A PENTUPLY-BRIDGING THIOCARBONYL GROUP - X-RAY CRYSTAL-STRUCTURE OF A SALT OF THE 1-THIO-2-PHENYL-1,2-DICARBADODECABORATE(12) ANION, [LH]+[S(PH)C2B10H10]- (L = 1,8-N,N,N1,N1-TETRAMETHYLNAPHTHALENE DIAMINE)

The carboranyl sulphide anion [1,2-S(Ph)C2B10H10]-, characterized as its salt [C10H6(NMe2)2H]+[S(Ph)C2B10H10]- (1), has been prepared from the carboranyl thiol and proton sponge and characterized by X-ray crystallography. The anion has a nido-shaped [PbCB10H10] residue in which the CB4 pentagonal face is capped by a mu5-thiocarbonyl unit [C-S distance 1.729(4) angstrom], attached by bonds of length C-C 1.835(5) angstrom [C(1) to C(2)], C-B 1.742(6), 1.695(5), 1.704(6) and 1.749(6) angstrom [C(1) to B(3), (4), (5) and (6)]. This slipped structure reflects delocalization of the anionic charge from the sulphur atom into the polyhedron, a delocalization supported by AM1 calculations and also reflected in B-11 chemical shift data which show a pronounced antipodal effect.