Thio ligand binding in dinitrosyl iron-sulfur complexes: Quantitative structure–activity relationships

Abstract

Energies of the Fe–S coordination bonds D298Fe-S in dinitrosyl iron-sulfur complexes [Fe+(NO)2L2] (DNICs) have been determined from the DFT calculations at the TPSSH/def2-TZVP level of theory and implicit water model. The thio ligand (L) abstraction and exchange for H2O molecule were considered for 26 thiocarbonyl and thiolate DNICs. Quantitative structure–activity relationships have been examined between D298Fe-S and the reactivity indices (RI) of free L. The Fe–S bond energies and the energies of hydrolysis in DNICs linearly correlate with the partial electronic charge on S and properties derived from the energies of frontier MOs in L. Two-parameter linear regression models based on RI of only a free L were built to evaluate stability of DNICs in hydrolysis of L or substitution for other thio ligands. In particular, the predicted D298Fe-S of glutathione in DNIC qualitatively agree with the known experimental data on iron-sulfur-nitrosyl complexes.