Synthesis and properties of new (Phosphinoylmethyl)pyridine N-oxides

Sylvie L. Pailloux, Daniel Rosario-Amorin, Manab Chakravarty, Jean Michel Camus, Karen Ann Smith, Eileen N. Duesler, Diane A. Dickie, Robert T. Paine, Kevin K. Klausmeyer, Daniel A. Padron, Benjamin P. Hay, Laetitia H. Delmau

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

Syntheses for 2-[1-(diarylphosphinoyl)-1-(pyridin-2-yl)methyl]pyridines, (8a, b), and 2-[1-(diarylphosphinoyl)-1, 1-bis(methylpyridin-2yl)methyl] pyridines, (11a, b), (Ar = C6H5 and 2-CF3C 6H4), based on substitution of 2-methylpyridine fragments onto the exo methylene carbon atom of 2-[(diaryl)phosphinoylmethyl]pyridine platforms, are described. N-oxidations of 8a, b and 11a, b produced the 2-[1-(diarylphosphinoyl)-1-(1-oxy-pyridin-2yl)methyl]pyridine N-oxides (5a, b) and the 2-[1-(diarylphosphinoyl)-1, 1-bis(1-oxy-methylpyridin-2-yl)methyl] pyridines (6a, b), respectively. The "short-arm" pyridine fragment of 11a, b resists N-oxidation, and the fully oxidized molecules, 2-[1-(diarylphosphinoyl)-1, 1-bis(1-oxy-methylpyridin-2-yl)methyl]pyridine N-oxides (7a, b) were not isolated. Molecular mechanics calculations for gas phase 1:1 ligand/lanthanide complexes indicated that 5a should accommodate a tridentate NO(meNO)PO coordination mode with minimal steric strain. In contrast, 7a cannot form tetradentate NO(meNO)2PO chelates; however, tridentate binding should be accessible with minimal ligand strain. Coordination complexes of 8a, b, 5a, b, 6a, b and 11a, b with Ln(NO3)3 salts were isolated and a X-ray crystal structure for [Er(8a)(NO 3)3(MeOH)2]·CH2Cl 2, revealed a monodentate Er-O=P interaction. On the other hand, complexes formed by a more symmetrical trifunctional phenylphosphino-bis-2- methylpyridine N, N, P-trioxide ligand, (meNO)2PO*, {La[(meNO)2PO*)](OTf)2(MeOH)3(H 2O)+}(OTf-) and {Pr[(meNO)2PO* )](OTf)(MeOH)4+}(OTf-)2, realized a tridentate coordination mode. Solvent extraction behaviors for EuIII and AmIII in nitric acid solutions using 5a, b, 6a, b, Ph 3PO and the parent bifunctional ligand 2-[(diphenylphosphanyl)methyl] pyridine N, P-dioxide (3a) in 1, 2-dichloroethane were assessed, and 5a, b and 6a, b were found to behave more like Ph3PO than 3a.

Original languageEnglish (US)
Pages (from-to)1101-1116
Number of pages16
JournalZeitschrift fur Anorganische und Allgemeine Chemie
Volume639
Issue number7
DOIs
StatePublished - Jun 2013

Keywords

  • Actinides
  • Coordination chemistry
  • Lanthanides
  • Phosphine oxides
  • Pyridine N-oxides
  • Solvent extraction
  • X-ray diffraction

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