Directing Boron–Phosphorus Bonds in Crystalline Solid: Oxidative Polymerization of P═B═P Monomers into 1D Chains

Over 20 years after the last inorganic ternary B-P compound was reported, Na 2 BP 2 , a new compound containing one-dimensional B-P polyanionic chains has been synthesized. Common high-temperature synthetic methods required for the direct reaction of boron and phosphorus negate the possible formation of metastable or low temperature phases. In this study, oxidative elimination was used to successfully condense 0D BP 2 3- anionic monomers found in a Na 3 BP 2 precursor into unique 1D BP 2 2- chains consisting of five-member B 2 P 3 rings connected by bridging P atoms in the crystal structure of Na 2 BP 2 . The synthesis was guided by in situ X-ray powder diffraction studies, which revealed the metastable nature of the products of oxidative elimination reactions. Na 2 BP 2 is predicted to be an electron balanced semiconductor which was confirmed by UV-vis spectroscopy with the experimentally determined band gap of 1.1 eV.