Si–H addition followed by C–H bond activation induced by a terminal thorium imido metallocene: a combined experimental and computational study

The Si–H bond addition to a terminal actinide imido complex was comprehensively studied. The base-free thorium imido [η5-1,2,4-(Me3C)3C5H2]2ThN(p-tolyl) (1) activates Si–H bonds in PhSiH3 or Ph2SiH2 to give the thorium amido hydrido metallocenes [η5-1,2,4-(Me3C)3C5H2]2Th(H)[N(p-tolyl)SiH2Ph] (2) and [η5-1,2,4-(Me3C)3C5H2]2Th(H)[N(p-tolyl)SiHPh2] (3), respectively. Complex 2 readily inserts unsaturated molecules into the Th–H bond, whereas complex 3 reversibly activates an intramolecular aromatic C–H bond to yield [η5-1,2,4-(Me3C)3C5H2]2Th[η2-N,C-{N(p-MeC6H3)(SiHPh2)}] (4) and H2. The experimental results have been complemented by density functional theory (DFT) studies and provide a detailed understanding of the observed reactivity. In addition, a comparison between Th and early transition metals reveals that the Th4+ behaves more like an actinide than a transition metal.