Rational Design and Smart Synthesis of Non-Transition-Metal Systems for Small Molecules Activation (SM-Act)

非过渡金属系统（即主基团化合物）激活小分子是具有挑战性的。热稳定的主基团化合物具有与开壳过渡金属配合物相当的反应性和性质，因此是有吸引力的合成目标。本课题旨在探索由n-杂环乙烯基（NHV）和n-杂环偏乙烯基（NHVD）配体稳定的以磷和砷为中心的自由基和自由基类化合物。这些配体是很强的给体和给体。此外，它们的电子和立体特征为未配对电子自旋密度的离域提供了独特的平台，从而形成了包含C2E2， C2EE ‘， C2E4或C2E2E ’ 2片段（通常为环）的非常稳定的分子框架（E = P, E ' = As）。对所提出的化合物进行系统的实验和理论研究将使我们了解它们的电子结构和成键情况，以及它们与小分子（如H2， O2， CO, N2O， CO2等）的反应性。将研究配体结构对所提化合物的结构和性质的影响，以概述调节其性质的关键因素。研究这类开壳主基团不仅对提高我们对化学键的认识有重要意义，而且对认识它们在合成和材料科学中的潜在应用也有重要意义。

Small molecules activation by non-transition metal systems (i.e. main-group compounds) is challenging. Thermally stable main-group compounds with a reactivity and properties comparable to open-shell transition-metal complexes are therefore appealing synthetic targets. This proposal aims at the exploration of phosphorus- and arsenic-centered radical and radicaloid compounds stabilized by unconventional carbon-donor ligands, namely N-heterocyclic vinyl (NHV) and N-heterocyclic vinylidene (NHVD) ligands. These ligands are very strong delta- as well as pi-donors. Moreover, their electronic and steric features provide a unique platform for the delocalization of unpaired electron spin density, leading to the formation of very stable molecular frameworks containing a C2E2, C2EE′, C2E4, or C2E2E′2 moiety (usually rings) (E = P, E′ = As). Systematic experimental and theoretical studies of the proposed compounds will enable us to understand their electronic structure and bonding situation, as well as their reactivity with small molecules (e. g. H2, O2, CO, N2O, CO2 etc). The impact of the ligand architecture on the structure and properties of proposed compounds will be studied to outline the key factors that regulate their properties. Investigation of such open-shell main-group species is not only important to enhance our understanding about chemical bonding but also to recognize their potential applications in synthesis and materials science.