A cyano-bridged bimetallic ferrimagnet: Synthesis, X-ray structure and magnetic study

Mixing of trans-[Mn(cyclam)Cl-2]Cl (cyclam = 1,4,8,11-tetraazacyclotetradecane) and potassium hexacyanochromate (K-3[Cr(CN)(6)]) aqueous solutions instantaneously yields a 1D infinite chain complex {[Mn(cyclam)(mu-CN)(2)Cr(CN)(4)].H2O}(n) (1). The crystal structure of 1, crystallizing in the monoclinic system with space group P2(1)/n has been solved from X-ray powder diffraction data following direct space approach and refined by the Rietveld method. The structure analysis of 1 reveals alternating [Cr(CN)(6)](3-) and [Mn(cyclam)](3+) ions generating one-dimensional polymeric (-Cr-CN-Mn-NC-)(n) chain propagating along the [0 0 1] direction. The coordination environment of both the metal ions, Mn(III) and Cr(III), is octahedral. While a notable distortion in the coordination environment around Mn(III) centers was observed in complex 1, Cr(III) centers have suffered no such distortion. A ferrimagnetic interaction between the heterobimetallic centers was evidenced through variable temperature magnetic susceptibility measurements. The AC susceptibility measurement reveals that the compound 1 undergoes spontaneous ferrimagnetic ordering. Ferrimagnetic ordering has been rarely observed among the cyanobridged compounds in the previous studies. (C) 2010 Elsevier Ltd. All rights reserved.