Theoretical and experimental studies of diruthenium tetracarboxylates structure, spectroscopy and electrochemistry

MARIA ANA CASTRO; ADRIAN E. ROITBERG; FABIO D. CUKIERNIK

INORGANIC CHEMISTRY

American Chemical Society

Año: 2008 p. 4682 - 4690

0020-1669

Quantum mechanical calculations at the density functional theory (DFT) level have been performed on diruthenium tetracarboxylates of different levels of molecular complexity: from unsolvated monomers to oligomers. The agreement between the calculated and experimental molecular structures and vibrational modes of the simple [Ru2(µ-O2CCH3)4]0/+ and [Ru2(µ-O2CCH3)4(H2O)2]0/+ systems made us confident in our calculation methodology. Therefore, it has been applied to the analysis of two different kinds of properties of these compounds: the trends in the UV/vis spectroscopy and electrochemistry along the [Ru2(µ-O2CCH3)4X2]- (X = Cl-, Br-, I-) series, and the crystalline polymorphism related to the polymeric strand conformation in extended Ru2(µ-O2CR)4Cl compounds. For the [Ru2(µ-O2CCH3)4X2]- series, we report new spectroscopic and electrochemical results and interpret the trends on the basis of time dependent DFT-polarized continuum model calculations, local charge and spin analysis, and X donor properties. As far as the polymeric conformation is concerned, it has been previously suggested that the Ru-Cl-Ru angle results from a compromise between packing, orbital overlap, and microsegregation. Our calculations on [Ru2(µ-O2CCH3)4Cl]2Cl- and [Ru2(µ-O2CCH3)4Cl]3Cl- oligomers provide insights on the influence of the first two factors on the strand conformation and allows a suggestion on what is the equatorial aliphatic chains influence on this issue.