Interplay of Ionic Species in Salts of Homoleptic Quaternary Phosphonium Cations Bearing Linear Biphenyl Moieties

Monica Bernard Tan, Alexandre N. Sobolev, Colin L. Raston, Scott J. Dalgarno, Irene Ling

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Quaternary phosphonium salts are popular candidates used in many chemical transformations and synthetic chemistry, notably in catalysis. We have examined the single crystals of two bulky phosphonium compounds, tetra([1,1′-biphenyl]-4-yl) phosphonium dicyanamide (C48H36P+·N(CN)2, compound 1), and tetra([1,1′-biphenyl]-4-yl) phosphonium bromide hydrate (C48H36P+·Br, CH3CN, H2O, compound 2), and herein report the structural properties for the compounds with an emphasis on the influence of the ion-ion interaction towards self-assembly; the overall self-assembly for both structures is very similar, with subtle differences in the cell parameters. The symmetrical tetra ([1,1′-biphenyl]-4-yl) phosphonium cations in both compounds self-assembled to form robust stacked columns in the solid-state, with voids occupied by anions or solvent molecules. Quantitative examination of intermolecular interactions using Hirshfeld surface analysis found that classical and non-classical hydrogen bonding appears to be the dominant contributor in stabilizing the self-assembly in both cases. The present work can not only benefit in understanding the mutual interaction between the sterically encumbered tetra ([1,1′-biphenyl]-4-yl) phosphonium cations and between counterions, but also provide insights for the self-assembled arrays in the solid-state.

Original languageEnglish
Article number59
Number of pages10
Issue number1
Early online date29 Dec 2022
Publication statusPublished - Jan 2023


  • biphenyl
  • crystal structure
  • Hirshfeld surface
  • phosphonium
  • self-assembly


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