Reduction of (chloro)-μ-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)] with organic N-bases

Abstract

ABSTRACT:The interaction of (chloro)-m-nitrido-bis[(tetra-tert-butyl-phthalocyaninato)iron(IV)] Cl(FePc) 2 N with organic N-bases L as electron-donors (L = diethylamine, imidazole, 1-methylimidazole, 2-methylimidazole) with the formation of one-electron reduced species (L)PcFe III -N=Fe IV Pc(L) was investigated in benzene at 298 K by UV-visible spectroscopy. The reaction was established to be stepwise process including fast reversible axial binding of two substrate molecules onto iron cations followed by slow one-electron metal-centered reduction. The results of IR, ESI-MS and EPR study support the formation of final product with Fe +3 -N=Fe +4 unit and two substrate molecules in the first coordination sphere. The reaction kinetics was studied, the pre-equilibrium constants K eq and rate constants k were obtained. The K eq and k values were found to be linearly correlated with basicity of substrates pК a . The possibility of the transition Fe 4+ → Fe 3+ is promoted by electron-donor properties of substrate combined with the presence of both electron-rich macrocycle and p-backdonation Fe ← N Pc .