SCHEDULED MAINTENANCE
New square-pyramidal organoantimony(V) compounds; crystal structures of (biphenyl-2,2′-diyl)phenylantimony(V) dibromide, dichloride and diisothiocyanate, Sb(2,2′-C12H8)PhX2 (X = Br, Cl or NCS), and of octahedral SbPh(o-O2C6Cl4)Cl2 ·OEt2
Abstract
Oxidative addition between
(biphenyl-2,2′-diyl)phenylantimony(III),
Sb(2,2′-C
12
H
8
)Ph 1 and Br
2
or
SO
2
Cl
2
gave
Sb(2,2′-C
12
H
8
)PhBr
2
2 and
Sb(2,2′-C
12
H
8
)PhCl
2
3,
respectively, while the corresponding fluoride
Sb(2,2′-C
12
H
8
)PhF
2
4 and the
thiocyanate
Sb(2,2′-C
12
H
8
)Ph(NCS)
2
5 were
obtained by metathesis reactions between 3 and KF and KSCN,
respectively. Compounds 2 and 3 are isostructural but, in contrast to
the closely related SbPh
3
X
2
species, individual
molecules have square-pyramidal geometry. Again in contrast to
SbPh
3
X
2
compounds, secondary
antimony–halogen interactions trans to the apical carbon
atom lead to solid-state dimers, implying Lewis acidity at antimony.
Antimony in the thiocyanate 5 showed similar square-pyramidal geometry
with N-bonded thiocyanate groups but bridging by one thiocyanate again
gives dimers in the solid. Oxidative addition between SbPhCl
2
and tetrachloro-ortho-benzoquinone in ether solution gave the
tetrachlorocatechol analogue of 3 as a six-co-ordinate ether solvate,
SbPh(o-O
2
C
6
Cl
4
)·OEt
2
6. If the weak bond to ether is ignored, antimony again has
square-pyramidal geometry but formation of the adduct again points to
antimony Lewis acidity. A non-solvated substituted catecholate,
SbPh(o-O
2
C
6
H
2
Bu
t
2
-3,5)Cl
2
8, was also synthesized but crystals
suitable for X-ray diffraction could not be obtained.
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