title: Photoelectron spectroscopy and DFT calculations of easily ionized quadruply bonded Mo2(4+) compounds and their bicyclic guanidinate precursors.
abstract: A series of five bicyclic guanidinate compounds containing various combinations of five- and six-membered rings and substituted alkyl groups have been shown by photoelectron spectroscopy to be easily ionized, with the one having two six-membered rings and four ethyl groups being the most easily ionized. The corresponding anions are capable of forming paddlewheel compounds having quadruply bonded Mo2(4+) units which are also easy to ionize. The most easily ionized compound is the ethyl-substituted Mo2(TEhpp)4 complex which has a broad first ionization band centered around 4.27 +/- 0.03 eV and an ionization onset at the very low energy of 3.93 +/- 0.03 eV. Even the compound with ligands containing two five-membered rings, which favors a long Mo-Mo separation because of the large ligand bite, has an ionization energy (4.78 eV) that is less than those of well-known organometallic reducing agents such as (eta5-C9Me7)2Co and (eta5-C5Me5)2Cr.
authors.affiliation: Department of Chemistry and Laboratory of Molecular Structure and Bonding, PO Box 30012, Texas A & M University, College Station, Texas 77842-3012, USA. cotton@tamu.edu
authors.forename: F Albert
authors.initials: FA
authors.lastname: Cotton
authors.forename: Jason C
authors.initials: JC
authors.lastname: Durivage
authors.forename: Nadine E
authors.initials: NE
authors.lastname: Gruhn
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Lichtenberger
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Murillo
authors.forename: Laura O
authors.initials: LO
authors.lastname: Van Dorn
authors.forename: Chad C
authors.initials: CC
authors.lastname: Wilkinson