Inorganic Chemistry

A Free Phosphaborene Stable at Room Temperature


  • Jiancheng Li Southern University of Science and Technology ,
  • Zhihao Lu Southern University of Science and Technology ,
  • Liu Leo Liu Southern University of Science and Technology


Free phosphaborenes (R−P=B−R) are PB analogs of alkynes and their isolation is a long-sought-after goal. Herein, we demonstrate that the combination of a π-donating and a π-accepting substituent with bulky flanking arene rings enables the isolation of a crystal-line free phosphaborene 5 at room temperature. This electron push-pull cooperation, combined with the kinetic protection, hinders its inherent tendency to oligomerize. This species features a PB double bond consisting of a conventional σ bond and a delocalized π bond. The lone pair of electrons at P slightly contributes to the PB bonding. Preliminary reactivity studies show that 5 undergoes facile (cyclo)addition reactions with p-methyl benzaldehyde, p-fluoroacetophenone and carbon disulfide, the last of which results in facile PB double bond cleavage. Our strategy has a significant impact on the future synthesis of ambiphilic heterodiatomic multiply bonded main group species.

Version notes

Data updated and MS revised


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Supplementary material

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Supporting Information