Diiron(III) and polymeric iron(III)–sodium complexes with bridging and terminal pyridonate ligands: structures and magnetic properties

Abstract

The reaction of anhydrous iron(III) chloride or [NEt₄]₂[Fe₂Cl₆O] with equimolar quantities of 6-chloro-2-pyridone (Hchp) and NaOMe in MeOH afforded, after recrystallisation from tetrahydrofuran (thf), the one-dimensional polymer [{Fe(µ-chp)₆Na₃(µ-MeOH)₆·2thf}_n]1. When the reaction of FeCl₃ with NaOMe and Hchp was performed in the presence of 4,4′-dimethyl-2,2′-bipyridine (dmbipy) or 1,10-phenanthroline (phen) the dinuclear complexes [Fe₂(µ-OMe)₂(chp)₄(dmbipy)₂]·2MeOH 2 or [Fe₂(µ-OMe)₂(chp)₄(phen)₂]·2MeOH 3 resulted. The molecular structures at 150 K and magnetic properties between 1.8 and 280 K of 1–3 have been investigated. Complex 1 displays magnetic behaviour consistent with a paramagnet while 2 and 3 exhibit antiferromagnetic exchange interactions between the spins of the iron(III) ions through OMe bridges (J=–26.8 to –28.6 cm^–1).