STRUCTURAL INVESTIGATIONS OF THE ORGANOANTIMONY(V) HALIDES PH(4)SBX AND PH(3)SBX(2)(X=CL, BR OR I) IN THE SOLID-STATE AND IN SOLUTION

X-Ray crystallography revealed a distorted trigonal-bipyramidal structure for Ph(4)Sbl, with Sb-C-ax 2.141(3), Sb-C-eq 2.103(3)-2.117(3) Angstrom and a long Sb-l distance of 3.341(1) Angstrom in monoclinic crystals of P2(1)/n symmetry. Consideration of the weak Sb-X bonds in Ph(4)SbX (X = Cl, Br or I) leads to reassignment of their Raman spectra; Ph(4)Sbl ionises forming [Ph(4)Sb](+) in acetonitrile, as shown by C-13 and Sb-121 NMR spectra. The halide Ph(3)Sbl(2) is reported in two phases, yellow. orthorhombic (Fdd2) crystals isomorphous with Ph(3)SbBr(2) and off-white, cubic (P4(3)32) crystals. In each the molecule is trigonal-bipyramidal. with axial Sb-l bonds of 2.865(1) Angstrom in the former and 2.885(1) Angstrom in the latter, and small differences in their respective bond angles. The phenyl groups of the cubic form are in the regular propeller arrangement whereas one group of the orthorhombic form has a reversed orientation. The vibrational spectra of the two forms differ slightly.