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,4is the only reported tetravalent transuranic azide. All compounds were additionally characterized in solution usingpara-magnetic NMR spectroscopy showing an expectedC(3)-symmetry at low temperatures.