New types of di-, tetra-, hexa- and octanuclear Ag(i) complexes containing 1,3-adamantanedicarboxylic acid

Abstract

This article represents a systematical investigation on the structures of silver(I) dicarboxylate incorporating secondary ligands, revealing that the secondary interactions could play an important role in interlinking low-dimensional entities to high-dimensional supramolecular frameworks. A new 2D silver(I) crystalline dicarboxylate, {[Ag₆(ADC)₃(H₂O)_1.5]₂·5.18H₂O}_n (1) (H₂ADC = 1,3-adamantanedicarboxylic acid), has been obtained by slow diffusion of corresponding precursors. To investigate the influence of the properties of pyridylic neutral ligands on the complex structures based on compound 1, five kinds of neutral ligands (bipy = 4,4′-bipyridine; bpa = 1,2-bis(4-pyridyl)ethane; bpe = 1,2-bis(4-pyridyl)ethene; bpp = 1,3-bis(4-pyridyl)propane; bpdap = N,N′-bis(3-pyridyl)-2,6-diaminopyridine) were selected, and a series of new silver(I) dicarboxylate have been synthesized: {[Ag(bpa)(HADC)]}_n (2), {[Ag(bpp)(HADC)]·CH₃OH}_n (3), {[Ag₄(bpe)₃(ADC)₂]·2H₂O}_n (4), {[Ag(bipy)(HADC)]·H₂O}_n (5), {[Ag₂(bipy)₂(ADC)]·6H₂O}_n (6), and [Ag₈(bpdap)₄(ADC)₄]·2C₂H₅OH·6H₂O (7). Single-crystal X-ray structural analysis shows that complexes 1 and 4 are formed by hexanuclear and tetranuclear Ag(I) clusters with weak Ag–Ag interactions. Complexes 2 and 3 are dinuclear structures, 5 and 6 exhibit an infinite 1D chain structure, whereas 7 is a discrete octanuclear Ag(I) unit. The structures of 1–7 span from dinuclear, tetranuclear, hexanuclear, to octanuclear Ag(I) complexes, which indicates that secondary ligands do play important roles in the formation of such coordination architectures. Thermal stability, X-ray powder diffraction and luminescent properties of the compounds are also discussed.