Synthesis, crystal structures and magnetic properties of copper(II) complexes with nitronyl nitroxide

Two novel adducts of formula [Cu(pfpr)(2)(NITmNO2)](2) (I) and Cu(hfac)(2)(NITmNO2) (II), where pfpr=pentafluoropropionate, hfac=hexafluoroacetylacetonate and NITmNO2 = 2-(3-nitrophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide have been synthesized. Compound (I) is the first example of copper (II)-nitroxide complexes bridged by pfpr. Its structure consists of binuclear units with the tetrakis(pentafluoropropionate) bridging two copper ions. Each copper ion has a distorted trigonal-bipyramidal coordination. Compound (II) is a mononuclear complex with a five-coordinated distorted square-pyramidal environment. The variable temperature magnetic susceptibilities show that there are antiferromagnetic interactions between copper ions and radicals for compound (I), and compound (II) is diamagnetic. (C) 1999 Elsevier Science Ltd. All rights reserved.