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在电子和质子的转移中进行，实际上，这种概念用于光系统II的水氧化（PS II）。在PS II中的氧气进化中心，四个连续的单电子传输步骤导致水的氧化。四个电子传输步骤中的三个很可能是耦合到质子传输的。（几乎）简单的质子和电子转移避免了高能中间体的形成，这些中间体可以在连续的传输步骤中形成。模仿这种反应是从化石到可持续燃料的能量变化的关键步骤。 C1燃料或H2的合成需要电子以减少前体CO2或质子。水是一种廉价且可广泛可用的电子来源，水氧化反应中唯一的侧面产品是天然气氧。除其他外，可以通过过渡金属复合物进行水的氧化。该项目靶向小分子的激活，尤其是水的氧化以及钴和铜复合物的笑气（N2O）的裂解减少。与地球丰富的金属离子铜和钴的络合物能够积累两个或多个氧化还原等效物，因此可以促进多步氧化还原反应。这些复合物具有非常强大的配体脚手架。此外，它们可能稳定在原位形成的中间体，并通过将电子捐赠/接受与质子捐赠/接受度耦合，避免在反应级联中形成高能中间体。NovelCobalt和Copper Complexse将合成并随后对其构建Proton Coupled Electron的能力进行研究，并随后进行研究。然后，该概念将用于激活小分子。将探索（电）化学水分裂催化的稳定的单核化合物，可以累积多种氧化还原等效物。此外，将合成具有中央RS的铜配合物 - 将单位合成并用于N2O分解的功能研究，作为N2O-还原酶的模型化合物。 N2O是二硝化的第二产物，并通过将两个电子和两个质子转移到N2O中，在N2中由N2O还原酶自然分解。