Expanding the Nonaqueous Chemistry of Neptunium: Synthesis and Structural Characterization of [Np(NR2)3Cl], [Np(NR2)3Cl]−, and [Np{N(R)(SiMe2 CH2)}2(NR2)]− (R = SiMe3)

• Published in: Inorganic chemistry 2021-02, Vol.60 (4), p.2740-2748
• Main Authors: Staun, Selena L, Stevens, Lauren M, Smiles, Danil E, Goodwin, Conrad A. P, Billow, Brennan S, Scott, Brian L, Wu, Guang, Tondreau, Aaron M, Gaunt, Andrew J, Hayton, Trevor W
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.0c03616

Reaction of 3 equiv of NaNR2 (R = SiMe3) with NpCl4(DME)2 in THF afforded the Np­(IV) silylamide complex, [Np­(NR2)3Cl] (1), in good yield. Reaction of 1 with 1.5 equiv of KC8 in THF, in the presence of 1 equiv of dibenzo-18-crown-6, resulted in formation of [{K­(DB-18-C-6)­(THF)}3(μ3-Cl)]­[Np­(NR2)3Cl]2 (4), also in good yield. Complex 4 represents the first structurally characterized Np­(III) amide. Finally, reaction of NpCl4(DME)2 with 5 equiv of NaNR2 and 1 equiv of dibenzo-18-crown-6 afforded the Np­(IV) bis­(metallacycle), [{Na­(DB-18-C-6)­(Et2O)0.62­(κ1-DME)0.38}2(μ-DME)]­[Np­{N(R)­(SiMe2 CH2)}2(NR2)]2 (8), in moderate yield. Complex 8 was characterized by 1H NMR spectroscopy and X-ray crystallography and represents a rare example of a structurally characterized neptunium–hydrocarbyl complex. To support these studies, we also synthesized the uranium analogues of 4 and 8, namely, [K­(2,2,2-cryptand)]­[U­(NR2)3Cl] (2), [K­(DB-18-C-6)­(THF)2]­[U­(NR2)3Cl] (3), [Na­(DME)3]­[U­{N(R)­(SiMe2 CH2)}2(NR2)] (6), and [{Na­(DB-18-C-6)­(Et2O)0.5(κ1-DME)0.5}2(μ-DME)]­[U­{N(R)­(SiMe2 CH2)}2(NR2)]2 (7). Complexes 2, 3, 6, and 7 were characterized by a number of techniques, including NMR spectroscopy and X-ray crystallography.