A diferric complex from metal-assisted methanolysis of di-2,6-(2-pyridylcarbonyl)-pyridine: Structural, magnetic and spectroscopic (Mössbauer, EPR) studies

Abstract

Complex [Fe 2{pyCO(OMe)pyCO(OMe)py} 2(MeO) 2](ClO 4) 2·MeOH ( 1·MeOH) is prepared by reaction of iron(III) perchlorate and dpcp in MeOH at ambient temperature. It crystallizes in the triclinic P 1 ¯ space group and it consists of two centrosymmetric dinuclear crystallographically independent molecules. The dpcp ligand is in its bis-hemiacetal form; both its hydroxyl functions are deprotonated whereas its central pyridine is protonated. Variable-temperature magnetic susceptibility measurements revealed a weak intramolecular antiferromagnetic coupling ( J = −15.6 cm −1; H ˆ = - 2 J S ˆ 1 S ˆ 2 ). Mössbauer spectroscopy showed an asymmetric quadrupole-split doublet, the asymmetry of which was assigned to the anisotropy of the excited states of 1, thermally populated at higher temperatures.