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

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)(SPhF5)], [Zn(L3S)(SBz)] (Bz = CH2Ph), [Zn(L3S)(OPhp-NO2)], and [Zn(L3S)(2)]. In addition, the octahedral complex [Zn-2{(L3S)(2)Zn}{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.