Alkylamine-Templated Niccolite Frameworks of [Ga III M II (HCOO) 6 ] - (M = Fe, Ni): Structure, Magnetism, and Dielectricity.

The five heterometallic formate frameworks [EtA][GaIII FeII (HCOO)6 ] (1; EtA = CH3 CH2 NH3 + ), [DMA][GaIII FeII (HCOO)6 ] (2; DMA = (CH3 )2 NH2 + ), [DEtA][GaIII FeII (HCOO)6 ] (3; DEtA = (CH3 CH2 )2 NH2 + ), [MA][GaIII NiII (HCOO)6 ] (4; MA = CH3 NH3 + ), and [DMA][GaIII NiII (HCOO)6 ] (5) were synthesized through solvothermal methods. Complexes 1-5 are isotructural, and all crystallize in the trigonal P3̅1 c space group. Each metal center is 6-connected, with each HCOO- bridging ligand in an anti-anti mode to build a three-dimensional niccolite-like architecture. All of the complexes exhibit weak ferromagnetism at low temperature. A variable-temperature (VT) dielectric study indicates that the dielectric anomaly is induced by the freezing of motions from the protonated amines during the freezing process.