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.