The synthesis, structure, and reactivity of an actinide metallacyclopropene were comprehensively studied. The reduction of [η(5)-1,2,4-(Me3C)3C5H2]2ThCl2 (1) with potassium graphite (KC8) in the presence of diphenylacetylene (PhC≡CPh) yields the first stable actinide metallacyclopropene [η(5)-1,2,4-(Me3C)3C5H2]2Th(η(2)-C2Ph2) (2). The magnetic susceptibility data show that 2 is indeed a diamagnetic Th(IV) complex, and density functional theory (DFT) studies suggest that the 5f orbitals contribute to the bonding of the metallacyclopropene Th-(η(2)-C═C) moiety. Complex 2 shows no reactivity toward alkynes, but it reacts with a variety of heterounsaturated molecules such as aldehyde, ketone, carbodiimide, nitrile, organic azide, and diazoalkane derivatives. DFT studies complement the experimental observations and provide additional insights. Furthermore, a comparison between Th and group 4 metals reveals that Th(4+) shows unique reactivity patterns.

N-H ketoimines 3a-3v are readily prepared in high yield via organometallic addition to nitriles and isolated as corresponding bench-stable hydrochloride salts. Homogeneous asymmetric hydrogenation of unprotected N-H ketoimines 3a-3v using Ir-(S,S)-f-binaphane as catalyst provides chiral amines 4a-4v in 90-95% yield with enantioselectivities up to 95% ee.

The first highly enantioselective iridium-catalyzed hydrogenation of cyclic enamines has been developed. This new reaction provided an efficient method for the synthesis of optically active cyclic tertiary amines including natural product crispine A.

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.