Synthesis, structure, and magnetic properties of cyanide-bridged low-dimensional heterometallic Fe(III)-Mn(II) complexes.

With trans-dicyanideiron(III) precursor K[Fe(salen)(CN)(2)] x CH(3)OH (1) (H(2)salen = N,N'-bis(salicyl)ethylenediamine) as a building block, four new cyanide-bridged heterometallic Fe(III)-Mn(II) complexes {Fe(salen)(CN)(2)[Mn(bipy)(2)]} x CH(3)OH x 2 H(2)O (2), {Fe(salen)(CN)(2)[Mn(phen)(2)]} x CH(3)OH (3), and {[Fe(salen)(CN)(2)][Mn(L)]}ClO(4) x CH(3)OH [L = L(a) (4) and L(b) (5)] have been successfully assembled. Single X-ray diffraction analyses reveals the trinuclear Fe(III)(2)Mn(II) nature of complexes 2 and 3 comprised of one Mn(bipy)(2)/Mn(phen)(2) and two Fe(salen)(CN)(2) units, and the one-dimensional cyanide-bridged cationic polymeric single chain nature of complexes 4 and 5 consisting of alternating units of Mn(L) (L = L(a) and L(b)) and Fe(salen)(CN)(2) with free ClO(4)(-) as balanced anions. Investigations into the magnetic properties of these four heterometallic cyanide-bridged Fe(III)-Mn(II) complexes reveals the overall antiferromagnetic interaction between neighbouring Fe(III) and Mn(II) ions through the bridging cyanide group. On the basis of the Hamiltonian H = -2JS(Mn)(S(Fe(1)) + S(Fe(2))), the magnetic simulation for the trimeric complexes 2 and 3 gives the magnetic coupling constant 2J(MnFe) = -2.68(4) cm(-1) for 2 and 2J(MnFe) = -2.46(8) cm(-1) for 3, respectively. A best-fit to the magnetic susceptibilities of 4 and 5 based on the one-dimensional alternating chain model leads to the magnetic coupling constants 2J(1) = -6.50(2) and 2J(2) = -1.57(1) cm(-1) for 4 and 2J(1) = -5.35(2) and 2J(2) = -0.93(1) cm(-1) for 5.