The molecular structures and magnetic properties of μ 3-tetranuclear β-diketonate copper complexes [Cu(bzac)(μ 3-OC 2H 4OCH 3)] 4 and [Cu(μ-dbm)(μ 3-OC 2H 4OCH 3)] 4

Abstract

[Cu(bzac)(OC 2H 4OCH 3)] 4 1 1 Ligand abbrevations used for β-diketonate anions are as follows: bzac = benzoylacetonato(1-phenyl-1,3-butanedionato); tfac = 1,1,1-trifluoroacetylacetonato (1,1,1-trifluoro-2,4-pentanedionato); hfac = 1,1,1-5,5,5-hexafluoroacetylacetonato(1,1,1-5,5,5-hexafluoro-2,4-pentanedionato); acac = acetylacetonato(2,4-pentanedionato); pvac = dipivaloylacetonato(2,2,6,6-tetramethyl-3,5-heptanedionato); and dbm = dibenzoylmethanato (1,4-diphenyl-1,3-propanedionato). ( I) and [Cu(dbm)(OC 2H 4OCH 3] 4 1 ( II) have been shown to be tetrameric in the solid state. Compound I has a pseudo-cubane type structure with μ 3-alkoxide oxygens occupying four bridging positions. Two methoxy oxygens are also within bonding distance of copper(II) ions. Compound II has a stepped configuration with a chelate ring and alkoxide oxygens as bridging centres. None of the methoxy oxygens is clearly chelating. Magnetic susceptibility data versus temperature data to 4 K for the complexes show antiferromagnetic coupling which can be treated by “pairs of equal dimers” procedures. The complexes decompose in stages at temperatures below 350°C at atmospheric pressure to give CuO.