Quantum-Chemical Calculations of Ruthenium Nitrosyl Complexes with Tetradentate Macrocyclic Ligands

The geometric structure of the ground state and of metastable isomers of nitrosyl complexes trans-Ru(P)(NO)(Cl)] (P = porphinate dianion) and trans-Ru(NO)(salen)(X)]^q salen = N,N'-ethylenebis(salicylideniminate) dianion; X = Cl^- (q = 0), H₂O (q = +1)] was optimized within the framework of the density functional method (SVWN/LanL2DZ+6-31G). The local minima corresponding to metastable isomers with a linear NO coordination through the oxygen atom and with a side ² NO coordination were found on the potential energy surfaces of these compounds. The second metastable states of all the three complexes have a lower energy. The difference in energies between the stable and metastable isomers is the least in the case of the complex trans-Ru(NO)(salen)(Cl)].