15min:

M. A. DUNCAN, DEPARTMENT OF CHEMISTRY, UNIVERSITY OF GEORGIA, ATHENS, GA. 30602; D. VAN HEIJNSBERGEN, G. VON HELDEN AND G. MEIJER, F. O. M. LABORATORY FOR PLASMAPHYSICS RIJNHUISEN, EDINSONBAAN 14, NL-3439 MN NIEUWEGEIN, THE NETHERLANDS.

Metal ion-benzene complexes of the form M⁺(benzene)_1,2 (M=V, Ti, Al) are produced by laser vaporization in a pulsed nozzle source, mass-selected in an ion-trap mass spectrometer and excited in the infrared with a free electron laser. Multiphoton dissociation occurs by the elimination of benzene molecules. The photofragment yield versus wavelength produces IR resonance-enhanced multiphoton photodissociation (IR-REMPD) spectroscopy for these complexes. Vibrational bands in the 600-1800cm^-1 region are characteristic of the benzene molecular moiety perturbed by the metal bonding. Experimental data are compared to the IR spectra derived from density functional calculations. Vibrational patterns in V⁺(C₆H₆) indicate that the metal is bound in an ⁶ -bonding configuration, while V⁺(C₆H₆)₂ is a sandwich. Trapped-ion IR-REMPD is a general method to access the vibrational spectra of novel organometallic complexes.