Multinuclear silver(i) XPhos complexes with cyclooctatetraene: photochemical C–C bond cleavage of acetonitrile and cyanide bridged Ag cluster formation

Abstract

Cationic mono-, di-, tri- and tetra-nuclear silver complexes with Buchwald-type phosphane (XPhos) and cyclooctatetraene (COT) have been synthesized and characterized. Formation of [(XPhos-Ag)_n(COT)][SbF₆]_n (n = 1 and 2) complexes was confirmed by single-crystal X-ray crystallography and multinuclear NMR spectroscopy. Variable-temperature NMR spectroscopy in CD₂Cl₂ solution shows the fluxionality of the COT ring in the mono-Ag(I) XPhos complex. Fluxionality of COT was also confirmed in the case of the di-Ag(I) XPhos complex by solid-state and solution ³¹P NMR spectroscopy. The C–C bond cleavage of coordinated acetonitrile [XPhos-Ag(I)-NCCH₃] resulting in cyanide bridged Ag cluster formation [(XPhos-Ag)₂(μ-CN)_n(μ-Ag)_n−1] (n = 1, 2, 3 and 4) upon light excitation of [(XPhos-Ag)_n(COT)] was confirmed by HRESI-MS, UV-Absorption and HR-TEM.