Crystallographic, X-ray Absorption, and IR Studies of Solid- and Solution-State Structures of Tris(nitrato) N,N,N‘,N‘-Tetraethylmalonamide Complexes of Lanthanides. Comparison with the Americium Complex

To fine-tune the design of optimized donor ligands for nuclear waste actinide selective extraction, both electronic and molecular structures of the actinide complexes that are formed must be investigated. In particular, to achieve the selective complexation of transplutonium 3+ ions versus lanthanide 3+ ions is one of the major challenges, given the chemical similarities between these two f-element families. In this work, the structure of solvent-phase M(NO3)3(TEMA)2 complexes (Ln = Nd, Eu, Ho, Yb, Lu, Am; TEMA = N,N,N‘,N‘-tetraethylmalonamide) was investigated by liquid-phase spectroscopic methods among which extended X-ray absorption fine structure played a major role. In addition, the crystal structures of the species Nd(NO3)3(TEMA)2 and Yb(NO3)3(TEMA)2 have been determined by X-ray diffraction. Nd(NO3)3(C11N2O2H22)2 crystallizes in the monoclinic system (P21 space group; a = 11.2627(4) A, b = 20.5992(8) A, c = 22.2126(8) A; α = γ = 90°, β = 102.572(1)°; Z = 6), and Yb(NO3)3(C11N2O2H22)2 crystallizes i...