Enantiomerically Pure Tetravalent Neptunium Amidinates: Synthesis and Characterization

The synthesis of a tetravalent neptunium amidinate [NpCl((S)‐PEBA)(3)] (1) ((S)‐PEBA=(S,S)‐N,N′‐bis‐(1‐phenylethyl)‐benzamidinate) is reported. This complex represents the first structurally characterized enantiopure transuranic compound. Reactivity studies with halide/pseudohalides yielding [NpX((S)‐PEBA)(3)] (X=F (2), Br (3), N(3) (4)) have shown that the chirality‐at‐metal is preserved for all compounds in the solid state. Furthermore, they represent an unprecedented example of a structurally characterized metal–organic Np complex featuring a Np−Br (3) bond. In addition, 4 is the only reported tetravalent transuranic azide. All compounds were additionally characterized in solution using para‐magnetic NMR spectroscopy showing an expected C (3)‐symmetry at low temperatures.