Structural constraint at a P-P bond: phosphinophosphination of alkenes, alkynes, and carbonyls by a concerted mechanism.

Structurally constraining p-block elements has become a powerful strategy for bond activation chemistry with main group compounds. Traditionally, this approach focuses on mononuclear centers, yet applying structural constraints to systems with element-element bonds remains underexplored. In this study, we introduce a cation featuring a structural constraint-elongated P-P bond that spontaneously adds to unactivated alkynes, alkenes, aldehydes, and ketones.

Small Ring Molecules Comprising 3-6 Boron Atoms: An Account on Synthesis, Structure, and Orbital Engineering.

ConspectusUnlike carbon, boron does not usually form ring compounds due to its electron-deficiency-driven affinity toward polyhedral geometries. The polyhedral boranes having -, -, -, or -shapes can be structurally and electronically correlated using various electron counting rules developed by Wade, Mingos, and one of us. However, in the last few decades, boron chemistry progressed significantly toward ring systems.

Nitrogen monoxide and calix[4]pyrrolato aluminate: structural constraint enabled NO dimerization.

The dimerization of nitrogen monoxide (NO) is highly relevant in homo- and heterogeneous biochemical and environmental redox processes, but a broader understanding is challenged by the endergonic nature of this equilibrium. The present work describes NO-dimerization leveraged by structurally constrained aluminum and metal-ligand cooperativity at the anionic calix[4]pyrrolato aluminate(III). Quantum chemical calculations reveal the driving force for N-N bond formation, while reactivity tests shed light on subsequent redox chemistry and NO decomposition at metal surfaces.

Second Generation of Cata-Annulated Azaacene Bisimides: Towards Electron-Accepting Materials.

This work presents the 2 generation of cata-annulated azaacene bisimides with increased electron affinities (up to -4.38 eV) compared to their consaguine conventional azaacenes. These compounds were synthesized via Buchwald-Hartwig coupling followed by oxidation with MnO .

Acceleration Effect of Bowl-Shaped Structure in Aerobic Oxidation Reaction: Synthesis of Homosumanene ortho-Quinone and Azaacene-Fused Homosumanenes.

An oxidation reaction of hydroxyhomosumanene on silica gel providing homosumanene ortho-quinone and its synthetic application for azaacene-fused homosumanenes is described. Hydroxyhomosumanene is photochemically oxidized by air, when it is coated on silica gel; this aerobic oxidation proceeds faster than that of planar analogues. The difference of such reactivity was attributed to the unusual keto-enol tautomerization due to structural difference between planar and curved π-system.

Valence Tautomerism of p-Block Element Compounds - An Eligible Phenomenon for Main Group Catalysis?

Valence tautomerism has had a remarkable impact on several branches of transition metal chemistry. By switching between different valence tautomeric states, physicochemical properties and reactivities can be triggered reversibly. Is this phenomenon transferrable into the p-block - or is it already happening there? This collects observations of p-block element-ligand systems that might be assignable to valence tautomerism.

Electron-beam lithography of cinnamate polythiophene films: conductive nanorods for electronic applications.

We report the electron-beam induced crosslinking of cinnamate-substituted polythiophene proceeding excited state [2+2]-cycloaddition. Network formation in thin films is evidenced by infrared spectroscopy and film retention experiments. For the polymer studied herin, the electron-stimulated process appears to be superior to photo (UV)-induced crosslinking as it leads to less degradation.

The inversion of tetrahedral p-block element compounds: general trends and the relation to the second-order Jahn-Teller effect.

The tetrahedron is the primary structural motif among the p-block elements and determines the architecture of our bio- and geosphere. However, a broad understanding of the configurational inversion of tetrahedral compounds is missing. Here, we report over 250 energies (DLPNO-CCSD(T)) for square planar inversion of third- and fourth-period element species of groups 13, 14, and 15.

Derivatization of an especially electron-rich diborane.

Starting with electron-rich ditriflato-diborane B(hpp)(OTf) (hpp = 1,3,4,6,7,8-hexahydro-2-pyrimido[1,2-]pyrimidinate), novel symmetric and unsymmetric diboranes B(hpp)X and B(hpp)XY with X,Y = Br, NCS, N or OTf are synthesized by substitution reactions with S1 mechanisms. The stability of the unsymmetric diboranes with respect to dismutation equilibria is evaluated.

Cucurbitimines - imine cages with concave walls.

The variety of shape-persistent organic cages by imine bond formation has tremendously enlarged in recent years by using different building blocks (aldehydes and amines) in the condensation reactions. Here, we describe the use of a kinked tetraldehyde to generate pumpkin-shaped cages with concave walls, similar to cucurbiturils.

On-surface synthesis of π-conjugated ladder-type polymers comprising nonbenzenoid moieties.

On-surface synthesis provides a powerful approach toward the atomically precise fabrication of π-conjugated ladder polymers (CLPs). We report herein the surface-assisted synthesis of nonbenzenoid CLPs from cyclopenta-annulated anthracene monomers on Au(111) under ultrahigh vacuum conditions. Successive thermal annealing steps reveal the dehalogenative homocoupling to yield an intermediate 1D polymer and the subsequent cyclodehydrogenation to form the fully conjugated ladder polymer.

Triptycene End-Capped Indigo Derivatives - Turning Insoluble Pigments to Soluble Dyes.

The synthesis of a highly soluble triptycene end-capped indigo and its bay annulated derivative is reported. Both compounds have been studied by absorption and emission spectroscopy cyclic voltammetry, as well as theoretical calculations and compared to the parent indigo and bay annulated indigo. Besides a large improvement of solubility in organic solvents by the factor of approx.

Building complex carbon skeletons with ethynyl[2.2]paracyclophanes.

Ethynyl[2.2]paracyclophanes are shown to be useful substrates for the preparation of complex, highly unsaturated carbon frameworks. Thus both the pseudo-geminal- 2 and the pseudo-ortho-diethynylcyclophane 4 can be dimerized by Glaser coupling to the respective dimers 9/10 and 11/12.

Improved Thin-Film Transistor Performance Through a Melt of Poly(para-phenyleneethynylene).

The performance of polymer field-effect transistors (PFETs) based on short rigid rod semiconducting poly(2,5-didodecyloxy-p-phenyleneethynylene) (D-OPPE) is highlighted. The controlled heating and cooling of thin films of D-OPPE allows for a recrystallization from the melt, boosting the performance of D-OPPE-based transistors. The improved film properties induced by controlled annealing lead to a hole field-effect mobility around 0.

Gold-catalyzed synthesis of chroman, dihydrobenzofuran, dihydroindole, and tetrahydroquinoline derivatives.

Different furans containing an ynamide or alkynyl ether moiety in the side chain were prepared. The gold-catalyzed transformation of these compounds delivered dihydroindole, dihydrobenzofuran, chroman, and tetrahydroquinoline derivatives at room temperature through very fast reactions. Furthermore, the stabilizing effect of the heteroatom directly attached to the intermediate arene oxides led to highly selective reactions, even in the case of only mono-substituted furans, which is quite different from previous results obtained with non-heteroatom-substituted alkynes.

Structural variation in transition-metal bispidine compounds.

The experimentally determined molecular structures of 40 transition metal complexes with the tetradentate bispyridine-substituted bispidone ligand, 2,4-bis(2-pyridine)-3,7-diazabicyclo[3.3.1]nonane-9-one [M(bisp)XYZ]n+; M = CrIII, MnII, FeII, CoII, CuII, CuI, ZnII; X, Y, Z = mono- or bidentate co-ligands; penta-, hexa- or heptacoordinate complexes) are characterized in detail, supported by force-field and DFT calculations.

A Very Rigid Bis-bispidine Tetraazamacrocycle and Its Unusual Copper(II) Complex.

The absorption maximum of the orange-colored copper(II) complex of the cyclam derivative L, which has two 3,7-diazabicyclo[3.3.1]nonane units, occurs at 390 nm.