Dicyclohexyl(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphine–dichlorophenylborane

In the crystal structure of the title compound, C39H54BCl2P, the phospho­rus atom is coordinated by a dichloro­phenyl­borane unit. The substituted biphenyl group and the two cyclo­hexyl groups at the phospho­rus atom are arranged in such a way to avoid steric crowding in the mol­ecule as far as possible

Piperidino Substituted [1]Borametallocenophanes. Synthesis, Reactivity, and Structure

ansa-Metallocenes and related complexes have considerable potential as catalyst precursors in the Ziegler-Natta type olefin polymerization. In the present paper we report about the synthesis of piperidinyl-substituted [1]borametallocenophanes of titanium and zirconium. Furthermore, the first example of a base stabilized alkyl-substituted [1]borazirconocenophane was fully characterized and tested for its properties in the polymerization of ethene

Dynamic, reversible oxidative addition of highly polar bonds to a transition metal

The combination of Pt0 complexes and indium trihalides leads to compounds that form equilibria in solution between their In-X oxidative addition (OA) products (PtII indyl complexes) and their metal-only Lewis pair (MOLP) isomers (LnPt→InX3). The position of the equilibria can be altered reversibly by changing the solvent, while the equilibria can be reversibly and irreversibly driven towards the MOLP products by addition of further donor ligands. The results mark the first observation of an equilibrium between MOLP and OA isomers, as well as the most polar bond ever observed to undergo reversible oxidative addition to a metal complex. In addition, we present the first structural characterization of MOLP and oxidative addition isomers of the same compound. The relative energies of the MOLP and OA isomers were calculated by DFT methods, and the possibility of solvent-mediated isomerization is discussed

Oxidation, Coordination, and Nickel-Mediated Deconstruction of a Highly Electron-Rich Diboron Analogue of 1,3,5-Hexatriene

The reductive coupling of an N-heterocyclic carbene (NHC) stabilized (dibromo)vinylborane yields a 1,2-divinyldiborene, which, although isoelectronic to a 1,3,5-triene, displays no extended π conjugation because of twisting of the C2B2C2 chain. While this divinyldiborene coordinates to copper(I) and platinum(0) in an η2-B2 and η4-C2B2 fashion, respectively, it undergoes a complex rearrangement to an η4-1,3-diborete upon complexation with nickel(0)

Isolierung und Reaktivität eines s-Block-Metall-Antiaromaten

Das Konzept der Aromatizität und der Antiaromatizität ist seit langem bekannt, und zahlreiche Belege für dieses Phänomen wurden durch Moleküle, welche auf Elementen des p-, d- und f-Blocks des Periodensystems der Elemente (PSE) basieren, geliefert. Aufgrund der begrenzten Varianz des Oxidationszustandes von s-Block-Metallen konnten diese bisher nicht mit komplexen π-Bindungssystemen interagieren. Daher gibt es keine bzw. nur schlecht beschriebene Beispiele für antiaromatische Systeme mit s-Block-Metallen. Durch die Verwendung von spektroskopischen, strukturanalytischen und quantenchemischen Methoden konnte eine heterocyclische Verbindung hergestellt und charakterisiert werden, welche das Erdalkalimetall Beryllium enthält und signifikante Antiaromatizität aufweist. Weiterhin beschreiben wir die Reaktivität gegenüber Lewis-Basen und die chemische Reduktion dieser Verbindung

New outcomes of Lewis base addition to diboranes(4): electronic effects override strong steric disincentives

Two surprising new outcomes of the reaction of Lewis bases with dihalodiboranes(4) are presented, including sp2–sp3 diboranes in which the Lewis base unit is bound to a highly sterically congested boron atom, and a rearranged double base adduct. The results provide a fuller understanding of the reactivity of diboranes, a poorly-understood class of molecule of critical importance to synthetic organic chemistry

Experimentelle und theoretische Untersuchungen zu Clustermolekülen mit dem NB 2 -, NB 3 -, CB 3 -, und B 4 -Gerüst

The reaction of Tri-tert-butylazadiboriridin with Halogenides of maingroup 3 and 5 elements leads to an opening of the BB-bond. Only in case of Trifluorophosphane a cyclic product was obtained. Nitrils and Isothiocyanats yield cyclic or bicyclic products, the structures of which were derived from comparison of experimental and calculated spectra. It was shown that H– reacts with NB2R3 to give a three-membered-ring consisting of a BN-double-bond and a BHtBu group. The reaction-path of H– with NB2H3 was calculated with ab initio-methods. Other anionic bases like R’O–, R’S–, R’2N–, R’2P– gave no reaction with NB2H3. This was explained by discussion of HOMO’s of these bases. For the reactions of NB2R3 with Lewis-acids R’BH2 was previously found that bicyclobutane-type products exhibit an equilibrium between the Cs exo-form and the chiral endo-form. The ab initio calculations show, that the reasonable isomerization path seems to be the inversion of the NB3 skeleton with partial opening of BB-bond. For the compound CB3H4R3, the structure of which was unknown, the DFT/GIAO-calculations revealed that it is bicyclobutane-type one, and hence, it can be considered as a nido-tetraborane

Experimentelle und theoretische Untersuchungen zu Clustermolekülen mit dem NB 2 -, NB 3 -, CB 3 -, und B 4 -Gerüst

The reaction of Tri-tert-butylazadiboriridin with Halogenides of maingroup 3 and 5 elements leads to an opening of the BB-bond. Only in case of Trifluorophosphane a cyclic product was obtained. Nitrils and Isothiocyanats yield cyclic or bicyclic products, the structures of which were derived from comparison of experimental and calculated spectra. It was shown that H– reacts with NB2R3 to give a three-membered-ring consisting of a BN-double-bond and a BHtBu group. The reaction-path of H– with NB2H3 was calculated with ab initio-methods. Other anionic bases like R’O–, R’S–, R’2N–, R’2P– gave no reaction with NB2H3. This was explained by discussion of HOMO’s of these bases. For the reactions of NB2R3 with Lewis-acids R’BH2 was previously found that bicyclobutane-type products exhibit an equilibrium between the Cs exo-form and the chiral endo-form. The ab initio calculations show, that the reasonable isomerization path seems to be the inversion of the NB3 skeleton with partial opening of BB-bond. For the compound CB3H4R3, the structure of which was unknown, the DFT/GIAO-calculations revealed that it is bicyclobutane-type one, and hence, it can be considered as a nido-tetraborane

Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties

The behavior of the redox‐active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI)$_{3}$] and [Bi(ATI)$_{2}$L$_{n}$][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable‐temperature) NMR spectroscopy, line‐shape analysis, and single‐crystal X‐ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann–Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand‐ and metal‐centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds. This adds important facets to the rich redox chemistry of ATIs and to the redox chemistry of bismuth compounds, which is, so far, largely unexplored

Cationic Bismuth Aminotroponiminates: Charge Controls Redox Properties

The behavior of the redox‐active aminotroponiminate (ATI) ligand in the coordination sphere of bismuth has been investigated in neutral and cationic compounds, [Bi(ATI)$_{3}$] and [Bi(ATI)$_{2}$L$_{n}$][A] (L=neutral ligand; n=0, 1; A=counteranion). Their coordination chemistry in solution and in the solid state has been analyzed through (variable‐temperature) NMR spectroscopy, line‐shape analysis, and single‐crystal X‐ray diffraction analyses, and their Lewis acidity has been evaluated by using the Gutmann–Beckett method (and modifications thereof). Cyclic voltammetry, in combination with DFT calculations, indicates that switching between ligand‐ and metal‐centered redox events is possible by altering the charge of the compounds from 0 in neutral species to +1 in cationic compounds. This adds important facets to the rich redox chemistry of ATIs and to the redox chemistry of bismuth compounds, which is, so far, largely unexplored