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, Na2BP2, 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 BP23– anionic monomers found in a Na3BP2 precursor
into unique 1D BP22– chains consisting
of five-member B2P3 rings connected by bridging
P atoms in the crystal structure of Na2BP2.
The synthesis was guided by in situ X-ray powder
diffraction studies, which revealed the metastable nature of the products
of oxidative elimination reactions. Na2BP2 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.