title: Zinc-thiolate complexes of the bis(pyrazolyl)(thioimidazolyl)hydroborate tripods for the modeling of thiolate alkylating enzymes.
abstract: The new tripod ligands bis(pyrazolyl)(3-tert-butyl-2-thioimidazol-1-yl)hydroborate (L(1)) and bis(pyrazolyl)(3-isopropyl-2-thioimidazol-1-yl)hydroborate (L(2)), together with zinc nitrate or zinc chloride and the corresponding thiolates, have yielded a total of 17 zinc-thiolate complexes. These comprise aliphatic as well as aromatic thiolates and a cysteine derivative. Structure determinations have confirmed the tetrahedral ZnN(2)S(2) coordination in the complexes. Upon reaction with methyl iodide, the species L(1).Zn-SR are slowly converted to L(1).Zn-I and the free thioethers CH(3)SR. A kinetic analysis has shown these alkylations to be about 1 order of magnitude slower than those of the tris(pyrazolyl)borate complexes Tp(Ph,Me)Zn-SR. Alkylations with trimethyl phosphate were found to proceed very slowly even in DMSO at 80 degrees C.
authors.affiliation: Institut für Anorganische und Analytische Chemie der Universität Freiburg, Germany.
authors.forename: Mian
authors.initials: M
authors.lastname: Ji
authors.forename: Boumahdi
authors.initials: B
authors.lastname: Benkmil
authors.forename: Heinrich
authors.initials: H
authors.lastname: Vahrenkamp
mesh_terms: D000478:Alkylation; D002384:Catalysis; D002712:Chlorides; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000138:chemical synthesis; D004798:Enzymes / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008667:Metalloproteins / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D008956:Models, Chemical; D008968:Molecular Conformation; D015394:Molecular Structure; D009566:Nitrates; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D015032:Zinc / Q000737:chemistry* / Q000378:metabolism; D017967:Zinc Compounds
chemical_list: D002712:Chlorides; D004798:Enzymes; D008667:Metalloproteins; D009566:Nitrates; D013438:Sulfhydryl Compounds; D017967:Zinc Compounds; C016837:zinc chloride; C042103:zinc nitrate; D015032:Zinc; D003545:Cysteine