N-heterocyclic carbene analogues with low-valent group 13 and group 14 elements: syntheses, structures, and reactivities of a new generation of multitalented ligands.

Since the discovery of the first stable N-heterocyclic carbene (NHC) in the beginning of the 1990s, these divalent carbon species have become a common and available class of compounds, which have found numerous applications in academic and industrial research. Their important role as two-electron donor ligands, especially in transition metal chemistry and catalysis, is difficult to overestimate. In the past decade, there has been tremendous research attention given to the chemistry of low-coordinate main group element compounds. Significant progress has been achieved in stabilization and isolation of such species as Lewis acid/base adducts with highly tunable NHC ligands. This has allowed investigation of numerous novel types of compounds with unique electronic structures and opened new opportunities in the rational design of novel organic catalysts and materials. This Review gives a general overview of this research, basic synthetic approaches, key features of NHC–main group element adducts, and might be...

NHCs in Main Group Chemistry.

Oxidative addition and reductive elimination are key steps in a wide variety of catalytic reactions mediated by transition-metal complexes. Historically, this reactivity has been considered to be the exclusive domain of d-block elements. However, this paradigm has changed in recent years with the demonstration of transition-metal-like reactivity by main-group compounds. This Review highlights the substantial progress achieved in the past decade for the activation of robust single bonds by main-group compounds and the more recently realized activation of multiple bonds by these elements. We also discuss the significant discovery of reversible activation of single bonds and distinct examples of reductive elimination at main-group element centers. The review consists of three major parts, starting with oxidative addition of single bonds, proceeding to cleavage of multiple bonds, and culminated by the discussion of reversible bond activation and reductive elimination. Within each subsection, the discussion is...

Oxidative Addition and Reductive Elimination at Main-Group Element Centers

N-Heterocyclic carbenes (NHC) are nowadays ubiquitous and indispensable in many research fields, and it is not possible to imagine modern transition metal and main group element chemistry without t...

N-Heterocyclic Carbene Adducts of Main Group Elements and Their Use as Ligands in Transition Metal Chemistry.

Zwitterionic and Donor-Stabilized N-Heterocyclic Silylenes (NHSis) for Metal-Free Activation of Small Molecules

Dehydrochlorination to Silylenes by N-Heterocyclic Carbenes

In recent years, unsaturated silicon compounds (silylenes and silicon multiple-bonding species) have attracted much attention owing to their significant roles in the development of silicon chemistry. Silanimines (R2Si =NR), as silicon analogues of imines, are, in general, short-lived and highly reactive species in the absences of efficient protecting groups on both the silicon and nitrogen atoms. By taking advantage of donor–acceptor stabilization concepts, a fair number of donor-stabilized silanimines have been isolated and structurally characterized since the first isolable silanimine was reported in 1986. It is well-known that organosilicon hydrides have been widely used as hydrosilylation reagents in organic synthesis. However, unsaturated silicon hydrides, in which the hydride ligands are bonded to an unsaturated silicon atom, are extremely rare. The lack of these species may be related to their intrinsic high reactivity arising from a reactive hydride ligand being attached to the unsaturated silicon atom. Among these, hydrosilanimines (RHSi=NR) are interesting and attractive synthetic targets because of their fundamental interest considering the relative stability of hydrosilanimines and their corresponding silylene isomers (RSiNHR). Furthermore, it has been recently shown that transition-metal–hydrosilanimine complexes are useful for some stoichiometric and catalytic transformations. However, stable hydrosilanimines are still elusive, presumably owing to their high reactivity and lack of synthetic methods for their synthesis. Herein, we report the first donor-stabilized hydrosilanimine prepared by the reaction of RSiHCl2 (1, R= ArACHTUNGTRENNUNG(SiMe3)N , Ar= 2,6-iPr2C6H3) with N-heterocyclic carbenes (NHCs; Scheme 1). In addition, we demonstrate that the reactions of 1 with NHCs are significantly influenced by the steric effects of the substituents on the NHC nitrogen atoms. We and others have previously reported NHC-mediated dehydrochlorination reactions for the generation of stable and transient silylenes. To extend that methodology, we examined the reactions of the silylamino-substituted dichlorosilane RSiHCl2 (1) with NHCs. As previously observed in the reactions of various N-heterocyclic chlorosilanes with NHCs, the products varied largely depending on the reaction conditions and the substrates employed. Therefore, it is essential to probe the steric effects of NHCs on the reaction. Thus, the less-hindered 1,3,4,5-tetramethylimidazol-2-ylidene (IMe4) and the bulky 1,3-bis(tert-butyl)imidazol-2-ylidene (ItBu2) were chosen for this study. [9] The reaction of 1 with one equivalent of IMe4 in C6D6 at room temperature gave a complicated mixture of products as indicated by NMR analysis. However, unexpectedly, the reaction of 1 with two equivalents of IMe4 in tetrahydrofuran at low temperature gave 1-hydrosilanimine 2 (Scheme 1) as yellow crystals in 26 % yield along with some insoluble materials. Compound 2 is air and moisture sensitive, and it is soluble in common hydrocarbon solvents such as n-hexane and toluene. The proton NMR spectrum of 2 indicated the presence of one Si H (d= 6.21 ppm, JSi-H = 218 Hz) bond, two Ar rings, one SiMe3 group, and one IMe4 group in the structure. The detailed structure of 2 was finally determined by single-crystal X-ray analysis. X-ray structural analysis of 2 revealed that it was an NHC-stabilized 1-hydrosilanimine (Figure 1). The central silicon atom was four-coordinate and adopted a distorted [a] H. Cui, Prof. Dr. C. Cui State Key Laboratory of Elemento-organic Chemistry Nankai University Tianjin, 300071 (China) Fax: (+86)-22-23503461 E-mail : cmcui@nankai.edu.cn Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/asia.201100022. Scheme 1. Synthesis of 2 and 3. IMe4 = 1,3,4,5-tetramethylimidazol-2-ylidene.

Synthesis of a Base‐Stabilized 1‐Hydrosilanimine via NHC‐Mediated Dehydrohalogenation of Hydrochlorosilane

Metal-Free, Stereospecific Bis-Silylation of Functionalized Alkynes with NHC-Supported Silylaminosilylene

Synthesis and Reactions of a Redox-Active α-Diimine Aluminum Complex

A stable cross-conjugated diradical was prepared by the reaction of a donor-acceptor-donor (D-A-D) molecule with B(C6F5)3. Its geometry and electronic structure were characterized by single crystal X-ray diffraction, EPR spectroscopy, SQUID measurement, UV/vis spectroscopy, and DFT calculation. It has an open-shell singlet ground state with a thermally excited triplet state. It can be viewed as an intramolecular radical ion pair, and the formation mechanism is proposed as an intramolecular single electron transfer that occurs from the bis(triarylamine) donor fragment to the central dioxophenyl acceptor moiety, induced by the acidic boron atom. This work provides a Lewis acid induced approach to the formation of neutral and cross-conjugated diradicals.

The Lewis Acid Induced Formation of a Stable Diradical with an Intramolecular Ion Pairing State.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Haiyan Cui

Author Tools

Chat about Author