In this work, we present the first application of our recursive approach for the analytic calculation of the anharmonic vibrational frequencies and infrared and Raman intensities of methanimine as well as nitromethane and its mono- and di-deuterated isotopomers. Methanimine has been shown to be very sensitive to the numerical differentiation parameters52 and thus provides a good illustration of the advantages of the analytic approach. The nitromethane isotopomers have been selected because experimental spectra display a large number of combination and overtone bands, for which calculation calls for the use of an anharmonic treatment. We remark that anharmonic effects have also been found to contribute appreciably to the spectroscopic intensities for several other molecules.38