Studies of the [Cr(CN)5NO]3− and [Cr(NH3)5NO]2+ complex ions via density functional theory

Based on the density functional theory, the properties of the spin ground state of chromium-nitrosyl complex ions [Cr(CN)5NO]3− and [Cr(NH3)5NO]2+ are studied via B3LYP hybrid method. Their vibrational frequencies, atomic net charges, and spin densities are analyzed. The related complexes Cr(CN)6n- (n = 3, 4, and 5) and Cr(NH3)6m+ (m = 1, 2, and 3) are employed as reference compounds to determine the characteristics of the central chromium. Furthermore, the excitation energies are evaluated using the CIS method. Our calculated N-O stretching frequencies and excitation energies are in good agreement with the IR and UV-vis data. Results indicate that the effective Cr oxidation states for both ions are close to Cr(II) when compared with experimental data.