Hexanuclear copper(II) complex of a novel poly(pyridine) ligand exhibiting unique long distance ferromagnetic interactions through a nitrato-O,O ′ bridge

Abstract

A novel hexanuclear copper complex [Cu 6(NO 3) 12(opytrizediam) 2(H 2O)][(CH 3) 2CO] 0.5(CH 3CH 2CH 2OH) 0.5 ( 1) with a NO 3 bridge has been synthesized by reaction of Cu(NO 3) 2 · 3H 2O with the new potentially octadentate ligand opytrizediam in n-propanol/acetone solution (opytrizediam= N, N ′-{2,4-di[(di-pyridin-2-yl)amine]-1,3,5-triazine} ethylenediamine). A single-crystal X-ray diffraction analysis showed the presence of six structurally different copper centres. The coordination spheres of four copper(II) ions are best described as square-pyramidal CuN 2O 3 chromophores while the two other copper(II) ions are in a trigonal-bipyramidal CuN 4O environment. Variable-temperature studies on 1 revealed a unique ferromagnetic coupling of two copper(II) ions bridged by a didentate nitrate anion and separated by a distance of 6.391(6) Å, with J=8.6(1) cm −1.