Synthetic and computational study of geminally bis(supermesityl) substituted phosphorus compounds

Conor G. E. Fleming, Alexandra M. Z. Slawin, Kasun S. Athukorala Arachchige, Rebecca Randall, Michael Buehl, Petr Kilian*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Reaction chemistry of an extremely sterically encumbered phosphinic chloride (Mes*)(2)P(=O) Cl (Mes* = 2,4,6-tri-t-butylphenyl, supermesityl) was investigated. This compound, as well as other compounds bearing two supermesityl groups placed geminally at the central phosphorus atom, shows extremely low reactivity at the phosphorus centre. Nevertheless, some synthetically significant transformations were possible. Reduction with hydridic reagents under forcing conditions yielded the phosphine oxide (Mes*)(2)P(=O)H and a secondary phosphine Mes*(2,4-tBu(2)C(6)H(3))PH. Deprotonation of (Mes*)(2)P(=O)H gave the corresponding phosphinite, which afforded very crowded tertiary phosphine oxides (Mes*)(2)P(=O) R (R = Me and Et) on reactions with electrophiles. While the reaction of the phosphine Mes*(2,4-tBu(2)C(6)H(3))PH with sulfur was surprisingly facile (although under forcing conditions), we have been unable to chlorinate or deprotonate this phosphine. All new compounds were fully characterised with multinuclear NMR, IR, Raman, MS, microanalyses and single crystal X-ray diffraction. Our computations (B3LYP and M06-2X level) show that strain energies of (synthetically accessible) geminally substituted compounds are extremely high (180 to 250 kJ mol(-1)), the majority of the strain is stored as boat distortions to the phenyl rings in Mes* substituents.

Original languageEnglish
Pages (from-to)1437-1450
Number of pages14
JournalDalton Transactions
Volume42
Issue number5
Early online date6 Nov 2012
DOIs
Publication statusPublished - Nov 2012

Keywords

  • REDOX PROPERTIES
  • BIDENTATE LIGANDS
  • ORGANOPHOSPHORUS COMPOUNDS
  • PHOSPHINE OXIDES
  • BIS(2,4,6-TRI-TERT-BUTYLPHENYL)PHOSPHINIC CHLORIDE
  • DERIVATIVES
  • MAIN-GROUP ELEMENTS
  • CHEMISTRY
  • REDUCTION
  • THERMOCHEMISTRY

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