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

The thermal properties of Cp*W­(NO)­(H)­(η³-CH₂CHCMe₂) (<b>1</b>), Cp*W­(NO)­(H)­(η³-CH₂CHCHPh) (<b>2</b>), and Cp*W­(NO)­(H)­(η³-CH₂CHCHMe) (<b>3</b>) (Cp* = η⁵-C₅Me₅) have been investigated. Thermolyses of <b>1</b>–<b>3</b> in <i>n</i>-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) (<b>4a</b>) and Cp*W­(NO)­(H)­(η³-MeCHCHCHMe) (<b>4b</b>) and their coordination isomers. Similarly, <b>1</b> reacts with cyclohexane and <i>n</i>-heptane to form Cp*W­(NO)­(H)­(η³-C₆H₉) and isomers of Cp*W­(NO)­(H)­(η³-C₇H₁₃), respectively. It is likely that complexes <b>1</b>–<b>3</b> 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 <i>N</i>-methylmorpholine. Thus, the thermolysis of <b>1</b> in <i>N</i>-methylmorpholine affords a single organometallic complex, Cp*W­(NO)­(η²-CH₂NC₄H₈O)­(η¹-CH₂CH₂CHMe₂) (<b>7</b>). Complexes <b>2</b> and <b>3</b> react with <i>N</i>-methylmorpholine in an identical manner. Finally, <b>1</b> 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