Spectroscopic, Electrochemical and Computational Studies of Rhenium(I) and Ruthenium(II) Complexes Incorporating the Novel Tetradentate Ligand 1,4-bis(4-(4?-methyl)-2,2?-bipyridyl)-2,3-diaza-1,3-butadiene (BBDB) and its Derivatives

CATTANEO, MAURICIO; VERGARA, MÓNICA M.; GARCÍA POSSE, MÓNICA E.; FAGALDE, FLORENCIA; PARELLA, TEODOR; KATZ, NÉSTOR E.

POLYHEDRON

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2014 vol. 70 p. 20 - 28

0277-5387

The novel tetradentate ligand 1,4-bis(4-(4'-methyl)-2,2'-bipyridyl)-2,3-diaza-1,3-butadiene (BBDB) was synthesized and characterized by spectroscopic techniques. New complexes of Re and Ru of formulae: [Re(BBDB)(CO)3(Cl)], [(CH3CN)(CO)3Re(mu-BBDB)Re-(CO)3(CH3CN)]2+, [(bpy)2Ru-(mu-BBDB)Ru(bpy)2]4+, [(NH3)4Ru(mu-BBDB)- Ru(NH3)4]4+ (bpy = 2,2'-bipyridine) and complexes of Ru with 4-Me-4'-CO2H-bpy ( = 4-methyl-4'-carboxylic acid-2,2'-bipyridine) - the hydrolyzed derivative of BBDB - of formulae: [(Ru(4-Me-4'-CO2H-bpy)(bpy)2]2+ and [Ru(4-Me-4'-CO2H-bpy)(CN)4]2- were prepared and characterized by spectroscopic, electrochemical and computational techniques. The disclosed enhanced electronic coupling in the mixed-valent complex with ruthenium ammines can be explained by the electronic delocalization imposed by the C=N-N=C backbone. DFT and TD-DFT calculations can predict the optical properties and electronic structures of the reported complexes and comparisons with calculations performed on previously reported complexes with 4-pyridinaldazine can account for their photophysical behaviour.