Ligand field analysis of nitrosylruthenium complexes with octahedral geometry

Kaneko, Masashi   ; Kato, Akane* ; Nakashima, Satoru*; Kitatsuji, Yoshihiro  ; Watanabe, Masayuki   

Ruthenium exists as ruthenium nitrosyls, [Ru(NO)], in high-level radioactive liquid waste and shows various stabilities depending on concentrations of nitrate and hydroxide ions. The detailed stabilities, however, remain to be unclear. As the first step to understand the stabilities of ruthenium nitrosyls, the present study focuses on the structural and bonding properties of the nitrosylruthenium species with fundamental ligands, such as chloride ion and ammonia. We modeled the ruthenium species by referring the corresponding single crystal structures and calculated the stable geometries under aqueous condition. The result reproduced the ruthenium-ligand bond lengths and the stretching vibrational energies of nitrosyl group. We also estimated Ru Mssbauer isomer shifts based on electron density analysis and succeeded in reproducing the ismoer shifts. In the presentation, we will indicate the correlation between the isomer shifts and ligand field splitting derived by molecular orbital analysis and discuss an origin of the stability of ruthenium nitrosyls.