Three Cyanide-Bridged One-Dimensional Single Chain CoIII-MnII Complexes: Rational Design, Synthesis, Crystal Structures and Magnetic Properties

摘要

Two pyridinecarboxamide dicyanidecobalt(III) building blocks and two mononuclear seven-coordinated macrocycle manganese(II) compounds have been rationally selected to assemble cyanide-bridged heterobimetallic complexes, resulting in three cyanide-bridged CoIII-MnII complexes. Single X-ray diffraction analysis show that these complexes {[Mn(L1)][Co(bpb)]}ClO4·CH3OH·0.5H2O (1), {[Mn(L2)][Co(bpb)]}ClO4·0.5CH3OH (2) and {[Mn(L1)][Cobpmb]}ClO4·H2O (3) (L1 = 3,6-diazaoctane-1,8-diamine, L2 = 3,6-dioxaoctano-1,8- diamine; bpb2− = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb2− = 1,2-bis(pyridine-2-carboxamido)-4- methyl-benzenate) all present predictable one-dimensional single chain structures. The molecular structures of these one-dimensional complexes consists of alternating units of [Mn(L)]2+ (L = L1 or L2) and [Co(L`)(CN)2]− (L` = bpb2−, or bpmb2−), forming a cyanide-bridged cationic polymeric chain with free ClO4 - as the balance anion. The coordination geometry of manganese(II) ion in the three one-dimensional complexes is a slightly distorted pentagonal-bipyrimidal with two cyanide nitrogen atoms at the trans positions and N5 or N3O2 coordinating mode at the equatorial plane from ligand L1 or L2. Investigation over magnetic properties of these complexes reveals that the very weak magnetic coupling between neighboring Mn(II) ions connected by the diamagnetic dicyanidecobalt(III) building block. A best-fit to the magnetic susceptibility of complex 1 leads to the magnetic coupling constants J = −0.084(3) cm−1.