Theoretical insights on the complexation of Am(III) and Cm(III) with amide-type ligands

Separation of adjacent actinides (An) americium and curium is a critical and challenging step in advanced nuclear fuel cycles. Herein, we performed a quantum chemical calculation to explore the separation behavior of Am(III) from Cm(III) by two representative amide-type ligands, N,N '-dimethyl-N,N '-dioctyl-2-(2-hexyloxyethyl)malonamide (DMDOHEMA) and N,N,N ',N ',N '',N ''-hexaalkyl-nitrilotriacetamide (NTAamide). It was found that the better energy match of Am 5f orbitals and O, N 2p orbitals of the amide-type ligands resulted in the selective ability of these ligands to Am3+ over Cm3+. Complexation reaction analysis predicted that An(DMDOHEMA)(2)(NO3)(3) and [An(NTAamide)(2)](3+) were the most probable species in the separation processes.