Imidazole-Substituted Oxoverdazyl Radical As a Mediator of Intramolecular and Intermolecular Exchange Interaction

The 3-(2′-imidazolyl)-1,5-dimethyl-6-oxoverdazyl radical (imvd•) and the corresponding tetrazane H3imvd were prepared and structurally characterized, the former as two different hydrates. Reaction of imvd• with [M(hfac)2] led to the formation of monometallic complexes [M(hfac)2(imvd•)] (M = Ni and Mn). They were characterized by single-crystal X-ray diffraction. In the solid state, all four radical-containing compounds exhibit imidazole−oxoverdazyl π stacking. Following the structural analysis, imvd• behaves as an antiferromagnetic (AF) coupled chain with J = −100 cm−1 (H = −J∑SiSi+1). The magnetic behavior of [M(hfac)2(imvd•)] complexes is interpreted with a four-coupled spin model with a metal ion radical intramolecular interaction (JMn = −62.5 cm−1 and JNi = 193 cm−1; H = −JSMSimvd) and an AF intermolecular interaction (JMn′ = −12.6 cm−1 and JNi′ = −4.3 cm−1) related to imidazole−oxoverdazyl π stacking.