Novel copper(I)- and copper(II)-guanazolate complexes: Structure, network topologies, photoluminescence, and magnetic properties

Hydrothermal reactions of copper(I) or copper(II) salts with guanazole (3,5-diamino-1,2,4-triazole = Hdatrz) have yielded three novel 3D Cu-guanazolate complexes, that is, [Cu7Br6][Cu-7(datrz)(2)] (1), [Cu(datrz)] (2), and (Cu-4(datrz)(2)(OH)(2)(SO4)(2)] (3). Complex 1 presents the first example in Cu(I) halide complexes with its Cu(I) bromide units {CU7Br6}(n)(n+) adopting a 3D network, which is constructed from two unprecedented substructures: the edge-sharing eight-membered {CU7Br6}(n) rings and the three-bladed paddle-wheel-like {CU7Br6}(n) units. Guanazolate ligands in I adopt an unprecedented pentadentate bridging mode and some bromide ligands exhibit a rare umbrella-like mu(4) coordination geometry. The first binary Cu(I) guanazolate 2 exhibits a seldom reported twofold interpenetrated 1vt-a net, which can be partially controlled through the fixing effect of inter-ligand hydrogen bonds. Cu(II) complex 3 comprises a rarely encountered 12-connected tetranuclear {Cu-4(mu(3)-OH)(2)} SBU, which is bridged by guanazolate ligands adopting a peculiar quadridentate coordination mode. This complex displays a non-interpenetrated peu net, which is first constructed from multinuclear Cu(II) SBUs. Both 1 and 2 exhibit strong, broad, and unstructured emissions with long luminescence lifetimes, which may be assigned to the (3)[MLCT] ES, and the (3)[MC] or (3)[MMLCT] ES could also be possible for 1. Complex 3 exhibits magnetic properties with four Cu(II) centers antiferromagnetically coupled in a tetranuclear array, which enables multiple and strong exchange interactions of J(1) = -95.1, J(2) = -152.7, and J(3) = -55.4 cm(-1). All compounds of this study display a medium to high thermal stability, and complex 1 shows the highest one with its structure framework unchanged up to 540 degrees C. Some significant structure-function correlations are discussed in this study as well.