CRYSTAL AND MOLECULAR-STRUCTURES OF SOME TRI-ARYLTIN ISOTHIOCYANATES (AR3SNNCS, AR = C6H5, P-CH3C6H4, O-CH3C6H4, O-CH3OC6H4) AND OF THE ADDUCT METHYLPHOSPHORAMIDE(N-THIOCYANATO)TRIS(O-TOLYL)TIN

Full crystal structures are reported for several tri-aryltin isothiocy anates, Ar3SnNCS [Ar= Ph (A), p-Tol (B), o-Tol (C), o-CH3OC6H4 (D)], a s well for the adduct (o-Tol)(3)SnNCS . HMPA (E) (HMPA = hexamethylpho sphoramide). Compound B like A has bridging thiocyanates with five-coo rdinate tin but C and D are the first accurately characterised monomer ic Ar3SnNCS, with four-coordinate tin. The adduct has unambiguously fi ve-coordinate fin even with the ortho-methyls present. The small but s ignificant changes in thiocyanate bond lengths correlate with changes in the geometry at tin, and these changes confirm that nu(CN) values d o indeed accurately monitor trends in modes of thiocyanate bonding whe n involving coordination to the same type of Lewis acid environment. ( C) 1998 Elsevier Science S.A. All rights reserved.