A Novel Molecular Gallium Phosphonate Cage Containing Sandwiched Lithium Ions: Synthesis, Structure, and Reactivity

The reaction between tert -butylphosphonic acid and an equimolar quantity of LiGaMe 4 in THF and n -hexane (1:1) yields the first molecular lithium gallium phosphonate Li 4 [(MeGa) 6 (μ 3 -O) 2 ( t -BuPO 3 ) 6 ]·(THF) 4 ( 1 ) in 70% yield. Compound 1 has been fully characterized by means of analytical and spectroscopic techniques as well as a single crystal X-ray diffraction study. Compound 1 represents the first molecular ionic gallophosphonate cage which contains coordinated lithium ions in the form of a one-dimensional wire and can be regarded as a potential precursor for the subsequent synthesis of molecular sieves and ion conductors. Compound 1 is unreactive toward air and moisture at room temperature. Treatment of 1 with D 2 O even at 70 °C does not lead to the hydrolysis of the Ga−C bonds. Treatment of a benzene- d 6 solution of 1 with 12-crown-4 followed by D 2 O leads to the facile conversion of the product into the neutral cubic gallium phosphonate cage [ t -BuPO 3 GaMe] 4 ( 2 ).