Rational design of cyanide-bridged heterometallic M(I)-Mn(II) (M = Ag, Au) one-dimensional chain complexes: synthesis, crystal structures and magnetic properties

Two mononuclear seven-coordinated macrocycle Mn(II) compounds and four new cyanide-bridged M-I-Mn-II (M = Ag, Au) one-dimensional chain complexes have been synthesized and crystallographically characterized: [Mn(L-1)Cl-2] center dot H2O (1), [Mn(L-2)Cl-2]center dot H2O (2), [Ag(CN)(2)Mn(L-1)][Ag(CN)(2)] (3), [Ag(CN)(2)Mn(L-2)][Ag(CN)(2)] center dot 1.5H(2)O (4), [Au(CN)(2)Mn(L-1)][Au(CN)(2)] (5) and [Au(CN)(2)Mn(L-2)][Au(CN)(2)] center dot 1.5H(2)O (6). The structure of the one-dimensional complexes consists of alternating units of [Mn(L)](2+) and [M(CN)(2)](-), generating a cyanide-bridged cationic polymeric chain with [M(CN)(2)](-) as the counteranion. In all complexes, the coordination geometry of manganese ion is a slightly distorted pentagonal-bipyrimidal with the cyanide nitrogen atoms at the trans positions and N-5 or N3O2 coordinating mode in the equatorial plane from ligand L-1 or L-2. Investigation over magnetic properties of these four one-dimensional complexes reveals the whole very weak antiferromagnetic interaction between neighbouring Mn(II) ions bridged by the long NC-M-CN unit. A best-fit to the magnetic susceptibility of these complexes leads to the magnetic coupling constant of J = -0.065(2), -0.23(3), -0.15(6) and -0.13(5) cm(-1) for complex 3, 4, 5, and 6, respectively.