Synthesis and properties of antimony(III) and bismuth(III) halide complexes of diphosphines and diarsines.: Crystal structures of [Bi2I6{o-C6H4(AsMe2)2}2], [Sb2Br6{o-C6H4(PPh2)2}2], [Sb2Cl6{o-C6H4(AsMe2)2}], and [BiCl3{o-C6H4(P(O)Ph2)2}(thf)]

The reaction of SbX3 or BiX3 (X=Cl, Br or I) with the diarsines o-C6H4(AsMe2)(2) or Ph2AsCH2CH2AsPh2, the triarsine MeC(CH2AsMe2)(3), or the diphosphines o-C6H4(PMe2)(2) or o-C6H4(PPh2)(2) (L), yield complexes of 1:1 stoichiometry MX3L irrespective of the reactant ratios used. X-Ray structures of [Bi2I6{o-C6H4(AsMe2)(2)}(2)] and [Sb2Br6{o-C6H4(PPh2)(2)}(2)] reveal distorted octahedral Bi or Sb coordination spheres, linked via asymmetric halide-bridges. Bond lengths suggest a bonding model based upon primary bonding in pyramidal MX3 groups with weaker secondary interactions to the diphosphine or diarsine and the longer distance bridging halide. [Sb2Cl6{o-C6H4(AsMe2)(2)}] is obtained by partial decomposition of [Sb2Cl6{o-C6H4(AsMe2)(2)}(2)] in hot ethanol and contains Sb{o-C6H4(AsMe2)(2)}Cl-2 and SbCl4 units linked via asymmetric chlorine bridges into puckered chains, which associate further through long Sb . . . Cl contacts to produce a polymeric sheet structure. The mononuclear species [BiCl3{o-C6H4(P(O)Ph-2)(2)}(thf)] obtained from BiCl3 and o-C6H4(P(O)Ph-2)(2) in thf is a distorted octahedron with a BiCl3O3 donor set.