Thermal Chemistry of Cp*W(NO)(H)(η3-allyl) Complexes

The thermal properties of Cp*W(NO)(H)(η3-CH2CHCMe2) (1), Cp*W(NO)(H)(η3-CH2CHCHPh) (2), and Cp*W(NO)(H)(η3-CH2CHCHMe) (3) (Cp* = η5-C5Me5) have been investigated. Thermolyses of 1–3 in n-pentane lead to the loss of the original allyl ligand and the formation of the same mixture of isomeric products, namely, Cp*W(NO)(H)(η3-CH2CHCHEt) (4a) and Cp*W(NO)(H)(η3-MeCHCHCHMe) (4b) and their coordination isomers. Similarly, 1 reacts with cyclohexane and n-heptane to form Cp*W(NO)(H)(η3-C6H9) and isomers of Cp*W(NO)(H)(η3-C7H13), respectively. It is likely that complexes 1–3 first effect the selective, single-terminal C–H activation of the linear alkanes, but the first-formed products are thermally unstable and undergo two additional successive C–H activations to form the final allyl complexes. Consistent with this view is the fact that a bis(alkyl) intermediate complex can be trapped with N-methylmorpholine. Thus, the thermolysis of 1 in N-methylmorpholine affords a single organometallic complex, Cp*W(NO)(η2-CH2NC4H8O)(η1-CH2CH2CHMe2) (7). Complexes 2 and 3 react with N-methylmorpholine in an identical manner. Finally, 1 effects the multiple C–H activations of 1-chloropropane and 1-chlorobutane and forms the corresponding Cp*W(NO)(Cl)(η3-allyl) complexes. All new complexes have been characterized by conventional spectroscopic and analytical methods, and the solid-state molecular structures of most of them have been established by single-crystal X-ray crystallographic analyses