Theoretical and Experimental Studies of diruthenium tetracarboxylates strcture, spectroscopy and electrochemistry

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

INORGANIC CHEMISTRY

American Chemical Society

Año: 2008 vol. 47 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(m-O2CCH3)4]0/+ and [Ru2(m-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: trends in the UV/vis spectroscopy and electrochemistry along the [Ru2(m-O2CCH3)4X2]- (X= Cl-, Br-, I-) series, and the crystalline polymorphism related to the polymeric strand conformation in extended Ru2(m-O2CR)4Cl compounds. For the [Ru2(m-O2CCH3)4X2]- series, we report new spectroscopic and electrochemical results and interpret the trends on the basis of TDDFT-PCM (time dependent DFT-polarized continuum model), local charge and spin analysis and X’s 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(m-O2CCH3)4Cl]2Cl- and [Ru2(m-O2CCH3)4Cl]3Cl- oligomers provide insights on the influence of the two first factors on the strand conformation, and allows a suggestion on what is the equatorial aliphatic chain’s influence on this issue.