| Abstrakt: |
Aldehydes react with W2(OCH2tBu)6(py)2 to give W2(μ-CHR)(O)(OCH2tBu)6(py) compounds, where R = alkyl or aryl, which, in the presence of excess pyridine, yield W2(μ-CR)(μ-O)(OCH2tBu)5(py)2 compounds and neopentanol. A relative order of rates of reductive cleavage of the C&dbd;O bond is found to be aryl > alkyl, and for p-X-C6H4CHO, the rates follow the order X = CF3 > H > F > Me > OMe. Four complexes have been structurally characterized by single-crystal X-ray crystallography: W2(μ-CHcC3H5)(O)(OCH2tBu)6(py), 1; W2(μ-CH(tolyl))−(O)(OCH2tBu)6(py), 2; W2(μ-CcC3H5)(μ-O)(OCH2tBu)5(py)2, 3, and W2(μ-C(p-MeOC6H4))(OCH2tBu)5(py)2, 4. Factors influencing the reductive cleavage of the C&dbd;O bond are discussed in light of earlier studies of related reactions, and most notably comparisons are made with the development of a molecular alternative to the McMurry reagent. |
