Photoelectron spectroscopy of V-x(coronene)(y) and Ti-x(coronene)(y) anions

Gas-phase anion complexes are produced containing one or more vanadium or t itanium atoms bound to one or more molecules of the polycyclic aromatic hyd rocarbon (PAH) coronene (C24H12). These species are prepared with coinciden t laser vaporization of a metal rod and a pressed pellet of coronene in a p ulsed-nozzle cluster source. The anion complexes produced are mass-selected with a time-of-flight spectrometer and photoexcited with various Nd:YAG la ser harmonics. A, magnetic bottle instrument is employed for time-of-flight photoelectron spectroscopy measurements on these complexes. Electron affin ities (EA's) are observed to be greater for the organometallic complexes th an they are for the isolated metal clusters or the isolated coronene molecu le. EA's increase with the number of metal atoms in the complex. The spectr a observed for V-coronene complexes are similar in appearance to those seen previously for V-benzene and V-C-60 suggesting that the metal binds as a p i complex in a symmetric ring site. V-(coronene)(2) complexes exhibit diffe rent spectra under different conditions attributed to the formation of sand wich and external-metal isomers.