1-D polymers with alternate Cu2 and Ln2 units (Ln = Gd, Er, Y) and carboxylate linkages.

Three isostructural Cu2Ln2 1-D polymers [Cu2Ln2L10(H2O)4·3H2O]n where Ln = Gd (1), Er (2), and Y (3) and HL= trans-2-butenoic acid, were synthesized and characterized by X-ray crystallography, electron paramagnetic resonance, and magnetic measurements. Pairs of alternate Cu2 and Ln2 dinuclear units are combined into a linear array by a set of one covalent η2:η1:μ2 carboxylate oxygen and two H bonds, at Cu···Ln distances of ca. 4.5 A. These units exhibit four η1:η1:μ2 and two η2:η1:μ2 carboxylate bridges, respectively. Magnetic measurements between 2 and 300 K, fields B0 = μ0H between 0 and 9 T, and electron paramagnetic resonance (EPR) measurements at the X-band and room temperature are reported. The magnetic susceptibilities indicate bulk antiferromagnetic behavior of the three compounds at low temperatures. Magnetization and EPR data for 1 and 3 allowed evaluation of the exchange couplings between both Cu and Gd ions in their dinuclear units and between Cu and Gd neighbor ions in the spin chains. The da...