(O2AsPh2) or Na(O2AsMe2). The compounds have been characterised by a range of spectroscopic methods
and crystal structures are reported for two quadruply bridged, [(SbPh2)2(µ-O)2(µ-O2AsMe2)2] and [{Sb(p-
MeC6H4)2}2(µ-O)2(µ-O2AsMe2)2], and four triply bridged compounds, [(SbPh3)2(µ-O)(µ-O2PMe2)2], [(SbPh3)2-
(µ-O)(µ-O2AsMe2)2], [(SbPh3)2(µ-O)(µ-O2AsPh2)2] and [{Sb(p-MeC6H4)3}2(µ-O)(µ-O2PMe2)2]. Related
trimethylantimony() compounds, i.e. [{SbMe3(O2PMe2)}2O] and [{SbMe3(O2AsPh2)}2O], which are highly
moisture sensitive, have also been obtained.
Until recently there were very few diantimony compounds
known in which the atoms are spanned by either three or four
bridging groups and when this work was started only two com-
pounds containing quadruple bridges had been characterised.
The first was the zwitterionic [(SbPh2)2(µ-O)2(µ-O2SbPh2)2],1
obtained as a by-product in the oxidation of triphenylantimony
while the second was an anionic species, [(SbPh2)2(µ-O)2(µ-
MoO4)2]2Ϫ, containing two oxo and two molybdate bridges.2,3
More recently two further species, [(SbPh2)2(µ-O)2(µ-O2PR2)2]
where R = cyclohexyl or cyclooctyl, have been synthesized.4
There is a more extensive series of triply bridged compounds,
synthesized by Schmidt and others, which contain in addition
to dioxo chelating ligands both oxo and either hydroxo or
alkoxo bridges. The general formula is [(SbCl3)2(µ-O)(µ-OR)-
potentially good bridging ligands but complex redox reactions
occur with these antimony() compounds and reduction prod-
ucts such as [SbPh2(S2PR2)] can be isolated.18
Discussion
Quadruply bridged compounds
Preparation. Quadruply bridged diantimony compounds
[(SbPh2)2(µ-O)2(µ-O2AsR2)2], where R = Me 1 or Ph 2, have
been prepared by treating [(SbPh2BrO)2], which contains a four-
membered Sb2O2 ring, with 2 mol of either Na(O2AsMe2) or
Na(O2AsPh2) in dichloromethane. They are high-melting stable
compounds, which crystallise as chloroform solvates. An
attempt to introduce a single arsinate bridge by treating
[(SbPh2BrO)2] with 1 mol of Na(O2AsMe2) gave a complex
reaction mixture and only a small amount of unidentified crys-
talline material was isolated. Similar reactions with related
phosphinates, Na(O2PMe2) and Na(O2PPh2), however, failed to
give the expected quadruply bridged analogues, and with
dimethylphosphinate a triply bridged compound, [(SbPh3)2(µ-
O)(µ-O2PMe2)2] 3, was obtained. This can only arise by an
extensive rearrangement, involving loss of an oxo bridge and
gain of one phenyl group per antimony, and currently no real-
istic mechanism can be advanced.
7
(µ-X)] with, for example, R = H, X = O2CMe,5 O2CCl3,6 HSO4
or ClO4;8 R = Me, X = SO4Me,9 SO2Me,10 SO3Me10 or
O2PMe(OMe);11 and R = Et, X = O2PEt(OEt)11 or O2PMe-
(OMe).11 Bridging in the tetranuclear compound, [Sb4Ph8-
O6(MeCO2H)3],12 is similar with pairs of antimony atoms
spanned by hydroxo, oxo and acetate bridges. Pairs of antimony
atoms can also be bridged by either three halogens or two halo-
gens and one oxygen, as in [NMe4]3[(SbCl3)2(µ-Br)3]13 and
[Hpy]2[(SbCl2)2(µ-O)(µ-X)2], where py = pyridine and X = Br or
Cl,14 respectively.
One triply bridged compound, [(SbCl3)2(µ-O)(µ-O2PMe2)2],
with an oxo and two dimethylphosphinate bridges has previ-
ously been synthesized 15 and, while this work was in progress,
two further compounds of this type [(SbPh2Cl)2(µ-O)(µ-
O2PR2)2],16 where R = cyclo-hexyl or -octyl, were isolated.
Crystal structures for both [(SbCl3)2(µ-O)(µ-O2PMe2)2] and
[(SbPh2Cl)2(µ-O){µ-O2P(C6H11)2}2] show octahedral co-
ordination at antimony with bidentate phosphinate groups; the
geometry is similar in the related carboxylate-bridged com-
pound [(SbF3)2(µ-O)(µ-O2CCF3)2].17
Phosphinates and arsinates can, however, behave as either
unidentate or chelating ligands and the work described in this
paper was carried out to define further the conditions under
which the groups might bridge between pairs of antimony
atoms already linked by either one or two oxygen atoms. The
starting materials were the singly bridged dihalides
[(SbR3X)2O], where X = Br or Cl and R = phenyl, p-tolyl or
methyl, and the double bridged analogues [(SbR2BrO)2] where
R = phenyl or p-tolyl. Related dithiophosphinates are also
Unexpectedly, a third quadruply bridged compound, [{Sb(p-
MeC6H4)2}2(µ-O)2(µ-O2AsMe2)2] 4, was obtained in low yield
by treating [{Sb(p-MeC6H4)3Br}2O] with 2 mol of Na(O2AsMe2)
in dichloromethane. In this case, rearrangement with gain of an
oxo bridge and loss of a p-tolyl group from each antimony may
result from hydrolysis and elimination of toluene as shown in
equation (1).
[{Sb(p-MeC6H4)3Br}2O] ϩ 2Na(O2AsMe2) ϩ H2O →
[{Sb(p-MeC6H4)2}2(µ-O)2(µ-O2AsMe2)2] ϩ
2NaBr ϩ 2MeC6H5 (1)
Spectroscopy. All three quadruply bridged compounds 1, 2
and 4 give complex infrared spectra with many bands associated
with aryl groups,19 but an intense broad band centred at ca. 800
cmϪ1 can be assigned to AsO2 stretching. The fact that the
antisymmetric and symmetric modes are not resolved is taken
to point to symmetrical bonding. Rather surprisingly, it is not
J. Chem. Soc., Dalton Trans., 1997, Pages 2785–2792
2785

View Article Online
Fig. 2 Molecular structure and atom numbering scheme for [{Sb(p-
MeC6H4)2}2(µ-O)2(µ-O2AsMe2)2] 4
Fig. 1 Molecular structure and atom numbering scheme for [(SbPh2)2-
(µ-O)2(µ-O2AsMe2)2]ؒ2CHCl3 1
Table 2 Selected bond distances (Å) and angles (Њ) for [{Sb(p-
MeC6H4)2}2(µ-O)2(µ-O2AsMe2)2] 4, with e.s.d.s in parentheses*
Sb(1)᎐O(3)
Sb(1)᎐O(3A)
Sb(1)᎐O(2)
Sb(1)᎐O(1)
Sb(1)᎐C(1)
2.007(3)
2.007(3)
2.087(3)
2.084(3)
2.148(4)
Sb(1)᎐C(8)
As(1)᎐O(1A)
As(1)᎐O(2)
As(1)᎐C(15)
As(1)᎐C(16)
2.161(4)
1.701(3)
1.703(3)
1.904(4)
1.903(4)
Table 1 Selected bond distances (Å) and angles (Њ) for [(SbPh2)2(µ-
O)2(µ-O2AsMe2)2]ؒ2CHCl3 1, with estimated standard deviations
(e.s.d.s) in parentheses*
Sb(1)᎐O(1)
Sb(1)᎐O(1Ј)
Sb(1)᎐O(2)
Sb(1)᎐O(3)
Sb(1)᎐C(1)
1.995(3)
2.004(3)
2.101(3)
2.083(3)
2.157(4)
Sb(1)᎐C(7)
As(1)᎐O(2)
As(1)᎐O(3Ј)
As(1)᎐C(13)
As(1)᎐C(14)
2.156(4)
1.709(3)
1.711(3)
1.909(4)
1.911(4)
Sb(1)᎐O(1)᎐As(1A) 119.5(1)
O(1)᎐Sb(1)᎐C(1)
C(1)᎐Sb(1)᎐C(8)
O(1)᎐Sb(1)᎐O(2)
O(3A)᎐Sb(1)᎐C(8)
O(3)᎐Sb(1)᎐C(1)
O(1A)᎐As(1)᎐O(2) 113.4(1)
C(15)᎐As(1)᎐C(16) 110.4(2)
Sb(1)᎐O(3)᎐Sb(1A) 101.0(1)
93.2(1)
99.0(2)
173.0(1)
167.2(1)
171.0(1)
O(3)᎐Sb(1)᎐O(3A)
O(3)᎐Sb(1)᎐O(2)
O(3A)᎐Sb(1)᎐O(2)
O(3)᎐Sb(1)᎐O(1)
O(3A)᎐Sb(1)᎐O(1)
O(3)᎐Sb(1)᎐C(8)
O(2)᎐Sb(1)᎐C(8)
O(1)᎐Sb(1)᎐C(8)
O(3A)᎐Sb(1)᎐C(1)
O(2)᎐Sb(1)᎐C(1)
79.0(1)
85.4(1)
89.4(1)
89.9(1)
84.6(1)
89.3(1)
95.1(1)
90.1(2)
92.9(1)
90.6(1)
O(1)᎐Sb(1)᎐O(1Ј)
O(1)᎐Sb(1)᎐O(2)
O(1Ј)᎐Sb(1)᎐O(2)
O(1)᎐Sb(1)᎐O(3)
O(1Ј)᎐Sb(1)᎐O(3)
O(1)᎐Sb(1)᎐C(1)
O(2)᎐Sb(1)᎐C(1)
O(3)᎐Sb(1)᎐C(1)
O(1Ј)᎐Sb(1)᎐C(7)
O(2)᎐Sb(1)᎐C(7)
79.5(1)
89.9(1)
85.5(1)
85.3(1)
90.7(1)
92.5(1)
88.6(1)
94.6(1)
91.1(1)
94.7(1)
O(3)᎐Sb(1)᎐C(7)
C(1)᎐Sb(1)᎐C(7)
O(2)᎐Sb(1)᎐O(3)
O(1Ј)᎐Sb(1)᎐C(1)
O(1)᎐Sb(1)᎐C(7)
O(2)᎐As(1)᎐O(3Ј)
89.6(1)
97.4(1)
174.3(1)
170.0(1)
169.3(1)
114.0(1)
Sb(1)᎐O(2)᎐As(1)
Sb(1)᎐O(1)᎐As(1A) 119.5(1)
119.0(1)
C(13)᎐As(1)᎐C(14) 110.0(2)
* Atoms designated A are related by the symmetry operation Ϫx,
1 Ϫ y, Ϫz.
Sb(1)᎐O(1)᎐Sb(1Ј)
Sb(1)᎐O(2)᎐As(1)
Sb(1)᎐O(3)᎐As(1Ј)
100.5(1)
119.0(1)
119.5(1)
Table 3 Comparison of Sb2O2 mean ring parameters
* Atoms carrying a prime are related by the symmetry operation 1 Ϫ x,
1 Ϫ y, 2 Ϫ z.
Compound
Sb᎐O/Å O᎐Sb᎐O/Њ Sb᎐O᎐Sb/Њ Ref.
1
4
2.000
2.007
79.5
79.0
77.1
72.7
77.5
78.6
100.5
101.0
103.0
107.3
102.5
101.5
This work
This work
2
1
1
21
[{SbPh2(MoO4)O}2]2Ϫ 2.019
[{SbPh2O(O2SbPh2)}2] 2.089
possible to assign any bands to the Sb2O2 ring modes, which
20
occur for the starting material between 495 and 670 cmϪ1
.
1
[(SbPh3O)2]
[(SbPh2BrO)2]
2.002
1.986
There were no unexpected features in the H NMR spectra
for the three compounds but [(SbPh2)2(µ-O)2(µ-O2AsPh2)2] 2
showed a broad unresolved multiplet at δ 7.30–7.80. All three
compounds show parent ions in their FAB mass spectra,
although for 2 the highest mass ion is attributed to [M ϩ 2H]ϩ.
Subsequent fragmentation, as expected, involves loss of both
aryl and arsinate groups and there are a number of prominent
monoantimony species, including [SbPh2(O2AsMe2)]ϩ for 1,
[SbPh2(O2AsPh2) ϩ H]ϩ for 2 and the rearrangement ion [Sb-
(p-MeC6H4)3(O2AsMe2)]ϩ is the base peak for 4.
tute the other two bridging groups, is highly symmetrical with
identical As᎐O bond lengths, i.e. As(1)᎐O(2) 1.709(3) Å and
As(1)᎐O(3Ј) 1.711(3) Å, implying complete delocalisation of
the π component of the As᎐O system. The arsenic atom is
basically tetrahedral although the O(2)᎐As(1)᎐O(3Ј) angle is
opened to 114.0(1)Њ. This together with angles of ca. 119.5Њ at
O(2) and O(3) probably represents the extent of the flexibility in
this part of the system towards matching ligand bite with
Sb ؒ ؒ ؒ Sb separation.
Structures. Single-crystal structures have been determined for
[(SbPh2)2(µ-O)2(µ-O2AsMe2)2] 1, as a bis(chloroform) solvate,
and [{Sb(p-MeC6H4)2}2(µ-O)2(µ-O2AsMe2)2] 4. The molecular
structure of 1, which has crystallographic Ci symmetry, is shown
in Fig. 1 and selected bond distances and angles are listed in
Table 1. The determination confirms the presence of a quad-
ruply bridged structure with octahedrally co-ordinated
antimony atoms. The Sb᎐O distances in the four-membered
ring [1.995(3) and 2.004(3) Å] are effectively equal, in contrast
to those in the starting material, which are either ‘short’ (1.936,
1.918 Å) or ‘long’ (2.061, 2.030 Å) depending on their position
in the trigonal-bipyramidal co-ordination about antimony.20
Co-ordination of the dimethylarsinate groups, which consti-
Co-ordination about antimony is distorted octahedral with
the O(1)᎐Sb(1)᎐O(1Ј) angle associated with the four-membered
ring constrained to 79.5(1)Њ. An important point is that the
trans angle involving the bridging groups [O(2)᎐Sb(1)᎐O(3)
174.3(1)Њ] is close to 180Њ implying that incorporation of the
bridging arsinate groups imposes no great strain. This structure
is clearly very similar to that of [(SbPh2)2(µ-O)2(µ-MoO4)2]2Ϫ 2
,
where the significantly longer Mo᎐O separations (mean 1.83 Å;
cf. As᎐O, mean 1.71 Å) imply a larger bite and even less strain.
Compound 4, [{Sb(p-MeC6H4)2}2(µ-O)2(µ-O2AsMe2)2] (see
Fig. 2 and Table 2) has a closely related structure with again
2786
J. Chem. Soc., Dalton Trans., 1997, Pages 2785–2792

View Article Online
crystallographically imposed Ci symmetry, symmetrically co-
ordinated dimethylarsinate groups [As(1)᎐O1(A) and As(1)᎐
O(2) 1.701(3) and 1.703(3) Å, respectively] and similar geom-
etries about antimony and arsenic. An interesting feature
in both compounds is the relative orientations of the aryl
groups. The C(1)–C(6) group is almost coplanar with the Sb2O2
plane (4.0Њ between best-fit planes) while the C(8) to C(14)
group is almost perpendicular (94.5Њ).
energy than corresponding bands (ca. 800 cmϪ1) for related
quadruply bridged compounds. The IR spectra for [(SbMe3)2(µ-
O)(µ-O2PMe2)2] 8 and [(SbMe3)2(µ-O)(µ-O2AsPh2)2] 9 may be
unreliable, as hydrolysis appears to take place, but for 8 the
broad bands at 1172 and 1020 cmϪ1 may be assigned tentatively
to P᎐O stretches of bidentate O2PMe2 groups, while the broad
795 cmϪ1 band for 9 can probably be assigned to the related
As᎐O stretches.
Table 3 summarises data for compounds containing Sb2O2
rings, showing there is little variation in either Sb᎐O distances
(ca. 2.00 Å) or angles (ca. 78Њ) in 1 and 4 compared with those
in related compounds. The only noticeable difference is with the
zwitterionic [{SbPh2O(O2SbPh2)}2] where bridging oxo groups
are involved in additional bonding to the antimony centres of
the bridging diphenylstibinate moieties. With the exception of
[(SbPh2BrO)2], the rings are centrosymmetric and the com-
pounds have near D2h local symmetry.
Proton NMR spectra for the arylantimony compounds point
to complex solution behaviour and it is clear that, unless strin-
gent precautions to exclude moisture are taken, there is either
complete or partial hydrolysis to hydroxo-species, such as
SbR3(O2MRЈ2)(OH). Using CDCl3 as received and with no pre-
cautions against moisture during solution preparation, i.e.
‘moist’ CDCl3, the spectrum of [(SbPh3)2(µ-O)(µ-O2PMe2)2] 3
can be assigned to a single species with the expected 3:1 ratio
of phenyl and dimethylphosphinate groups. Following related
studies on [(SbPh3X)2O] solutions, where X = Br or Cl,22 this is
assigned to the hydroxo-species [SbPh3(O2PMe2)(OH)] formed
as a result of hydrolysis by adventitious water. As with the hal-
ide systems, recrystallisation of the NMR sample gave quanti-
tative recovery of 3 and no evidence for the hydroxo-species in
the solid.
Under strictly anhydrous conditions, i.e. with dried CDCl3, a
sealed NMR tube and manipulations carried out in a nitrogen-
filled glove-box, there were signals for two species, neither of
which was the hydrolysis product, and the oxo bridge is pre-
sumed to be intact in each. The O2PMe2 group of the first
species A showed a doublet at δ 0.72 [2J(HP) = 14 Hz] and two
triplets and a doublet [3J(HH) = 7 Hz] in the phenyl region.
For the second species B the O2PMe2 signal collapsed to a
broad featureless signal with two second-order multiplets,
centred at δ 7.38 and 7.68, in the phenyl region. The A:B ratio
was ca. 2:3. It is difficult to assign structures to these species
with any certainty but it is likely that one has the solid-state
structure with bridging dimethylphosphinate groups (see later),
while in the second the dimethylphosphinate groups could, per-
haps, be chelating or even unidentate.
The p-tolyl derivative 7 behaved similarly with a single hydro-
lysed species in ‘moist’ CDCl3 and two species with chemical
shifts closely related to those discussed above in anhydrous
solutions. Species A is dominant with an A:B ratio of ca. 5:1.
Exposure of the anhydrous sample to moisture led to a spec-
trum showing signals for all three species. Two species were also
present for [(SbPh3)2(µ-O)(µ-O2AsMe2)2] 5 in dry CDCl3 and,
although both dimethylarsinate signals (δ 0.71 and 1.89) were
broad and featureless, the phenyl region clearly showed two
distinct sets of signals. The first was a triplet, triplet, doublet
pattern at δ 7.17, 7.27 (masked by a multiplet from a second spe-
cies) and 7.61 for the meta, para and ortho protons, respectively,
while the second showed multiplets at δ 7.27 and 7.71. The ratio
of the two species was ca. 2:1.
In contrast, solution spectra for [(SbMe3)2(µ-O)(µ-O2PMe2)2]
8 and [(SbMe3)2(µ-O)(µ-O2AsPh2)2] 9 were more straight-
forward and only one species was observed in each case. The
SbMe3 signals were at higher field (δ 1.66) compared with those
for related compounds, e.g. δ 1.96 for [(SbMe3Cl)2O] and 2.07
for [{SbMe3[S2P(OMe)2]}2O].23 The 13C shifts for the methyl
groups at antimony were similar, δ 16.3 and 16.8 respectively,
again to higher field than those for [{SbMe3[S2P(OMe)2]}2O] (δ
18.6).
Triply bridged compounds
Preparations. Triply bridged compounds, [(SbPh3)2(µ-O)(µ-
O2MR2)2] (M = P, R = Me 3; M = As, R = Me 5 or Ph 6), were
prepared in good yield as stable crystalline solids by reactions
of [(SbPh3Br)2O], with 2 mol of the appropriate Na(O2MR2)
but only unidentified products were obtained in the reaction
with Na(O2PPh2). Reaction between [{Sb(p-MeC6H4)3Br}2O]
and 2 mol of Na(O2PMe2) gave the expected bridged com-
pound, [{Sb(p-MeC6H4)3}2(µ-O)(µ-O2PMe2)2] 7, in good yield,
but surprisingly the o-tolyl analogue could not be obtained
from [{Sb(o-MeC6H4)3Br}2O] and 2 mol of Na(O2PMe2). An
attempt to form an unsymmetrically substituted compound,
[(SbPh3)2(µ-O)(µ-O2AsMe2)Br], from (SbPh3Br)2O and 1 mol
of Na(O2AsMe2) gave only mixtures of 5 and unchanged
(SbPh3Br)2O.
Related trimethylantimony() compounds, [(SbMe3)2(µ-
O)(µ-O2PMe2)2] 8 and [(SbMe3)2(µ-O)(µ-O2AsPh2)2] 9, were
prepared in good yield from [(SbMe3Cl)2O] and 2 mol of either
Na(O2PMe2) or Na(O2AsPh2), but they are highly moisture
sensitive and handling, even with stringent Schlenk and glove-
box techniques, was extremely difficult. Conventional micro-
analysis and IR spectroscopy were not possible but satisfactory
1H and 13C-{1H} NMR spectra were obtained and these com-
pounds are considered to have the same triply bridged struc-
tures as those described above.
It was noted above that reaction of [{Sb(p-MeC6H4)3Br}2O]
with 2 mol of Na(O2AsMe2) gave, instead of the expected triply
bridged product, a quadruply bridged rearrangement com-
pound 4, formed presumably because of its greater stability.
This is all the more surprising as the related phenylated starting
material, [(SbPh3Br)2O], reacts with Na(O2AsMe2) to give
[(SbPh3)2(µ-O)(µ-O2AsMe2)2] 5 in good yield. Detailed examin-
ation of the latter reaction by 1H NMR spectroscopy, however,
does show evidence for formation of 1, the analogous
rearrangement product, but here rearrangement is of minor
importance.
Spectroscopy. The IR spectrum of [(SbPh3)2(µ-O)(µ-
O2PMe2)2] 3 contains a strong, broad band at 1112 cmϪ1
,
assigned to the νasym(PO2) mode, and a doublet at 1046 and
1032 cmϪ1, probably the in- and out-of-phase components of
νsym(PO2). For related tin dimethylphosphinates,21 bands
between 1200 and 1000 cmϪ1 are associated with either chelat-
ing or bridging ligands, supporting triply bridged structures
here. Bands for [{Sb(p-MeC6H4)3}2(µ-O)(µ-O2PMe2)2] 7 are at
similar positions, with νasym(PO2) assigned to peaks at 1120 and
The FAB mass spectra of the triply bridged triarylantimony
compounds, in contrast to those of the quadruply bridged
compounds, do not show the parent ion. The spectra of
[(SbPh3)2(µ-O)(µ-O2PMe2)2] 3, [(SbPh3)2(µ-O)(µ-O2AsMe2)2] 5
and [{Sb(p-MeC6H4)3}2(µ-O)(µ-O2PMe2)2] 7 all show peaks
resulting from loss of one ligand and are assigned to the
appropriate [(SbR3)2(µ-O)(µ-O2MMe2)]ϩ (R = aryl) ions. Major
species in all the spectra are monometallic [SbR3(O2MMe2)]ϩ
and simple arylantimony ions.
1111 cmϪ1 and νsym(PO2) at 1048 and 1033 cmϪ1
.
Spectra of the arsinates, [(SbPh3)2(µ-O)(µ-O2AsMe2)2] 5 and
[(SbPh3)2(µ-O)(µ-O2AsPh2)2] 6, contain intense broad bands at
852 and 831 cmϪ1, respectively, consistent with the presence of
bridging (O2AsR2) groups; these are at significantly higher
J. Chem. Soc., Dalton Trans., 1997, Pages 2785–2792
2787

View Article Online
Table 4 Selected bond distances (Å) and angles (Њ) for [(SbPh3)2(µ-
O)(µ-O2MMe2)2]ؒ0.5C6H14 where M = P 3 or As 5 and for [{Sb(p-
MeC6H4)3}2(µ-O)(µ-O2MMe2)2]ؒ0.5C6H14 where M = P 7, with e.s.d.s in
parentheses
3
5
7
Sb(1)᎐O(1)
Sb(1)᎐O(3)
Sb(1)᎐O(5)
Sb(1)᎐C(11)
Sb(1)᎐C(21)
Sb(1)᎐C(31)
Sb(2)᎐O(1)
Sb(2)᎐O(2)
Sb(2)᎐O(4)
Sb(2)᎐C(41)
Sb(2)᎐C(51)
Sb(2)᎐C(61)
M(1)᎐O(2)
M(1)᎐O(3)
M(1)᎐C(1)
M(1)᎐C(2)
M(2)᎐O(4)
M(2)᎐O(5)
M(2)᎐C(3)
M(2)᎐C(4)
1.958(3)
2.153(3)
2.171(3)
2.164(5)
2.152(5)
2.155(5)
1.952(3)
2.194(3)
2.154(3)
2.153(5)
2.163(5)
2.151(5)
1.519(4)
1.528(4)
1.798(5)
1.789(6)
1.514(4)
1.525(4)
1.787(6)
1.795(6)
1.963(4)
2.122(4)
2.137(4)
2.177(6)
2.164(6)
2.164(6)
1.963(4)
2.154(4)
2.100(4)
2.173(7)
2.167(6)
2.154(7)
1.671(5)
1.685(5)
1.913(7)
1.911(7)
1.680(4)
1.687(5)
1.904(7)
1.916(7)
1.972(5)
2.139(5)
2.170(5)
2.158(8)
2.163(8)
2.159(5)
1.954(5)
2.215(5)
2.213(5)
2.144(7)
2.144(7)
2.156(5)
1.521(5)
1.533(5)
1.783(8)
1.800(8)
1.524(5)
1.526(5)
1.788(8)
1.792(8)
Fig.
3
Molecular structure and atom numbering scheme for
[(SbPh3)2(µ-O)(µ-O2PMe2)2]ؒ0.5C6H14 3, structures for compounds 5
and 7 are similar
Structures. Single-crystal structure determinations were car-
ried out for four of these triply bridged compounds, three of
which (3, 4 and 7) were hemihexane solvates, while the fourth (6)
was a chloroform solvate. The overall structures of all four
compounds, [(SbPh3)2(µ-O)(µ-O2PMe2)2]ؒ0.5C6H14 3, [(SbPh3)2-
(µ-O)(µ-O2AsMe2)2]ؒ0.5C6H14 5, [(SbPh3)2(µ-O)(µ-O2AsPh2)2]ؒ
CHCl3 6 and [{Sb(p-MeC6H4)3}2(µ-O)(µ-O2PMe2)2]ؒ0.5C6H14 7,
are very similar; 3 and 5 are isostructural. A diagram showing
the structure of 3, with the skeletal numbering scheme, which is
appropriate for all four compounds, is shown in Fig. 3. Selected
bond distances and angles for compounds 3, 4 and 7 are listed
in Table 4 while those for 6 with diphenylarsinate bridges are in
Table 5.
O(1)᎐Sb(1)᎐O(3)
O(1)᎐Sb(1)᎐O(5)
O(3)᎐Sb(1)᎐O(5)
O(3)᎐Sb(1)᎐C(11)
O(5)᎐Sb(1)᎐C(11)
O(1)᎐Sb(1)᎐C(21)
O(3)᎐Sb(1)᎐C(21)
C(11)᎐Sb(1)᎐C(21)
O(1)᎐Sb(1)᎐C(31)
O(5)᎐Sb(1)᎐C(31)
C(11)᎐Sb(1)᎐C(31)
C(21)᎐Sb(1)᎐C(31)
O(1)᎐Sb(1)᎐C(11)
O(5)᎐Sb(1)᎐C(21)
O(3)᎐Sb(1)᎐C(31)
O(1)᎐Sb(2)᎐O(2)
O(1)᎐Sb(2)᎐O(4)
O(2)᎐Sb(2)᎐O(4)
O(2)᎐Sb(2)᎐C(41)
O(4)᎐Sb(2)᎐C(41)
O(1)᎐Sb(2)᎐C(51)
O(4)᎐Sb(2)᎐C(51)
C(41)᎐Sb(2)᎐C(51)
O(1)᎐Sb(2)᎐C(61)
O(2)᎐Sb(2)᎐C(61)
C(41)᎐Sb(2)᎐C(61)
C(51)᎐Sb(2)᎐C(61)
O(1)᎐Sb(2)᎐C(41)
O(2)᎐Sb(2)᎐C(51)
O(4)᎐Sb(2)᎐C(61)
O(2)᎐M(1)᎐O(3)
C(1)᎐M(1)᎐C(2)
O(4)᎐M(2)᎐O(5)
C(3)᎐M(2)᎐C(4)
Sb(1)᎐O(1)᎐Sb(2)
Sb(2)᎐O(2)᎐M(1)
Sb(1)᎐O(3)᎐M(1)
Sb(2)᎐O(4)᎐M(2)
Sb(1)᎐O(5)᎐M(2)
83.8(1)
85.8(1)
83.7(1)
83.7(2)
83.7(2)
91.5(2)
88.9(2)
97.4(2)
91.5(2)
88.5(2)
99.6(2)
98.7(2)
164.5(2)
172.4(2)
171.2(2)
84.9(1)
84.3(1)
82.0(1)
84.1(2)
84.0(2)
91.8(2)
88.4(2)
97.3(2)
91.8(2)
89.7(2)
98.4(2)
99.7(2)
165.0(2)
170.2(2)
171.2(2)
115.5(2)
107.7(3)
115.0(2)
106.7(3)
144.2(2)
133.6(2)
128.4(2)
130.6(2)
133.5(2)
85.2(2)
87.7(2)
83.1(2)
85.3(2)
83.4(2)
90.8(2)
88.4(2)
96.7(2)
91.2(2)
90.6(2)
97.4(2)
97.8(2)
167.7(2)
171.5(2)
172.8(2)
85.4(2)
86.0(2)
82.7(2)
84.6(2)
85.0(2)
92.8(2)
88.7(2)
95.9(3)
91.1(2)
90.5(2)
96.7(3)
98.0(3)
167.3(2)
171.4(2)
172.8(2)
115.6(2)
110.0(3)
113.9(2)
108.3(4)
145.5(2)
130.2(2)
123.6(2)
126.2(2)
129.6(2)
84.3(2)
85.8(2)
82.4(2)
85.5(2)
83.5(2)
91.9(2)
88.4(3)
97.2(3)
92.4(2)
89.3(2)
96.3(3)
99.8(3)
166.1(2)
170.8(2)
171.3(2)
84.6(2)
82.2(2)
85.8(2)
81.6(2)
82.4(2)
94.8(3)
87.4(3)
97.2(3)
94.1(3)
89.0(2)
100.0(3)
97.8(3)
160.0(2)
173.2(2)
174.0(2)
115.1(3)
107.1(4)
114.8(3)
106.4(4)
143.6(3)
134.1(3)
129.2(3)
125.8(3)
133.1(3)
The structure determinations confirm that all four com-
pounds are triply bridged diantimony species with one oxygen
and two phosphinate or arsinate bridges and the structures are
comparable with those of [(SbCl3)2(µ-O)(µ-O2PMe2)2]15 and
[(SbPh2Cl)2(µ-O){µ-O2P(C6H11)2}2].16 Antimony atoms are in
distorted octahedral co-ordination to three oxygen and three
carbon atoms in the fac isomeric form. The Sb᎐O᎐Sb bridge
bonds are equal in 3 and 5 while in 6 and 7 the differences (ca.
0.02 Å) are on the limit of significance. As shown in Table 6,
mean bridging distances in the present compounds are longer
than those in the three compounds previously investigated,
which have either chlorine or fluorine substituents on antimony,
and the expected increased Lewis acidity would probably
account for the bond shortening. The Sb᎐O᎐Sb angles in three
of the compounds reported here are comparable with that in
[(SbPh2Cl)2(µ-O){µ-O2P(C6H11)2}2]16 but again there are con-
sequences if antimony carries three electronegative substituents
when the angle closes substantially. The bridge angle in 6, on
the other hand, is increased to 151.7Њ and is probably a con-
sequence of the change from methyl substituents at arsenic in 5
to phenyl groups in 6. We have previously commented 18 on the
fact that, in a series of compounds, substantial structural
changes sometimes result from substituent changes at a
‘remote’ atom and this seems to be another such example.
There is extensive delocalisation of the π component of the
co-ordinated diorgano-phosphinate or -arsinate groups, giving
almost symmetrical bridges. An interesting feature in the struc-
tures of compounds 5 and 6 is the shortness of the As᎐O bonds
(mean 1.681 and 1.686 Å, respectively) compared with those in
the quadruply bridged compounds 1 (mean 1.710 Å) and 4
(mean 1.702 Å) discussed above. This was to some extent
expected as the As᎐O stretching vibrations in the IR spectra of
5 and 6 were at higher energy.
nylarsinate 6. The Sb᎐O᎐M angles are also increased and are
larger in the phosphinates (mean 131.0Њ), as a consequence of
the shorter P᎐O bond length, than in the corresponding arsi-
nates (mean 127.6Њ). For comparison, these angles in the quad-
ruply bridged arsinates (1 and 2) are further reduced to a mean
of 119.2Њ presumably as the double oxygen bridge reduces the
Sb ؒ ؒ ؒ Sb separation.
Owing to bridging, the tetrahedral geometry at phosphorus
or arsenic is distorted with O᎐M᎐O angles increased to ca. 115Њ
in the methyl-substituted products and to ca. 119Њ in the diphe-
It was not possible to assign unequivocally similar triply
bridged structures to the trimethylantimony compounds, 8 and
9, although such structures are likely. Decreased antimony
2788
J. Chem. Soc., Dalton Trans., 1997, Pages 2785–2792

View Article Online
overlayered with twice the volume of hexane to give the product
as colourless crystals. Yield 3.98 g (86%), m.p. 324–327 ЊC
(Found: C, 39.4; H, 3.8. Calc. for C28H32As2O6Sb2: C, 39.2;
H, 3.8%); δH [250 MHz, CDCl3, room temperature (r.t.)] 2.00
(12 H, s, AsMe), 7.33 [12 H, m, m- and p-H of Ph] and 7.83 (8
H, m, o-H of Ph); ν max/cmϪ1 (Nujol) 1430s, 1072m, 817vs (sh),
796vs, 738s, 696s, 652m, 608m, 518s, 487s and 466m; FAB mass
spectrum m/z 858 (100, Mϩ), 721 (30, [M Ϫ O2AsMe2]ϩ), 704
(28, [M Ϫ 2Ph]ϩ), 567 (43, [M Ϫ 2Ph Ϫ O2AsMe2]ϩ), 413 {26%,
[(SbO)2O2AsMe2]ϩ}.
Table 5 Selected bond distances (Å) and angles (Њ) for [(SbPh3)2(µ-
O)(µ-O2AsPh2)2]ؒCHCl3 6, with e.s.d.s in parentheses
Sb(1)᎐O(1)
Sb(1)᎐O(3)
Sb(1)᎐O(5)
Sb(1)᎐C(11)
Sb(1)᎐C(21)
Sb(1)᎐C(31)
Sb(2)᎐O(1)
Sb(2)᎐O(2)
Sb(2)᎐O(4)
Sb(2)᎐C(41)
1.967(5)
2.148(5)
2.152(5)
2.135(7)
2.156(7)
2.158(7)
1.947(4)
2.169(4)
2.141(5)
2.167(7)
Sb(2)᎐C(51)
Sb(2)᎐C(61)
As(1)᎐O(2)
As(1)᎐O(3)
As(1)᎐C(71)
As(1)᎐C(81)
As(2)᎐O(4)
As(2)᎐O(5)
As(2)᎐C(91)
As(2)᎐C(101)
2.166(7)
2.148(7)
1.699(5)
1.680(4)
1.926(7)
1.921(7)
1.686(5)
1.677(5)
1.919(7)
1.923(7)
[(SbPh2)2(ì-O)2(ì-O2AsPh2)2] 2. This was prepared in a simi-
lar manner from [(SbPh2BrO)2] (3.2 g, 4 mmol) and sodium
diphenylarsinate (2.60 g, 9.2 mmol) in dichloromethane (10
cm3) after refluxing for 40 h. A small amount of product was
obtained after repeated crystallisations from chloroform–
hexane. Yield 0.14 g (3%), m.p. 260–266 ЊC (Found: C, 51.2; H,
3.4. Calc. for C48H40As2O6Sb2: C, 52.1; H, 3.6%); δH (250 MHz,
CDCl3, r.t.) 7.30–7.80 (40 H, br m, AsPh and SbPh); ν max/cmϪ1
(Nujol) 1087w, 823vs (sh), 812vs, 735s, 691s, 490m and 457m;
FAB mass spectrum m/z 1108 (73, [M ϩ 2H]ϩ), 953 (16,
[M Ϫ 2Ph ϩ H]ϩ), 845 (38, [M Ϫ O2AsPh2]ϩ), 691 {100,
[(SbPh2O)2O2As]ϩ}, 537 (75, [SbPh2O2AsPh2]ϩ) and 459 (36%,
[SbPhO2AsPh2]ϩ).
O(1)᎐Sb(1)᎐O(3)
O(1)᎐Sb(1)᎐O(5)
O(3)᎐Sb(1)᎐O(5)
O(3)᎐Sb(1)᎐C(11)
O(5)᎐Sb(1)᎐C(11)
O(1)᎐Sb(1)᎐C(21)
O(3)᎐Sb(1)᎐C(21)
C(11)᎐Sb(1)᎐C(21)
O(1)᎐Sb(1)᎐C(31)
O(5)᎐Sb(1)᎐C(31)
C(11)᎐Sb(1)᎐C(31)
86.6(2)
86.4(2)
80.2(2)
86.3(2)
83.4(2)
90.9(2)
89.5(2)
98.1(3)
87.7(2)
89.7(2)
97.7(3)
O(1)᎐Sb(2)᎐C(51)
O(4)᎐Sb(2)᎐C(51)
C(41)᎐Sb(2)᎐C(51)
O(1)᎐Sb(2)᎐C(61)
O(2)᎐Sb(2)᎐C(61)
C(41)᎐Sb(2)᎐C(61)
91.9(2)
90.4(2)
97.4(3)
92.6(2)
86.7(2)
95.7(3)
C(51)᎐Sb(2)᎐C(61) 100.1(3)
O(1)᎐Sb(2)᎐C(41)
O(2)᎐Sb(2)᎐C(51)
O(4)᎐Sb(2)᎐C(61)
O(2)᎐As(1)᎐O(3)
166.2(3)
173.1(2)
169.4(2)
118.8(2)
C(21)᎐Sb(1)᎐C(31) 100.4(3)
C(71)᎐As(1)᎐C(81) 109.3(3)
O(4)᎐As(2)᎐O(5) 118.6(2)
C(91)᎐As(2)᎐C(101) 106.8(3)
O(1)᎐Sb(1)᎐C(11)
O(5)᎐Sb(1)᎐C(21)
O(3)᎐Sb(1)᎐C(31)
O(1)᎐Sb(2)᎐O(2)
O(1)᎐Sb(2)᎐O(4)
O(2)᎐Sb(2)᎐O(4)
O(2)᎐Sb(2)᎐C(41)
O(4)᎐Sb(2)᎐C(41)
168.4(2)
169.4(2)
168.7(2)
86.3(2)
85.9(2)
82.8(2)
83.3(2)
83.9(2)
[(SbPh3)2(ì-O)(ì-O2PMe2)2] 3. (a) From [(SbPh3Br)2O]. A
solution of µ-oxo-bis[bromotriphenylantimony()] (0.53 g, 0.60
mmol) in dichloromethane (20 cm3) was added to a stirring
suspension of sodium dimethylphosphinate (0.16 g, 1.34 mmol)
and dichloromethane (10 cm3) and the mixture refluxed for 24
h. After filtration and removal of the solvent, the product was
obtained by overlayering a chloroform solution with twice the
volume of hexane. Yield 0.48 g (88%), m.p. 188–192 ЊC (Found:
C, 53.1; H, 5.1. Calc. for C40H42O5P2Sb2: C, 52.9; H, 4.7%);
δH (250 MHz, CDCl3, r.t.) moist solvent, 1.00 [6 H, d, 2J(HP) 14,
PMe], 7.57 (9 H, m, m- and p-H of Ph) and 8.21 (6 H, m, o-H of
Sb(1)᎐O(1)᎐Sb(2)
Sb(2)᎐O(2)᎐As(1)
Sb(1)᎐O(3)᎐As(1)
Sb(2)᎐O(4)᎐As(2)
Sb(1)᎐O(5)᎐As(2)
151.7(3)
125.9(2)
129.1(3)
128.6(2)
127.4(2)
Table 6 Comparison of Sb᎐O mean bridge parameters
Compound
Sb᎐O/Å
Sb᎐O᎐Sb/Њ
Ref.
3
5
6
7
1.955
1.963
1.957
1.963
1.942
144.2
145.5
151.7
143.6
136.0
144.7
131.1
This work
This work
This work
This work
15
2
Ph); anhydrous solvent, species A, 0.72 [12 H, d, J(HP) 14,
MeP], 7.16 [12 H, t, 3J(HH) 7, m-H of Ph], 7.45 [6 H, t, 3J(HH)
3
7, p-H of Ph] and 7.56 [12 H, d, J(HH) 7 Hz, o-H of Ph];
[{SbCl3(O2PMe2)}2O]
[{SbPh2Cl[O2P(C6H11)2]}2O] 1.937
[{SbF3(O2CCF3)}2O] 1.893
species B, 1.03 (12 H, br, PMe), 7.38 (18 H, m, m- and p-H of
Ph) and 7.68 (12 H, m, o-H of Ph); ν max/cmϪ1 1430m, 1301m,
1112vs, 1062m, 1046vs, 1032vs, 998w, 871m, 863m, 749s, 735s,
693s, 659w, 512w, 487w, 464m and 437w; FAB mass spectrum
m/z 831 (4, [M Ϫ Ph]ϩ), 815 (9, [M Ϫ O2PMe2]ϩ), 661 {5,
[(SbPh2)2O(O2PMe2)]ϩ} and 445 {100%, [SbPh3(O2PMe2)]ϩ}.
(b) From [(SbPh2BrO)2]. A mixture of [(SbPh2BrO)2] (0.53
g, 0.7 mmol), sodium dimethylphosphinate (0.17 g, 1.4 mmol)
and toluene (30 cm3) was stirred at reflux for 24 h. The mixture
was filtered and the solvent removed in a vacuum to give a
residue which was recrystallised from chloroform–hexane mix-
ture. Yield 77 mg (12%).
16
17
Lewis acidity as a consequence of the electron-donating methyl
groups could, however, influence ligand secondary bonding
leading to changes in co-ordination mode.
Experimental
Diphenylantimony bromide oxide was prepared by oxidising
diphenylantimony() bromide with tert-butyl hydroperoxide20
and µ-oxo-bis[bromotriphenylantimony()], µ-oxo-bis[chloro-
[{Sb(p-MeC6H4)2}2(ì-O)2(ì-O2AsMe2)2] 4. A mixture of µ-
oxo-bis[bromotris(p-tolyl)antimony()] (0.42 g, 0.43 mmol),
sodium dimethylarsinate (0.17 g, 1.06 mmol) and dichloro-
methane (20 cm3) was stirred under reflux for 16 h. After
filtration of the precipitated sodium bromide and evaporation
of the solvent, the remaining white solid was recrystallised from
a chloroform–hexane mixture to give the required product.
Yield 0.10 g (26%), m.p. 313–320 ЊC (Found: C, 41.7; H,
4.45. Calc. for C32H40As2O6Sb2: C, 42.05; H, 4.4. Calc. for
C46H54As2O5Sb2: C, 51.1; H, 5.0%); δH (250 MHz, CDCl3, r.t.)
1.96 (12 H, s, AsMe), 2.32 (12 H, s, MeC6H4), 7.15 [8 H, d,
triphenylantimony()]
and
µ-oxo-bis[bromotris(p-tolyl)-
antimony()] by partial hydrolysis of the appropriate triaryl-
antimony() dihalide.24 µ-Oxo-bis[chlorotrimethylantimony()]
was obtained by treating trimethylantimony dichloride with the
corresponding dihydroxide.25 Dimethylphosphinic acid was
obtained by the method of Reinhardt et al. 26 and the sodium
salts Na(O2AsMe2), Na(O2AsPh2), Na(O2PMe2) and Na-
(O2PPh2) by treating stoichiometric amounts of the corres-
ponding acid with sodium ethoxide in ethanol.
Preparations
3
3J(HH) 8, m-H of aryl] and 7.73 [8 H, d, J(HH) 8 Hz, o-H of
[(SbPh2)2(ì-O)2(ì-O2AsMe2)2] 1. A solution of diphenylanti-
mony bromide oxide (4.00 g, 5.4 mmol) in dichloromethane (50
cm3) was added to a stirring suspension of sodium dimethyl-
arsinate (1.90 g, 11.9 mmol) and dichloromethane (10 cm3) and
the mixture refluxed for 24 h. After filtration and removal of the
solvent, the remaining solid was recrystallised from chloroform
aryl]; ν max/cmϪ1 1492m, 1307w, 1270w, 1183m, 1070m, 1018w,
901m, 869m, 824vs (sh), 805vs, 793s (sh), 722w, 652m, 609m,
578m, 516s, 488s and 430w; FAB mass spectrum m/z 915 (24,
[M ϩ H]ϩ), 577 {13, [Sb(p-MeC6H4)2(O2AsMe2)2]ϩ}, 531 {100,
[Sb(p-MeC6H4)3(O2AsMe2)]ϩ} and 349 {12%, [Sb(p-MeC6H4)-
(O2AsMe2)]ϩ}.
J. Chem. Soc., Dalton Trans., 1997, Pages 2785–2792
2789

View Article Online
Table 7 Crystallographic data a for quadruply bridged compounds 1 and 4
1
4
Chemical formula
M
C30H34As2Cl6O6Sb2
1096.61
C32H40As2O6Sb2
913.98
Crystal size/mm
Space group
0.30 × 0.25 × 0.15
P21/a
0.35 × 0.24 × 0.06
P21/c
a/Å
b/Å
c/Å
13.830(3)
10.2590(3)
14.5744(12)
113.13(2)
1901.5(7)
1.915
36.09
13.3821(13)
11.4790(10)
11.2265(10)
99.411(5)
1701.3(3)
1.784
β/Њ
U/Å3
Dc/g cmϪ3
µ/cmϪ1
35.58
F(000)
1064
896
Index ranges (for unique data)
Total data collected
Unique data
Ϫ16 < h < 14, 0 < k < 12, 0 < l < 17
8051
2932
Ϫ10 < h < 16, Ϫ12 < k < 13, Ϫ11 < l < 13
7176
2960
Rint
0.0766
0.0502
Observed data [I > 3σ(I)]
Absorption correction
minimum
2172
DIFABSb
Gaussian
0.394
0.961
maximum
1.044
0.810
Structure solution
Refinement
Data, variables
Goodness of fit (S)
Final difference map features/e ÅϪ3
R
Direct (SIR 92)
Full-matrix least squares on F
2172, 209
1.309
ϩ1.18, Ϫ0.70
0.0276
Direct (SHELXS 86)
Full-matrix least squares on F2
2933, 195
1.065
ϩ0.604, Ϫ1.120
RЈ
0.0306
R observed data [I > 2σ(I)] (all data)
RЈ observed data (all data)
0.0315 (0.0355)
0.0794 (0.0873)
a
Details in common: monoclinic; Z = 2; Mo-Kα radiation (λ 0.710 69 Å); θ limits 3–25Њ; 150 K. b Ref. 27.
Table 8 Crystallographic data * for triply bridged compounds 3 and 5–7
3
5
6
7
Chemical formula
M
Crystal size/mm
Space group
C43H49O5P2Sb2
951.30
0.20 × 0.18 × 0.14
C2/c
C43H49As2O5Sb2
1039.16
0.32 × 0.20 × 0.16
C2/c
C61H51As2Cl3O5Sb2
1363.77
0.15 × 0.10 × 0.10
P21/a
C49H61O5P2Sb2
1035.47
0.24 × 0.22 × 0.18
P21/n
a/Å
b/Å
c/Å
26.704(3)
16.879(3)
22.1874(12)
125.35(1)
8157.0(6)
8
27.176(3)
16.826(2)
22.637(3)
126.887(8)
8278.7(2)
8
11.804(12)
40.910(4)
12.738(4)
115.71(4)
5542.2(6)
4
12.038(12)
17.127(13)
23.35(2)
90.27(3)
4814.6(3)
4
β/Њ
U/Å3
Z
Dc/g cmϪ3
1.549
14.52
1.667
29.34
1.635
23.57
1.429
12.36
µ/cmϪ1
F(000)
3832
4120
2704
2108
θ Limits/Њ
3–25
2–25
3–25
3–25
Index ranges (for unique data)
Ϫ29 < h < 23,
0 < k < 18, 0 < l < 25
120
Ϫ29 < h < 30,
0 < k < 18, 0 < l < 24
150
Ϫ13 < h < 11,
0 < k < 45, 0 < l < 14
120
Ϫ13 < h < 13,
0 < k < 19, 0 < l < 26
150
T/K
Total data collected
Unique data
17 558
6171
17 594
6406
21 169
7933
23 252
7414
Rint
0.0481
0.0913
0.1616
0.0937
Observed data [I > 3σ(I)]
Absorption correction
minimum
4315
DIFABS
0.855
6128
DIFABS
0.773
4900
DIFABS
0.849
None
maximum
1.160
1.115
1.118
Structure solution
Data, variables
Goodness of fit (S)
Final difference map features/e ÅϪ3
R
Direct (SIR 92)
4315, 455
1.080
ϩ1.10, Ϫ0.73
0.0344
Direct (SHELXS 86)
6406, 467
0.935
Direct (SIR 92)
6128, 658
1.073
ϩ2.09, Ϫ2.05
0.0702
Direct (SIR 92)
4900, 517
1.134
ϩ0.74, Ϫ0.49
0.0367
ϩ1.736, Ϫ0.643
RЈ
0.0698
0.0942
0.0912
R observed data [I > 2σ(I)] (all data)
RЈ observed data (all data)
0.0422 (0.0633)
0.0940 (0.1247)
* Details in common: monoclinic; Mo-Kα radiation (λ 0.710 69 Å); full-matrix least-squares refinement on F2.
[(SbPh3)2(ì-O)(ì-O2AsMe2)2] 5.
A
mixture of µ-oxo-
of the solvent in a vacuum, the product was obtained by diffu-
sion of hexane vapour into a concentrated chloroform solution.
Yield 0.62 g (74%), m.p. 241–245 ЊC (Found: C, 47.85; H, 4.3.
Calc. for C40H42As2O5Sb2: C, 48.2; H, 4.25%); δH (250 MHz,
bis[bromotriphenylantimony()] (0.74 g, 0.84 mmol), sodium
dimethylarsinate (0.36 g, 2.3 mmol) and dichloromethane (35
cm3) was stirred at reflux for 20 h. After filtration and removal
2790
J. Chem. Soc., Dalton Trans., 1997, Pages 2785–2792

View Article Online
CDCl3, r.t.) 0.71 (br s, AsMe), 1.89 (br s, AsMe) (integrals
unreliable due to peak broadness); phenyl region, species A,
7.17 [12 H, t, 3J(HH) 7, m-H of Ph], 7.27 [6 H (masked), t, p-H
sensitive crystals of the required compound, shown by 1H
NMR spectroscopy to be a dichloromethane solvate. Again sat-
isfactory microanalytical results could be obtained. Yield 0.60 g
(75%). δH (250 MHz, CDCl3, r.t., Teflon-sealed tube under N2)
1.66 (18 H, s, MeSb), 5.27 (2 H, s, CH2Cl2), 7.41 (12 H, m, m-
and p-H of Ph) and 7.70 (8 H, m, o-H of Ph); δC(69 MHz,
CDCl3, r.t.) 16.8 (SbMe), 128.7 (m-C of Ph), 130.4 (p-C of Ph),
131.2 (o-C of Ph) and 138.2 (ipso-C of Ph); ν max/cmϪ1 1307m,
1216w, 1180w, 1157w, 1088s, 1066m, 1025m, 998m, 896s, 795vs
(br), 740vs (br), 720vs (br), 692vs (br), 574s, 526w, 481s and
462s (possible decomposition in Nujol).
3
of Ph] and 7.61 [12 H, d, J(HH) 7 Hz, o-H of Ph]; species B,
7.27 (18 H, m, m- and p-H of Ph) and 7.71 (12 H, m, o-H of
Ph); ν max/cmϪ1 1429s, 1265m, 1185m, 1069s, 1023w, 852vs (br),
738vs, 698vs, 657m, 641m, 465s and 421m; FAB mass spectrum
m/z 996 (0.4, Mϩ), 859 (6, [M Ϫ O2AsMe2]ϩ), 489 {61,
[SbPh3(O2AsMe2)]ϩ}, 335 {28, [SbPh(O2AsMe2)]ϩ} and 275
(39%, SbPh2ϩ).
[(SbPh3)2(ì-O)(ì-O2AsPh2)2] 6.
A
mixture of µ-oxo-
bis[bromotriphenylantimony()] (0.60 g, 0.68 mmol), sodium
diphenylarsinate (0.49 g, 1.7 mmol) and dichloromethane (35
cm3) was stirred at reflux for 24 h. After filtration and removal
of the solvent, the residue was purified by diffusion of hexane
into a concentrated chloroform solution. Yield 0.63 g (74%),
m.p. 244–247 ЊC (Found: C, 53.1; H, 3.7. Calc. for C60H50-
As2O5Sb2: C, 57.9; H, 4.05. Calc. for C60H50As2O5Sb2ؒCHCl3:
C, 53.7; H, 3.8%); δH (250 MHz, CDCl3, r.t.) 6.97 (m), 7.08
Crystallography
Crystallographic quality single crystals for all compounds were
obtained by slow diffusion of hexane vapour into concentrated
chloroform solutions of the compounds.
Crystallographic data are summarised in Table 7 for the
quadruply bridged compounds and in Table 8 for the triply
bridged species. The tables also contain details of the method
of solution and the refinement conditions. Approximately one
hemisphere of data was collected at low temperature using
either a Delft Instruments FAST TV area-detector diffract-
ometer, equipped with rotating-anode FR591 generator (for 1,
3 and 5–7) or a Siemens SMART area-detector diffractometer
(for 4). The data were corrected for Lorentz-polarisation effects,
merged and systematically absent reflections removed. An
absorption correction was usually applied (see Tables 7 and 8).
Structures were solved by direct methods (SIR 9228 or
SHELXS 8629) and refined by full-matrix least squares
(SHELXL 9330 or CRYSTALS31); hydrogen atoms were placed
at their calculated positions and refined riding on their respect-
ive carbon atoms. A standard weighting scheme was applied
and corrections were made for extinction where appropriate.
CCDC reference number 186/589.
3
(m), 7.33 (m), 7.43 (m), 7.58 [d, J(HH) 7 Hz] and 8.04 (m);
ν max/cmϪ1 (Nujol) 1440s, 1430s, 1306m, 1183m, 1090s, 1069s,
1023m, 999m, 831vs (br), 735vs, 692vs, 658m, 609w, 536m,
464s and 410m.
[{Sb(p-MeC6H4)3}2(ì-O)(ì-O2PMe2)2] 7. A solution of µ-oxo-
bis[bromotris(p-tolyl)antimony()] (0.59 g, 0.61 mmol) in
dichloromethane (20 cm3) was added to a suspension of sodium
dimethylphosphinate (0.15 g, 1.3 mmol) in dichloromethane (10
cm3) which was stirred at room temperature for 18 h. After
filtration and removal of the solvent in a vacuum, the remaining
white solid was purified by overlayering a chloroform solution
with three times the volume of hexane. Yield 0.35 g (58%)
(Found: C, 55.2; H, 5.4. Calc. for C46H54O5P2Sb2: C, 55.7; H,
5.5%); δH (250 MHz, CDCl3, r.t.) moist solvent, 0.97 [6 H, d,
2J(HP) 14, PMe], 2.40 (9 H, s, MeC6H4), 7.51 [6 H, d, 3J(HH) 8,
m-H of aryl] and 8.12 [6 H, d, 3J(HH) 8, o-H of aryl]; anhydrous
solvent, species A, 0.70 [12 H, d, 2J(HP) 14, PMe], 2.38 (18 H, s,
MeC6H4), 7.10 [12 H, d, 3J(HH) 8, m-H of aryl] and 7.55 [12 H,
d, 3J(HH) 8, o-H of aryl]; species B, 1.05 (12 H, br, PMe), 2.39
Acknowledgements
We thank Professor M. B. Hursthouse and the EPSRC Crystal-
lographic Service (compounds 1, 3 and 5–7) and Dr. O. V.
Shishkin (compound 4) for X-ray data collection.
3
(18 H, s, MeC6H4), 7.25 [12 H, d, J(HH) 8, m-H of aryl] and
3
7.61 [12 H, d, J(HH) 8 Hz, o-H of aryl]; ν max/cmϪ1 (Nujol)
References
1298m, 1187m, 1120s, 1111vs, 1048vs, 1033vs, 863s, 801s,
732s, 705w, 576w and 487s; FAB mass spectrum m/z 962
(4, [M Ϫ 2Me]ϩ), 899 (0.4, [M Ϫ O2PMe2]ϩ) and 487 {100%,
[Sb(p-MeC6H4)3(O2PMe2)]ϩ}.
1 J. Bordner, G. O. Doak and T. S. Everett, J. Am. Chem. Soc., 1986,
108, 4206.
2 B.-Y. Liu, Y.-T. Ku, M. Wang, B.-Y. Wang and P.-J. Zheng, J. Chem.
Soc., Chem. Commun., 1989, 651.
3 I. G. Southerington, M. J. Begley and D. B. Sowerby, J. Chem. Soc.,
Chem. Commun., 1991, 1555.
4 M. A. Said, K. C. K. Swamy, D. M. Poojary, A. Clearfield, M. Veith
and V. Huch, Inorg. Chem., 1996, 35, 3235.
5 F. J. Koller, W. Schwarz and A. Schmidt, Z. Naturforsch., Teil B,
1979, 34, 563.
6 S. Blösl, W. Schwarz and A. Schmidt, Z. Anorg. Allg. Chem., 1981,
474, 51.
7 S. Blösl, W. Schwarz and A. Schmidt, Z. Anorg. Allg. Chem., 1982,
495, 165.
8 C. H. Belin, M. Chaabouni, J. L. Pascal and J. Potier, Inorg. Chem.,
1982, 21, 3557.
9 S. Blösl, W. Schwarz and A. Schmidt, Z. Anorg. Allg. Chem., 1982,
495, 177.
10 S. Blösl and A. Schmidt, Z. Anorg. Allg. Chem., 1985, 523, 99.
11 A. Sauvigny, J. E. Faerber, A. Rihm, H. Thurn and A. Schmidt,
Z. Anorg. Allg. Chem., 1995, 621, 640.
12 D. B. Sowerby, M. J. Begley and P. L. Millington, J. Chem. Soc.,
Chem. Commun., 1984, 896.
13 M. Hall, M. Nunn, M. J. Begley and D. B. Sowerby, J. Chem. Soc.,
Dalton Trans., 1986, 1231.
14 M. J. Begley, M. Hall, M. Nunn and D. B. Sowerby, J. Chem. Soc.,
Dalton Trans., 1986, 1735.
15 S. Blösl, W. Schwarz and A. Schmidt, Z. Naturforsch., Teil B, 1983,
38, 143.
[(SbMe3)2(ì-O)(ì-O2PMe2)2] 8.
A solution of µ-oxo-
bis[chlorotrimethylantimony()] (0.84 g, 2 mmol) in dichloro-
methane (20 cm3) was added to a suspension of sodium
dimethylphosphinate (0.46 g, 4.4 mmol) also in dichlorometh-
ane (20 cm3) at 0 ЊC under an atmosphere of argon and the
mixture stirred at room temperature for 6 h. The mixture was
filtered and the clear filtrate concentrated to ca. 5 cm3. Over-
layering with hexane (15 cm3) gave extremely moisture-sensitive
crystals of the required compound, which were isolated by
decantation and dried in a vacuum. Yield 0.90 g (84%). Owing
to the extreme air sensitivity of this compound, satisfactory
microanalytical results could not be obtained. δH (250 MHz,
CDCl3, r.t., Teflon-sealed tube under N2) 1.13 [12 H, d, 2J(HP)
14, PMe] and 1.66 (18 H, s, SbMe); δC(69 MHz, CDCl3, r.t.)
1
16.3 (s, SbMe) and 18.8 [d, J(CP) 104 Hz, PMe]; ν max/cmϪ1
1421s, 1286s, 1262w, 1221s, 1172vs (br), 1020vs (br), 851vs (br),
753vs (br), 692s, 578s, 531m, 512w, 482vs and 420vs (possible
decomposition in Nujol).
[(SbMe3)2(ì-O)(ì-O2AsPh2)2] 9.
A mixture of µ-oxo-
bis[chlorotrimethylantimony()] (0.39 g, 0.93 mmol), sodium
diphenylarsinate (0.28 g, 1.0 mmol) and dichloromethane (35
cm3) at 0 ЊC was treated as described above to yield moisture-
16 M. A. Said, K. C. K. Swamy, K. Babu, K. Aparna and M. Nethaji,
J. Chem. Soc., Dalton Trans., 1995, 2151.
J. Chem. Soc., Dalton Trans., 1997, Pages 2785–2792
2791

View Article Online
26 H. Reinhardt, D. Bianchi and D. Molle, Chem. Ber., 1957, 90,
17 D. P. Bullivant, M. F. A. Dove and M. J. Haley, J. Chem. Soc.,
Dalton Trans., 1980, 109.
1656.
18 M. N. Gibbons, C. Silvestru, I. Haiduc and D. B. Sowerby, Poly-
hedron, 1996, 15, 4573.
27 N. G. Walker and D. Stuart, DIFABS, Acta Crystallogr., Sect. A,
1983, 39, 158.
19 D. H. Whiffen, J. Chem. Soc., 1956, 1350.
28 A. Altomare, G. Cascarano, C. Giacovazzo and A. Guagliardi,
J. Appl. Crystallogr., 1993, 26, 343.
29 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
30 G. M. Sheldrick, SHELXL 93, Institut für Anorganische Chemie
der Universität Göttingen, 1993.
31 D. J. Watkin, J. R. Carruthers and D. W. Betteridge, CRYSTALS
User’s Guide, Chemical Crystallography Laboratory, University of
Oxford, 1985.
20 D. M. Wesolek, D. B. Sowerby and M. J. Begley, J. Organomet.
Chem., 1985, 293, C5; I. G. Southerington, G. E. Forster, M. J.
Begley and D. B. Sowerby, J. Chem. Soc., Dalton Trans., 1995, 1995.
21 A.-F. Shihada, Z. Naturforsch., Teil B, 1994, 49, 1319.
22 M. N. Gibbons, A. J. Blake and D. B. Sowerby, J. Organomet.
Chem., in the press.
23 S. Kraft and M. Wieber, Z. Anorg. Allg. Chem., 1992, 607, 153.
24 L. Kolditz, M. Gitter and E. Rösel, Z. Anorg. Allg. Chem., 1962,
316, 270.
25 G. G. Long, G. O. Doak and L. D. Freedman, J. Am. Chem. Soc.,
1964, 86, 209.
Received 2nd April 1997 Paper 7/02244A
2792
J. Chem. Soc., Dalton Trans., 1997, Pages 2785–2792