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Zinc Complexes of Amino Acids and Peptides, 9[ ]. Coordination of Cysteine and Histidine Derivatives to the Pyrazolylborate‐Zinc Unit
Author(s) -
Ruf Michael,
Burth Rainer,
Weis Karl,
Vahrenkamp Heinrich
Publication year - 1996
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19961291017
Subject(s) - chemistry , histidine , imidazole , zinc , denticity , cysteine , chelation , cationic polymerization , stereochemistry , carboxylate , amino acid , medicinal chemistry , polymer chemistry , metal , organic chemistry , biochemistry , enzyme
Abstract Highly substituted pyrazolylborate ligands Tp R,Me were used to limit the coordination number of zinc towards cysteine‐ and histidine‐derived coligands. Monodentate thiolate attachment (→ 1a–f ) was achieved with N ‐ and C ‐protected cysteine, monodentate carboxylate attachment (→ 3 ) with N ‐protected histidine. C ‐protected cysteine was found to form a five‐membered N,S ‐chelate ring ( 2 ). While imidazole coordination with N ‐ and C ‐protected histidine could not be achieved, cationic pyrazolylborate‐zinc‐coligand complexes [TpZn–L] + ( 4a, b ) were obtained for L = 2‐methylimidazole. The new complexes were characterized by their spectra and three structure determinations.