Resonant two-photon ionization spectrum of C6H5CH3...N-2 has been recorded, which exhibits rich information about the van der Waals vibrational modes and internal rotation of N-2. An ab initio calculation shows a C-s point group for the complex, in which the mass center of N-2 is similar to0.35 nm above the benzene ring and the molecular axis of N-2 is in the symmetry plane but tilted slightly away from the CH3 group by similar to2degrees. With the help of isotopic substitution, quantum mechanics calculations, and systematic comparisons, we have tentatively assigned all the observed spectral features. The van der Waals bonding is shown to have an inhibitory effect on the internal rotation of the CH3 group. Bond dissociation energies for the complex C6H5CH3...N-2 in the excited electronic state and in the ground electronic state are estimated to be 494 and 474 cm(-1), respectively, in good agreement with the calculated value. (C) 2003 American Institute of Physics.