title: 2-Thienylcarboxylato and 2-thienylthiocarboxylato ligands bonded to MM quadruple bonds (M = Mo or W): a comparison of ground state, spectroscopic and photoexcited state properties.
abstract: The compounds M(2)(TiPB)(2)(OSC-2-Th)(2) have been prepared from the reactions between M(2)(TiPB)(4) and Th-2-COSH (2 equiv) in toluene solution, where M = Mo (Mo(2)ThCOS) or W (W(2)ThCOS), TiPB = 2,4,6-triisopropylbenzoate and Th = thienyl. The molybdenum and tungsten compounds are pink and blue, air-sensitive, ether soluble solids that show M(+) ions in the mass spectrometer and metal and ligand based reversible oxidation and reduction waves, respectively, by cyclic voltammetry. Electronic structure calculations on the model compounds M(2)(O(2)CH)(2)(OSC-2-Th)(2) indicate that the highest occupied molecular orbital (HOMO) is principally M(2)delta and the lowest unoccupied molecular orbital (LUMO) is thienylthiocarboxylate pi* but with significant metal-sulfur mixing. The intense visible absorptions arise from (1)MLCT, M(2)delta to thienylthiocarboxylate. The photoexcited states of these molecules have been studied by transient absorption spectroscopy and steady state emission. These properties are compared with those of previously reported thienylcarboxylate compounds, M(2)(TiPB)(2)(O(2)C-2-Th)(2), where M = Mo (Mo(2)ThCO(2)) or W (W(2)ThCO(2)).
authors.affiliation: Department of Chemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, USA.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Alberding
authors.forename: Malcolm H
authors.initials: MH
authors.lastname: Chisholm
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Chou
authors.forename: Yagnaseni
authors.initials: Y
authors.lastname: Ghosh
authors.forename: Terry L
authors.initials: TL
authors.lastname: Gustafson
authors.forename: Yao
authors.initials: Y
authors.lastname: Liu
authors.forename: Claudia
authors.initials: C
authors.lastname: Turro