A new family of mono- and dicarboxylic ruthenium complexes [Ru(DIP)2(L2)]2+ (DIP=4,7-diphenyl-1,10-phenanthroline):: Synthesis, solution behavior, and X-ray molecular structure of trans-[Ru(DIP)2(MeOH)2][OTf]2

A new family of ruthenium complexes of general formula [Ru(DIP)(2)(L-2)](2+), where DIP) 4,7-diphenyl-1,10-phenanthroline,a bidentate ligand with an extended aromatic system, was prepared and fully characterized. When L is a monodentate ligand, the following complexes were obtained: L = CF3SO3-1 (2), CH3CN (3), and MeOH (4). When L-2 is a bidentate ligand, the compounds [Ru(DIP)(2)(Hcmbpy)][Cl](2) (5) and [Ru(DIP)(2)(H(2)dcbpy)][Cl](2) ( 6) were prepared (Hcmbpy = 4-carboxy-4'-methyl-2,2-bipyridine, H(2)dcbpy = 4,4'-dicarboxy-2,2'-bipyridine). Complex [Ru(DIP)(2)(MeOH)(2)][OTf](2) (4) displayed a trans configuration of the DIP ligands, which is rare for octahedral complexes featuring DIP bidentate ligands. DFT calculations carried out on 4 showed that the cis isomer is more stable by 12.2 kcal/ mol relative to the trans species. The solution behaviors of monocarboxylic complex [ Ru( DIP) 2( Hcmbpy)][Cl](2) ( 5) and dicarboxylic complex [Ru(DIP)(2)(H(2)dcbpy)][Cl](2) (6) were investigated by H-1 NMR spectroscopy. VT-NMR, concentration dependence, and reaction with NaOD allowed us to suggest that aggregation of the cationic species in solution, especially for 6, originates mainly from hydrogen bonding interactions.