期刊
POLYHEDRON
卷 23, 期 2-3, 页码 481-488出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.poly.2003.11.035
关键词
zinc; enzyme; thiolate; alkylation
The tris(2-mercapto-1-arylimidazolyl)hydroborato complexes {[Tm-Ar]Zn(mim(Ar))}[ClO], which feature tetrahedrally coordinated zinc centers in a sulfur rich environment, may be prepared by the reaction of [Tm-Ar]Li with Zn(ClO4)(2) in the presence of 2-mercapto-1-arylimidazole (mim(Ar); Ar = Ph, p-Tol). X-ray diffraction studies demonstrate that the mim(Ar) ligands are almost orthogonal to the Zn-S-C plane, in contrast to the almost planar arrangement that is calculated for {[Tm-H]Zn(mim(H))}(+) and {[Tm-H]Zn(mim(Me))}(+). The orthogonal arrangement observed experimentally for both {[Tm-Ph]Zn(mim(Ph))}(+) and {[TMp-Tol]Zn(Mim(p-Tol))}(+) is a consequence of the existence of a N-H...O hydrogen bond between the N-H group of the mim(Ar) ligand and a molecule of methanol. Evidently, the hydrogen bonding interactions in {[Tm-Ar]Zn(mim(Ar))...(HOMe)}(+) are sufficiently strong to counter the electronic destabilization resulting from rotation of the mimAr ligand from the Zn-S-C plane. The mim(Ph) ligand of {[Tm-Ph]Zn(mim(Ph))}(+) may be immediately displaced by I- to give [Tm-Ar]ZnI; however, {[Tm-Ph]Zn(mim(Ph))}(+) does not react rapidly with MeI, thereby demonstrating that the zinc coordinated mim(Ph) ligand is less susceptible to electrophilic attack than is a zinc thiolate ligand. (C) 2003 Published by Elsevier Ltd.
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