Proton and deuteron NMR spectra of single crystals of diamminesilver dinitroargentate, [Ag(NH3)2]Ag(NO2)2 and [Ag(ND3)2]Ag(NO2)2, were studied at room temperature. Rapid reorientational motions of the ammine groups around their C3 axes were found. The orientations of the C 3 rotation axes within the crystal coincide (deviation = 0.9°) with the directions Ag-N in the diamminesilver ions as found by an x-ray crystal structure determination of the compound. A small deviation from linearity of the bond angle N-Ag-N within the ion [H3NAgNH3] + found röntgenographically is supported by the NMR experiments. The deuterium quadrupole coupling constant e 2qQh-1 at room temperature is 71.6±0.5 kHz. A comparison of this value with the data reported for solid ND3 supports the assumption of only small changes in the geometrical and electronical structure of the ammonia molecule by the coordination to the silver ion. © 1978 American Institute of Physics.