M[TCNQ]y-Based Magnets (M = Mn, Fe, Co, Ni; TCNQ = 7,7,8,8-tetracyano-p-quinodimethane)

Abstract

A family of molecule-based magnets of general formula M[TCNQ]y (M = Mn, Fe, Co, Ni; TCNQ = 7,7,8,8-tetracyano-p-quinodimethane) has been synthesized and characterized. The materials have been synthesized from both Ma(CO)b and [M(NCMe)6][SbF6]2 starting materials, complementing previous studies utilizing [M(NCMe)6][BF4]2. Magnetic ordering was observed for all materials with Tc values between 8 K [M = Ni from Ni(CO)4] and 60 K {M = Mn from [Mn(NCMe)6][SbF6]2}. The materials from [M(NCMe)6][SbF6]2 displayed the highest critical temperatures, followed by those from Ma(CO)b. With the exception of M = Ni, the lowest Tc's are obtained from the [M(NCMe)6][BF4]2 route, which was previously reported. The materials from [M(NCMe)6][SbF6]2 also exhibit the highest coercivity, followed by those from [M(NCMe)6][BF4]2. With the exception of M = Fe, the materials from Ma(CO)b exhibit the lowest coercive fields. In general, magnets made from [M(NCMe)6][SbF6]2 have a reduced χ‘ ‘(T) frequency dependence with respect to mat...