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Molecular self-modification: homolog of a manganese laundry bleach catalyst oxidatively transforms its tetradentate ligand into a novel hexadentate derivative

  • Guochuan Yin
  • Suparna Baksi Roy
  • Andrew M. Danby
  • Victor Day
  • John Carter
  • William M. Scheper
  • Daryle H. Busch
Original Article

Abstract

On the basis of mass spectral studies alone, the relatively new manganese complex, Mn(Et2EBC)Cl2 (Et2EBC = 4,11-diethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane), a homolog of the well proven, peroxide-based laundry bleach, Mn(Me2EBC)Cl2, has been reported to undergo a sequence of 2-electron oxidation steps, ultimately converting its ethyl groups into chelated ethoxo and methylene carboxylato groups, [MnIV{(OCH2CH2)(O2CCH2)}EBC)](PF6)2. We report here the isolation and characterization of that unusual product, and provide insight into the remarkable catalytic pathway to its formation. At temperatures above 0 °C, oxidation by aqueous H2O2 reliably transforms Mn(Et2EBC)Cl2 into [MnIV{(OCH2CH2)(O2CCH2)}EBC)]2+. The experimental data for this intramolecular ethyl group transformation is consistent with oxygen insertion into a methyl C–H moiety of the ethyl group, –NCH2C(–H)H2, by the MnIV–OOH functional group.

Keywords

Molecular self-modification Oxidation catalyst Hexadentate ligand Manganese(IV) complex Bleach catalyst Insertion mechanism Cross-bridged macrocycle Inorganic chemistry Transition metal chemistry Manganese chemistry Reaction mechanisms Oxygen atom insertion 

Notes

Acknowledgment

Support by the Procter and Gamble Company is deeply appreciated, and we also thank the National Science Foundation Engineering Research Center Grant (EEC-0310689), at the University of Kansas, for partial support. At KU, MS analyses of the manganese(IV) complex under various conditions were performed under the guidance of R. C. Drake, and the crystal structure was determined by Dr Victor Day.

Supplementary material

10847_2011_9974_MOESM1_ESM.doc (97 kb)
Supplementary material 1 (DOC 97 kb)

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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Guochuan Yin
    • 1
  • Suparna Baksi Roy
    • 1
  • Andrew M. Danby
    • 1
  • Victor Day
    • 1
  • John Carter
    • 2
  • William M. Scheper
    • 2
  • Daryle H. Busch
    • 1
  1. 1.Department of ChemistryThe University of KansasLawrenceUSA
  2. 2.The Procter and Gamble CompanyCincinnatiUSA

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