Selective activation and functionalization of linear alkanes initiated under ambient conditions by a tungsten allyl nitrosyl complex

The new tungsten allyl nitrosyl complex, Cp*W(NO)(eta(3)-CH2CHCHMe)(CH2CMe3) (1) (Cp* = eta(5)-C5Me5; Me = CH3), selectively activates the terminal C-H bonds of n-pentane at room temperature and forms the thermally stable compound, Cp*W(NO)(eta(3)-CH2CHCHMe)(CH2CH2CH2CH2Me) (2), from which the n-pentyl ligand may be selectively released as 1-iodopentane by treatment with I-2. Current experimental evidence suggests that the C-H activation chemistry derived from 1 proceeds via two distinct steps: (1) formation of the intermediate eta(2)-diene complex, Cp*W(NO)(eta(2)-CH2CHCHCH2) (A) via intramolecular beta-H elimination of neopentane from 1, and (2) incorporation of n-pentane into A via intermolecular beta-H addition to produce 2. Intermediate A can be trapped by PMe3 as the Cp*W(NO)(eta(2)-CH2CHCHCH2)(PMe3) adduct (3), and the solid-state molecular structures of 1, 2, and 3 have been established by single-crystal X-ray crystallographic analyses.