Room-temperature single-crystal X-ray studies are recorded for some dimethyl
sulfoxide (dmso) solvates of bismuth(III) bromide and iodide. Colourless
BiBr3.3dmso is triclinic,
P-1, a
8·467(4), b 9·109(4),
c 13·901(4) Å, α 76·34(4),
β 76·95(4), γ 64·56(4)°, Z
= 2; conventional R on
|F| was 0·050 for
No 2306 independent
‘observed’ (I >
3σ(I)) reflections. The complex is mononuclear
with a quasi-octahedral fac-bismuth environment,
[(dmso-O)3BiBr3],
isomorphous with the previously determined chloride. Orange
BiI3-2dmso is triclinic,
P-1, a
12·558(2), b 8·962(2),
c 8·342(1) Å, α 61·85(1),
β 78·27(1), γ 76·89(2)°, Z
= 2 f.u., R 0·048 for
No 1953. The complex is binuclear,
a pair of iodide atoms bridging the two bismuth atoms,
[(dmso-O)2I2Bi(µ-I)2BiI2(O-dmso)2];
the two O-dmso ligands about each six-coordinate bismuth lie
trans. Red BiI3.2 ⅔ dmso is
triclinic, P-1,
a 16·435(6), b
14·926(2), c 12·396(3) Å, α
74·89(2), β 73·24(2), γ 79·18(2)°,
Z = 6, R 0·059 for
No 5858. The complex is
[Bi(O-dmso)8]
[Bi2I9], the
eight-coordinate metal environment of the cation being, unusually,
dodecahedral; in the anion a pair of quasi-octahedral six-coordinate bismuth
atoms are bridged by three iodides,
[I3Bi(µ-I)3BiI3]3-.
Bands in the far-infrared and Raman spectra due to the
v(BiX) modes are assigned and discussed in relation to
the structures of the complexes. The assignment of the
v(BiO) modes is discussed.
