Berreau Lisa M, Saha Amrita, Arif Atta M
Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, UT 84322-0300, USA.
Dalton Trans. 2006 Jan 7(1):183-92. doi: 10.1039/b512515d. Epub 2005 Nov 23.
A recently reported binuclear zinc hydroxide complex (L(1)Zn(2))(mu-OH)(2) (, L(1) = 2,6-bis[(bis(2-pyridylmethyl)amino)methyl]-4-methylphenolate monoanion) containing a single bridging hydroxide was examined for thioester hydrolysis reactivity. Treatment of it with hydroxyphenylthioacetic acid S-methyl ester in dry CD(3)CN results in no reaction after approximately 65 h at 45(1) degrees C. Binuclear zinc hydroxide complexes of the N-methyl-N-((6-neopentylamino-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine (L(2)) and N-methyl-N-((6-neopentylamino-2-pyridyl)methyl)-N-((2-pyridyl)ethyl)amine (L(3)) chelate ligands were prepared by treatment of each ligand with molar equivalent amounts of Zn(ClO(4))(2).6H(2)O and KOH in methanol. These complexes, (L(2)Zn)(2)(mu-OH)(2)(2) and (L(3)Zn)(2)(mu-OH)(2)(2) (), which have been structurally characterized by X-ray crystallography, behave as 1 : 1 electrolytes in acetonitrile, indicating that the binuclear cations dissociate into monomeric zinc hydroxide species in solution. Treatment of them with one equivalent of hydroxyphenylthioacetic acid S-methyl ester per zinc center in acetonitrile results in the formation of a zinc alpha-hydroxycarboxylate complex, [(L(2))Zn(O(2)CCH(OH)Ph)]ClO(4).1.5H(2)O or [(L(3))Zn(O(2)CCH(OH)Ph)]ClO(4).1.5H(2)O, and CH(3)SH. These reactions, to our knowledge, are the first reported examples of thioester hydrolysis mediated by zinc hydroxide complexes. The results of this study suggest that a terminal Zn-OH moiety may be required for hydrolysis reactivity with a thioester substrate.
最近报道了一种含单个桥连氢氧化物的双核氢氧化锌配合物(L(1)Zn(2))(μ-OH)(2)（L(1) = 2,6-双[(双(2-吡啶甲基)氨基)甲基]-4-甲基苯酚单阴离子），并对其硫酯水解反应活性进行了研究。在干燥的CD(3)CN中，于45(1)℃下将其与羟基苯硫代乙酸S-甲酯处理约65小时后未发生反应。通过将N-甲基-N-((6-新戊基氨基-2-吡啶基)甲基)-N-((2-吡啶基)甲基)胺（L(2)）和N-甲基-N-((6-新戊基氨基-2-吡啶基)甲基)-N-((2-吡啶基)乙基)胺（L(3)）螯合配体与摩尔当量的Zn(ClO(4))(2).6H(2)O和KOH在甲醇中反应，制备了双核氢氧化锌配合物。这些配合物(L(2)Zn)(2)(μ-OH)(2)(2)和(L(3)Zn)(2)(μ-OH)(2)(2)（已通过X射线晶体学进行了结构表征）在乙腈中表现为1:1电解质，这表明双核阳离子在溶液中解离为单体氢氧化锌物种。在乙腈中，每个锌中心用一当量的羟基苯硫代乙酸S-甲酯处理它们，会形成锌α-羟基羧酸盐配合物[(L(2))Zn(O(2)CCH(OH)Ph)]ClO(4).1.5H(2)O或[(L(3))Zn(O(2)CCH(OH)Ph)]ClO(4).1.5H(2)O以及CH(3)SH。据我们所知，这些反应是首次报道的由氢氧化锌配合物介导的硫酯水解实例。该研究结果表明，与硫酯底物发生水解反应活性可能需要一个末端Zn-OH部分。
