Synthesis and structures of one-dimensional co-ordination polymers derived from bismuth(III) selenoether macrocyclic complexes

Treatment of BiX3 (X=Cl or Br) with [8]aneSe(2) (1,5-diselenacyclooctane), [16]aneSe(4) (1,5,9,13-tetraselenacyclohexadecane), [24]aneSe(6) (1,5,9,13,17,21-hexaselenacyclotetracosane) yielded species of formula [BiX3(L)] in moderate to high yield as intensely coloured powdered solids. The crystal structures of [BiCl3([8]aneSe(2))] and [BiBr3([16]aneSe(4))] each reveal infinite one-dimensional ladder structures derived from almost planar Bi2X6 dimer units linked by mu-bridging cyclic selenoethers. Each Bi is co-ordinated to a Se2X4 donor set, with the Se donor atoms occupying mutually trans co-ordination sites. The selenoether ligands adopt exocyclic arrangements and, in [BiBr3([16]aneSe(4))], it is two trans Se atoms which co-ordinate to Bi-III, leaving the other two Se atoms non-co-ordinating. The structures of these species are contrasted with related complexes involving acyclic selenoether ligands and with the few structurally characterised bismuth(III) halide complexes with macrocyclic thioether ligands.