ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The synthesis and properties of the molecular reduction device 7b (CoII-V5++) consisting of a reduction catalyst (a derivative of vitamin B12, CoII) and a covalently linked 10-electron reservoir (five viologen units, V++) is described. The five viologen subunits were introduced at C(2) and C(3) of the side chains c and g and b, e and f, respectively, of an appropriate derivative of heptamethyl cob(III)yrinate by N-alkylation of 1-methyl-4,4′-bipyridinium iodide (see Scheme). The pentaviologen-linked corrinatocobalt(II) complex 7b behaves as a molecular electron trap with respect to the CoIII/CoII redox couple. The phenomenon is related to the structural and thermodynamic relation of the corrin and viologen subunits in 7b, i.e. the relative redoc energies and the spherical inner-outer arrangement of the types of redox systems. When completely reduced to CoI-V50, 7b exhibits multiple reductive elimination of trans-1,2-dibromocyclohexane to cyclohexene under concomitant oxidation to CoII-V5++. Rate measurements indicate that the reduction occurs via CoI which is regenerated by intramolecular electron transfer from the periphery of the molecule, i.e. by V0 and V++.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19920750107
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