Magnetic and spectroscopic investigations of tetra(4-t-butyl)phthalocyano complexes of mu-oxo-bridged iron(II) dimer

The tetra(4-t-butyl)phthalocyanine derivative of the mu-oxo dimer of Fe was studied by ESR and Mossbauer spectroscopic and magnetic susceptibility met hods. The Mossbauer spectrum of the iron complex shows Delta E-Q = 1.34 mm s(-1) and delta = 0.14 mm s(-1). The susceptibility data measured as a func tion of temperature fit the S-1 = S-2 = 1 dimer with J = -5.2 cm(-1) and th us the oxidation state of iron is suggested as +2. The weak exchange coupli ng is attributed to the presence of the bulky t-butyl groups on phthalocyan ine. It is proposed that the two phthalocyanine moieties are not superimpos able on one another owing to the steric hindrance posed by the t-butyl grou ps of Pc-t. This is likely to lead to a rotation of one of the FePct moieti es about the Fe-O-Fe axis as well as an increase in Fe-O distance. (C) 1998 John Wiley & Sons, Ltd.