Cyano-Bridged Mn^III₃M^III (M^III = Fe, Cr) Complexes:  Synthesis, Structure, and Magnetic Properties

Two cyano-bridged tetranuclear complexes composed of Mn(III) salen (salen = N,N‘-ethylene bis(salicylideneiminate)) and hexacyanometalate(III) (M = Fe, Cr) in a stoichiometry of 3:1 have been selectively synthesized using {NH₂(n-C₁₂H₂₅)₂}₃[M^III(CN)₆] (M^III = Fe, Cr) starting materials:  [{Mn(salen)(EtOH)}₃{M(CN)₆}] (M = Fe, 1; Cr, 2). Compounds 1 and 2 are isostructural with a T-shaped structure, in which [M(CN)₆]^3- assumes a meridional-tridentate building block to bind three [Mn(salen)(EtOH)]⁺ units. The strong frequency dependence and observation of hysteresis on the field dependence of the magnetization indicate that 1 is a single-molecule magnet.