A Base-Free Terminal Actinide Phosphinidene Metallocene: Synthesis, Structure, Reactivity, and Computational Studies

The synthesis, structure, and reactivity
of a base-free terminal
actinide phosphinidene metallocene have been comprehensively studied.
The salt metathesis reaction of the thorium methyl iodide complex
Cp‴2Th­(I)­Me (2; Cp‴ = η5-1,2,4-(Me3C)3C5H2) with Mes*PHK (Mes* = 2,4,6-(Me3C)3C6H2) in THF furnishes the first stable base-free terminal
phosphinidene actinide metallocene, Cp‴2ThPMes*
(3). Density functional theory (DFT) shows that the bonds
between the Cp‴2Th2+ and [PMes*]2– fragments are more covalent than those in the related
thorium imido complex. While the phosphinidene complex 3 shows no reactivity toward alkynes, it reacts with a variety of
heterounsaturated molecules such as CS2, isothiocyanate,
nitriles, isonitriles, and organic azides, forming carbodithioates,
imido complexes, metallaaziridines, and azido compounds. These experimental
observations are complemented by DFT computations.