Reactions of [SbR3X2]2O with carboxylates and the crystal structures of [SbPh3(O2CCF3)2]2O and [SbMe3(O2CCH3)2]2O

Article abstract of DOI:10.1016/S0022-328X(97)00759-6

Reactions of [SbPh₃Br]₂O and [SbMe₃Cl]₂O with a number of carboxylates lead to halogen substitution and formation of either [SbR₃(O₂CR′)]₂O or SbR₃(O₂CR′)₂. X-ray structures for two of the products, [SbPh₃(O₂CCF₃)]₂O and [SbMe₃(O₂CCH₃)]₂O, show that the carboxylates are unidentate. From NMR spectroscopy, the oxygen bridged compounds are hydrolysed by adventitious water giving SbR₃(O₂CR′)OH in solution but when R = phenyl the original compounds can be recovered on crystallisation.

Full text of DOI:10.1016/S0022-328X(97)00759-6

Journal of Organometallic Chemistry 555 (1998) 271–278
Reactions of [SbR3X2]2O with carboxylates and the crystal structures
of [SbPh3(O2CCF3)2]2O and [SbMe3(O2CCH3)2]2O
Martin N. Gibbons, D. Bryan Sowerby *
Department of Chemistry, Uni6ersity of Nottingham, Nottingham, NG7 2RD, UK
Received 25 October 1997
Abstract
Reactions of [SbPh3Br]2O and [SbMe3Cl]2O with a number of carboxylates lead to halogen substitution and formation of either
[SbR3(O2CR%)]2O or SbR3(O2CR%)2. X-ray structures for two of the products, [SbPh3(O2CCF3)]2O and [SbMe3(O2CCH3)]2O, show
that the carboxylates are unidentate. From NMR spectroscopy, the oxygen bridged compounds are hydrolysed by adventitious
water giving SbR3(O2CR%)OH in solution but when R=phenyl the original compounds can be recovered on crystallisation.
© 1998 Elsevier Science S.A. All rights reserved.
Keywords: Antimony(V); Carboxylates; Hydrolysis; Crystal structure; NMR spectra
O)4(v-OH)2(v-O2CMe)2] · HO2CMe,
and
related
1. Introduction
molecules [8,9]; bridging trifluoroacetate groups are
present in both [(SbF3)2(v-O)(v-O2CCF3)2] and
[(SbF4)2(v-F)(v-O2CCF3)] [10]. Antimony(III) com-
pounds containing bridging carboxylates, include
Sb(O2CMe)3 [11], Sb(O2CCF3)3 [12] and SbPh2(O2CMe)
[13].
Chelating, rather than bridging, carboxylates, how-
ever, are present in both [SbPh2(O2CMe)2]2O [8] and
[SbPh2(O2CPh)2]2O [14], giving antimony atoms in
seven-fold coordination. Related oxo-bridged com-
pounds, [SbPh3(O2CR)]2O, are also known [15] but
X-ray structures are not available. Here the lower
Lewis acidity from the presence of three phenyl groups
may, as for SbPh3(O2CR)2 compounds, lead to uniden-
tate coordination and this paper describes new results
in this area.
We have previously reported [1] that reactions be-
tween oxo-bridged di-antimony compounds, such as
[SbPh3Br]2O and [SbMe3Cl]2O, and phosphinates and
arsinates lead to products in which the new ligands also
bridge between antimony centres and this paper de-
scribes similar reactions with related carboxylates.
Carboxylates are versatile ligands and although there
are examples where the ligand is unidentate, for exam-
ple, three of the acetate groups in SbPh(O2CMe)4 [2],
bidentate behaviour is more often observed, especially
where the central atom is coordinatively unsaturated.
This is the case with the fourth, chelating, acetate in
SbPh(O2CMe)4. Reduction of antimony Lewis acidity
also leads to basically unidentate carboxylates in, for
example, SbPh3(O2CMe)2 [3] and SbPh3(O2CPh)2 [4],
but even here there are weak secondary chelating Sb...O
interactions. Bridging carboxylates, on the other hand,
are present in [(SbCl3)2(v-O)(v-OR1)(v-O2CR2)], where
R1=H, R2=Me [5], CCl3, Pri [6] and R1=Me, R2=
CF3, Et [7] and in the ‘cage’ compound, [(SbPh2)4(v-
2. Results and discussion
2.1. Preparations
Three oxygen bridged bis(triphenylantimony) dicar-
* Corresponding author. Tel.: +44 115 9513561.
boxylates, [SbPh3(O2CCF3)]2O 1, [SbPh3(O2CCCl3)]2O
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(97)00759-6

272
M.N. Gibbons, D.B. Sowerby / Journal of Organometallic Chemistry 555 (1998) 271–278
2 and [SbPh3(O2CCHCl2)]2O 3 have been prepared by
treating [SbPh3Br]2O with the appropriate carboxylic
acid in the presence of triethylamine, as described previ-
ously [15] (Eq. (1)). Related reactions with either
chloroacetic acid or benzoic acid, however, led to
bridge cleavage (Eq. (2)) and the products were
SbPh3(O2CCH2Cl)2 4 and SbPh3(O2CPh)2 5, respec-
tively. Bridge cleavage giving SbPh3(O2CMe)2 6 also
occurred in the reaction of [SbPh3Br]2O with 2 mol of
Ag(O2CMe), but even with prolonged reaction times
there was no reaction with either Na(O2CMe) or
(MeCO)2O.
O2CCF3)], presumed to have symmetrically bridging
trifluoroacetate groups, Dw (153 cm−1) is, as expected,
substantially lower [6]. It is interesting that in spite of
the similarity in stoichiometry between
1
and
[SbF3(O2CCF3)]2O [12], the latter contains symmetri-
cally bridging trifluoroacetate groups; this change in
trifluoroacetate coordination is probably due to the
increased antimony Lewis acidity from the presence of
fluorines on antimony.
Dw values for compounds 2–8 clearly point to the
presence of unidentate carboxylate groups and this has
been confirmed by X-ray crystallography for two
mono-antimony compounds, SbPh3(O2CR)2 where R=
Ph 5 [4] or Me 6 [3]. In each case, the solid state
structure, however, includes weak secondary bonds be-
tween antimony and the double bonded oxygen of the
carboxylate group. In some spectra the carboxylate
bands are split, i.e. wasym(CO2) for 3 and 4 and
wsym(CO2) for 4, probably showing the in-phase and
out-of-phase components and it is interesting that for
1–3 the frequency of wasym(CO2) decreases with increase
in pKa of the parent carboxylic acid. All oxygen bridged
compounds show a band at 710–750 cm−1, assigned to
Sb–O–Sb stretching.
[SbPh3Br]2O+2HO2CR+2Et3N
“[SbPh3(O2CR)]2O+2Et3NHBr
R=CF3 1, CCl3 2 and CHCl2 3
[SbPh3Br]2O+4HO2CR+2Et3N
“2SbPh3(O2CR)2+2Et3NHBr+H2O
R=CH2Cl 4 and Ph 5
(1)
(2)
Rather surprisingly, both [SbMe3(O2CMe)]2O 7 and
[SbMe3(O2CBut)]2O 8 were obtained in good yield from
[SbMe3Cl]2O and two mols of, respectively,
Ag(O2CMe) or Na(O2CBut) and the silver acetate reac-
tion clearly follows a different course from that with
[SbPh3Br]2O. Neither the expected substitution product
nor the bridge cleavage product was obtained on treat-
ment of [SbMe3Cl]2O with two mols of HO2CCF3 in
the presence of triethylamine and 1H NMR spec-
troscopy showed the presence of a number of uniden-
tified products.
2.3. NMR spectroscopy
The NMR behaviour of the triphenylantimony
bridged compounds 1–3 is similar to that observed
previously with [SbPh3Br]2O and related compounds
[18] in that there is ready hydrolysis by traces of
moisture from the CDCl3 solvent and elsewhere to give
monoantimony hydroxo species, SbPh3(OH)(O2CR),
and if no precautions are taken to dry the solvent
rigorously, the spectra contain signals associated with
both this species (B) and the unhydrolysed oxygen
bridged starting compound (A). A solution of 3, pre-
pared under strictly anhydrous conditions, showed only
the triplet, triplet, doublet pattern of peaks for the
m-(7.30) p- (7.45) and o- (7.60 ppm) protons of the
phenyl groups of the unhydrolysed compound (A); the
2.2. Infrared spectroscopy
IR spectroscopy provides a method of assessing car-
boxylate coordination modes from the position of, and
separation (Dw) between, the antisymmetric and sym-
metric CO2 stretching modes. Deacon and coworkers
[16] point out that for acetates and trifluoroacetates this
correlation is limited to recognition of:
1. Complexes with unidentate carboxylates where
Dwunidentate\Dwionic, and;
2. Complexes with chelating or bridging carboxylates,
where Dwbridging or chelating is often BDwionic. (Dwionic
values are 164 and 223 cm−1, respectively, for the
acetate and trifluoroacetate.)
Table 1
Selected IR bands (cm−1
)
Compound
wa(CO2) ws(CO2)
Dw w(Sb–O–Sb)
Selected IR data for compounds 1–8 are summarised
in Table 1 and, in cases where previous data are
available, they are in good agreement [15,17]. Bands for
[SbPh3(O2CCF3)]2O 1 at 1714 cm−1 and 1437 cm−1
give Dw=277 cm−1, only slightly greater than the ionic
value but close to that in Sb(O2CCF3)3 (293 cm−1),
which is known to have effectively unidentate trifl-
uoroacetate groups [12]. In [(SbCl3)2(v-O)(v-OH)(v-
[SbPh3(O2CCF3)]2O 1
1714
1437
1289
277 742
412 737
356 740
[SbPh3(O2CCCl3)]2O 2 [15] 1701
[SbPh3(O2CCHCl2)]2O 3
SbPh3(O2CCH2Cl)2
SbPh3(O2CPh)2
1694/1669 1325
1672/1654 1346/1332 324 737
1645
1630
1623
1620
4
5
1324
1318
1374
1326
321
312
249 710
294 750
SbPh3(O2CMe)2 6 [17]
[SbMe3(O2CMe)]2O 7
[SbMe3(O2CBut)]2O 8

M.N. Gibbons, D.B. Sowerby / Journal of Organometallic Chemistry 555 (1998) 271–278
273
2.4. Mass spectrometry
dichloroacetate proton gave a singlet at 5.55 ppm.
After this sample was exposed to atmospheric mois-
ture for 24 h, additional signals appeared at 5.75
(singlet, CHCl2), 7.53 (multiplet, m- and p-Ph) and
8.11 (multiplet, o-Ph) ppm, associated with the hy-
drolysis product, SbPh3(OH)(O2CCHCl2) (B). Simi-
larly, under anhydrous conditions, the 13C{1H} spec-
The highest mass fragment in the FAB spectrum of
[SbPh3(O2CCHCl2)]2O 3 was Sb2Ph6O(O2CCHCl2)+
(m/z 847) and a second diantimony ion at m/z 811
results from subsequent loss of chlorine and hydrogen
giving Sb2Ph6O(O2CCCl)+. Further ions were assigned
to SbPh3(O2CCHCl2)+, SbPh3OH+, SbPh2+, SbPh+,
SbO2C+ and the commonly observed Ph2+ ion.
Major fragmentation in the EI spectrum of
SbPh3(O2CCH2Cl)2 4 is via loss of carboxylate giving
SbPh3(O2CCH2Cl)+ and SbPh2+ but loss of phenyl is
much less probable. The Sb(O2CCH2Cl)+ ion was
present along with the rearrangement ion SbPh3Cl+.
Fragmentation of SbPh3(O2CMe)2 6 followed a similar
route.
trum of
3
showed only resonances for the
non-hydrolysed compound at 67.8 (Cl2CH), 129.3 (m-
Ph), 131.1 (p-Ph), 133.7(o-Ph) and 138.1(ipso-Ph) ppm.
Crystallisation of solutions containing the hydroxo-
compound led, as previously observed with related
compounds [18], to recovery of only the oxo-bridged
original, implying that hydroxo compounds are un-
stable in the solid state.
Solutions of 1 and 2, prepared with no precau-
tions against contamination by atmospheric moisture,
clearly showed two sets of signals; the triplet, triplet,
doublet pattern of the oxo-bridged parents (A) [at
7.31, 7.45 and 7.52 ppm, respectively, for 1 and 7.35,
7.48 and 7.53 ppm for 2] and the two multiplets [at
7.53 (m- and p-Ph) and 8.06 (o-Ph) ppm for 1 and
at 7.53 and 8.12 ppm for 2] of the hydrolysis pro-
ducts, SbPh3(OH)(O2CR) (B). Again, crystallisation of
NMR samples led to quantitative recovery of the origi-
nal compounds. Proton spectra of SbPh3(O2CCH2Cl)2
4, SbPh3(O2CPh)2 5 and SbPh3(O2CMe)2 6 all showed
the second order phenyl multiplets, typical of
monomeric trigonal bipyramidal SbPh3X2 com-
pounds.
Under strictly anhydrous conditions, the proton
spectrum of [SbMe3(O2CMe)]2O 7 showed the expected
singlets at 1.62 and 1.83 ppm for, respectively, the
Me-Sb and Me-CO2 resonances and exposure to atmo-
spheric moisture gave new peaks at 1.82 and 1.90 ppm,
suggesting hydrolysis with the probable (unconfirmed)
formation of SbMe3(OH)(O2CMe). In contrast to the
behaviour of solutions of 1–3, the parent compound
was not recovered on crystallisation and hydrolysis
appears to be irreversible. It is interesting to note here
that stable antimony(V) hydroxo species usually require
the presence of sterically demanding groups, e.g.
Sb(mesityl)3Br(OH) [18] and Sb(mesityl)3(OH)2 [19]
are known, but recently a related methylantimony
compound, SbMe3(OH)(O2PPh2), has been identified
[20]. The 13C{1H} spectrum of 7 under anhydrous
conditions showed the expected signals at 14.5 (Me-
Sb), 23.3 (Me-CO2) and 176.4 (MeCO2) ppm. The
Me-Sb signal in the 1H spectrum of [Sb-
Me3(O2CBut)]2O 8 under anhydrous conditions was at
1.59 ppm, with a singlet for the But protons at 1.03
ppm, while the 13C{1H} NMR showed singlets at 14.3
(Me-Sb), 27.7 (CMe3), 39.1 (O2C-CMe3) and 183.5
(O2CBut).
The highest mass peak in the EI spectrum of
[SbMe3(O2CMe)]2O 7 was Sb2Me6O(O2CMe)+ (m/z
407) and two further diantimony fragments, Sb2Me6O+
and Sb2Me4O+, were also observed; other notable
peaks were SbMe3(O2CMe)+, SbMe3OH+, Sb-
MeOH+ and SbMe2+.
2.5. X-ray crystallography
Single crystal X-ray structures have been determined
for [SbPh3(O2CCF3)]2O 1 and [SbMe3(O2CMe)]2O 7.
2.5.1. Structure of [SbPh3(O2CCF3)]2O 1
The molecular structure of 1 is shown in Fig. 1 with
selected bond lengths and angles in Table 2. The deter-
mination was not completely satisfactory as the C(3)
trifluoroacetate group was disordered and could not be
adequately modelled but it confirms that the trifl-
uoroacetate groups are basically unidentate, as sug-
gested by the IR spectrum. Unreliable bond parameters
for the C(3) trifluoroacetate group have been omitted
from Table 2. Antimony shows trigonal bipyramidal
geometry with equatorial phenyls [Sb–C 2.100(6)–
˚
2.112(6) A] and oxygens from the bridge and a trifl-
uoroacetate in axial positions. Secondary bonding via
the formally non-bonded oxygens is very weak
˚
[Sb(1)...O(3), Sb(2)...O(5), 3.196(4), 3.402(4) A, respec-
tively] and opening of one of the equatorial angles at
each antimony [C(11)–Sb(1)–C(31) 128.5(2)°, C(41)–
Sb(2)–C(61) 123.9(2)°] is probably as a consequence of
this.
The bridging oxygen angle, 137.9(2)°, falls at the
lower end of the range for compounds of this type, cf.
139.0° in [SbPh3Cl]2O [21], 170.2 and 176.6° in
[SbPh3Br]2O [22] and 180° in one form of [SbPh3I]2O
[23], and the bridge is slightly asymmetric [Sb(1)–O(1)
˚
1.983(4), Sb(2)–O(1) 1.966(4) A]. These distances
˚
(mean 1.975 A) are substantially shorter than those to
˚
the carboxylate oxygens (mean 2.239 A), which in turn
are significantly longer than formal Sb–O single bonds

274
M.N. Gibbons, D.B. Sowerby / Journal of Organometallic Chemistry 555 (1998) 271–278
Fig. 1. Structure of [SbPh3(O2CCF3)]2O 1 showing the atom numbering scheme.
˚
in 1, and clearly replacement of fluorine by phenyl
significantly reduces antimony Lewis acidity and conse-
quently the extent of secondary bonding.
(ca. 2.03 A) in SbPh3(OMe)2 [24] and Sb(mesityl)3(OH)2
[19]. This elongation may be a consequence of a small
contribution from the ionic form, [(SbPh3)2O]2+
2[O2CCF3)]−, and is supported by the fact that the
phenyl groups are all bent away from the bridging
oxygen (mean O(1)–Sb–C 94.1°).
2.5.2. Structure of [SbMe3(O2CMe)]2O 7
The molecular structure of 7 is shown in Fig. 2 with
selected bond lengths and angles in Table 3. Antimony
geometry is again trigonal bipyramidal and a crystallo-
graphic two-fold axis passes through the bridging oxy-
gen. The Sb–O–Sb angle is 140.1(4)° and the bridge is
This determination also confirms the structural dif-
ferences between this compound and the formally simi-
lar [SbF3(O2CCF3)]2O, which contains symmetrically
bridging trifluoroacetate groups and octahedral geome-
try at antimony [10]. The Sb–O(carboxylate) distances
˚
necessarily symmetrical [Sb–O 1.978(2) A]. As expected
˚
in the latter (2.028 and 2.107 A) are shorter than those
from IR spectroscopy, the acetates are near unidentate
with again only weak secondary interactions (Sb...O
Table 2
˚
˚
3.207(4) A) with acetate C–O distances of 1.304(9) A
˚
Selected bond distances (A) and angles (°), with estimated standard
deviations in parentheses, for [SbPh3(O2CCF3)]2O 1
˚
[C(4)–O(2)] and 1.218(8) A [C(4)–O(3)], compared
with values of 1.43 and 1.23 A for single and double
˚
bonds, respectively.
Sb(1)–O(1)
Sb(1)–O(2)
1.983(4) Sb(1)–O(1)–Sb(2)
2.255(4) O(1)–Sb(1)–O(2)
3.196(4) O(1)–Sb(1)–C(11)
2.109(5) O(1)–Sb(1)–C(21)
2.107(5) O(1)–Sb(1)–C(31)
2.109(5) C(11)–Sb(1)–O(2)
1.966(4) C(21)–Sb(1)–O(2)
2.222(4) C(31)–Sb(1)–O(2)
3.402(4) C(11)–Sb(1)–C(21) 111.6(2)
2.112(6) C(11)–Sb(1)–C(31) 128.5(2)
2.100(6) C(21)–Sb(1)–C(31) 118.9(2)
2.108(6) O(1)–Sb(2)–O(4)
1.235(5) O(1)–Sb(2)–C(41)
1.258(5) O(1)–Sb(2)–C(51)
1.509(6) O(1)–Sb(2)–C(61)
88.1(2)
137.9(2)
179.0(1)
90.6(2)
95.7(2)
94.2(2)
88.5(2)
84.2(2)
86.7(2)
All three equatorial angles deviate from the ideal
120° but contrary to the situation in 1, the largest angle
[C(1)–Sb(1)–C(2) 123.2(3)°] is not that associated with
the secondary Sb...O interaction, which occurs between
the C(2) and C(3) methyls [C(2)–Sb(1)–C(3) 122.5(3)°].
Bonds between antimony and the carboxylate are again
Sb(1)...O(3)
Sb(1)–C(11)
Sb(1)–C(21)
Sb(1)–C(31)
Sb(2)–O(1)
Sb(2)–O(4)
Sb(2)...O(5)
Sb(2)–C(41)
Sb(2)–C(51)
Sb(2)–C(61)
O(3)–C(1)
˚
longer (2.197(4) A) than expected but the increase is
lower than in 1 and consequently less ionic character is
presumed to be present.
178.8(2)
91.0(2)
100.3(2)
92.5(2)
O(2)–C(1)
C(1)–C(2)
3. Experimental details
C(41)–Sb(2)–O(4)
C(51)–Sb(2)–O(4)
C(61)–Sb(2)–O(4)
C(41)–Sb(2)–C(51) 119.2(2)
C(41)–Sb(2)–C(61) 123.9(2)
C(51)–Sb(2)–C(61) 115.1(2)
79.5(2)
88.7(2)
3.1. Preparation of [SbPh3(O2CCF3)]2O 1
Trifluoroacetic acid (0.24 g, 2.08 mmol) was added
slowly to a stirred suspension of [SbPh3Br]2O) [18] (0.92
g, 1.04 mmol) and toluene (25 cm3), leading to dissolu-
O(3)–C(1)–O(2)
128.6(4)

M.N. Gibbons, D.B. Sowerby / Journal of Organometallic Chemistry 555 (1998) 271–278
275
Fig. 2. Structure of [SbMe3(O2CCH3)]2O 7 showing the atom numbering scheme.
tion. Triethylamine (0.21 g, 2.08 mmol) was then added
and the mixture stirred at room temperature for 16 h.
Precipitated triethylammonium bromide was filtered off
and evaporation of solvent in a vacuum yielded a white
solid, which was recrystallised from a mixture of chlo-
roform and hexane. Yield 0.61 g (62%). M.p. 228–
3JHH=7 Hz, o-Ph-A), 7.53 (18H, m, m- and p-Ph-B)
8.12 (12H, m, o-Ph-B), where A is [SbPh3(O2CCCl3)]2O
and B is SbPh3(OH)(O2CCCl3). IR (nujol mull, CsI):
1701vs, 1435s, 1289vs, 1074w, 997w, 834s, 738vs, 691vs,
454m cm−1. Found: C, 46.8; H, 3.8. C40H30Cl6O5Sb2
calc.: C, 45.9; H, 2.9%
1
230°C. H NMR (CDCl3, 250 MHz, RT) l 7.31 (12H,
t, 3JHH=7 Hz, m-Ph-A), 7.45 (6H, t, 3JHH=7 Hz,
p-Ph-A); 7.52 (12H, d, 3JHH=7 Hz, o-Ph-A), 7.53
(18H, m, m- and p-Ph-B), 8.06 (12H, m, o-Ph-B),
3.3. Preparation of [SbPh3(O2CCHCl2)]2O 3
Similarly, dichloroacetic acid (0.36 g, 2.81 mmol),
[SbPh3Br]2O (1.00 g, 1.13 mmol) and triethylamine
(0.29 g, 2.81 mmol) in toluene (20 cm3) gave crystals of
the required compound. Yield 0.51 g (46%). M.p. 211–
where
A
is [SbPh3(O2CCF3)]2O and
B
is
SbPh3(OH)(O2CCF3). IR (nujol mull, CsI): 1714vs,
1437s, 1393m, 1185vs, 1144s, 998w, 841w, 794w, 742vs,
721m, 691m, 456m cm−1. Found: C, 50.5; H, 3.4.
C40H30F6O5Sb2 calc.: C, 50.7; H, 3.2%
1
214°C. H NMR (CDCl3, 250 MHz, RT) l 5.55 (2H, s,
3
CHCl2-A), 5.75 (2H, s, CHCl2-B), 7.30(12H, t, JHH
=
7 Hz, m-Ph-A), 7.45 (6H, t, 3JHH=7 Hz, p-Ph-A),
7.60 (12H, d, 3JHH=7 Hz, o-Ph-A), 7.53 (18H, m,
m- and p-Ph-B), 8.11 (12H, m, o-Ph-B), where
3.2. Preparation of [SbPh3(O2CCCl3)]2O 2
A
is
[SbPh3(O2CCHCl2)]2O
and
B
is
[SbPh3Br]2O (1.00 g, 1.13 mmol) was treated with
trichloroacetic acid (0.37 g, 2.27 mmol) and triethy-
lamine (0.23 g, 2.28 mmol) in toluene (30 cm3) and after
filtration and evaporation to dryness, the remaining
solid was crystallised from chloroform. Yield 0.38 g
(32%). M.p. 170–174°C (177°C [15]). 1H NMR (CDCl3,
SbPh3(OH)(O2CCHCl2). Under strictly anhydrous con-
ditions signals due to A only were observed. 13C{1H}
NMR (CDCl3, 69 MHz, RT, anhydrous, signals due to
A only observed) l 67.8 (Cl2CH), 129.3 (m-Ph), 131.1
(p-Ph), 133.7 (o-Ph), 138.1 (ipso-Ph), quaternary car-
boxylate carbon not observed. IR (nujol mull, CsI):
1694s, 1669s, 1435s, 1325vs, 1193m, 740vs, 692s, 459s
cm−1. Mass spectrum (FAB), m/z (rel. int. (%)): 847
(Sb2Ph6O(O2CCHCl2)+, 49), 811 (Sb2Ph6O(O2CCCl)+,
18), 479 (SbPh3(O2CCHCl2)+, 23), 369 (SbPh3OH+,
5), 275 (SbPh2+, 23), 198 (SbPh+, 23), 154 (Ph2+, 100),
77 (Ph+, 43). Found: C, 48.3; H, 3.3. C40H32Cl4O5Sb2
calc.: C, 49.1; H, 3.3%
3
250 MHz, RT) l 7.35 (12H, t, JHH=7 Hz, m-Ph-A),
7.48 (6H, t, 3JHH=7 Hz, p-Ph-A), 7.53 (12H, d,
Table 3
˚
Bond distances (A) and angles (°), with estimated standard deviations
in parentheses, for [SbMe3(O2CCH3)]2O 7
Sb(1)–O(1)
Sb(1)–O(2)
Sb(1)...O(3)
Sb(1)–C(1)
Sb(1)–C(2)
Sb(1)–C(3)
O(2)–C(4)
O(3)–C(4)
C(4)–C(5)
1.978(2)
2.197(4)
3.207(4)
2.104(6)
2.098(8)
2.102(7)
1.304(9)
1.218(8)
1.506(11)
Sb(1)–O(1)–Sb(1a)
O(1)–Sb(1)–O(2)
O(1)–Sb(1)–C(1)
O(1)–Sb(1)–C(2)
O(1)–Sb(1)–C(3)
C(1)–Sb(1)–O(2)
C(2)–Sb(1)–O(2)
C(3)–Sb(1)–O(2)
C(1)–Sb(1)–C(2)
C(1)–Sb(1)–C(3)
C(2)–Sb(1)–C(3)
O(3)–C(4)–O(2)
140.1(4)
179.8(2)
97.4(2)
92.4(2)
90.7(3)
82.4(2)
87.6(2)
89.5(3)
123.2(3)
113.2(3)
122.5(3)
124.0(7)
3.4. Reaction of [SbPh3Br]2O with two mols of
HO2CCH2Cl
A stirred suspension of [SbPh3Br]2O (0.99 g, 1.12
mmol) and toluene (20 cm3) was treated with
chloroacetic acid (0.22 g, 2.36 mmol) giving a clear
solution. Addition of triethylamine (0.24 g, 2.36 mmol)
led to the immediate formation of a white precipitate.
The mixture was stirred at ambient temperature for 24
Sb(1a) is generated by the symmetry transformation −x, y, 0.5−z.

276
M.N. Gibbons, D.B. Sowerby / Journal of Organometallic Chemistry 555 (1998) 271–278
h and then filtered to remove insolubles. Removal of
solvent in a vacuum gave a white solid which was
recrystallised from a chloroform-hexane mixture to give
crystals of SbPh3(O2CCH2Cl)2 4. Yield 0.56 g (46%
based on [SbPh3Br]2O). M.p. 132–135°C (132–133°C
1008w, 932m, 915w, 688m, 672w, 609w, 486m cm−1
.
Mass spectrum (EI) m/z (rel. int. (%)): 411
(SbPh3(O2CMe)+, 61), 393 (SbPh2(O2CMe)2+, 20), 369
(SbPh3OH+,
11),
352
(SbPh3+,
7),
334
(SbPh2(O2CMe)+, 8), 275 (SbPh2+, 18), 257
(SbPh(O2CMe)+, 27), 215 (SbPhOH+, 22), 198
(SbPh+, 100), 180 (Sb(O2CMe)+, 35), 154 (Ph2+, 91),
77 (Ph+, 41), 60 (HO2CMe+, 10). Found: C, 56.1; H,
4.6. C22H21O4Sb calc.: C, 56.1; H, 4.5%
1
[17]). H NMR (CDCl3, 250 MHz, RT) l 3.86 (4H, s,
CH2Cl), 7.55 (9H, m, m- and p-Ph), 8.03 (6H, m,
o-Ph). 13C{1H} NMR (CDCl3, 69 MHz, RT) l 42.5
(ClCH2), 129.6 (m-Ph), 131.7 (p-Ph), 133.9 (o-Ph),
135.8 (ipso-Ph), 169.9 (O2C). IR (nujol mull, CsI):
1673w, sh, 1646vs, 1481m, 1435s, 1366m, 1332vs,
1259m, 1228w, 1073m, 1021m, 998m, 773vs, 737s, 692s,
461s, 452s cm−1. Mass spectrum (EI), m/z (rel. int.
3.7. Preparation of [SbMe3(O2CMe)]2O 7
All manipulations in this and the following experi-
ment were carried out under anhydrous argon using
stringent Schlenk and glovebox techniques.
(%)):
461
(SbPh2(O2CCH2Cl)2+,
6),
445
(SbPh3(O2CCH2Cl)+, 74), 387 (SbPh3Cl+, 17), 275
(SbPh2+, 14), 214 (Sb(O2CCH2Cl)+, 33), 198 (SbPh+,
47), 154 (Ph2+, 100), 77 (Ph+, 38). Found: C, 48.8; H,
3.5. C22H19Cl2O4Sb calc.: C, 48.9; H, 3.6%
A solution of [SbMe3Cl]2O (0.67 g, 1.59 mmol) in
dichloromethane (20 cm3) was added to a suspension of
silver acetate (0.58 g, 3.5 mmol) and dichloromethane
(10 cm3) in the dark. The mixture was then stirred for
ca. 24 h at room temperature, after which precipitated
silver salts were removed by filtration. The pale purple
solution was then evaporated a give an off-white pow-
der, which was crystallised from a dichloromethane-
pentane mixture to give the required compound 7.
3.5. Reaction of [SbPh3Br]2O with two mols of
HO2CPh
As described above, [SbPh3Br]2O (1.02 g, 1.15 mmol),
benzoic acid (0.30 g, 2.42 mmol) and triethylamine
(0.25 g, 2.42 mmol) were stirred in toluene (25 cm3) and
the oily residue, which remained after filtration and
evaporation of the solution, was crystallised from chlo-
roform/hexane to give SbPh3(O2CPh)2 5. Yield 0.22 g
(16% based on [SbPh3Br]2O). M.p. 172–175°C (176–
1
Yield 0.60 g (81%); m.p. 174–176°C. H NMR (250
MHz, CDCl3, RT) l 1.62 (18H, s, Me-Sb), 1.83 (6H, s,
O2CMe). Decomposition noted after exposure to atmo-
spheric moisture. 13C{1H} NMR (69 MHz, CDCl3, RT)
l 14.5 (Me-Sb), 23.3 (O2CMe), 176.4 (O2CMe). IR
(nujol mull, CsI): 1623s, 1374s, 1311s, 1097(w, br),
1015m, 925m, 851s, 710s, 658s, 577m, 527w, 493m
cm−1. Mass spectrum (EI), m/z (rel. int. (%)): 409
(Sb2Me6O(O2CMe)+, 3), 351 (Sb2Me6O+, 30), 321
(Sb2Me4O+, 18), 225 (SbMe3(O2CMe)+,100), 183
(SbMe3OH+, 49), 153 (SbMeOH+, 28), 151 (SbMe2+,
23). Found: C, 25.6; H, 5.2. C10H24O5Sb2 calc.: C, 25.7;
H, 5.2%.
1
177°C [25]. H NMR (CDCl3, 250 MHz, RT) l 7.36
(4H, t, 3JHH=7.5 Hz, m-Ph-benzoate), 7.47 (2H, t,
3JHH=7.5 Hz, p-Ph-benzoate), 7.51 (9H, m, m- and
3
p-Ph-Sb), 7.96 (4H, d, JHH=7.5 Hz, o-Ph-benzoate),
8.14 (6H, m, o-Ph-Sb). IR (nujol mull, CsI): 1645s,
1577w, 1536w, 1435s, 1324vs, 1300s, 1125w, 1068w,
1024w, 998w, 764vs, 734vs, 718s, 691s, 449s cm−1
.
Found: C, 64.0; H, 4.1. C32H25O4Sb calc.: C, 64.6; H,
4.2%.
3.8. Preparation of [SbMe3(O2CBut)]2O 8
3.6. Reaction of [SbPh3Br]2O with two mols of
AgO2CMe
A solution of [SbMe3Cl]2O (0.37 g, 0.88 mmol) in
dichloromethane (20 cm3) was added to a suspension of
sodium trimethylacetate (0.22 g, 1.80 mmol) and
dichloromethane (10 cm3). After stirring at room tem-
perature for 16 h, the mixture was filtered to give a
clear solution. Evaporation of volatiles in a vacuum
gave crude product which was crystallised from a mix-
ture of toluene and hexane to give [SbMe3(O2CBut)]2O
8. Yield 0.32 g (66%). 1H NMR (250 MHz, CDCl3, RT)
l 1.03 (18H, s, O2CBut), 1.59 (18H, s, Me-Sb). [Traces
of the new compound SbMe3(O2CBut)2 were also de-
tected before recrystallisation, l 1.08 (18H s, O2CBut),
1.7 (9H, s, Me-Sb).] 13C{1H} NMR (69 MHz, CDCl3,
RT) l 14.3 (Me-Sb), 27.7 (CMe3), 39.1 (CMe3), 183.5
(O2CBut). IR (nujol mull, CsI): 1620s, 1326s, 1211s,
849w, br, 750s, 603m, 550w cm−1. Mass spectrum (EI),
Silver acetate (0.33 mg, 1.97 mmol) was added to a
stirring solution of [SbPh3Br]2O (0.70 g, 0.79 mmol) in
dichloromethane (30 cm3) and the mixture was stirred
in the dark under reflux for 16 h. After removal of
insolubles, the solvent was evaporated to give an off-
white product which was recrystallised from chloro-
form/hexane to give well-formed crystals of
SbPh3(O2CMe)2 6. Yield 0.34 g (46% based on
[SbPh3Br]2O). M.p. 209–212°C (213–215°C [24]). 1H
NMR (CDCl3, 250 MHz, RT) l 1.84 (6H, s, O2CMe),
7.49 (9H, m, m- and p-Ph), 8.01 (6H, m, o-Ph).
13C{1H} NMR (CDCl3, 69 MHz, RT) l 22.1 (CH3),
129.1 (m-Ph), 130.9 (p-Ph), 133.8 (o-Ph), 139.0 (ipso-
Ph), 175.7(O2C). IR (nujol mull, CsI): 1630s, 1318s,

M.N. Gibbons, D.B. Sowerby / Journal of Organometallic Chemistry 555 (1998) 271–278
277
refined on F2o by full matrix least squares using all
unique data (SHELXL-93) [28].
Table 4
Crystallographic data
The C(3) trifluoroacetate group of 1 was disordered
and during refinement was restrained to have bond
parameters similar to those of the C(1) group. Thermal
parameters for the fluorines of the C(3) group were
high and it was not to possible to model accurately the
electron density in terms of alternative atom positions;
bond parameters for this group are therefore not in-
cluded in Table 2. The phenyl hydrogen atoms were
Compound
1
7
Chemical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
C40H30F6O5Sb2
948.1
0.32×0.12×0.10
Monoclinic
P21/c
20.436(2)
10.1755(9)
19.518(5)
112.494(13)
3749.8(11)
4
1.679
Mo–Kh (0.71069)
15.14
1864
2–25
C10H24O5Sb2
467.8
0.28×0.21×0.07
Monoclinic
C2/c
14.249(3)
8.684(3)
14.177(3)
114.58(2)
1595.3(7)
4
1.948
Mo–Kh (0.71069)
33.93
904
2–25
˚
a (A)
˚
b (A)
˚
˚
c (A)
placed at calculated positions [d(C–H) 0.95 A] and
refined with fixed isotropic thermal parameters, riding
i (°)
Volume (A )
3
˚
on the attached carbon atom. Hydrogen atoms in 7
Z
˚
Dc (g cm−3
)
˚
were treated similarly [d(C–H) 0.98 A].
Radiation (A)
Full details of the atomic coordinates, thermal
parameters and bond lengths and angles have been
deposited with the Cambridge Crystallographic Data
Centre.
v (cm−1
F(000)
)
q limits (°)
Index ranges
(for unique data)
−23BhB23
−11BkB11
−22BlB17
−15BhB12
−9BkB10
−12BlB16
Acknowledgements
Temperature (K)
150
150
Total data collected 15116
3168
1236
0.1220
Direct methods
We thank Professor M.B. Hursthouse and the EP-
SRC Crystallographic Service for X-ray data collection.
Unique data
R(int)
5572
0.0884
Structure solution
Direct methods
(
SHELXS-86
)
(SHELXS-86)
Refinement
Data / variables
Goodness of Fit
(S)
Full matrix-LS on F2 Full matrix-LS on F2
5572/478
0.935
1204/83
1.100
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0.0609
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˚
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R observed data
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