Magnetic properties and superexchange in single chloride-bridged copper(II) chain compounds

Abstract

Magnetic susceptibility data have been measured in the temperature range 1.75 to 60 K for the following structurally characterized, single chloride-bridged copper(II) chain compounds: dichlorobis(dimethyl sulphoxide)copper(II), dichlorobis(imidazole)copper(II), aquo(caffeine)dichlorocopper(II), and dichloro[2-(2′-methylaminoethyl)pyridine]copper(II). The first two compounds exhibit antiferromagnetic intrachain interactions with exchange coupling constants of –6.1 and –2.1 cm^–1, respectively, while the second two compounds exhibit ferromagnetic interactions with J values of 0.48 and 1.58 cm^–1 respectively. Except for dichlorobis(imidazole)copper(II), which undergoes long-range magnetic ordering below 7.7 K, the exchange coupling constants become more negative as the angle at the chloride bridge increases from 113.6° in dichloro[2-(2′-methylaminoethyl)pyridine]copper(II) to 144.6° in dichlorobis(dimethyl sulphoxide)copper(II).