A unique tetranuclear Mn(II) cluster bridged by carboxyl substituted nitronyl nitroxide radical: Crystal structure and magnetic properties

One unique radical-bridged Mn(II) cluster [Mn4(hfac)6(NIToBA)2(HIMoBAH)(H2O)3] (1) (hfac = hexafluoroacetylacetonate, NIToBAH = 2-(2-carboxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-oxide, HIMoBAH = 2-(2-carboxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-hydroxy) has been synthesized and structurally and magnetically characterized. The core of complex 1 features four Mn(II) ions bridged by three carboxyl groups and two nitroxide groups to form a crown-like ring structure. This complex exhibits strong antiferromagnetic interaction because the NO groups are directly coordinated to the metal ions.