Syntheses, Structures, and Magnetic Properties of Three Cyano-Bridged Fe II -Mo III Single-Molecule Magnets.

Three new cyano-bridged Fe-Mo complexes assembled from the [Mo(CN)] unit, Fe ions, and three pentadentate NO ligands, namely {[FeH(dapab)][Mo(CN)]}·2HO·3.5MeCN (), [Fe(Hdapb)(HO)][Fe(Hdapb)(HO)][Mo(CN)]·4HO·3MeCN (), and [Fe(Hdapba)(HO)][Mo(CN)]·6HO () (Hdapab = 2,6-diacetylpyridine bis(2-aminobenzoylhydrazone), Hdapb = 2,6-diacetylpyridine bis(benzoylhydrazone), Hdapba = 2,6-diacetylpyridine bis(4-aminobenzoylhydrazone)), have been synthesized and characterized. Single-crystal structure analyses suggest that complex contains a one-dimensional (1D) chain structure where two Fe ions are bridged by the in situ generated [Mo(CN)] unit through two -cyanide groups into trinuclear FeMo clusters that are further linked by the amino of the ligand into an infinite chain. Complexes and are cyano-bridged FeMo trinuclear clusters with two Fe ions connected by the [Mo(CN)] and [Mo(CN)] units, respectively. Direct current magnetic studies confirmed the ferromagnetic interactions between the cyano-bridged Fe and Mo centers and significant easy-axis magnetic anisotropy for all three complexes. Furthermore, complexes exhibit slow magnetic relaxation under a zero dc field, with relaxation barriers of 42.3, 21.6, and 14.4 K, respectively, making them the first examples of cyano-bridged Fe-Mo single-molecule magnets.