Knowledge Bank

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 $\eta 6\pi$-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.