Syntheses, crystal structures, electronic spectra and magnetic properties for new ion-pair complexes of [M(phen) ₃][Ni(mnt) ₂] (M ²⁺=Ni ²⁺,Fe ²⁺; phen=l,10-phenathroline, mnt ^2-=maleonitriledithiolate)

Two new bimetallic ion-pair compounds, [M(phen) ₃][Ni(mnt) ₂] (phen = 1,10-phenanthroline, mnt ^2-= maleonitriledithiolate; M=Ni ²⁺, 1; Fe ²⁺, 2), have been prepared and characterized structurally. Two ion-pair crystals, crystallizing in monoclinic space group P2 ₁/n, have quite similar cell parameters and packing structures, and two compounds do not show the absorption in the near-IR region. Compound 1 exhibits the Curie-Weiss-type paramagnetic behavior in the temperature range 2~400 K and the existence of weakly antiferromagnetic coupling between magnetic [Ni(phen) ₃] ²⁺ ions and the Ni ²⁺ ion in the octahedral coordination sphere has an S=1 ground state. While 2 displays the diamagnetic behavior above ~40 K with a weak Curie-Weiss type paramagnetic tail below 40 K, indicated the Fe ²⁺ center in the [Fe(phen) ₃] ²⁺ ion having a low-spin state. The weak paramagnetic behavior in the low-temperature region results from a trace amount of [Ni(mnt) ₂] ^- species. CCDC: 860552, 1; 860551, 2.