Solvation and Ion Association in the System AgNO3-CH3CN: A Raman and Infrared Spectral Study

Detailed studies of the Raman and infrared line parameters of AgNO3-CH3CN systems ranging from dilute solutions to 9 M are reported. A concentration quotient of 1.1 M-1 was obtained for the formation of the Ag+ NO3- ion pair when C < 4 M. The complex appears to have point group C-s(sigma(v)) with Ag+ in a "roll-on" position. The Ag+ ion is solvated by four molecules of CH3CN; nitrate ion replaces three of these when bound to Ag+. When C > 4 M, multiple ion aggregates form in the solution. A low-frequency 110 cm(-1) line is ascribed to librational motions of NO3-, probably bound to Ag+.