Supramolecular assemblies based on organometallic quinonoid linkers: a new class of coordination networks

Self-assembly of coordination frameworks exhibiting original architectures is an active area of research. Generally, such assemblies are constructed from organic spacers and transition metals of different geometrical structures. Herein, we report a novel class of supramolecular coordination assemblies with organometallic linkers based on metalated quinonoid and thioquinonoid complexes that serve as spacers. The organometallic ligands are stable and have the general formula [Cp*M(eta(4)-benzoquinone)] (o- and p-benzoquinone, Cp*=C(5)Me(5), M=Rh, Ir) and [Cp*Ir(eta(4)-thiobenzoquinone)] (o- and p-thiobenzoquinone). These units bind through both oxygen or sulfur atoms to metal ions of different coordination geometry, such as Cu(I), Ag(I), and Pt(II), to generate supramolecular coordination networks, with the metalated quinonoid or thioquinonoid linkers acting as backbones and the metal centers as nodes. This novel family of supramolecular assemblies exhibits short pi-pi and MM interactions. These results illustrate successfully the role of the organometallic linkers to produce an impressive range of novel supramolecular architectures that hold promise for the development of functional materials.     

Transition metal complexes meet the rylenes

This Perspective highlights an emerging area of metal-organic chromophore science related to the photochemistry and photophysics of coordination compounds and organometallic structures covalently tethered to rylene (naphthalene-cored) imide and diimide scaffolds. This combination of molecules renders highly colourful structures producing an array of excited state behaviour and in some instances strongly aggregated self-assembled metal-organic architectures.     

From molecules to aggregates

The preparation of organometallic oxides, imides and nitrides is described. The molecular structures of these compounds resemble those found in binary systems. However, due to the organic envelope of the molecular solids, they are soluble in organic solvents, easy to crystallize and unambiguously characterizable by single X-ray structural analysis and NMR investigations. Moreover, inorganic oxides can be incorporated in organometallic phosphonates or organoalumoxanes. Herein we describe the organometallic phosphonates as hosts with a hydrophobic exterior.     

Efficient fuel cell catalysts emerging from organometallic chemistry

During the last few decades organometallic methodologies have generated a number of highly effective electrocatalyst systems based on mono‐ and bimetallic nanosparticles having controlled size, composition and structure. In this microreview we summarize our results in fuel cell catalyst preparation applying triorganohydroborate chemistry, ‘reductive particle stabilization’ using organoaluminum compounds, and the controlled decomposition of organometallic complexes. The advantages of organometallic catalyst preparation pathways are exemplified with Ru? Pt nanoparticles@C as promising anode catalysts to be used in direct methanol oxidation fuel cells (DMFC) or in polymer electrolyte fuel cells (PEMFC) running with CO‐contaminated H₂ as the feed. Recent findings with highly efficient PtCo₃@C fuel cell catalysts applied for the oxygen reduction reaction (ORR) and with the effect of Se‐doping on Ru@C ORR catalysts clearly demonstrate the benefits of organometallic catalyst synthesis. Copyright © 2010 John Wiley & Sons, Ltd.     

Supramolecular Organometallic Polymer Chemistry: Self-Assembly of a Novel Poly(ferrocene)-b-polysiloxane-b-poly(ferrocene) Triblock Copolymer in Solution

Micelles with unprecedented flowerlike arrangements of the poly(ferrocene) cores (shown in the TEM image) are among the supramolecular architectures generated in the self-assembly of a novel organometallic triblock copolymer from silicon-bridged [1]ferrocenophane monomers and [Me₂SiO]₃ in hexane, a solvent selective for the central polysiloxane block.     

Benzodiazepines: Drugs with Chemical Skeletons Suitable for the Preparation of Metallacycles with Potential Pharmacological Activity

The synthesis of organometallic compounds with potential pharmacological activity has attracted the attention of many research groups, aiming to take advantage of aspects that the presence of the metal-carbon bond can bring to the design of new pharmaceutical drugs. In this context, we have gathered studies reported in the literature in which psychoactive benzodiazepine drugs were used as ligands in the preparation of organometallic and metal complexes and provide details on some of their biological effects. We also highlight that most commonly known benzodiazepine-based drugs display molecular features that allow the preparation of metallacycles via C-H activation. These organometallic compounds merit further attention regarding their potential biological effects, not only in terms of psychoactive drugs but also in the search for drug replacements, for example, for cancer treatments.     

Synthesis of Organometallic Compounds in Flow

Microreactor technology has proved to be an important technique in organic synthesis, especially when organometallic compounds are used, because it allows running rapid reactions with reactive and instable intermediates. This review will highlight the preparation of main‐group organometallic compounds deriving from Lithium, Magnesium, Zinc and Aluminum and their applications in flow conditions.     

The Synthesis of Stable,Complex Organocesium Tetramic Acids through the Ugi Reaction and Cesium‐Carbonate‐Promoted Cascades

Two structurally unique organocesium carbanionic tetramic acids have been synthesized through expeditious and novel cascade reactions of strategically functionalized Ugi skeletons delivering products with two points of potential diversification. This is the first report of the use of multicomponent reactions and subsequent cascades to access complex, unprecedented organocesium architectures. Moreover, this article also highlights the first use of mild cesium carbonate as a cesium source for the construction of cesium organometallic scaffolds. Relativistic DFT calculations provide an insight into the electronic structure of the reported compounds.     

The Synthesis of Stable,Complex Organocesium Tetramic Acids through the Ugi Reaction and Cesium‐Carbonate‐Promoted Cascades

Two structurally unique organocesium carbanionic tetramic acids have been synthesized through expeditious and novel cascade reactions of strategically functionalized Ugi skeletons delivering products with two points of potential diversification. This is the first report of the use of multicomponent reactions and subsequent cascades to access complex, unprecedented organocesium architectures. Moreover, this article also highlights the first use of mild cesium carbonate as a cesium source for the construction of cesium organometallic scaffolds. Relativistic DFT calculations provide an insight into the electronic structure of the reported compounds.     

Synthesis of 9-substituted-1,4,5,8-tetraazaphenanthrenes

The synthesis of 9-substituted-1,4,5,8-tetraazaphenanthrenes was undertaken in the course of a study aimed at the preparation of organometallic complexing agents.     

Regio- and chemoselective metalation of arenes and heteroarenes using hindered metal amide bases

The preparation of highly functionalized organometallic compounds can be achieved by direct C H activation of a broad range of unsaturated substrates using lithium chloride solubilized 2,2,6,6‐tetramethylpiperidide bases (TMP_nMX_m⋅p LiCl). These are excellent reagents for converting a wide range of aromatic and heterocyclic substrates into valuable organometallic reagents with broad applications in organic synthesis.     

Toward single-site, immobilized molecular catalysts: site-isolated Ti ethylene polymerization catalysts supported on porous silica

A new, general patterning methodology that may allow for the preparation of site-isolated organometallic catalysts on a silica surface is reported. The technique is demonstrated with Group 4 polymerization catalysts. The catalysts synthesized via the patterning method have up to a 10-fold increase in activity as compared to materials prepared by traditional techniques. In addition to supporting Group 4 polymerization catalysts, the patterned aminosilica is a possible support for other metal complexes, allowing for the synthesis of a wide array of immobilized single-site organometallic catalysts.     

Asymmetric synthesis via chiral acetal templates. 8. Reactions with organometallic reagents

The titanium tetrachloride catalyzed coupling of organometallic reagents with chiral acetals 1 is shown to provide a convenient route for the preparation of a variety of chiral alcohols 4 of high optical purity.     

Methode generale de preparation de N-alkyl N-trimethylsilyl alkoxymethylamines,agents efficaces de monoalkylaminomethylation d'organometalliques

The easy preparation of N-alkyl N-trimethylsilyl alkoxymethylamines is described; these new reagents are very convenient to lead to unsymmetrical secondary amines from organometallic compounds.     

Organometallic Tetrazole Derivatives: Preparation and Application to Organic Synthesis

The data are integrated and systematized on preparation procedures and application to the organic synthesis of organometallic tetrazole derivatives, including 5-metallated tetrazoles and tetrazoles with a metal-carbon bond in a substituent, and also organotin tetrazoles.     

Switching stereoselectivity in rhodium-catalysed 1,4-additions: The asymmetric synthesis of 2-substituted pyrrolizidinones

The appropriate choice of organometallic nucleophile enables the straightforward preparation of different stereoisomers of 2-substituted pyrrolizidinones utilising the rhodium-catalysed 1,4-addition reaction.     

Selones as intermediates in the preparation of extremely sterically hindered molecules

The preparation and reactions of selones, selenium analogues of ketones, are described with particular emphasis on their utility in the preparation of extremely sterically hindered molecules. Mechanistic questions related to these reactions are discussed and evidence for “active selenium” is presented. Selenophilic additions of organometallic compounds to selones are also reported.     

"三明治"化合物——二茂铁

二茂铁是一种结构很特殊的化合物,它的发现在金属有机化合物研究中具有里程碑意义。简介了二茂铁的发现、结构确定、制备和应用。     

Strained metallocenophanes and related organometallic rings containing pi-hydrocarbon ligands and transition-metal centers

The structures, bonding, and ring-opening reactions of strained cyclic carbon-based molecules form a key component of standard textbooks. In contrast, the study of strained organometallic molecules containing transition metals is a much more recent development. A wealth of recent research has revealed fascinating nuances in terms of structure, bonding, and reactivity. Building on initial work on strained ferrocenophanes, a broad range of strained organometallic rings composed of a variety of different metals, pi-hydrocarbon ligands, and bridging elements has now been developed. Such strained species can potentially undergo ring-opening reactions to functionalize surfaces and ring-opening polymerization to form easily processed metallopolymers with properties determined by the presence of the metal and spacer. This Review summarizes the current state of knowledge on the preparation, structural characterization, electronic structure, and reactivity of strained organometallic rings with pi-hydrocarbon ligands and d-block metals.     

Synthesis of functionalized 2-arylpyridines from 2-halopyridines and various aryl halides via a nickel catalysis

An efficient nickel-catalyzed method devoted to the direct formation of functionalized 2-arylpyridines is described avoiding the prior preparation of organometallic species. Various functionalized 2-arylpyridines are obtained in moderate to excellent yields by a one-step chemical procedure from corresponding halides. The NiBr₂(2,2′-bipyridine) complex appears to be an extremely suitable catalyst for the activation in the presence of manganese dust of aromatic halides and pyridyl halides functionalized by reactive groups. The versatility of this original process represents a simple alternative to most known methods using organometallic reagents.