87761-99-7Relevant academic research and scientific papers
Reactions of metal-metal multiple bonds. 9. α-Diketone adducts of ditungsten hexaalkoxides: W2(OR)6(O2C2R′ 2)2 (M-M)
Chisholm, Malcolm H.,Huffman, John C.,Ratermann
, p. 4100 - 4105 (2008/10/08)
α-Diketones, R′C(O)C(O)R′, where R′ = Me, Ph, and p-tolyl, react with ditungsten hexaalkoxides in hydrocarbon solvents to give adducts W2(OR)6(O2C2R′ 2)2, where R = t-Bu and i-Pr. In the solid state, the compounds W2(O-i-Pr)6(O2C2R′ 2)2, where R′ = Me and p-tolyl, adopt a common edge-shared bioctahedral W2O10 unit with Ci symmetry. The halves of the molecule are joined by a pair of μ-O-i-Pr bridges and a W-W single bond of distance 2.750 (2) A? (R′ = p-tolyl) and 2.744 (3) A? (R′ = Me), the latter being averaged for two independent molecules. The W-O, C-O, and C-C distances associated with the coordinated α-diketone ligands indicate that they have been reduced to 2e ligands. These results complement recent findings of Cotton, Walton, and co-workers, who found that ketones react with W2Cl4(OR)4(HOR)2 (M=M) compounds to give W2Cl4(OR)2(O2C2R 4)2 (M-M) compounds, and provide further evidence of the reducing properties of W-W multiple bonds. 1H NMR studies indicate that a number of isomers are present in solution and that at high temperatures (>80 °C), in toluene-d8, these compounds are fluxional: bridge ? terminal OR exchange and O2C2R′2 site exchange rapidly equilibrate all isomers. These processes do not involve dissociation of the α-diketone (2e) ligands. Crystal data are as follows. For W2(O-i-Pr)6(O2C2(C7H 7)2)2 at -162°C: monoclinic, a = 20.124 (1) A?, b = 9.735 (1) A?, c = 12.651 (1) A?, β = 90.23 (5)°, space group P21/a with Z = 2. For W2(O-i-Pr)6(O2C2Me2) 2 at -162°C: triclinic, a = 22.127 (14) A?, b = 9.750 (4) A?, c = 9.361 (4) A?, α = 76.11 (3)°, β = 64.27 (3)°, γ = 69.03 (3)°, space group P1 with Z = 2.
