Construction and Reactivity of Benzimidazole-Modified Thiolate-Bridged Diiron Complexes with Different Electronic Structures

Abstract

Thiolate-bridged diiron complexes have drawn extensive attention due to their wide applications in the biomimetic simulation for the structure and function of various metalloenzymes and the related bioinspired catalysis. Through the introduction of the functional subunit into the bridging thiolate ligands, the resulting thiolate-bridged diiron complexes with different geometric and electronic structures can exhibit distinct reactivity. Herein, we utilize a half-sandwich type of mononuclear iron complex as the reaction precursor to construct two novel thiolate-bridged diiron complexes featuring the benzimidazole moiety through the oxidative dimerization strategy. X-ray diffraction analysis reveals the two thiolate ligands containing the benzimidazole group in a syn arrangement bridge the two iron centers through the sulfur and nitrogen atoms. Furthermore, Mössbauer spectroscopy and computational studies suggest two complexes both possess two low-spin Fe^III ions, but adopt different magnetic couplings to give different electronic structures. Notably, difference in geometric and electronic structures between two complexes results in the distinct reactivity toward the azide species.