Synthesis of phosphate stabilised iodanes and their application in intramolecular aryl migrations.

A diverse set of hydroxy-benzo[]iodadioxaphosphinine oxides and derived diaryl iodonium salts are prepared and two examples are characterized by X-ray crystallography, featuring an out-of-plane geometry of the hypervalent bond for both compound classes. Treatment of the phosphate-stabilized diaryliodonium salts with Ca(OH) results in an efficient base-induced intramolecular aryl migration under aqueous conditions, yielding iodo-substituted diaryl ethers with yields up to 94%. Our findings highlight the synthetic potential of this previously underexplored compound class in organic transformations.

Electronic Coupling in Triferrocenylpnictogens.

From a fundamental perspective, studies of novel mixed-valent complexes containing ferrocenyl units are motivated by the prospect of improving and extending electron transfer models and theories. Here, the series of triferrocenylpnictogens FcE was extended to the heavier analogues (E = As, Sb, and Bi), and the influence of the bridging atom was investigated with FcP as a reference. Electrochemical studies elucidate the effect of electrostatic contribution on the large redox splitting (Δ ) exhibited by the compounds and solvent stabilization in the case of FcAs.

Oxidation of benzylic alcohols to carbonyls using -heterocyclic stabilized λ-iodanes.

We present -heterocycle-stabilized iodanes (NHIs) as suitable reagents for the mild oxidation of activated alcohols. Two different protocols, both involving activation by chloride additives, were used to synthesize benzylic ketones and aldehydes without overoxidation in up to 97% yield. Based on MS experiments an activated hydroxy(chloro)iodane is proposed as the reactive intermediate.

PTaN (x=0.1-0.15): A Phosphorus Tantalum Nitride Featuring Mixed-Valent Tantalum and P/Ta Disorder Visualized by Scanning Transmission Electron Microscopy.

We report on the synthesis, crystal, and electronic structure, as well as the magnetic, and electric properties of the phosphorus-containing tantalum nitride PTaN (x=0.1-0.15).

Methyl Methacrylate Copolymer with Pendant Thioxanthenone Groups as Active Layer for Resistive Memory Devices.

An electro-active copolymer of methyl methacrylate and 2-((4-acroylpiperazine-1-yl)methyl)-9H-thioxanthene-9-one (poly(MMA-co-ThS)) was synthesized by radical polymerization. The copolymer has good solubility in most organic solvents, thermal stability up to 282 °C and excellent ability to form thin films on silicon wafers. Poly(MMA-co-ThS) films exhibited an electrochemical and electrochromic activity resulting in the formation of long-lived radical anion states of pendant thioxanthone groups inside the film.

Multicationic Tetrahedra Networks: Alkaline-Earth-Centered Polyhedra and Non-Condensed AlN-Octahedra in the Imidonitridophosphates AEAlPN(NH) (AE=Ca, Sr, Ba).

A series of isostructural imidonitridophosphates AEAlPN(NH) (AE=Ca, Sr, Ba) was synthesized at high-pressure/high-temperature conditions (1400 °C and 5-9 GPa) from alkaline-earth metal nitrides or azides CaN/Sr(N)/Ba(N) and the binary nitrides AlN and PN. NHF served as a hydrogen source and mineralizing agent. The crystal structures were determined by single-crystal X-ray diffraction and feature a three-dimensional network of vertex-sharing PN-tetrahedra forming diverse-sized rings that are occupied by aluminum and alkaline earth ions.

Boosting quantum yields and circularly polarized luminescence of penta- and hexahelicenes by doping with two BN-groups.

The incorporation of boron-nitrogen (BN) units into polycyclic aromatic hydrocarbons (PAHs) as an isoelectronic replacement of two carbon atoms can significantly improve their optical properties, while the geometries are mostly retained. We report the first non-π-extended penta- and hexahelicenes comprising two aromatic 1,2-azaborinine rings. Comparing them with their all-carbon analogs regarding structural, spectral and (chir)optical properties allowed us to quantify the impact of the heteroatoms.

1,2,3,4-Tetrafluorobiphenylene: A Prototype Janus-Headed Scaffold for Ambipolar Materials.

The title compound was synthesized by Ullmann cross-coupling in low yield as the first representative of [n]phenylene containing hydrocarbon and fluorocarbon rings. Stille/Suzuki-Miyaura cross-coupling reactions, as well as substitution of fluorine in suitable starting compounds, failed to give the same product. The geometric and electronic structures of the title compound were studied by X-ray diffraction, cyclic voltammetry and density functional theory calculations, together with Hirshfeld surface and reduced density gradient analyses.

Synthesis and crystal structure of 2-(anthracen-9-yl)-1-(-butyl-dimethyl-sil-yl)-3,6-di-hydro-1λ,2λ-aza-borinine.

The title compound, CHBNSi (), is an asymmetric 1,2,3,6-tetra-hydro-1,2-aza-borinine consisting of a BN-substituted cyclo-hexa-diene analog with a -anthracenyl substituent. A ring-closing metathesis with subsequent substitution of the obtained BCl 1,2-aza-borinine using anthracenyl lithium yielded the title compound . The asymmetric unit ( = 8) belongs to the ortho-rhom-bic space group and shows an elongated N-C bond compared to previously reported BN-1,4-cyclo-hexa-diene [Abbey (2008 ▸) , 7250-7252].

Synthesis and crystal structure of bis-(9-mesityl-9,10-di-hydro-10-aza-9-borabenzo[]quinolinato-κ,)zinc(II).

The title compound, [Zn(CHBN)] ( ), is an overall uncharged chelate that consists of two units of an N-deprotonated 10-aza-9-borabenzo[]quinoline ligand () per Zn center. It was synthesized in two steps by treating the protonated ligand with lithium bis-(tri-methyl-sil-yl)amide and further conversion with di-ethyl-zinc. Its asymmetric unit comprises one fragment; the mol-ecule is completed by application of inversion symmetry at Zn.

A Photomechanical Film in which Liquid Crystal Design Shifts the Absorption into the Visible Light Range.

Liquid crystalline polymer networks (LCN) with azobenzene monomers bend reversibly under UV-light irradiation, combining photomechanical and photothermal effects. However, the harmful nature of UV-light limits their use in biology and soft robotics. Although visible light-absorbing tetra-ortho-fluoro-substituted azobenzenes exist, liquid crystalline monomers have never been prepared.

Tuning Molecular Electron Affinities against Atomic Electronegativities by Spatial Expansion of a π-System.

2,1,3-Benzochalcogenadiazoles C R N E (E/R; E=S, Se, Te; R=H, F, Cl, Br, I) and C H R N E (E/R'; E=S, Se, Te; R=Br, I) are 10π-electron hetarenes. By CV/EPR measurements, DFT calculations, and QTAIM and ELI-D analyses, it is shown that their molecular electron affinities (EAs) increase with decreasing Allen electronegativities and electron affinities of the E and non-hydrogen R (except Cl) atoms. DFT calculations for E/R+e⋅ →[E/R]⋅ electron capture reveal negative ΔG values numerically increasing with increasing atomic numbers of the E and R atoms; positive ΔS has a minor influence.

One-Pot Synthesis of Heteroatom-Bridged Cyclic Diaryliodonium Salts.

Two one-pot procedures for the construction of - and -bridged diaryliodonium triflates are described. An effective aryne-mediated arylation of -iodophenols and -sulfonamides provides diarylether and diarylamine intermediates, which are subsequently oxidized and cyclized to the corresponding diaryliodaoxinium and -iodazinium salts. Different derivatizations were applied to demonstrate their capacity as useful building blocks and gain a deeper understanding toward the general reactivity of these underdeveloped but potentially highly useful compounds.

Spectroelectrochemical study of the reduction of 2-methyl-9-thioxanthene-9-one and its ,-dioxide and electronic absorption spectra of their molecular ions.

2-Methyl-9-thioxanthene-9-one (1) and its S,S-dioxide (2) are the precursors of pendant groups that determine the reduction potentials of electro-active polyimides, which exhibit electrochromic behavior and are used in organic electronics. Electrochemical reduction of 1 and 2 leads to the formation of the corresponding persistent radical anions and dianion (for ,-dioxide). Using 3D spectroelectrochemistry, all anions have been shown to exhibit strong absorption in the UV-VIS-NIR wavelength region.

Pseudocyclic bis-N-heterocycle-stabilized iodanes - synthesis, characterization and applications.

Bis-N-heterocycle-stabilized λ3-iodanes (BNHIs) based on azoles are introduced as novel structural motifs in hypervalent iodine chemistry. A performance test in a variety of benchmark reactions including sulfoxidations and phenol dearomatizations revealed a bis-N-bound pyrazole substituted BNHI as the most reactive derivative. Its solid-state structure was characterized via X-ray analysis implying strong intramolecular interactions between the pyrazole nitrogen atoms and the hypervalent iodine centre.

Experimental and Theoretical Studies of a Spirostannole and Formation of a Pentaorganostannate.

A new spirostannole, 1,1',3,3'-tetrakis(5-methylthiophen-2-yl)-4,4',5,5',6,6',7,7'-octahydro-2,2'-spirobi[benzo[]stannole] (), is synthesised and the molecular structure is compared with the optimised geometry from DFT calculations. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are twice degenerated and show a small HOMO-LUMO energy gap of 3.2 eV.

Sila-Ibuprofen.

The synthesis, characterization, biological activity, and toxicology of sila-ibuprofen, a silicon derivative of the most common nonsteroidal anti-inflammatory drug, is reported. The key improvements compared with ibuprofen are a four times higher solubility in physiological media and a lower melting enthalpy, which are attributed to the carbon-silicon switch. The improved solubility is of interest for postsurgical intravenous administration.

Iodolopyrazolium Salts: Synthesis, Derivatizations, and Applications.

The synthesis of iodolopyrazolium triflates via an oxidative cyclization of 3-(2-iodophenyl)-1-pyrazoles is described. The reaction is characterized by a broad substrate scope, and various applications of these novel cyclic iodolium salts acting as useful synthetic intermediates are demonstrated, in particular in site-selective ring openings. This was finally applied to generate derivatives of the anti-inflammatory drug celecoxib.

Aggregation induced emission - emissive stannoles in the solid state.

The optoelectronic and structural properties of six stannoles are reported. All revealed extremely weak emission in solution at 295 K, but intensive fluorescence in the solid state with quantum yields (ΦF) of up to 11.1% in the crystal, and of up to 24.

One-Pot Synthesis and Conformational Analysis of Six-Membered Cyclic Iodonium Salts.

Two one-pot procedures for the construction of carbon-bridged diaryliodonium triflates and tetrafluoroborates are described. Strong Brønsted acids enable the effective Friedel-Crafts alkylation with diversely substituted -iodobenzyl alcohol derivatives, providing diphenylmethane scaffolds, which are subsequently oxidized and cyclized to the corresponding dibenzo[,]iodininium salts. Based on NMR investigations and density functional theory (DFT) calculations, we could verify the so-far-undescribed existence of two stable isomers in cyclic iodonium salts substituted with aliphatic side chains in the carbon bridge.

Synthesis and crystal structure of ()-1,2-bis-[2-(methyl-sulfan-yl)phen-yl]diazene.

The title compound, CHNS, was obtained by transmetallation of 2,2'-bis-(tri-methyl-stann-yl)azo-benzene with methyl lithium, and subsequent quenching with dimethyl di-sulfide. The asymmetric unit comprises two half-mol-ecules, the other halves being completed by inversion symmetry at the midpoint of the azo group. The two mol-ecules show only slight differences with respect to N=N, S-N and aromatic C=C bonds or angles.

Thermochromic Behavior of Yttrium-Substituted Bismuth Oxides.

High-temperature thermochromic materials are poorly explored in fundamental research, let alone applied research, although these materials may be used as low-cost, intuitively usable sensing materials in an industrial environment. Yet, only few of these materials have been described systematically. We describe a series of yttrium-substituted bismuth oxides (BiY)O (0.

Negishi's Reagent Versus Rosenthal's Reagent in the Formation of Zirconacyclopentadienes.

Zirconacyclopentadienes are versatile precursors for a large number of heteroles, which are accessible by Zr-element exchange reactions. The vast majority of reports describe their preparation by the use of Negishi's reagent, which is a species that is formed in situ. The zirconacyclopentadiene is then formed by the addition of one equivalent of a diyne or two equivalents of a monoyne moiety to this Negishi species.

Synthesis, Structure, Thermal Behavior and / Isomerization of 2,2'-(EMe₃)₂ (E = C, Si, Ge, Sn) Substituted Azobenzenes.

The synthesis of a series of 2,2'-bis(trimethyltetrel) azobenzenes is reported, evaluating the different synthetic approaches that different group 14 element substituents individually require. The synthetic access to the carbon substituted congener is very different from the heavier tetrels, in that the key step is the formation of the N=N bond in azobenzene, rather than the azobenzene-C bond. Sn could be introduced with a cross-coupling route, whereas the Si and Ge congeners were prepared by a stannylation-lithiation-electrophilic quenching sequence.

Radical Anions, Radical-Anion Salts, and Anionic Complexes of 2,1,3-Benzochalcogenadiazoles.

By means of cyclic voltammetry (CV) and DFT calculations, it was found that the electron-acceptor ability of 2,1,3-benzochalcogenadiazoles 1-3 (chalcogen: S, Se, and Te, respectively) increases with increasing atomic number of the chalcogen. This trend is nontrivial, since it contradicts the electronegativity and atomic electron affinity of the chalcogens. In contrast to radical anions (RAs) [1] and [2] , RA [3] was not detected by EPR spectroscopy under CV conditions.