title: Are tetrathiooxalate and diborinate bridged compounds related to oxalate bridged quadruply bonded compounds of molybdenum?
abstract: The electronic structures of the compounds [(HCO(2))(3)M(2)](2)(bridge), where M = Mo and bridge is C(2)O(4)(2-), C(2)S(4)(2-) or B(2)O(4)H(2)(2-) are compared based on calculations employing density functional theory. The planar structure, D(2h), for the oxalate and tetrathiooxalate is the ground state and the splitting of the two M(2)delta orbitals is found to be significantly larger for the tetrathiooxalate due primarily to the lower energy of the C(2)S(4)(2-) LUMO, which interacts with the in-phase combination of the M(2)delta orbitals. An attempt to prepare the compound [((t)BuCO(2))(3)Mo(2)](2)(mu-S(2)CCS(2)) is reported, which yielded a material that was not soluble in organic solvents and has not been fully characterized. Calculations on the borinate bridged compound with mu-B(2)O(4)H(2)(2-) revealed the surprising prediction that the B-B bond is reductively cleaved and the [Mo(2)(4+)] centers oxidized: the bridge is [O(2)B(mu-H)](2)(4-).
authors.affiliation: Department of Chemistry, The Ohio State University, 100 W. 18th Ave., Columbus, OH 43210, USA. chisholm@chemistry.ohio-state.edu
authors.forename: Malcolm H
authors.initials: MH
authors.lastname: Chisholm
authors.forename: Namrata
authors.initials: N
authors.lastname: Singh