Manganese(II)-octacyanometallate(V) bimetallic ferrimagnets with T(c) from 41 to 53 K obtained in acidic media.

A series of three-dimensional (3D) octacyanometallate-based bimetallic magnets, {[Mn(H(2)O)][Mn(0.75)(HCOO)(0.5)(H(2)O)(0.5)][W(CN)(8)] x H(2)O}(4n) (1), {[Mn(2)(HCOO)(HCOOH)][M(CN)(8)] x H(2)O}(n) (M = W (2) and Mo (3)), and {[Mn(2)(HCOO)(HCOOH)][W(CN)(8)] x CH(3)OH}(n) (M = W (4) and Mo (5)), were synthesized by the reaction of octacyanometallates A(3)[M(CN)(8)] x nH(2)O (A = Na, Cs, and (C(4)H(9))(3)NH; M = W and Mo; and n = 2 or 4) with manganese salt (Mn(CH(3)COO)(2) x 4 H(2)O, Mn(ClO(4))(2) x 6 H(2)O, and MnCl(2) x 4 H(2)O) in aqueous or methanolic solution containing formic acid. All complexes crystallize in the tetragonal or orthorhombic system. Complex 1 shows an unexpected 3D network structure by connections of manganese ions and octacyanotangstate-manganese double layers via cyanide bridges, while other complexes have typical structure constructions similar to the reported complexes {MnL[M(CN)(8)]}(n) (L = CH(3)COO(-), Cl(-), and H(2)O), which the CN group of [W(V)(CN)(8)] coordinates to eight Mn(II) ions forming a -[W(CN)(8)]-Mn(4)-[W(CN)(8)]-Mn(4)- columnar chain, and then all chains share Mn(II) ions as the nodes interlocking with each other to form the 3D networks. Magnetic studies indicate that the cyanide group mediates the antiferromagnetic coupling between octacyanometallates and manganese ions in all complexes, and the ferrimagnetic phase transition temperatures are 53, 52, 42, 49, and 41 K for 1-5, respectively.