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Complexation of Cu 2+ by Binucleating Macrocycles Containing the N 6 Donor Set
Author(s) -
Cruse Richard W.,
Kaderli Susan,
Spieler Walter,
Zuberbühler Andreas D.
Publication year - 1988
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19880710308
Subject(s) - chemistry , cyclic voltammetry , crystallography , stereochemistry , stability constants of complexes , electrochemistry , aqueous solution , electrode
The hexadentate ligands 1,4,7,12,15,18‐hexaazacyclododecosane ([2]aneN 6 ) and 1,4,7,14,17,20‐hexaazacyclohexacosane ([26]aneN 6 ) both form eight complexes with Cu 2+ , three of them being binuclear. The corresponding stability constants have been determined potentiometrically, and the electronic absorption spectra have been obtained from spectrophotometric data. Possible interactions of the Cu 2+ pairs in the three binuclear complexes have, in addition, been investigated by ESR and and linear ‐sweep voltammetry (LSV). The binuclear complex of [22]aneN 6 with one addditional OH group is exceptionally stable, ESR‐silent, and the results of the LSV‐experiments are characteristically different from those of the other binuclear complexes with both ligands. This indicates that [22]aneN 6 forms a very stable hydroxo‐bridged binuclear Cu 2+ complex Cu 2 L(OH) 3+ , whereas in the case of [26]andN 6 no bridged Cu 2+ pair exists.