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, [Cu 7 Br 6 ][Cu(datrz) 2 ] ( 1 ), [Cu(datrz)] ( 2 ), and [Cu 4 (datrz) 2 (OH) 2 (SO 4 ) 2 ] ( 3 ). Complex 1 presents the first example in Cu(I) halide complexes with its Cu(I) bromide units {Cu 7 Br 6 } n n + adopting a 3D network, which is constructed from two unprecedented substructures: the edge-sharing eight-membered {Cu 4 Br 4 } n rings and the three-bladed paddle-wheel-like {Cu 4 Br 4 } n units. Guanazolate ligands in 1 adopt an unprecedented pentadentate bridging mode and some bromide ligands exhibit a rare umbrella-like μ 4 coordination geometry. The first binary Cu(I) guanazolate 2 exhibits a seldom reported two-fold interpenetrated lvt-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 ( μ 3 -OH) 2 } SBU, which is bridged by guanazolate ligands adopting a peculiar quadridentate coordination mode. This complex displays a non-interpenetrated pcu 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 °C. Some significant structure−function correlations are discussed in this study as well.