Crystal structures and vibrational and solid-state (CPMAS) NMR spectroscopy of some bis(triphenylphosphine)silver(I) sulfate, selenate and phosphate systems

Abstract

The crystal structures of [Ag2(PPh3)4(EO4)]·2H2O (E = S 1 or Se 2) showed that these contain [Ag2(PPh3)4(EO4)] units with three-coordinate silver and EO42− bridging the two silver atoms via two oxygen atoms. The complexes [Ag(PPh3)2(HEO4)]·H2O (E = S 3 or Se 4) contain [Ag(PPh3)2(HEO4)] molecules in which HEO4− is terminally bound to the silver atoms by a single oxygen atom. The complex [Ag(PPh3)2(H2PO4)]·2EtOH 5 contains [Ag(PPh3)2(H2PO4)] molecules in which H2PO4− is terminally bound to the silver atom, which is essentially three-coordinate. Heteronuclear 1J(107/109Ag,31P) and homonuclear 2J(31P,31P) spin–spin coupling constants for these compounds were determined by analysis of their high- (9.40 T) and very high-field (17.62 T) 31P CPMAS NMR spectra, with the aid of the 2-D 31P CPCOSY technique, and a strong inverse correlation was found between 1J(107/109Ag,31P) and the Ag–P bond length. IR and Raman studies show that the effect of a bound proton on the vibrational frequencies of EO42− is much greater than that of an attached metal atom.