Structure and physical properties of several pseudotetrahedral zinc complexes containing a new alkyl thiolate heteroscorpionate ligand

Abstract

A series of pseudotetrahedral and octahedral zinc(II) complexes of the heteroscorpionate ligand bis(3,5-dimethylpyrazolyl)(1-methyl-1-sulfanylethyl)methane (L3SH) have been synthesized and most characterized by X-ray crystallography. Pseudotetrahedral complexes isolated include [Zn(L3S)(CH₃)], [Zn(L3S)(Cl)], [Zn(L3S)(OAc)], [Zn(L3S)(SPh^F5)], [Zn(L3S)(SBz)] (Bz = CH₂Ph), [Zn(L3S)(OPh^p-NO₂)], and [Zn(L3S)₂]. In addition, the octahedral complex [Zn₂{(L3S)₂Zn}{O₂P(OPh)₂}₄] was also synthesized. Comparisons between these complexes and those of the corresponding tris(pyrazolyl)borate, Tp⁻, or aromatic phenol or benzenethiolate ligands (L1O)⁻ and (L2S)⁻ reveal significant differences. Among these is a change in binding of acetate from pure unidentate to anisobidentate as the ligand donor is changed from S to N to O. Trends such as these may aid in understanding how the donor set affects the structure and reactivity at pseudotetrahedral zinc centers in metalloproteins.