Cyanido-bridged dimetallic complexes derived from manganese(III) Schiff bases and pentacyanidonitrosylchromate(I): Synthesis, crystal structure and magnetic properties

Four cyanido-bridged Mn-III-Cr-I heterodimetallic complexes have been synthesized by the reactions of Mn-III Schiff-base complexes with the [Cr(CN)(5)(NO)](3-) building block. X-ray diffraction analysis reveals that [Mn(5-Cl-salen)(H2O)(2)]-[Mn-2(5-Cl-salen)(2)(H2O)(1.5)Cr(CN)(5)(NO)] (1) has a trinuclear structure, and [Mn-3(salen)(3)(H2O)(CH3CN)Cr(CN)(5)(NO)](.)0.5CH(3)CN(.)0.5MeOH(.)2H(2)O (2) and [Mn(5-Br-salen)(H2O)- (CH3OH)][Mn-2(5-Br-salen)(2)(CH3OH)Cr(CN)(5)(NO)](.)2H(2)O (3) have novel 1D chain topological structures, whereas [{Mn(saltmen)}(4)Cr(CN)(5)(NO)]ClO(4)(.)3H(2)O (4) displays a 2D layered network structure. Magnetic measurements show that the magnetic interaction between the Mn-III and Cr-I ions bridged by a cyanido group is antiferromagnetic for complexes 1-4. The magnetic fitting for the trinuclear complex 1 gives the magnetic coupling constant J = -10.4(1) cm(-1) and Y = -1.29(2) cm(-1) based on the isotropic Hamiltonian H = -2JS(Cr)[S-Mn(1) + S-Mn(2)] - 2J'SMn(1)SMn(2). Complex 2 exhibits 3D antiferromagnetic ordering (TN = 3.5 K) with a metamagnetic character below TN. Complex 3 exhibits an obvious frequency-dependent AC magnetic susceptibility below 4.0 K, which is due to the spin-glass behavior. The layered complex 4 displays 3D ferromagnetic ordering with T-c = 6.4 K due to the ferromagnetic interaction between the ferrimagnetic layers. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)