Molecular association and solvent effects in the electronic and NMR spectra of the tricyanoterpyridineruthenate(II) complex

摘要

Solvent effects on the electronic structure and NMR spectra of the [Ru(terpy)(CN)(3)](-) complex (terpy = 2,2':6',2"-terpyridine) have been investigated and interpreted using quantum mechanical semiempirical methods. A systematic splitting of the electronic bands in the visible is observed, in addition to their bathochromic shifts depending on the acceptor number of the solvent. The solvent-induced splittings are rationalized in terms of the involvement of several charge-transfer transitions exhibiting distinct participation of the ruthenium (II), terpy, and CN- orbitals. Direct evidence of solvent interaction at the cyanide ligands is observed in the [C-13]NMR spectra. The most enhanced solvent effects are at the middle C-13-4' and H-1-4' atoms of terpy, in complete agreement with the theoretical calculations. In D2O, stacking interactions involving the terpy ligands are detected from the [H-1]NMR spectra, leading to a bimolecular association constant of 90 mol(-1)-dm(3). In acetone-D2O mixed solvents, the spectroscopic changes are indicative of preferential solvation departing from the ideal linear behavior. [References: 43]