Low temperature ultraviolet photolysis of various glasses of the pentacyanonitrosylferrate(II) ion, [Fe(CN)5(NO)]2–

Abstract

Exposure of dilute solutions of [Fe(CN)₅(NO)]^2– ions to u. v. light at 77 K gave a range of paramagnetic products detected by e.s.r. spectroscopy. In aprotic solvents the major route involved electron transfer from solvent to give [Fe(CN)₅(NO)]^3–(I′) which, on annealing, gave [Fe(CN)₄(NO)]^2–(I)+ CN^–. Such a route cannot be invoked for aqueous systems and an alternative route involving photoionisation followed by electron capture to give [Fe(CN)₅(NO)]^3–(II) is suggested. Species (I′) and (I) have their unpaired electrons primarily in the 3d_z² ion orbital whereas for species (II) it is largely localised on the NO ligand. On annealing, species (II) also gave species (I) plus CN^–.