Influence of different solvents on structures and electronic properties of new Fe2S2 complexes containing bis(2-diphenylphosphinophenyl)ether

Abstract

In order to observe solvent effects on structures and properties of [FeFe]-hydrogenase, two Fe2S2 complexes, [Fe2(μ-pdt)(CO)4(DPEphos)] • CH2Cl2 (1) and [Fe2(μ-pdt)(CO)4 (DPEphos)] •[Fe2 (μ-pdt)(CO)4 (DPEphos)] (2) (DPEphos =bis(2-diphenyl phosphinophenyl)ether), have been prepared and characterized by IR, 1H NMR, 31P NMR, TG and X-ray crystal structure analysis. Structural analysis shows that the [Fe2(μ-pdt)(CO)4(DPEphos)] unit in 1 and 2 includes a butterfly Fe2S2 core, in which each iron atom is five-coordinated with a pseudo-square pyramidal geometry, and the change of the crystallization solvent from CH2Cl2 to toluene leads to the variation of crystallographic system, space group and the weak interactions. DFT studies indicate that the component of the HOMOs and LUMOs at different solvents for [Fe2(μ-pdt)(CO)4(DPEphos)] are nearly identical, which are primarily composed of CO, μ-pdt, Fe atoms and -Ph2P groups, coinciding with the change of DOS and PDOS at different solvents. Meanwhile, the HOMO and LUMO energies, HOMO → LUMO energy gap and Mülliken atomic charges at methanol, ethanol, dichloromethane and nitrobenzene are only a little change, which have much more changes than the relevant values at solvent-free model. All these show that the solvent has an important influence on structures and electronic properties of Fe2S2 complexes.