Solid-state 109Ag CP/MAS NMR spectroscopy of some diammine silver(I) complexes

Solid-state cross-polarization magic-angle spinning (CP/MAS) NMR spectra were recorded for the compounds [Ag(NH3)(2)](2)SO4, [Ag(NH3)(2)](2)SeO4 and [Ag(NH3)(2)]NO3, all of which contain the linear or nearly linear two-coordinate [Ag(NH3)(2)](+) ion. The Ag-109 CP/MAS NMR spectra show centrebands and associated spinning sideband manifolds typical for systems with moderately large shielding anisotropy, and splittings due to indirect (1)J(Ag-109,N-14) spin-spin coupling. Spinning sideband analysis was used to determine the Ag-109 shielding anisotropy and asymmetry parameters Deltasigma and eta from these spectra, yielding anisotropies in the range 1500-1600 ppm and asymmetry parameters in the range 0-0.3. Spectra were also recorded for N-15 and (for the selenate) Se-77. In all cases the number of resonances observed is as expected for the crystallographic asymmetric units. The crystal structure of the selenate is reported for the first time. One-bond (Ag-107,Ag-109,N-15) coupling constants are found to have magnitudes in the range 60-65 Hz. Density functional calculations of the Ag shielding tensor for model systems yield results that are in good agreement with the experimentally determined shielding parameters, and suggest that in the solid compounds Deltasigma and eta are reduced and increased, respectively, from the values calculated for the free [Ag(NH3)(2)](+) ion (1920 ppm and 0, respectively), primarily as a result of cation-cation interactions, for which there is evidence from the presence of metal-over-metal stacks of [Ag(NH3)(2)](+) ions in the solid-state structures of these compounds. Copyright (C) 2004 John Wiley Sons, Ltd.