Synthesis and Reactivity of molecular Silicas with and without Oxygen Defects and Their Chalcogen Analogues

有氧缺陷和无氧缺陷的分子二氧化硅及其硫属类似物的合成和反应性

• 批准号: 433309479
• 负责人: Professor Dr. Matthias Drieß
• 金额: --
• 依托单位: Arbeitsgruppe Metallorganische Chemie und Anorganische Materialien
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/433309479?language=en
• 关键词: Synthesis; Reactivity; molecular; Silicas; without

The fascinatingly diverse reactivity of silica and its heavy homologues towards various substrates (e.g., in order to immobilize metal sites or metal-based clusters on such surfaces) is strongly dependent on the chemical nature of the terminal groups and oxygen defects. In the case of silica, the presence of water and/or oxygen defects not only determines the concentration of terminal Si-OH groups but will also influence its morphological stability, that is, its tendency to undergo post-agglomerization. One way to unravel structure-reactivity relationships of such materials on the molecular level is provided by taking ad-vantage of molecular models featuring different sorts of terminations such as Si-O-Si, Si(OH)n, Si=O moieties, and even oxygen deficiency. However, the synthetic access to reliable model compounds is still very limited due to the lack of suitable molecular precursors. This is why the project is devoted to the development of unprecedented synthetic methods for the generation of well-defined molecular models of silica and its heavy homologues.Starting point of our investigation is the previously developed (‘water-free’) selective chalcogenation a bis-N-heterocyclic carbene stabilized zero-valent silicon complex (‘silylone’) which enabled the synthesis and isolation of corresponding compounds bearing mononuclear SiX, SiX2 (X = O, S, Se, Te) and Si(CO3)2 molecules. The donor-acceptor interaction of the latter with the bis-carbene ligands prevents them from polymerization. With this compounds in hand we will study the reactivity of these entities towards water and related OH containing compounds aiming at the synthesis (via consecutive selective hydrolysis) of the corresponding ligand supported mononuclear Si(OH)n compounds (n = 2,3,4), including attempts to isolate a complex of the elusive silic acid, Si(OH)4. Moreover, starting from acyclic and cyclic chlorosilanes of the type SinCl2n (n = 5,6) and their transformation to the corresponding siloxy- and hydroxo-substituted cyclosilanes, we will continue to investigate their ability to serve as molecular models of oxygen-deficient silicas and to act as molecular precursors to give oxygen-deficient silicas such as SiO by a non-hydrolytic pathway.

二氧化硅及其重同系物对各种底物（例如，以便在这样的表面上覆盖金属位点或金属基簇）强烈地依赖于端基和氧缺陷的化学性质。在二氧化硅的情况下，水和/或氧缺陷的存在不仅决定了末端Si-OH基团的浓度，而且还将影响其形态稳定性，即其经历后附聚的趋势。利用分子模型的优势，从分子水平上揭示了这类材料的结构-反应性关系，这些分子模型具有不同的末端，如Si-O-Si，Si（OH）n，Si=O结构，甚至是氧缺陷。然而，由于缺乏合适的分子前体，合成可靠的模型化合物仍然非常有限。这就是为什么该项目致力于开发前所未有的合成方法，以生成定义明确的二氧化硅及其重同系物分子模型。（“无水”）选择性硫族化双-N-杂环卡宾稳定的零价硅络合物（“甲硅烷基酮”），其使得能够合成和分离带有单核SiX、SiX 2（X = O、S、Se、Te）和Si（CO 3）2分子的相应化合物。后者与双卡宾配体的给体-受体相互作用阻止它们聚合。有了这些化合物在手，我们将研究这些实体对水和相关的含OH化合物的反应性，目的是合成（通过连续的选择性水解）相应的配体支撑的单核Si（OH）n化合物（n = 2，3，4），包括尝试分离难以捉摸的硅酸Si（OH）4的络合物。此外，从无环和环状氯硅烷的类型SinCl 2n（n = 5，6）和它们的转化为相应的甲硅烷氧基和羟基取代的环硅烷，我们将继续研究它们的能力，作为分子模型的缺氧二氧化硅和作为分子前体，以得到缺氧二氧化硅，如SiO通过非水解途径。