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

The use of N,N'-ethylenebis(salycylideiminato) (salen) complexes of Mn-III in assembling high-spin metal-cyanide coordination clusters with significant magnetic anisotropy is demonstrated. The reaction of [Mn(salen)(H2O)(2)](+) with [Cr(CN)(6)](3-) in aqueous solution generates {Cr[CNMn(salen)(H2O)](6)} [Cr(CN)(6)].6H(2)O (1), a previously reported compound featuring a heptanuclear cluster with a distorted octahedral geometry. A fit to the variable-temperature magnetic susceptibility data for I 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)(H2O)](2)} [Mn(salen)(H2O)(MeOH)](2)[Fe(CN)(6)].4H(2)O (2). The crystal structure and magnetic properties of this compound are reported. (C) 2003 Elsevier Ltd. All rights reserved.