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

Abstract

Three trinuclear sandwich-type cyanide-bridged M^III–Ni^II complexes, {[Ni(cyclm)[Fe(bpb)(CN)₂]₂}·8H₂O (1), {[Ni(cyclm)[Cr(bpb)(CN)₂]₂}·2H₂O (2), and {[Ni(cyclm)[Co(bpb)(CN)₂]₂}·CH₃OH·2H₂O (3) (cyclm = 1,4,8,11-tetraazacyclotetradecane), have been synthesized using K[M(bpb)(CN)₂] (M = Fe, Cr, Co; bpb = 1,2-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 M₂Ni model leads to magnetic coupling constants J = 5.47(1) cm⁻¹ for 1 and J = 6.37(2) cm⁻¹ for 2.

Graphical Abstract

Keywords:

• Cyanide-bridged
• Sandwich-like
• Crystal structure
• Magnetic property

Funding

This work was supported by the National Natural Science Foundation of China [grant number 21171107]; the Natural Science Foundation of Shandong Province [grant number ZR2011BM008]; the Science and Technology Project of High Education, Shandong Province [grant number J11LB09].