Issue Date: May 7, 2007
Unique C-H Activation
A new allyl nitrosyl complex of tungsten selectively activates the terminal C-H bond of linear alkanes under ambient conditions in a new way that could prove useful in chemical syntheses (J. Am. Chem. Soc. 2007, 129, 5372). The complex (structure on left) is thermally unstable, losing neopentane [C(CH3)4] at 20 °C by abstracting a hydrogen atom from the allyl ligand. The intermediate diene complex (center) then reacts with the alkane solvent—in this case, n-pentane—to add an n-pentyl ligand, essentially hiding the displaced terminal hydrogen within the diene ligand to restore the allyl ligand. The n-pentyl complex (right) can react with I2 to yield 1-iodopentane, the starting point for further derivatizations. "The most intriguing aspect of this chemistry," notes Peter Legzdins of the University of British Columbia, in Vancouver, who led the research, "is that the C-H bond activation yields a thermally stable—and isolable&mdah;allyl complex instead of a thermally unstable hydrido alkyl complex."
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