Neptunium Alkoxide Chemistry: Expanding Alkoxides to the Transuranium Elements.

Two oxo-containing neptunium(IV) tert -butoxides, [Np 3 O(O t Bu) 10 ] ( 1 ) and [K 4 Np 2 O(O t Bu) 10 ] ( 2 ), were synthesized using the ligand substitution between neptunium(IV) silylamides and HO t Bu, whereas the salt metathesis between [NpCl 4 (DME) 2 ] (DME = dimethoxyethane) and various amounts of LiO t Bu resulted in the formation of oxo-free alkoxides [Np(O t Bu) 4 (py) 2 ] ( 3 ; py = pyridine) and [Li(THF)] 2 [Np(O t Bu) 6 ] ( 4 ; THF = tetrahydrofuran). These complexes are the first structurally characterized neptunium(IV) alkoxides using single-crystal X-ray diffraction and solid-state absorption spectroscopy, which provide data for the development of anhydrous metal-organic neptunium chemistry.