A study on oxygen insertion in dinuclear silver cryptates

Two novel silver(I) cryptates are reported in this paper. [Ag-2((LO)-O-1)](ClO4)(2).H2O 1 and [Ag2L1](ClO4)(2) . 1.5H(2)O 2 were synthesized by the condensation of tris (3-aminopropyl) amine with m-phthalaldehyde in the presence of silver(I) ion, under aerobic and anaerobic conditions, respectively. (The ligand (LO)-O-1 represents the oxygen insertion product of L-1.) Cryptates 1, 2, and their hydrogenated ligand H-12((LO)-O-1) 3 and H12L1 4 ( obtained by reduction of the cryptates) were investigated by electrospray mass spectroscopy (ES-MS). 1 and 2 were also decomposed by HCl treatment and their products were separated and identified by HPLC and ES-MS. Our experiments show that cryptate 2 is able to activate dioxygen that results in quantitative aliphatic hydroxylation of L-1 on one of its HC = N bonds. Crystal structure analysis shows an interesting difference between 1 and 2 in that 1 is an oxygenated and 2 is a non-oxygenated cryptate. Up to date, ligand hydroxylation has not been achieved in silver(I) complex - O-2 systems.