The First Molecular Borophosphonate Cage: Synthesis, Spectroscopy, and Single-Crystal X-ray Structure

The synthesis of the first molecular borophosphonate, [ t -BuPO 3 BEt] 4 ( 1 ), has been achieved from the reaction of tert -butylphosphonic acid and triethylboron in refluxing toluene/1,4-dioxane. The inorganic B 4 O 12 P 4 cubic framework in 1 is enveloped by butyl and ethyl groups, making the compound highly soluble in common organic solvents. The reactive B−C bonds present in the four corners of 1 might offer the possibility of the use of this compound as a starting material for building supramoleclar borophosphonate/phosphate structures.