title: The very covalent diammino(o-benzoquinonediimine) dichlororuthenium(II). An example of very strong pi-back-donation.
abstract: The syntheses and X-ray structures of the complexes Ru(S-dmso)Cl2(opda) (1) and Ru(NH3)2Cl2(bqdi) (2) are described (opda= o-phenylenediamine, bqdi= o-benzoquinonediimine). Optical absorption and emission, vibrational (resonance Raman), and electrochemical data are discussed. We explore the nature of the ruthenium benzoquinone electronic interaction in species 2 primarily within the framework of density functional theory (DFT) but also using INDO/S to extract Coulombic and exchange integrals. The resonance Raman and emission data were understood in terms of a common set of coupled vibrations localized primarily within the ruthenium metallacycle ring. Experimental and computational data were also compared among a select group of ruthenium bqdi species with other spectator ligands, specifically ammonia, 2,2'-bipyridine, and 2,4-pentanedione. The changes in the electrochemistry, optical spectroscopy, and vibrational spectra with changing spectator ligand donicity were explained within a common theoretical (DFT) model which further provided a detailed analysis of the variation in the molecular orbital descriptions. With the application of an extended charge decomposition analysis (ECDA), a detailed picture emerged of the bonding between the bqdi ligand and the metal atom, illustrating the coupling between the orbitals of each fragment as a function of orbital symmetry and charge transfer between the fragments of the complex. Metal-to-bqdi pi-back-donation is seen to be very important.
authors.affiliation: Department of Chemistry, York University, CB124, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada.
authors.forename: Julia
authors.initials: J
authors.lastname: Rusanova
authors.forename: Eduard
authors.initials: E
authors.lastname: Rusanov
authors.forename: S I
authors.initials: SI
authors.lastname: Gorelsky
authors.forename: Dharamdat
authors.initials: D
authors.lastname: Christendat
authors.forename: Raluca
authors.initials: R
authors.lastname: Popescu
authors.forename: Abdiaziz A
authors.initials: AA
authors.lastname: Farah
authors.forename: Rémi
authors.initials: R
authors.lastname: Beaulac
authors.forename: Christian
authors.initials: C
authors.lastname: Reber
authors.forename: A B P
authors.initials: AB
authors.lastname: Lever