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Synthesis, Structure and Reactivities of Pentacoordinated Phosphorus–Boron Bonded Compounds

revised on 03.03.2020, 07:02 and posted on 04.03.2020, 05:27 by Nathan O'Brien, Naokazu Kano, Nizam Havare, Ryohei Uematsu, Romain Ramozzi, Keiji Morokuma
The isolation and reactivities of two pentacoordinated
phosphorus–tetracoordinated boron bonded compounds were explored. A strong Lewis acidic boron reagent and electronwithdrawing ligand system were required to form the pentacoordinated phosphorus state of the P–B bond. The first compound, a phosphoranyl-trihydroborate, gave a THF stabilised phosphoranyl-borane intermediate upon a single hydride abstraction in THF. This compound could undergo a unique rearrangement reaction, which involved a two-fold ring expansion, to give a fused bicyclic compound or it could act as a mono-hydroboration reagent. The hydroboration reactivity of the intermediate was found to be more reactive towards alkynes over alkenes with good to moderate regioselectivity towards the terminal carbon. The second compound, a phosphoranyl-triarylborate, was found to have different reactivity as it was highly stable towards acids and bases. This is thought to be due to the large bulk around the P–B bond as shown in the crystal structure.


Email Address of Submitting Author


University of Tokyo



ORCID For Submitting Author


Declaration of Conflict of Interest

There are no conflicts of interest.

Version Notes

Note: While this work was carried out at the University of Tokyo, Nathan O'Brien is currently located at Linköping University.