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Zur Stabilität und Struktur der Cu I ‐Komplexe des Imidazols und Histamins. Chemie des einwertigen Kupfers in homogener, polarer Lösung. 1. Mitteilung
Author(s) -
Sigwart C.,
Kroneck P.,
Hemmerich P.
Publication year - 1970
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.19700530125
Subject(s) - chemistry , ligand (biochemistry) , chelation , denticity , steric effects , hydrate , imidazole , aqueous solution , copper , medicinal chemistry , stereochemistry , crystallography , inorganic chemistry , crystal structure , receptor , organic chemistry , biochemistry
Univalent copper is stabilized in aqueous medium by the non‐protophilic ligand CH 3 CN, allowing ligand displacement reactions to be investigated as if a stable Cu I ‐hydrate did exist. Under these conditions the formation of Cu I ‐complexes with imidazole and its derivatives has been studied in polar solution in the absence of Cu II . Imidazole (ImH) acts upon Cu I as a bidentate ligand forming polynuclear chains according to the equationHistamine reacts in the same way, i. e. the coordination number of Cu I does not exceed 2; by comparison of the complexes of Cu I with histamine and its N‐methyl‐derivatives it is shown that no six‐membered chelate – which sterically would be possible – is built up. Trigonal as well as tetrahedral coordination of Cu I – i. e. chelate formation – in dilute polar solutions are confined to π‐ or d ‐acceptor ligands, e. g. bipyridine or methionine. Conclusions are drawn from this on the requirements for redox‐active copper in proteins.