Reductive nitrosylation of Iron(III) complexes of tetradentate ligands

Abstract

Two iron (III) complexes, 1 and 2 with L1 and L2, [ L1 = N,N′-bis(2- hydroxybenzyl) - 1, 2- diaminobenzene; L2 = N, N′- bis(2- hydroxybenzyl) ethylenediamine], respectively, were synthesized and characterized. In methanol solution of the complexes, the Fe(III) centre was found to reduce in presence of NO gas. The formation of [FeIII-NO] intermediate prior to the reduction of Fe(III) center was evidenced by UV-visible, solution FT-IR, X-band EPR studies. The presence of excess NO gas leads to the reductive nitrosylation of the complexes leading to the formation of corresponding Fe(II)-nitrosyl complexes, 3 and 4, respectively. The Fe(II)-nitrosyls were isolated as solid and characterized spectroscopically. Density Functional Theory (DFT) calculations were performed to optimize the structures of all the complexes. All the complexes are fully optimized using PBE functional and DNP basis set in the presence of methanol solvent. The Conductor-like Screening Model (COSMO) as incorporated into the DMol (Maron et al., 2013) [3] program with dielectric constant of 37.5 is adopted to study the solvent effect.