Structural and metal-halogen exchange reactivity studies of sodium magnesiate biphenolate complexes

Callum Yeardley, Alan R. Kennedy, Philippe C. Gros, Sabrina Touchet, Michael Fairley, Ross McLellan, Antonio J. Martínez-Martínez, Charles T. O'Hara

Research output: Contribution to journalArticlepeer-review

Abstract

Bimetallic sodium magnesiates have been employed in metal-halogen exchange for the first time. Utilising the racemic phenoxide ligand 5,5´,6,6´-tetramethyl-3,3´-di-tert-butyl-1,1´-biphenyl-2,2´-diol [(rac)-BIPHEN-H2], the dialkyl sodium magnesiates [(rac)-BIPHEN]Na2MgBu2(TMEDA)2 3 and [(rac)-BIPHEN]Na2MgBu2(PMDETA)2 4 have been synthesised. Both 3 and 4 can be easily prepared through co-complexation of di-n-butylmagnesium with the sodiated (rac)-BIPHEN precursor which can be prepared in situ in hydrocarbon solvent. Prior to the main investigation, synthesis of the sodiated precursor [BIPHEN]2Na4(THF)4 1 was explored in order to better understand the formation of sodium magnesiates utilising the dianionic (rac)-BIPHEN ligand as the parent ligand. In addition, a BIPHEN-rich sodium magnesiate [BIPHEN]2Na2Mg(THF)4 2 was prepared and characterised, and its formation was rationalised. Complex 1 and 4 have also been fully characterised in both solid and solution state. In terms of onward reactivity, 3 and 4 have been tested as potential exchange reagents with aryl and heteroaryl iodides to produce aryl and heteroaryl magnesium phenoxides utilising toluene as a non-polar hydrocarbon solvent. Complex 3 reacted smoothly to give a range of aryl and heteroaryl magnesium phenoxides, whilst 4’s reactivity is more sluggish.
Original languageEnglish
Pages (from-to)5257-5263
Number of pages7
JournalDalton Transactions
Volume49
Issue number16
Early online date3 Apr 2020
DOIs
Publication statusPublished - 28 Apr 2020

Keywords

  • bimetallic sodium magnesiates
  • metal-halogen exchange
  • hydrocarbon solvent

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