Ghosh Somdatta, Cirera Jordi, Vance Michael A, Ono Tetsuya, Fujisawa Kiyoshi, Solomon Edward I
Department of Chemistry, Stanford University, Stanford, California 94305, USA.
J Am Chem Soc. 2008 Dec 3;130(48):16262-73. doi: 10.1021/ja8044986.
A combination of spectroscopies and DFT calculations have been used to define the electronic structures of two crystallographically defined Cu(II)-phenolate complexes. These complexes differ in the orientation of the phenolate ring which results in different bonding interactions of the phenolate donor orbitals with the Cu(II), which are reflected in the very different spectroscopic properties of the two complexes. These differences in electronic structures lead to significant differences in DFT calculated reactivities with oxygen. These calculations suggest that oxygen activation via a Cu(I) phenoxyl ligand-to-metal charge transfer complex is highly endergonic (>50 kcal/mol), hence an unlikely pathway. Rather, the two-electron oxidation of the phenolate forming a bridging Cu(II) peroxoquinone complex is more favorable (11.3 kcal/mol). The role of the oxidized metal in mediating this two-electron oxidation of the coordinated phenolate and its relevance to the biogenesis of the covalently bound topa quinone in amine oxidase are discussed.
光谱学方法与密度泛函理论（DFT）计算相结合，用于确定两种晶体结构明确的铜（II）-酚盐配合物的电子结构。这两种配合物的酚盐环取向不同，导致酚盐供体轨道与铜（II）之间的键合相互作用不同，这反映在两种配合物截然不同的光谱性质上。电子结构的这些差异导致DFT计算得出的与氧的反应活性存在显著差异。这些计算表明，通过铜（I）苯氧基配体到金属的电荷转移配合物进行氧活化是高度吸热的（>50千卡/摩尔），因此是不太可能的途径。相反，酚盐的双电子氧化形成桥连的铜（II）过氧醌配合物更有利（11.3千卡/摩尔）。讨论了氧化态金属在介导配位酚盐的这种双电子氧化中的作用及其与胺氧化酶中共价结合的topa醌生物合成的相关性。
