Silver Pyroarsonates Obtained from Ag(I)-Mediated in Situ Condensation of Aryl Arsonate Ligands under Solvothermal Conditions

Four new layered silver­(I) organoarsonates, namely, [Ag3(L3)­(CN)] (1) (H2L3 = (PhAsO2H)2O), [Ag3(L4)­(CN)] (2) (H2L4 = (2-NO2-C6H4-AsO2H)2O),
[Ag3(HL5)­(H2L5)] (3) (H3L5 = 3-NO2-4-OH-C6H3-AsO3H2) and [Ag2(HL5)] (4), were synthesized under solvothermal
conditions. During the preparations of 1 and 2, condensation of organoarsonate ligands (H2L1 = Ph-AsO3H2; H2L2 =
2-NO2-C6H4-AsO3H2) 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 {L3}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 μ4-CN– anions with very short Ag···Ag contacts.
In 3, the hexanuclear {Ag6O12}
clusters are interconnected by bridging organoarsonate ligands into
a silver­(I) arsonate hybrid layer. In 4, the right-handed
{Ag4O4} 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.