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Activation of small molecules by copper and cobalt complexes via proton-coupled multi-electron transfer reactions and the application in catalysis

铜钴配合物质子耦合多电子转移反应活化小分子及其催化应用

基本信息

批准号：
243146177
负责人：
Professorin Dr. Inke Siewert
金额：
--
依托单位：
Institut für Anorganische Chemie
依托单位国家：
德国
项目类别：
Independent Junior Research Groups
财政年份：
2013
资助国家：
德国
起止时间：
2012-12-31 至 2020-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/243146177?language=en
关键词：
Activation small molecules copper cobalt

项目摘要

Many redox reactions in nature and chemistry proceed in the transfer of both, electrons and protons, and in fact, this concept is utilised in the water oxidation of the photosystem II (PS II). At the oxygen evolving centre in the PS II four consecutive single electron transfer steps lead to the oxidation of water. Three out of the four electron transfer steps are most likely coupled to a proton transfer. The (almost) simultaneous transfer of protons and electrons avoids the formation of high energy intermediates, which could be formed in consecutive transfer steps. The mimicking of this reaction is the key step for an energy change from fossil to sustainable fuels. The synthesis of C1-fuels or H2 requires electrons in order to reduce the precursors CO2 or protons. Water is a cheap and widely available source of electrons and the only side product in the water oxidation reaction would be the natural gas oxygen. Among others, the oxidation of water can be performed by transition metal complexes.The project targets the activation of small molecules, in particular the oxidation of water and the reductive cleavage of laughing gas (N2O) by cobalt and copper complexes. Complexes with the earth abundant metal ions copper and cobalt are able to accumulate two or more redox equivalents and thus, to facilitate multistep redox reactions. The complexes feature a very robust ligand scaffold. Furthermore, they may stabilise in-situ formed intermediates and avoid the formation of high energy intermediates in the reaction cascade by coupling electron donation/acceptance with proton donation/acceptance.Novel cobalt and copper complexes will be synthesised and subsequently investigated with respect to their ability to facilitate the proton coupled electron transfer. The concept will be then used to activate small molecules. Stable mono- and dinuclear compounds, which can accumulate multiple redox equivalents, will be exploited for (electro)chemical water splitting catalysis. In addition, copper complexes with a central RS−-unit will be synthesised and utilised for functional studies of N2O-decomposition as model compounds for the N2O-reductase. N2O is the second to last product of the denitrification and naturally decomposed by the N2O-reductase in N2 and water by transferring two electrons and two protons to N2O.

自然界和化学中的许多氧化还原反应都是在电子和质子的转移中进行的，事实上，这个概念被用于光系统 II (PS II) 的水氧化。在 PS II 的氧气放出中心，四个连续的单电子转移步骤导致水的氧化。四个电子转移步骤中的三个很可能与质子转移耦合。质子和电子（几乎）同时转移避免了高能中间体的形成，高能中间体可能在连续的转移步骤中形成。模仿这种反应是能源从化石燃料向可持续燃料转变的关键一步。 C1 燃料或 H2 的合成需要电子来还原前体 CO2 或质子。水是一种廉价且广泛可用的电子源，水氧化反应中唯一的副产物是天然气氧气。其中，水的氧化可以通过过渡金属络合物进行。该项目的目标是小分子的活化，特别是钴和铜络合物对水的氧化和笑气（N2O）的还原裂解。与地球上丰富的金属离子铜和钴的配合物能够积累两个或多个氧化还原当量，从而促进多步氧化还原反应。该复合物具有非常坚固的配体支架。此外，它们可以通过将电子给予/接受与质子给予/接受耦合来稳定原位形成的中间体，并避免在反应级联中形成高能中间体。将合成新型钴和铜配合物，并随后研究其促进质子耦合电子转移的能力。该概念随后将用于激活小分子。稳定的单核和双核化合物可以积累多个氧化还原当量，将用于（电）化学水分解催化。此外，将合成具有中心 RS--单元的铜配合物，并将其用作 N2O 还原酶的模型化合物，用于 N2O 分解的功能研究。 N2O 是反硝化作用的倒数第二个产物，通过 N2 和水中的 N2O 还原酶将两个电子和两个质子转移到 N2O 来自然分解。