Crystal Engineering Applied to Modulate the Structure and Magnetic Properties of Oxamate Complexes Containing the [Cu(bpca)]+Cation

Abstract

This work deals with the crystal engineering features of four related copper(II)-based compounds with formulas {[{Cu(bpca)}2(H2ppba)]·1.33DMF·0.66DMSO}n (2), [{Cu(bpca)(H2O)}2(H2ppba)] (3), [{Cu(bpca)}2(H2ppba)]·DMSO (4), and [{Cu(bpca)}2(H2ppba)]·6H2O (5) [H4ppba = N,N′-1,4-phenylenebis(oxamic acid) and Hbpca = bis(2-pyridylcarbonyl)amide] and how their distinct molecular and crystal structures translate into their different magnetic properties. 2 and 3 were obtained through the hydrolytic reaction of the double-stranded oxamato-based dipalladium(II) paracyclophane precursor of formula [{K4(H2O)2}{Pd2(ppba)2}] (1) with the mononuclear copper(II) complex [Cu(bpca)(H2O)2]+, either in a water–DMSO–DMF solvent mixture or in water, respectively. The straightforward reaction of the neutral H4ppba molecule with [Cu(bpca)(H2O)2]+ in a water–DMSO mixture afforded compound 4, whereas compound 5 resulted from the reaction between the copper(II) complex and the K2ppba salt in water. The [Pd2(ppba)2]4– tetraanionic u...