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Journal ArticleDOI

Synthesis of dinuclear N-heterocyclic dicarbene Au(III)/Au(III) and Au(II)/Au(II) complexes via oxidative addition of chlorine or bromine to Au(I)/Au(I) species

01 Sep 2012-Journal of Organometallic Chemistry (Elsevier)-Vol. 714, pp 41-46
TL;DR: In this paper, the same reaction output is now proposed also in the oxidative addition of bromine, as fully supported by the X-ray structure of complex [Au2Br2(MeImImIm-(CH2)3)-ImMe)2](PF6)2], where the main product is an Au(II)/Au(II) complex.
About: This article is published in Journal of Organometallic Chemistry.The article was published on 2012-09-01. It has received 25 citations till now. The article focuses on the topics: Oxidative addition.
Citations
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Journal ArticleDOI
TL;DR: This review focuses on the synthetic methods, characterization, structural features, and postassembly modifications of metallosupramolecular assemblies obtained from poly-NHC ligands.
Abstract: Although the coordination chemistry of N-heterocyclic carbenes (NHCs) with transition metals has been explored for half a century, only in the past ten years has the chemistry of metallosupramolecular assemblies based on poly-NHC ligands been studied more extensively. Remarkable discrete assemblies featuring poly-NHC ligands including two-dimensional metallacycles and three-dimensional metallaprisms/cages have since emerged. These assemblies are mostly obtained starting from various imidazolium or benzimidazolium salts. Driven by the increasing interest in new supramolecular architectures from carbon donor ligands, design, and construction of poly-NHC metal assemblies has become a rapidly growing area of research. The metal–carbene bond length is fixed to approximately 2.0 A in linear NHC–M–NHC complexes. This allows the use of such complexes bearing olefin-substituted NHC ligands as templates for subsequent photochemical [2 + 2] cycloaddition reactions. The postassembly modification of such assemblies ha...

216 citations

Journal ArticleDOI
TL;DR: Four novel dinuclear N-heterocyclic dicarbene gold(I) complexes with a propylene linker between the carbene moieties have been synthesized and their luminescence and electrochemical properties, together with their reactions towards bromine oxidative addition, have been screened.
Abstract: Four novel dinuclear N-heterocyclic dicarbene gold(I) complexes with a propylene linker between the carbene moieties have been synthesized and their luminescence and electrochemical properties, together with their reactivity towards bromine oxidative addition, have been screened. All the complexes emit in the solid state in the blue-green spectral range (400–500 nm) with appreciable intensities (Φem up to ≈10%). In cyclic voltammetry, the Au(I)/Au(0) peak splits at low temperature into two separate peaks relative to the couples Au(I)–Au(I)/Au(I)–Au(0) and Au(I)–Au(0)/Au(0)–Au(0), thus indicating the presence of an Au⋯Au interaction in the dinuclear complex. Oxidative addition of bromine affords as a major or unique product Au(II)–Au(II) complexes most likely as a consequence of the interaction between the two gold centres favoured by the propylene linker.

54 citations

Journal ArticleDOI
TL;DR: Eximers have also been shown to play an important role in photoredox binuclear gold catalysis, and some of the relaxation dynamics have recently been clarified.
Abstract: Excimers and exciplexes are defined as assemblies of atoms or molecules A/A' where interatomic/intermolecular bonding appears only in excited states such as [A2 ]* (for excimers) and [AA']* (for exciplexes). Their formation has become widely known because of their role in gas-phase laser technologies, but their significance in general chemistry terms has been given little attention. Recent investigations in gold chemistry have opened up a new field of excimer and exciplex chemistry that relies largely on the preorganization of gold(I) compounds (electronic configuration AuI (5d10 )) through aurophilic contacts. In the corresponding excimers, a new type of Au⋅⋅⋅Au bonding arises, with bond energies and lengths approaching those of ground-state Au-Au bonds between metal atoms in the Au0 (5d10 6s1 ) and AuII (5d9 ) configurations. Excimer formation gives rise to a broad range of photophysical effects, for which some of the relaxation dynamics have recently been clarified. Excimers have also been shown to play an important role in photoredox binuclear gold catalysis.

47 citations

Journal ArticleDOI
TL;DR: In this paper, Dinuclear silver complexes with bridging N-phosphorylated azolylidene ligands have been synthesized and transferred to other group 11 metal centers (Cu, Au).

40 citations

Journal ArticleDOI
TL;DR: New dinuclear di(N-heterocyclic carbene) silver(I), gold(I) and gold(III) complexes have been synthesised and their antiproliferative effects towards various cancer cell lines have been screened.

38 citations

References
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Journal ArticleDOI
TL;DR: New methods for the synthesis of complexes with N-heterocyclic carbene ligands such as the oxidative addition or the metal atom template controlled cyclized isocyanides have been developed recently.
Abstract: The chemistry of heterocyclic carbenes has experienced a rapid development over the last years. In addition to the imidazolin-2-ylidenes, a large number of cyclic diaminocarbenes with different ring sizes have been described. Aside from diaminocarbenes, P-heterocyclic carbenes, and derivatives with only one, or even no heteroatom within the carbene ring are known. New methods for the synthesis of complexes with N-heterocyclic carbene ligands such as the oxidative addition or the metal atom template controlled cyclization of β-functionalized isocyanides have been developed recently. This review summarizes the new developments regarding the synthesis of N-heterocyclic carbenes and their metal complexes.

2,454 citations

Journal ArticleDOI
TL;DR: The ways in which selectivity can be controlled in homogeneous Au catalysis are enumerated, in the hope that lessons to guide catalyst selection and the design of new catalysts may be distilled from a thorough evaluation of ligand, counterion, and oxidation state effects as they influence chemo-, regio-, and stereoselectivity in homogeneity AuCatalysis.
Abstract: 1.1. Context and Meta-Review Despite the ubiquity of metallic gold (Au) in popular culture, its deployment in homogeneous catalysis has only recently undergone widespread investigation. In the past decade, and especially since 2004, great progress has been made in developing efficient and selective Au-catalyzed transformations, as evidenced by the prodigious number of reviews available on various aspects of this growing field. Hashmi has written a series of comprehensive reviews outlining the progression of Au-catalyzed reaction development,1 and a number of more focused reviews provide further insight into particular aspects of Au catalysis. A brief meta-review of the available range of perspectives published on Au catalysis helps to put this Chemical Reviews article in context. The vast majority of reactions developed with homogeneous Au catalysts have exploited the propensity of Au to activate carbon-carbon π-bonds as electrophiles. Gold has come to be regarded as an exceedingly mild, relatively carbophilic Lewis acid, and the broad array of newly developed reactions proceeding by activation of unsaturated carbon-carbon bonds has been expertly reviewed.2 Further reviews and highlights on Au catalysis focus on particular classes of synthetic reactions. An excellent comprehensive review of Au-catalyzed enyne cycloisomerizations is available.3 Even more focused highlights on hydroarylation of alkynes,4 hydroamination of C-C multiple bonds,5 and reactions of oxo-alkynes6 and propargylic esters7 provide valuable perspectives on progress and future directions in the development of homogeneous Au catalysis. Most of the reviews on Au catalysis emphasize broad or specific advances in synthetic utility. Recently, we have invoked relativistic effects to provide a framework for understanding the observed reactivity of Au catalysts, in order to complement empirical advancements.8 In this Chemical Reviews article, we attempt to enumerate the ways in which selectivity can be controlled in homogeneous Au catalysis. It is our hope that lessons to guide catalyst selection and the design of new catalysts may be distilled from a thorough evaluation of ligand, counterion, and oxidation state effects as they influence chemo-, regio-, and stereoselectivity in homogeneous Au catalysis.

1,783 citations

Journal ArticleDOI
TL;DR: Thanks to gold-based catalysts, various organic transformations have been accessible under facile conditions with both high yields and chemoselectivity.
Abstract: Thanks to its unusual stability, metallic gold has been used for thousands of years in jewelry, currency, chinaware, and so forth. However, gold had not become the chemists’ “precious metal” until very recently. In the past few years, reports on gold-catalyzed organic transformations have increased substantially. Thanks to gold-based catalysts, various organic transformations have been accessible under facile conditions with both high yields and chemoselectivity.

1,698 citations

Journal ArticleDOI
TL;DR: The results show clear trends in gold-Catalyzed C-H Bond Functionalization and Selective Reductions, and catalytic Hydrogenation of Alkenes and 1,3-Dienes, as well as in other areas of science.
Abstract: 2.7. Hydroxylation Reactions of Allenes 3282 2.8. Hydroamination Reactions of Allenes 3284 2.9. Hydrothiolation of Allenes 3284 2.10. Hydroalxoxylation of Alkenes and 1,3-Dienes 3286 2.11. Hydroamination of Alkenes and 1,3-Dienes 3287 2.12. Hydrothiolation of Conjugated Olefins 3289 3. Activation of Carbonyl/Imine Groups and Alcohols 3289 3.1. Condensation Reactions 3289 3.2. Addition Reactions 3291 3.3. Aldol Reactions 3294 3.4. Hydroand Carbosilylation Reactions 3295 3.5. Nucleophilic Substitution Reactions of Alcohols 3297 4. Gold-Catalyzed C-H Bond Functionalization 3297 4.1. Csp3-H Bond Functionalization 3298 4.2. Csp2-H Bond Functionalization 3299 4.3. Csp-H Bond Functionalization 3304 5. Gold-Catalyzed Selective Reductions 3305 5.1. Catalytic Hydrogenation of Alkenes 3306 5.2. Selective Reductions of R, -Unsaturated Carbonyl Groups and 1,3-Dienes 3306

1,358 citations