Preparation of the copper(II) complex of the binucleating hexaaza macrocycle 2,5,8,17,20,23-hexaaza[9.9]paracyclophane and its solution chemistry, hydrolytic activity and acid dissociation kinetics

T Clifford, A M Danby, P Lightfoot, D T Richens, R W Hay

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32 Citations (Scopus)

Abstract

The binucleating hexaaza macrocycle 2,5,8,17,20,23-hexaaza[9.9]paracyclophane (PEA) and its N-permethylated derivative 2,5,8,17,20,23-hexamethyl-2,5,8,17,20,23-hexaaza[9.9]paracyclophane (Me(6)PEA) have been prepared. The copper(II) complex of PEA has been prepared and the stability constants of the copper complexes determined in aqueous solution by potentiometric and spectrophotometric methods. The protonation sites of PEA have been identified by NMR titration. The crystal structure of the complex [Cu-2(PEA)Cl-3]Cl-+(-).2.6MeCN .2.9H(2)O has been determined. The copper centres have an N3Cl2 donor set with a square pyramidal geometry. The Cu . . . Cu distance is 7.02 Angstrom. The copper complex catalyses hydrolysis of the phosphotriester 2,4-dinitrophenyl diethyl phosphate (DNPDEP) and the [Cu-2(PEA)(OH)(2)](2+) and [Cu-2(PEA)(OH)](3+) complexes have been identified as the active species. The acid catalysed dissociation of the copper complex has been studied by stopped-flow methods. The reaction is monophasic and displays saturation kinetics at high acidities.

Original languageEnglish
Pages (from-to)240-246
Number of pages7
JournalJournal of the Chemical Society, Dalton Transactions
Issue number3
DOIs
Publication statusPublished - 2001

Keywords

  • NUCLEAR MAGNETIC-RESONANCE
  • AMINO-ACIDS
  • SHIFTS
  • PHOSPHATE
  • LIGAND
  • DECOMPOSITION
  • MECHANISM
  • CATALYSIS
  • CRYSTAL

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