The rotationally resolved infrared spectrum of the v(2) stretching vibration of Ar . . . DN2+ has been observed by means of tunable diode laser absorption spectroscopy through a supersonic planar plasma. Its band origin is found at 1593.6058(2) cm(-1). and a large transition moment of 0.54 D is predicted from CCSD(T) calculations. An accurate mixed experimental/theoretical equilibrium structure is established, yielding R-Ar . . .H((e)) = 1.8851 Angstrom, R-H . . .N((e)) = 1.0752 Angstrom and R-NN((e)) = 1.0929 Angstrom.