Structural properties of platinum(II) biphenyl complexes containing 1,10-phenanthroline derivatives

Seven platinum(II) complexes formulated as Pt(bph)L, where bph is the 2,2'-biphenyl dianion and L = 4-methyl-1,10-phenanthroline (4-Mephen), 5-methyl-1,10-phenanthroline (5-Mephen), 5-chloro-1,10-phenanthroline (5-Clphen), 5,6-dimethyl-1,10-phenanthroline (5,6-Me(2)phen), 4,7-dimethyl-1,10-phenanthroline (4,7-Me(2)phen), 4,7-diphenyl-1,10-phenanthroline (4,7-Ph(2)phen) and 3,4,7,8-tetra-methyl-1,10-phenanthroline (3,4,7,8-Me(4)phen) are reported. Protons attached to the phen ligand resonate downfield from those attached to the bph ligand and two proton signals are split by interaction with Pt-195. Pt(bph)(3,4,7,8-Me(4)phen), Pt(bph)(4,7-Me(2)phen), Pt(bph)(5,6-Me(2)phen), Pt(bph)(4,7-Ph(2)phen) and Pt(bph)(5-Mephen) crystallize in the space groups Pna2(1), P2(1)/n, P2(1)/c, P - 1 and Pca2(1), respectively. The structures of the complexes deviate from true planarity and divide themselves into two groups where the bph and phen ligands cross in an X configuration or bow out in a butterfly (B) configuration. Circular dichroism revealed two different spectra with respect to the X and B configurations. (C) 2013 Elsevier B.V. All rights reserved.