Three Cyanide-Bridged Fe II-M II (M = Fe, Co and Mn) Complexes : Synthesis, Crystal Structures and Magnetic Properties

Three dinuclear cyanide-bridged complexes Fe II (PY 5 OMe 2 )CNM II (PY 5 OMe 2 )[OTf] 3 (M = Fe 1 , Co 2 , Mn 3 ; PY 5 OMe 2 = 2,6-bis-((2-pyridyl)methoxymethane)pyridine OTf = CF 3 SO 3- ) have been synthesized and characterized. Single-crystal diffraction analyses show these three dinuclear compounds are very similar in structure. And the M-N (M = Fe, Co and Mn) bond lengths for complexes 1 - 3 indicate that 2 and 3 are typical of a high spin (HS) complexes and 1 is evident a low spin (LS) Fe (II) complex at room temperature, confirmed by the temperature dependence of magnetic susceptibilities of complexes 1-3 . The different magnetic behaviors of complexes 1 - 3 reveal that in the three complexes all the cyanide-carbon coordinated Fe (II) are low-spin, and Co (II) for 2 and Mn (II) for 3 are both in a high-spin state through 2-400 K but the cyanide-nitrogen coordinated Fe (II) for complex 1 begins to occur a spin crossover (SCO) transition from 300 K