三价轻金属吡唑盐的二氧化碳亲和性（"亲羧性

IF 6.4 1区化学 Q1 CHEMISTRY, INORGANIC & NUCLEAR

Inorganic Chemistry Frontiers Pub Date : 2024-08-23 DOI:10.1039/D4QI01656D

Felix Kracht, Philipp Rolser, Klaus Eichele, Cäcilia Maichle-Mössmer and Reiner Anwander

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摘要

我们合成了三价第 3 族和第 13 族轻金属吡唑啉酸盐，并研究了它们对二氧化碳的反应性。同色复合物 Al(pztBu2)3 可逆地插入两个二氧化碳分子，生成 Al(CO2-pztBu2)2(pztBu2)，只有在高温（100 °C）下才会释放出二氧化碳。与此相反，供体稳定的 Sc(pztBu2)3(thf)形成单插入物种[Sc(μ-CO2-pztBu2)(pztBu2)2]2，在环境温度和压力下已经释放出二氧化碳，因此只能在低温下分离。至于钇络合物 Y(pztBu2)3(thf)2，在常温下无法观察到二氧化碳的插入。新型均相二异丙基吡唑烷酸铝[Al(pziPr2)3]2 显示出完全的二氧化碳插入，而二甲基吡唑烷酸铝只能分离出分离离子对[Al(N,N',N''-Al{pzMe2}3Me)2][Al(pzMe2)3Me]。钪配合物 Sc(pztBu2)3(thf)在 CO2 和环氧化物的催化环加成反应中表现最佳，揭示了亲羧性（=CO2 亲和力）和催化活性之间的反比关系。亲羧性是通过二氧化碳释放温度（通过 VT 1H NMR 光谱和热重分析）来评估的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

Carbon dioxide affinity (“carboxophilicity”) of trivalent light metal pyrazolates†

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Carbon dioxide affinity (“carboxophilicity”) of trivalent light metal pyrazolates†

Trivalent group 3 and 13 light metal pyrazolates were synthesised and their reactivity towards CO₂ was investigated. The homoleptic complex Al(pz^tBu₂)₃ reversibly inserts two molecules of CO₂ to afford Al(CO₂·pz^tBu₂)₂(pz^tBu₂), exhibiting CO₂ release only at elevated temperatures (>100 °C). In contrast, donor-stabilised Sc(pz^tBu₂)₃(thf) forms mono-inserted species [Sc(μ-CO₂·pz^tBu₂)(pz^tBu₂)₂]₂, which already releases CO₂ at ambient temperature and pressure and hence is isolable only at low temperature. For the yttrium complex Y(pz^tBu₂)₃(thf)₂, insertion of CO₂ is not observable at ambient temperature. The new homoleptic aluminium diisopropyl pyrazolate complex [Al(pz^iPr₂)₃]₂ shows exhaustive CO₂ insertion, while dimethyl pyrazolate could be isolated as the separated ion pair [Al(N,N′,N′′-Al{pz^Me₂}₃Me)₂][Al(pz^Me₂)₃Me]. The scandium complex Sc(pz^tBu₂)₃(thf) performed best in the catalytic cycloaddition reaction of CO₂ and epoxides, unveiling an inverse correlation of carboxophilicity ( CO₂ affinity) and catalytic activity. Carboxophilicity is assessed using CO₂-release temperature (via VT ¹H NMR spectroscopy and thermogravimetric analysis).