title: Ligand and coordination-plane distortions in platinum(II) complexes of isomers of dimethyl-2,2'-bipyridine.
abstract: Pseudo-square-planar platinum(II) complexes containing 4,4' (4,4'-Me(2)bipy), 5,5' (5,5'-Me(2)bipy) and 6,6' (6,6'-Me(2)bipy) isomers of dimethyl-2,2'-bipyridine (Me(2)bipy) were synthesized and structurally characterized to assess the effects of methyl-group position on structure. The Pt-N distances in (Me(2)bipy)PtCl(2) complexes fall in the typical range [2.017 (3)-2.032 (3) Angstroms]. Only minor distortions such as 2.4 and 5.5 degrees twisting of the two pyridyl rings in (4,4'-Me(2)bipy)PtCl(2) (I) and (5,5'-Me(2)bipy)PtCl(2) (II), respectively, occur. However, (6,6'-Me(2)bipy)PtCl(2) (III) is highly distorted: the two pyridyl rings in (III) have a large bowing angle (theta(B)) of 19.2 degrees . The presence of distortions in (III), but not in (I) and (II), is attributed to repulsions between the 6,6'-methyl groups and the cis chloro ligands. [(4,4'-Me(2)bipy)(2)Pt](BF(4))(2) (IV) undergoes a bow-incline deformation having a large theta(B) value (24.2 degrees), and the ligands are inclined relative to the coordination plane by 18.80 (13) degrees. Complex (IV) joins a small list of distorted bis-bipyridine complexes; this finding can be attributed to the unfavorable repulsions between the 6,6' hydrogen substituents of opposing ligands. Some of these complexes exhibit canting rather than bow-incline distortion, a trend suggesting that subtle solid-state effects determine the nature of the distortion.
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803-1804, USA.
authors.forename: Vidhi
authors.initials: V
authors.lastname: Maheshwari
authors.forename: Maria
authors.initials: M
authors.lastname: Carlone
authors.forename: Frank R
authors.initials: FR
authors.lastname: Fronczek
authors.forename: Luigi G
authors.initials: LG
authors.lastname: Marzilli
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D006859:Hydrogen / Q000737:chemistry; D007536:Isomerism; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D017671:Platinum Compounds / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: D008024:Ligands; D017671:Platinum Compounds; D011725:Pyridines; D010984:Platinum; D010165:Palladium; D006859:Hydrogen; D009584:Nitrogen