Phenylantimony(III) dithiocyanate and the crystal structure of K[SbPh(SCN)3]

Abstract

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, K₂[SbPh(SCN)₄], has also been isolated and K[SbPh₂(SCN)₂] can be obtained from SbPh₂(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 Å) and two cis 1,1-sulfur bridging thiocyanate groups (Sb–S 2.938, 2.999 Å) forming the basal plane. All thiocyanate groups are oriented in the same fashion leading to distorted octahedral co-ordination about potassium.