Selective Activation and Functionalization of Linear Alkanes Initiated under Ambient Conditions by a Tungsten Allyl Nitrosyl Complex

Abstract

The new tungsten allyl nitrosyl complex, Cp*W(NO)(η 3 -CH 2 CHCHMe)(CH 2 CMe 3 ) ( 1 ) (Cp* = η 5 -C 5 Me 5; Me = CH 3 ), selectively activates the terminal C−H bonds of n -pentane at room temperature and forms the thermally stable compound, Cp*W(NO)(η 3 -CH 2 CHCHMe)(CH 2 CH 2 CH 2 CH 2 Me) ( 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 η 2 -diene complex, Cp*W(NO)(η 2 -CH 2 CHCH CH 2 ) ( A ) via intramolecular β-H elimination of neopentane from 1, and (2) incorporation of n -pentane into A via intermolecular β-H addition to produce 2 . Intermediate A can be trapped by PMe 3 as the Cp*W(NO)(η 2 -CH 2 CHCH CH 2 )(PMe 3 ) adduct ( 3 ), and the solid-state molecular structures of 1, 2, and 3 have been established by single-crystal X-ray crystallographic analyses.