Cobalt-benzene cluster anions: Mass spectrometry and negative ion photoelectron spectroscopy

(Cobalt)(n)(benzene)(m)(-) cluster anions, (n,m) were generated by laser vaporization and studied by both mass spectrometry and anion photoelectron spectroscopy. Our assignment of the photoelectron spectrum of the (1,2) cluster anion suggests that it possesses a sandwich structure with the cobalt atom located between two parallel benzene rings, that the ground state of this anion is a singlet, and that the ground state of its corresponding neutral is a doublet. The photoelectron spectra of cobalt-rich cluster anions of the form (n,1) are interpreted as cobalt metal cluster anions which have been solvent-stabilized by their interaction with, in each case, a single benzene molecule. The photoelectron spectra of the benzene-rich cluster anions, (2,3), (2,2), and (3,3), are tentatively interpreted as suggesting extended sandwich structures for these anion complexes. (C) 2002 American Institute of Physics.