A Mössbauer investigation of the interaction of (Phthalocyaninato)iron(II) with molecular oxygen. Evidence for only one form of (μ-Oxo)bis phthalocyaninato)iron(III) is found

Magnetic and Spectroscopic Investigations of Tetra-(4-t-butyl)phthalocyano Complexes of μ-Oxo-bridged Iron(II) Dimer

The tetra(4-t-butyl)phthalocyanine derivative of the μ-oxo dimer of Fe was studied by ESR and Mössbauer spectroscopic and magnetic susceptibility methods. The Mössbauer spectrum of the iron complex shows ΔEQ= 1.34 mm s-1and δ = 0.14 mm s-1. The susceptibility data measured as a function of temperature fit the S1= S2= 1 dimer with J = -5.2 cm-1and thus the oxidation state of iron is suggested as +2. The weak exchange coupling is attributed to the presence of the bulky t-butyl groups on phthalocyanine. It is proposed that the two phthalocyanine moieties are not superimposable on one another owing to the steric hindrance posed by the t-butyl groups of Pct. This is likely to lead to a rotation of one of the FePctmoieties about the Fe - O - Fe axis as well as an increase in Fe - O distance.