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

•X-ray structures deviate from square planar into two types of structures, X and bowed (B) forms.•X and B forms exhibit circular dichroism in the solid state.•Circular dichroism spectra can be correlated with optimized structures determined by DFT calculations.•Heteronuclear interactions are observed by NMR between 195Pt and ring protons of phenanthroline and biphenyl ligand.•A Hammett sigma correlation exists with the most downfield proton resonance.

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-Me2phen), 4,7-dimethyl-1,10-phenanthroline (4,7-Me2phen), 4,7-diphenyl-1,10-phenanthroline (4,7-Ph2phen) and 3,4,7,8-tetramethyl-1,10-phenanthroline (3,4,7,8-Me4phen) 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 195Pt. Pt(bph)(3,4,7,8-Me4phen), Pt(bph)(4,7-Me2phen), Pt(bph)(5,6-Me2phen), Pt(bph)(4,7-Ph2phen) and Pt(bph)(5-Mephen) crystallize in the space groups Pna21, P21/n, P21/c, P − 1 and Pca21, 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.