Tri- and di-arylantimony(V) thiocyanates and mixed halide thiocyanates; crystal structure of triphenylantimony(V) di-isothiocyanate

Abstract

A series of triarylantimony(V) dithiocyanates has been prepared by oxidising the appropriate antimony(III) compound with thiocyanogen. IR and 14N NMR spectroscopy indicate the presence of terminally N-bonded thiocyanate groups and this has been confirmed by a crystal structure determination for the SbPh 3(NCS) 2. The asymmetric unit contains three independent trigonal bipyramidal molecules, which differ in the orientations of the axial N-bonded thiocyanates and the phenyl groups in the equatorial plane, and there may be weak CH·S interactions. Treatment of SbPh 2X 3, where X=Br or Cl, with KSCN gave K[SbPh 2(NCS) 4] and attempts to prepare SbPh 2(NCS) 3 and related diphenylantimony(V) mixed halide thiocyanates, SbPh 2X n (NCS) 3− n where X=Br or Cl and n=0–2, by treating appropriatediphenylantimony(III) precursors with thiocyanogen or thiocyanogen bromide or chloride gave products which in many cases underwent reorganisation during recrystallisation. Samples of SbPh 2(NCS) 3, SbPh 2Br(NCS) 2, SbPh 2Br 2(NCS) and SbPh 2Cl 2(NCS), and SbPh 3Br(NCS) have, however, been isolated as microcrystalline solids.