Periodic Reporting for period 4 - SMAC-MC (Small Molecule Activation by Main-Group Compounds)
Periodo di rendicontazione: 2023-01-01 al 2023-12-31
Many basic chemical processes require the cleavage, or activation, of strong covalent bonds in ubiquitous and inexpensive small molecules such hydrogen, nitrogen, ammonia, water and carbon dioxide. In nature, small molecule activation is done with the help of enzymes and a great deal of research efforts has been directed to achieve the same with manmade catalysts. An illustrative example is the Haber-Bosch process, which, like its biological counterpart nitrogen fixation, produces ammonia from N2 with the help of a catalyst. This process is vital for our society as the vast majority of the ammonia produced is consumed by the fertilizer industry, without which the world would face an imminent food crisis. Besides the Haber-Bosch process, there are many more chemical reactions performed at the industry level which involve the activation of small molecules and which would be impossible to perform without efficient catalysts.
This research project focussed on the interesting possibility to perform small molecule activation with main-group compounds that, in contrast to many transition metal catalysts, consist entirely of cheap earth-abundant elements. The overall objective of the project was to find new ways to achieve small molecule activation using main-group compounds that typically do not display such reactivity. Of key interest were main-group diradicaloids, compounds with metal-metal bonds and metalloid clusters, frustrated Lewis pairs as well as electron precise boron compounds. The planned initiatives were primarily of fundamental scientific importance but also of potential practical value as many main-group systems, such as frustrated Lewis pairs, are currently being examined as novel metal-free catalysts. The project resulted in the synthesis and characterization of several new main-group systems for small molecule activation and uncovered the mechanisms by which these interesting and novel species function.
This research project focussed on the interesting possibility to perform small molecule activation with main-group compounds that, in contrast to many transition metal catalysts, consist entirely of cheap earth-abundant elements. The overall objective of the project was to find new ways to achieve small molecule activation using main-group compounds that typically do not display such reactivity. Of key interest were main-group diradicaloids, compounds with metal-metal bonds and metalloid clusters, frustrated Lewis pairs as well as electron precise boron compounds. The planned initiatives were primarily of fundamental scientific importance but also of potential practical value as many main-group systems, such as frustrated Lewis pairs, are currently being examined as novel metal-free catalysts. The project resulted in the synthesis and characterization of several new main-group systems for small molecule activation and uncovered the mechanisms by which these interesting and novel species function.
Our research has resulted in the synthesis and/or characterization of several novel main-group compounds that can be potentially use in small molecule activation. These include, for example, monomeric alanediyls and their diradical dimers, dialumines, as well as compounds with metal-metal bonds between metals having different oxidation states. Investigations on the reactivities of these compounds with small molecules and the mechanisms involved have been performed to understand how the molecules can carry out such challenging chemical tasks. This information will help in designing new systems that perform specific bond activation processes with even better efficiency. In this context, the project led to the synthesis and characterization of a rare coordination complex of nitrous oxide that gave significant new insight to the metal binding abilities of this small molecule with high environmental importance (a greenhouse gas) as well as guidelines for the synthesis of metal complexes with even stronger binding to nitrous oxide. We have also reported a new bidentate ligand framework based on cyclic(alkyl)(amino) carbenes that have found extensive use in stabilizing highly reactive species as well as performing small molecule activation. All results of the project have been or will be published at scientific journals as well as presented at international conferences. The performed research has facilitated the training of highly qualified personnel including PhDs and postdoctoral researchers.
The research project involved innovative fundamental studies focussed on the electronic structures and reactivity of different types of novel main-group compounds capable of performing small molecule activation. The project combined experimental research with computational and theoretical analyses, leading to important insight not only into the electronic structures of the investigated systems but also into the reactions which they undergo or perform. The project advanced main-group chemistry in several frontiers and lead to improved understanding of how these reactive compounds can activate small molecules. Furthermore, the project revealed significant new information on the interaction between small molecules and metal centres and led to a new ligand system to be used in small molecule activation as well as in other fields of chemistry.