Synthesis, crystal structures, and magnetic properties of three K[M(bpb)(CN)_2]-based trinuclear sandwich-like heterobimetallic M(III)-Ni(II) (M = Fe, Cr, Co) complexes

摘要

Three trinuclear sandwich-type cyanide-bridged M~Ⅲ-Ni~Ⅱ complexes, {[Ni(cyclm)[Fe(bpb) (CN)_2]_2}-8H_2O (1), {[Ni(cyclm)[Cr(bpb)(CN)_2]_2}-2H_2O (2), and {[Ni(cyclm)[Co(bpb)(CN)_2]_2} -CH_3OH-2H_2O (3) (cyclm= 1,4,8,11 -tetraazacyclotetradecane), have been synthesized using K[M (bpb)(CN)_2] (M = Fe, Cr, Co; bpb= l,2-bis(pyridine-2-carboxamido)benzenate) as building block and one Ni(Ⅱ) compound containing a 14-membered macrocycle ring as assembling segment. All the complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray structure determination. Single X-ray diffraction analysis shows similar sandwich-like structures, in which the two cyanide-containing building blocks are monodentate through one of their two cyanides, coordinated face to face to the central Ni(Ⅱ). Investigation of the magnetic properties of 1 and 2 reveals ferromagnetic magnetic coupling between the neighboring Fe(Ⅲ)/Cr(Ⅲ) and Ni(Ⅱ) through the bridging cyanide. A best-fit to the magnetic susceptibilities of 1 and 2 based on the trinuclear M_2Ni model leads to magnetic coupling constants J= 5.47(1) cm~(-1) for 1 and J= 6.37(2)cm~(-1) for 2.