Influence of octacyanoniobate(IV)-bridging geometry on Tc in Mn2Nb ferrimagnets of identical 3D topology

A novel 3D cyano-bridged hybrid ferrimagnet {Mn2II(imH)2(H2O)4[NbIV(CN)8]}·4H2O1 (imH = imidazole) of Tc = 25 K is reported. Its 3D inorganic –Nb–CN–Mn– framework is built of two groups of mutually parallel 1D-ladders cross-linked at niobium centers. Imidazole molecules reveal terminal coordination mode only. We discuss structural features in the context of 3D –Nb–CN–Mn– framework of 1, comparing it with that of {Mn2II(pzdo)(H2O)4[NbIV(CN)8]}·5H2O2 ferrimagnet with Tc = 37 K reported by us [Inorg. Chem. 46 (2007) 10416]. The differences in Tc are explained in respect to the metric parameters and positions of bridging linkages at [Nb(CN)8]4− polyhedra. Comparison of infrared spectra of 1 and free imH is also provided.

Critical temperature Tc = 25 K of 3D cyano-bridged ferrimagnet {Mn2II(imH)2(H2O)4[Nb(CN)8]·4H2O}1 is correlated to the positions of Nb–CN–Mn linkages at [Nb(CN)8] node.Figure optionsDownload as PowerPoint slide