Interaction of tetrameric silver with ammonia in AgCs-rho zeolite

Abstract

Cationic silver clusters formed in c-irradiated AgCs-rho zeolite have been studied by EPR spectroscopy. Tetrameric silver is formed efficiently in the dehydrated form of zeolite as well as in samples exposed to ammonia. However, the hyperÐne splitting of the pentet in zeolite is distinctly smaller Ag 43`AgCs-rho/NH 3 due to the shift of spin density from silver to nitrogen nuclei, suggesting the formation of an Ag 4 3`Èammonia complex. The observed 14N and 15N superhyperÐne splitting from interacting and molecules 14NH 3 15NH 3 unequivocally proved the presence of a multicore complex. Based on the simulation of 14N and Ag 4 3`(NH 3 ) n 15N superhyperÐne interactions a structure of the complex was proposed in which two ammonia molecules are located close to the octagonal windows of two neighboring a-cages and four further molecules are placed in next-neighboring a-cages interacting with the Ag tetramer through square windows. When dehydrated AgCs-rho zeolite containing radiation-induced clusters is exposed to ammonia the Ag hyperÐne Ag 4 3s plitting of silver tetramer decreases from 13.9 to 10.7 mT proving that clusters are located in the sites Ag 4 3à ccessible to adsorbates.

Ligands of biologically active compounds in the nanochemistry of silver and gold (A review)

“…Baetzold [23] studied the properties of Ag 3 + clusters adsorbed on silver bromide. Gurin et al [24] observed Ag 8 clusters on zeolites, Sadlo et al [25] found stable Ag 4 3+ clusters in Ag 6 NaCs 5 (AlO 2 ) 12 (SiO 2 ) 36 × 44H 2 O crystals, and Kanan et al [26] showed the existence of Ag 3 + , …, Ag 6 + clusters on silver(I)-substituted zeolite A. It was established that silver retains high colloidal stability on adsorbent particles [27].…”