title: Clusters as Ligands. 4. Synthesis, Structure, and Characterization of the Tungsten(II)-Tungsten(III) Cluster Carboxylate {[Na][W(2){OOCCCo(3)(CO)(9)}(2)(OOCCF(3))(4)(THF)(2)]}(2).
abstract: The reaction of W(2)(OOCCF(3))(4) with (CO)(9)Co(3)CCOOH and Na[OOCCF(3)] in a nonpolar solvent mixture leads to the formation of the cluster of clusters {[Na][W(2){OOCCCo(3)(CO)(9)}(2)(OOCCF(3))(4)(THF)(2)]}(2), 1, in 40% yield. The structure of 1.3C(6)H(5)CH(3) in the solid state corresponds to a dimer of W(2) dinuclear complexes (monoclinic P2(1)/c, a = 15.234(6) Å, b = 23.326(11) Å, c = 20.658(7) Å, beta = 102.46(3) degrees; V = 7,168(5) Å(3); Z = 4; R(F)() = 8.39%). Each W(2) unit is bridged by two cis cluster carboxylates, and the remaining four equatorial sites are occupied by monodentate [OOCCF(3)](-) ligands. The axial positions contain coordinated THF. The W(2) carboxylate is opened up (W-W distance of 2.449(2) Å) so that the free ends of the [OOCCF(3)](-) ligands on both W(2) carboxylate units can cooperate in chelating two Na(+) ions thereby forming a dimer of W(2) complexes. A distinctive EPR spectrum with g = 2.08 is consistent with each W(2) carboxylate being a mixed-valent W(II)-W(III) species. The reaction of W(2)(OOCCF(3))(4) with (CO)(9)Co(3)CCOOH in THF in the absence of Na[OOCCF(3)] leads to the expected diamagnetic W(II)-W(II) cluster carboxylate W(2){OOCCCo(3)(CO)(9)}(3)(OOCCF(3))(THF)(2), 3.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, and Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716.
authors.forename: Victor
authors.initials: V
authors.lastname: Calvo-Perez
authors.forename: Thomas P.
authors.initials: TP
authors.lastname: Fehlner
authors.forename: Arnold L.
authors.initials: AL
authors.lastname: Rheingold