title: Coordination complexes of bismuth triflates with tetrahydrofuran and diphosphine ligands.
abstract: The reaction of CH3OSO2CF3 (MeOTf) with BiBr3 in tetrahydrofuran (THF) yields (THF)2BiBr2(OTf) (1), which is converted to (dmpe)BiBr2(OTf) (2Br) upon displacement of the THF ligands with bis(dimethylphosphino)ethane (dmpe). The chloride derivatives (dmpe)BiCl2(OTf) (2Cl) and (dmpe)BiCl(OTf)2 (3) are obtained from the reaction of BiCl3 and dmpe with 1 and 2 equiv of Me3SiOSO2CF3 (TMSOTf), respectively. The complexes readily decompose in solution to give elemental bismuth and a mixture of products. The solid-state structures reveal dimeric units bridged by both triflate O-S-O interactions and weak Bi-X-Bi interactions (X = Cl, Br). Comparison of the solid-state structures illustrates that both cis and trans configurations of halides are possible in complexes of the form L2BiX2(OTf), depending upon the denticity of the ligand. The experimentally observed configurations are consistent with minima calculated at the MP2 level for the triflate-free cations in the gas phase. Examination of the MP2-calculated electronic structure of 3 reveals the presence of low-lying π-type orbitals that may result in Z-type ligand activity. However, the attempted coordination of 3 with the electron-rich metal center in K2PdCl4, via metal-to-ligand back-donation, leads instead to halide abstraction, giving [(dmpe)2Pd][(CH3CN)2Bi2Cl6(OTf)2] (8). The anion in 8 consists of two octahedral bismuth environments bridged along one edge by two triflate anions. The results illustrate new coordination chemistry for bismuth.
authors.affiliation: Department of Chemistry, University of Victoria, Victoria, British Columbia, Canada V8W 3V6.
authors.forename: Saurabh S
authors.initials: SS
authors.lastname: Chitnis
authors.forename: Neil
authors.initials: N
authors.lastname: Burford
authors.forename: Andreas
authors.initials: A
authors.lastname: Decken
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ferguson