Synthesis, properties and crystal structures of benzene-1,2-dithiolato complexes of antimony-(III) and -(V)
Anaerobic treatment of SbCl3 with 1,2-(LiS)2C6H4 provided a reliable route to [Sb(1,2-S2C6H4)2]– which in turn produced [Sb(1,2-S2C6H4)3]– on reaction with 1,2-(HS)2C6H4 and O2 in very good yields ([NEt4]+ salt, ca. 82%). Tetraalkylammonium salts of [Sb(1,2-S2C6H4)2]– were isolated after metathesis with either [NEt4]Br ([NEt4]+ salt, ca. 72%) or [NBun4]l ([NBun4]+ salt, ca. 90%). Slowly cooling hot MeCN solutions of [Net4][Sb(1,2-S2C6H4)2] gave yellow single crystals. This compound is the first structurally characterized anionic thiolate complex of SbIII. In its structure the stereochemical influence of the lone pair of electrons leads to a distorted Ψ-trigonal-bipyramidal environment [Sax–Sb–Sax 158.95(3), Seq–Sb–Seq 105.08(3)°], however, the degree of distortion is less severe than expected for a complex with a normalized bite (b) of 1.31. Dark purple single crystals of [NEt4][Sb(1,2-S2C6H4)3] were obtained by slowly cooling hot MeCN–MeOH solutions. The co-ordination geometry about Sb is slightly distorted from octahedral with a twist angle of 49.22(3)° and most structural parameters are within 10% of octahedral values.