Multidisciplinary thesauri in Internet

Dentro de la serie de trabajos sobre tesauros en acceso abierto presentes en Internet, se presentan, en esta ocasión, los multidisciplinares y aquellos que, aún estando dedicados a una disciplina, recogen términos de diversas materias.Peer reviewe

The Chlorido-Bismuth Dication: A Potent Lewis Acid Captured in a Hepta-Coordinate Species with a Stereochemically Active Lone Pair

The stabilization of simple, highly reactive cationic species in molecular complexes represents an important strategy to isolate and characterize compounds with uncommon or even unprecedented structural motifs and properties. Here we report the synthesis, isolation, and full characterization of chlorido-bismuth dications, stabilized only by monodentate dimethylsulfoxide (dmso) ligands: [BiCl­(dmso)6]­[BF4]2 (1) and [BiCl­(μ2-dmso)­(dmso)4]2[BF4]4 (2). These compounds show unusual distorted pentagonal bipyramidal coordination geometries along with high Lewis acidities and have been analyzed by multinuclear NMR spectroscopy, elemental analysis, IR spectroscopy, single-crystal X-ray diffraction, and density functional theory calculations. Attempts to generate the bromido- and iodido-analogs gave dmso-stabilized tricationic bismuth species

Two Faces of the Bi O Bond: Photochemically and Thermally Induced Dehydrocoupling for Si O Bond Formation

The diorgano(bismuth)alcoholate [Bi((C6H4CH2)2S)OPh] (1-OPh) has been synthesized and fully characterized. Stoichiometric reactions, UV/Vis spectroscopy, and (TD-)DFT calculations suggest its susceptibility to homolytic and heterolytic Bi-O bond cleavage under given reaction conditions. Using the dehydrocoupling of silanes with either TEMPO or phenol as model reactions, the catalytic competency of 1-OPh has been investigated (TEMPO =(tetramethyl-piperidin-1-yl)-oxyl). Different reaction pathways can deliberately be addressed by applying photochemical or thermal reaction conditions and by choosing radical or closed-shell substrates (TEMPO vs. phenol). Applied analytical techniques include NMR, UV/Vis, and EPR spectroscopy, mass spectrometry, single-crystal X-ray diffraction analysis, and (TD)-DFT calculations

Dibora[2]ferrocenophane: a carbene-stabilized diborene in a strained cis-configuration

Unsaturated bridges that link the two cyclopentadienyl ligands together in strained ansa metallocenes are rare and limited to carbon-carbon double bonds. The synthesis and isolation of a strained ferrocenophane containing an unsaturated two-boron bridge, isoelectronic with a C=C double bond, was achieved by reduction of a carbene-stabilized 1,1’-bis(dihaloboryl)ferrocene. A combination of spectroscopic and electrochemical measurements as well as density functional theory (DFT) calculations was used to assess the influence of the unprecedented strained cis configuration on the optical and electrochemical properties of the carbene-stabilized diborene unit. Initial reactivity studies show that the dibora[2]ferrocenophane is prone to boron-boron double bond cleavage reactions

Das Dimethylbismut-Kation: Zugang zu dativen Bi-Bi-Bindungen und unkonventionellem Methylaustausch

Die Isolierung einfacher, hochreaktiver metallorganischer Verbindungen von grundlegendem Interesse gehört nach wie vor zu den schwierigsten Aufgaben in der Synthesechemie. Die detaillierte Charakterisierung solcher Verbindungen ist der Schlüssel zum Verständnis neuer Bindungsszenarien und Reaktivitäten. Das Dimethylbismut-Kation, [BiMe2(SbF6)] (1), wurde isoliert und charakterisiert. Seine Reaktion mit BiMe3 ermöglicht den Zugang zu einer bislang unbekannten dativen Bindung, der Bi→Bi-Donor/Akzeptor-Wechselwirkung. Der Austausch von Methylgruppen (der wohl einfachsten Kohlenwasserstoffeinheit) zwischen verschiedenen Metallatomen gehört zu den wichtigsten Reaktionstypen in der metallorganischen Chemie. Die Reaktion von 1 mit BiMe3 ermöglicht einen Methylaustausch über eine Rückseiten-SE2-Reaktion, welche zum ersten Mal im Detail für isolierbare, (pseudo-)homoleptische Hauptgruppenverbindungen untersucht wird

Main‐Group Metal Complexes in Selective Bond Formations Through Radical Pathways

Recent years have witnessed remarkable advances in radical reactions involving main‐group metal complexes. This includes the isolation and detailed characterization of main‐group metal radical compounds, but also the generation of highly reactive persistent or transient radical species. A rich arsenal of methods has been established that allows control over and exploitation of their unusual reactivity patterns. Thus, main‐group metal compounds have entered the field of selective bond formations in controlled radical reactions. Transformations that used to be the domain of late transition‐metal compounds have been realized, and unusual selectivities, high activities, as well as remarkable functional‐group tolerances have been reported. Recent findings demonstrate the potential of main‐group metal compounds to become standard tools of synthetic chemistry, catalysis, and materials science, when operating through radical pathways

Aminotroponiminates: Alkali Metal Compounds Reveal Unprecedented Coordination Modes

The coordination chemistry of alkalimetal aminotroponiminates (ATIs) was investigated based on (i) a lithium ATI, (ii) the first example of a sodium ATI, and (iii) the first example of a structurally characterized potassium ATI. In the lithium derivative of this series, the ATI ligand adopts a well-known κ²<i>N</i> binding mode. In contrast, the sodium and potassium ATIs show two different types of unprecedented polymeric structures in the solid state, unraveling a surprisingly rich coordination chemistry for the ATI ligand family. In the solid-state structure of the potassium compound, ATI ligands bridge the metal atoms in a μ₂-κ²<i>N</i> binding mode. The sodium compound reveals a μ₂-κ²<i>N</i>κ⁵<i>C</i> coordination mode with an unusual interaction of a metal center with a C₇ ATI ligand backbone. NMR studies suggest that this type of interaction might also be accessible in solution. It was further studied by DFT calculations. The tendency of monoanionic ATI ligands to interact with transition-metal centers via their C₇ ligand backbone was investigated experimentally and theoretically using Rh⁺ and W⁰ as examples for potentially arenophilic metals

Aminotroponiminates: Alkali Metal Compounds Reveal Unprecedented Coordination Modes

The coordination chemistry of alkalimetal aminotroponiminates (ATIs) was investigated based on (i) a lithium ATI, (ii) the first example of a sodium ATI, and (iii) the first example of a structurally characterized potassium ATI. In the lithium derivative of this series, the ATI ligand adopts a well-known κ²<i>N</i> binding mode. In contrast, the sodium and potassium ATIs show two different types of unprecedented polymeric structures in the solid state, unraveling a surprisingly rich coordination chemistry for the ATI ligand family. In the solid-state structure of the potassium compound, ATI ligands bridge the metal atoms in a μ₂-κ²<i>N</i> binding mode. The sodium compound reveals a μ₂-κ²<i>N</i>κ⁵<i>C</i> coordination mode with an unusual interaction of a metal center with a C₇ ATI ligand backbone. NMR studies suggest that this type of interaction might also be accessible in solution. It was further studied by DFT calculations. The tendency of monoanionic ATI ligands to interact with transition-metal centers via their C₇ ligand backbone was investigated experimentally and theoretically using Rh⁺ and W⁰ as examples for potentially arenophilic metals