Iodobismuthate(III) and Iodobismuthate(III)/Iodocuprate(I) Complexes with Organic Ligands

Pyridine ligand complexes of [Bu4N][BiI4] were prepared using chelating ligands 2,2-bipyridyl (2,2-Bpy), 1,10-phenanthroline (Phen), and 4-nitro-1,10-phenanthroline (NO(2)Phen), producing monomeric complexes [Bu4N][(2,2-Bpy)BiI4], [Bu4N][(Phen)BiI4], and [Bu4N][(NO(2)Phen)BiI4], and bridging ligands 4,4-bipyridyl (4,4-Bpy), pyrazine (Pyz), and aminopyrazine (NH(2)Pyz) resulting in formation of polymers [Bu4N](n)[(4,4-Bpy)BiI4](n) and [Bu4N](2n)[(RPyz)Bi2I8](n) (R = H, NH2). The latter contain edge-sharing Bi2I8 dimers. Organic ligand Bi-III/Cu-I clusters [Bu4N](2)[L2Bi2Cu2I10] {L = PPh3, P(OPh)(3)} and [Bu4N](2)[PyBi2Cu2I10] (Py = pyridine) have been prepared. All bismuthate(III) centers are distorted octahedra and all cuprate(I) centers are tetrahedral, with organic ligands bonded to Cu-I. The first neutral BiI3/CuI organic ligand complex [BiCu3I6(PPh3)(6)] is reported. Diffuse reflectance spectroscopy measurements reveal strong absorption bands for both iodobismuthate(III) and iodocuprate(I)/bismuthate(III) complexes in the UV and visible range. Despite the similarity in absorption bands, DFT calculations support a distinct shift in transition from a mixed halide/metal-to-ligand charge transfer (X/MLCT) to a metal-halide cluster-centered transition upon incorporation of copper(I) into the cluster.