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

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

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

Crystal structure solution of a high-pressure polymorph of scintillating MgMoO4 and its electronic structure

The structure of the potentially scintillating high-pressure phase of [Beta] - MgMoO 4 ( γ - MgMoO 4 ) has been solved by means of high-pressure single-crystal x-ray diffraction. The phase transition occurs above 1.5 GPa and involves an increase of the Mo coordination from fourfold to sixfold accommodated by a rotation of the polyhedra and a concommitant bond stretching resulting in an enlargement of the c axis. A previous high-pressure Raman study had proposed such changes with a symmetry change to space group P 2 / c . Here it has been found that the phase transition is isosymmetrical ( C 2 / m -> C 2 / m ). The bulk moduli and the compressibilities of the crystal axes of both the low- and the high-pressure phase, have been obtained from equation of state fits to the pressure evolution of the unit-cell parameters which were obtained from powder x-ray diffraction up to 12 GPa. The compaction of the crystal structure at the phase transition involves a doubling of the bulk modulus B 0 changing from 60.3(1) to 123.7(8) GPa and a change of the most compressible crystal axis from the (0, b , 0) direction in [Beta] - MgMoO 4 to the ( 0.9 a , 0, 0.5 a ) direction in γ - MgMoO 4 . The lattice dynamical calculations performed here on γ - MgMoO 4 served to explain the Raman spectra observed for the high-pressure phase of [Beta] - MgMoO 4 in a previous work demonstrating that the use of internal modes arguments in which the MoO n polyhedra are considered as separate vibrational units fails at least in this molybdate. The electronic structure of γ - MgMoO 4 was also calculated and compared with the electronic structures of [Beta] - MgMoO 4 and MgWO 4 shedding some light on why MgWO 4 is a much better scintillator than any of the phases of MgMoO 4 . These calculations yielded for γ - MgMoO 4 a Y 2 Γ -> Γ indirect band gap of 3.01 eV in contrast to the direct bandgaps of [Beta] - MgMoO 4 (3.58 eV at Γ ) and MgWO 4 (3.32 eV at Z ).The authors thank I. Collings and M. Handfland from the ID15B beamline at the ESRF for their help during the experiments, and O. Gomis from the Universitat Politècnica de València for the discussions. Most of the work presented in this work benefited from the financial support from the Spanish Ministerio de Ciencia e Innovación (MICINN) under Projects No. PID2019- 106383GB-C41/43 (MCIN/AEI/10.13039/501100011033), MALTA Consolider-Team network RED2018-102612- T (MINECO/AEI/10.13039/501100003329), and from the Generalitat Valenciana under Project PROMETEO/2018/123. V.M. also thanks the MICINN for the Beatriz Galindo distinguished researcher program (BG20/00077)

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

A Base-stabilized Iodoborylene Complex of Platinum(II)

Abstract The first base-stabilized iodoborylene platinum complex was prepared through the addition of 4-picoline (4-Pic) to a suspension of an iodo-bridged binuclear iodoboryl complex. An X-ray structure determination of the title compound has characterized the molecular structure as cis-[Pt{BI(4- Pic)}I2(PCy3)]. The bond lengths lie in the expected range for neutral, base-stabilized borylene complexes. The strong trans influence of the borylene moiety is reflected in the longer Pt-1 distance for the iodo ligand opposite the borylene, compared to that opposite the phosphine ligand</jats:p

1,2-Halosilane vs. 1,2-alkylborane elimination from (boryl)(silyl) complexes of iron: switching between borylenes and silylenes just by changing the alkyl group

The results present a new elimination reaction, the 1,2-alkylborane elimination, as a new route to silylene complexes.</p