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Biomimetic Thiolate Alkylation with Zinc Pyrazolylbis(thioimidazolyl)borate Complexes
Author(s) -
Ibrahim Mohamed M.,
He Guosen,
Seebacher Jan,
Benkmil Boumahdi,
Vahrenkamp Heinrich
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500276
Subject(s) - tripod (photography) , chemistry , zinc , alkylation , intramolecular force , boron , stereochemistry , medicinal chemistry , organic chemistry , catalysis , physics , optics
The NS 2 ZnX coordination in thiolate‐alkylating zinc enzymes is reproduced in (tripod)ZnX complexes with substituted pyrazolylbis(thioimidazolyl)borate tripod ligands. Intermediate (tripod)Zn nitrates and perchlorates are converted into (tripod)Zn thiolates, including the biologically relevant homocysteinate. Methylation with CH 3 I converts these to (tripod)ZnI and the corresponding thioethers CH 3 SR, including methionine. A kinetic investigation has shown the alkylations to be intramolecular S N 2 processes that take place at the zinc‐bound thiolates. They are considerably faster for the (NS 2 )Zn thiolates than for the (N 2 S)‐ and (N 3 )Zn‐thiolates with similar pyrazolylborate‐derived tripod ligands, in agreement with Nature’s choice of an NS 2 donor set for zinc. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)