Department of Chemistry & Biochemistry, Utah State University, Logan, UT 84322-0300, USA.
Dalton Trans. 2023 Mar 28;52(13):4152-4160. doi: 10.1039/d2dt03727k.
Mononuclear bipyridine (bpy)-ligated Co(II) chlorodiketonate complexes [(bpy)Co(R-PhC(O)C(Cl)C(O)R-Ph)]ClO (R = -H (8), -CH (9), and -OCH (10)), were prepared, characterized and investigated for O-dependent aliphatic C-C bond cleavage reactivity. Complexes 8-10 have a distorted psuedo-octahedral geometry. H NMR spectra of 8-10 in CDCN show signals for the coordinated diketonate moiety, and signals suggesting ligand exchange reactivity leading to the formation of a small amount of (bpy)Co (11) in solution. While 8-10 are air stable at room temperature, illumination at 350 nm results in oxidative cleavage reactivity within the diketonate moiety leading to the formation of 1,3-diphenylpropanetrione, benzoic acid, benzoic anhydride, and benzil. Illumination of 8 under O results in a high level of O incorporation (>80%) in the benzoate anion. The product mixture, high level of O incorporation, and additional mechanistic studies suggest a reaction sequence wherein light-induced reactivity leads to the formation of a triketone intermediate that undergoes either oxidative C-C bond cleavage or benzoyl migration promoted by a bipyridine-ligated Co(II) or Co(III) fragment.
单核双吡啶（bpy）配位的 Co(II) 氯代二酮酸盐配合物 [(bpy)Co(R-PhC(O)C(Cl)C(O)R-Ph)]ClO（R=-H（8）、-CH（9）和-OCH（10））被制备、表征并研究了其与 O 相关的脂肪族 C-C 键断裂反应活性。配合物 8-10 具有扭曲的拟八面体几何形状。8-10 在 CDCN 中的 1H NMR 谱显示出配位二酮酸部分的信号，以及表明配体交换反应性的信号，导致在溶液中形成少量 (bpy)Co（11）。虽然 8-10 在室温下在空气中稳定，但在 350nm 光照射下会导致二酮酸部分发生氧化断裂反应，生成 1,3-二苯基丙二酮、苯甲酸、苯甲酸酐和苯偶姻。在 O 下照射 8 会导致苯甲酸阴离子中 O 的高掺入水平（>80%）。产物混合物、高的 O 掺入水平和额外的机理研究表明，反应序列是光诱导反应导致三酮中间体的形成，该中间体通过双吡啶配位的 Co(II) 或 Co(III) 片段经历氧化 C-C 键断裂或苯甲酰迁移。
