DFT study of metastable linkage isomers of six-coordinate ruthenium nitrosyl complexes

Abstract

Abstract The linkage isomers of the [M(NO)(CN)5]2− (M = Fe, Ru, Os), [Ru(NO)Cl5]2−, trans-[Ru(NO)(NH3)4(L)]q+ (L = NH3, H2O, nicotinamide, imidazole, pyridine, pyrazine, NO2 −, OH−, Cl−), and trans-[Ru(NO)L4(OH)]q (L = pyridine, NO2 −) ions are studied by density functional theory. DFT calculations show that the electronic ground-state potential surface of these nitrosyl complexes has the local minima corresponding to η 2-NO and η 1-O linkage isomers, of which the former is characterized by lower energy. The stationary points on the ground state potential energy surface along the GS → MS2 → MS1 path for the [M(NO)(CN)5]2− (M = Fe, Ru, Os) and [Ru(NO)Cl5]2− complexes were found. The calculations of infrared spectra of linkage isomers [Ru(NO)Cl5]2− and [Ru(NO)(CN)5]2− are carried out. The analysis of quantum chemical bond orders indicates a noticeable delocalization of π-electron density along the Ltrans—M—NO axis and a possibility of direct interactions between NO and equatorial ligands in the structures with the bent {MNO} group.