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 -C₅ Me₅ )₂ Th=N(mesityl)(DMAP)] (3), prepared from [(η⁵ -C₅ Me₅ )₂ ThMe₂ ] (1) and mesitylNH₂ or [(η⁵ -C₅ Me₅ )₂ Th(NHmesityl)₂ ] (2) in the presence of 4-(dimethylamino)pyridine (DMAP), with copper(I) halides gave the first thorium-copper heterobimetallic compounds [(η⁵ -C₅ Me₅ )₂ Th(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 -C₅ Me₅ )₂ ThMe₂ ] (1). Furthermore, a comparison between Th and early transition metals confirmed that Th⁴⁺ exhibits distinctively different reactivity from d-transition metals.