Silver pyroarsonates obtained from Ag(Ⅰ)-mediated in situ condensation of aryl arsonate ligands under solvothermal conditions

摘要

Four new layered silver(Ⅰ) organoarsonates, namely, [Ag3(L ~3)(CN)] (1) (H_2L~3 = (PhAsO_2H) _2O), [Ag_3(L~4)(CN)] (2) (H_2L ~4 = (2-NO_2-C_6H_4-AsO _2H)_2O), [Ag_3(HL~5)(H _2L~5)] (3) (H_3L~5 = 3-NO _2-4-OH-C_6H_3-AsO_3H_2) and [Ag_2(HL~5)] (4), were synthesized under solvothermal conditions. During the preparations of 1 and 2, condensation of organoarsonate ligands (H_2L~1 = Ph-AsO_3H_2; H _2L~2 = 2-NO_2-C_6H_4-AsO _3H_2) and the decomposition of acetonitrile molecules to cyanide anions occurred. Single crystals of H2L4 ligand and compounds 1-4 were isolated, and their crystal structures have been determined by single crystal X-ray diffraction studies. In 1, the one-dimensional (1D) chains based on Ag(Ⅰ) ions and {L~3}~(2-) anions are further interconnected by CN- into two-dimensional (2D) layers. In 2, adjacent Ag(Ⅰ) ions within the silver(Ⅰ) organoarsonate layer are further bridged by μ_4-CN~- anions with very short Ag···Ag contacts. In 3, the hexanuclear {Ag _6O_(12)} clusters are interconnected by bridging organoarsonate ligands into a silver(Ⅰ) arsonate hybrid layer. In 4, the right-handed {Ag_4O_4} chains are further interconnected by organoarsonate ligands as well as additional Ag-O-Ag bridges into a novel silver(Ⅰ) arsonate layer. Compounds 1 and 2 display red and orange-red emissions, respectively, which may be assigned to be an admixture of ligand-to-metal charge transfer (LMCT) and metal-centered (4d-5s/5p) transitions perturbed by Ag(Ⅰ)···Ag(Ⅰ) interactions. Upon cooling from room temperature to 10 K, compound 1 exhibits interesting temperature-dependent emissions.