PHENYLANTIMONY(III) DITHIOCYANATE AND THE CRYSTAL-STRUCTURE OF K[SBPH(SCN)(3)]

It is not possible to isolate phenylantimony dithiocyanate from phenylantimony dichloride (1 mol) and 2 equivalents of potassium thiocyanate in acetonitrile and a salt. K[SbPh(SCN)(3)], is isolated instead. A tetrathiocyanate salt, K-2[SbPh(SCN)(4)], has also been isolated and K[SbPh(2)(SCN)(2)] can be obtained from SbPh(2)(SCN) and K(SCN). In K[SbPh(SCN)(3)], X-ray diffraction shows that all the thiocyanate groups are S-bonded and the compound has an unusual polymeric structure in which the sulfur atom of one thiocyanate group bridges between pairs of antimony atoms. Co-ordination about antimony is square pyramidal with an apical phenyl group and sulfur atoms of two terminal (Sb-S 2.573. 2.595 Angstrom) and two cis 1,1-sulfur bridging thiocyanate groups (Sb-S 2.938, 2.999 Angstrom) forming the basal plane. All thiocyanate groups are orientated in the same fashion leading to distorted octahedral co-ordination about potassium.