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

Article abstract of DOI:10.1016/0022-328X(95)05775-K

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 SbPh₃(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 SbPh₂X₃, where X = Br or Cl, with KSCN gave K[SbPh₂(NCS)₄] and attempts to prepare SbPh₂(NCS)₃ and related diphenylantimony(V) mixed halide thiocyanates, SbPh₂X_n(NCS)_{3 - n} where X = Br or Cl and n = 0-2, by treating appropriate diphenylantimony(III) precursors with thiocyanogen or thiocyanogen bromide or chloride gave products which in many cases underwent reorganisation during recrystallisation. Samples of SbPh₂(NCS)₃, SbPh₂Br(NCS)₂, SbPh₂Br₂(NCS) and SbPh₂Cl₂(NCS), and SbPh₃Br(NCS) have, however, been isolated as microcrystalline solids.