| Abstract
| - M[TCNQ]y (M = Mn, Fe, Co, Ni; TCNQ = 7,7,8,8-tetracyano-p-quinodimethane)molecule-based magnets have been synthesized via Ma(CO)b and [M(NCMe)6][SbF6]2. Tc's range between 8 K [M = Ni from Ni(CO)4] and 60 K {M = Mn from [Mn(NCMe)6][SbF6]2}. The synthetic route has a significant effect on the magnetic properties of the materials for a given metal. Enhanced Tc's are observed when less coordinating anions are used.
- 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 beensynthesized from both Ma(CO)b and [M(NCMe)6][SbF6]2 starting materials, complementing previous studiesutilizing [M(NCMe)6][BF4]2. Magnetic ordering was observed for all materials with Tc values between8 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. Withthe exception of M = Ni, the lowest Tc's are obtained from the [M(NCMe)6][BF4]2 route, which waspreviously reported. The materials from [M(NCMe)6][SbF6]2 also exhibit the highest coercivity, followedby those from [M(NCMe)6][BF4]2. With the exception of M = Fe, the materials from Ma(CO)b exhibitthe lowest coercive fields. In general, magnets made from [M(NCMe)6][SbF6]2 have a reduced χ‘ ‘(T)frequency dependence with respect to materials from [M(NCMe)6][BF4]2; thus, they exhibit less glassymagnetic behavior. Elemental analysis data indicate that small amounts of counterions and solvent arepresent in the products of these reactions, but less than better-coordinating [BF4]-. Thus, the syntheticroute has a significant effect on the magnetic properties of the materials, and enhanced Tc's are observedwhen less-coordinating anions are used. Although the structures of the materials are not known, it isproposed that the S = 1/2 [TCNQ]•- sp-hybridized Ns bond to multiple metal ions, thereby facilitatingmagnetic coupling and ordering.
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