High-spin metal–cyanide clusters: species incorporating [Mn(salen)] + complexes as a source of anisotropy

Abstract

The use of N, N′-ethylenebis(salycylideneiminato) (salen) complexes of Mn III in assembling high-spin metal–cyanide coordination clusters with significant magnetic anisotropy is demonstrated. The reaction of [Mn(salen)(H 2O) 2] +with [Cr(CN) 6] 3− in aqueous solution generates {Cr[CNMn(salen)(H 2O)] 6}[Cr(CN) 6]·6H 2O ( 1), a previously reported compound featuring a heptanuclear cluster with a distorted octahedral geometry. A fit to the variable-temperature magnetic susceptibility data for 1 revealed the presence of weak antiferromagnetic coupling of J=−2.5 cm −1 within the cluster, giving rise to an S=21/2 ground state. In addition, variable-field magnetization data collected at low temperatures revealed the presence of magnetic anisotropy in the ground state, with the best fit yielding zero-field splitting parameters of D=+0.19 cm −1 and |E|=0.036 cm −1. A reaction intended to produce a direct analogue of 1 by employing [Fe(CN) 6] 3− in place of [Cr(CN) 6] 3− instead gave an unusually complex compound of formula {Fe(CN) 4[CNMn(salen)(MeOH)] 2}{[Mn(salen)(H 2O)] 2}[Mn(salen)(H 2O)(MeOH)] 2[Fe(CN) 6]·4H 2O ( 2). The crystal structure and magnetic properties of this compound are reported.