Single-Crystal-to-Single-Crystal Transformation in Unusual Three-Dimensional Manganese(II) Frameworks Exhibiting Unprecedented Topology and Homospin Ferrimagnet

A new three-dimensional MnII complex, [Mn3(HCO2)2(L)2(OCH3)2], 1 (L = nicotinate N-oxide), was synthesized by solvothermal reaction and magnetically characterized. Complex 1 exhibits an unprecedented 3,6-connected 5-nodal net topology with Schläfli notation {42;6}4{43}2{46;66;83;10}2{48;66;8} and was assigned as a homospin ferrimagnet. Interestingly, when 1 was placed in air for ca. one month, the methoxy anions in 1 were gradually exchanged by hydroxyl anions and 1 underwent a single-crystal-to-single-crystal structural transition to a new but similar complex, [Mn3(HCO2)2(L)2(OH)2]·4H2O, 2. The anion exchange and water molecules filling the channels of 2 affect the magnetic behavior at low temperature compared to that of 1.