1D to 3D Heterobimetallic Complexes Tuned by Cyanide Precursors: Synthesis, Crystal Structures, and Magnetic Properties

Five new heterobimetallic complexes, namely, {[Ni­(L)]­[Fe­(bpb)­(CN)₂]}­ClO₄ (L = 2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]­heptadeca-1(17),13,15-triene, bpb^2– = 1,2-bis­(pyridine-2-carboxamido)­benzenate) (<b>1</b>), {[Ni­(L)]₃[M­(CN)₆]₂}·7H₂O (M = Fe (<b>2</b>), Cr (<b>3</b>)), {[Ni­(L)]₂[Mo­(CN)₈]}·CH₃CN·13H₂O (<b>4</b>), and {[Ni­(L)]₂[W­(CN)₈]}·16H₂O (<b>5</b>), were assembled from the polyaza macrocycle nickel­(II) compound and five cyanidometalate precursors containing different numbers of cyanide groups. Single-crystal X-ray diffraction analysis reveals their different structure ranging from a cyanide-bridged cationic polymeric single chain for <b>1</b>, a two-dimensional network for <b>2</b> and <b>3</b>, and a three-dimensional network for <b>4</b> and <b>5</b>. In addition, a systematic investigation over the magnetic properties of <b>1</b>–<b>3</b> indicates the ferromagnetic magnetic coupling between neighboring Fe­(III)/Cr­(III) and Ni­(II) ions through the bridging cyanide group. For complex <b>1</b>, the magnetic susceptibility has been simulated by the Seiden model using the Hamiltonian <i>H</i> = <i>–J</i>∑_<i>i=</i>0^<i>N</i><i>S</i>_<i>i</i><i>S</i>_<i>i+</i>1, leading to the magnetic coupling constant of <i>J</i> = 3.67 cm^–1. The two-dimensional magnetic complexes exhibit three-dimensional magnetic ordering behavior with a magnetic phase transition temperature of <i>T</i>_C = 4.0 K for <b>2</b> and <i>T</i>_N = 6.0 K for <b>3</b>, respectively