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

Mixing of trans-[Mn(cyclam)Cl2]Cl (cyclam = 1,4,8,11-tetraazacyclotetradecane) and potassium hexacyanochromate (K3[Cr(CN)6]) aqueous solutions instantaneously yields a 1D infinite chain complex {[Mn(cyclam)(μ-CN)2Cr(CN)4]·H2O}n (1). The crystal structure of 1, crystallizing in the monoclinic system with space group P21/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 cyano-bridged compounds in the previous studies.

Graphical abstractCyano-bridged one-dimensional chain compound {[Mn(cyclam)(μ-CN)2Cr(CN)4]·H2O}n (1) has been synthesized and characterized structurally and magnetically. The structure of the compound has been successfully solved using laboratory X-ray powder diffraction data following the direct space global optimization technique. The low temperature magnetic study revealed that the compound 1 undergoes paramagnetic ⇄ ferrimagnetic transition with concomitant spontaneous ordering below 10 K.Figure optionsDownload full-size imageDownload as PowerPoint slide