Experimental and Computational Studies on the Formation of Thorium-Copper Heterobimetallics

The formation of actinide–transition metal heterobimetallics mediated by a terminal actinide imido complex was comprehensively studied. The reaction of the thorium imido complex [(η5‐C5Me5)2Th=N(mesityl)(DMAP)] (3), prepared from [(η5‐C5Me5)2ThMe2] (1) and mesitylNH2 or [(η5‐C5Me5)2Th(NHmesityl)2] (2) in the presence of 4‐(dimethylamino)pyridine (DMAP), with copper(I) halides gave the first thorium–copper heterobimetallic compounds [(η5‐C5Me5)2Th(X){N(mesityl)Cu(DMAP)}] (X=Cl (4), Br (5), I (6)). Complexes 4–6 feature an unusual geometry with a short Th−Cu distance, which DFT studies attribute to a weak donor–acceptor bond from the Cu+ atom to the electropositive Th4+ atom. They are reactive species, as was shown by their reaction with the dimethyl complex [(η5‐C5Me5)2ThMe2] (1). Furthermore, a comparison between Th and early transition metals confirmed that Th4+ exhibits distinctively different reactivity from d‐transition metals. Time for thorium! Experimental and computational studies revealed that the thorium–copper bond is best described as a weak donor–acceptor interaction between the electron‐rich CuI and the electropositive ThIV atoms (see scheme).