Chand Kuldeep, Meitei Naorem Jemes, Chang Yu-Lun, Tsai Cheng-Long, Chen Hsing-Yin, Hsu Sodio C N
Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
ACS Omega. 2023 May 26;8(23):21096-21106. doi: 10.1021/acsomega.3c02004. eCollection 2023 Jun 13.
An investigation on the reactivity of O binding to unsymmetrical β-diketiminato copper(I) complexes by spectroscopic and titration analysis was performed. The length of chelating pyridyl arms (pyridylmethyl arm vs pyridylethyl arm) leads to the formation of mono- or di-nuclear copper-dioxygen species at -80 °C. The pyridylmethyl arm adduct (CuO) forms mononuclear copper-oxygen species and shows ligand degradation, resulting in the formation of (2,3)--(2,6-diisopropylphenyl)-4-((()-pyridin-2-ylmethylene)amino)pent-3-en-2-imine, which slowly converts to its cyclization isomer 1-(2,6-diisopropylphenyl)-4,6-dimethyl-2-(pyridin-2-yl)-1,2-dihydropyrimidine after addition of NHOH at room temperature. On the other hand, the pyridylethyl arm adduct [(Cu)(μ-O)] forms dinuclear species at -80 °C and does not show any ligand degradation product. Instead, free ligand formation was observed after the addition of NHOH. These experimental observations and product analysis results indicate that the chelating length of pyridyl arms governs the Cu/O binding ratio and the ligand degradation behavior.
通过光谱和滴定分析对O与不对称β-二酮亚胺基铜（I）配合物的反应活性进行了研究。螯合吡啶臂的长度（吡啶甲基臂与吡啶乙基臂）导致在-80°C下形成单核或双核铜-氧物种。吡啶甲基臂加合物（CuO）形成单核铜-氧物种并显示配体降解，导致形成（2,3）-（2,6-二异丙基苯基）-4-（（（）-吡啶-2-基亚甲基）氨基）戊-3-烯-2-亚胺，在室温下加入NHOH后，该物质缓慢转化为其环化异构体1-（2,6-二异丙基苯基）-4,6-二甲基-2-（吡啶-2-基）-1,2-二氢嘧啶。另一方面，吡啶乙基臂加合物[（Cu）（μ-O）]在-80°C下形成双核物种，并且没有显示任何配体降解产物。相反，加入NHOH后观察到游离配体的形成。这些实验观察结果和产物分析结果表明，吡啶臂的螯合长度决定了Cu/O结合比和配体降解行为。
