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Copyright © 2014 John Wiley & Sons, Ltd. The structure and dynamics of five-coordinate iridacyclopentadiene-chlorido and -hydrido complexes of the form [(PH 3 ) 2 Ir(CY = CYCY′ = CY′)X] (X = Cl or H and Y = F and/or H) are investigated by M06-2X/Def2-TZVPP density functional theory computation. For the symmetrically substituted ring systems (Y = Y′ = H and Y = Y′ = F) the minimum energy chlorido structures are Y-shaped trigonal bipyramids; whereas the hydrido complexes favor a T-structure. Both the symmetrically and unsymmetrically (Y = H, Y′ = F) substituted hydrido complexes exhibit double well potentials for the hydrido ligand wag motion within the metallacycle ring plane, the depths of the well depending on the degree of steric, and electronic interactions within the particular constitutional isomer.

Si(mply) rips it apart: C-F activation of fluorobenzene has been achieved using the extremely strong silyl Lewis acids [Et3Si(X)]+ (X=PhF or Et3SiH) and [(2,6-dixylyl-C6H 3)SiMe2] + paired with the anion CHB 11Cl11-. They abstract fluoride from unactivated fluorobenzene to give arylated products, consistent with phenyl-cation-like reactivity (see scheme). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Si(mply) rips it apart: C-F activation of fluorobenzene has been achieved using the extremely strong silyl Lewis acids [Et3Si(X)]+ (X=PhF or Et3SiH) and [(2,6-dixylyl-C6H 3)SiMe2] + paired with the anion CHB 11Cl11-. They abstract fluoride from unactivated fluorobenzene to give arylated products, consistent with phenyl-cation-like reactivity (see scheme). © 2010 Wiley-VCH Verlag GmbH & Co. KGaA.

Sly silyl caught in the act: Protonation of a mesitylene ring by the strongly acidic arenium carborane [CH(3)C(6)H(6)]- [CHB(11)Me(5)Br(6)] initiates a cascade reaction that results in a stable beta-silyl allyl cation (see picture, H yellow, C blue, silyl allyl group red). Remarkably, the driving force in the reaction suffices to disrupt a stable aromatic ring in favor of a cationic reactive intermediate.

A general synthetic approach to halogenated tetraaryl‐ammonium salts has been developed and illustrated crystallographically. Bromide ammonium salts used as common synthetic intermediates together with Suzuki coupling of these bromides to a family of boronic acids provided a simplified strategy for arylation. Resolution of the C2 subset of spiro‐bicarbazolium derivatives led to the first examples of enantiopure spiro‐bicarbazoliums and the assignment of their absolute configuration by comparison of computational and experimental electronic circular dichroism (ECD) spectra. An ECD comparison with Prelog's spirobifluorenes is provided. The absolute configuration of the meta‐bromide spiro‐bicarbazolium salt was confirmed by anomalous scattering. Cruciform and stellate tetra‐substituted salts provide a test of the limits of the methodology, and their structures suggest them to be candidates for MOF building blocks. [ABSTRACT FROM AUTHOR]

Regioselective and chemoselective electrophilic bromination of a wide series of activated arenes using N-bromo-succinimide (NBS) in acetonitrile occurs readily. Environmentally friendly conditions, large substrate scope, and ease of synthesis enhance the utility of this method over other electrophilic bromination conditions. Key words: arylbromides, electrophilic aromatic bromination, N-bromosuccinimide. La bromation electrophile chimioselective et regioselective d'une grande varietes d'arenes actives, a l'aide de N-bromo-succinimide dans l'acetonitrile, se fait facilement. Des conditions experimentales environnementalement correctes, un large eventail de substrats et la facilite de la synthese augmentent l'utilite de cette methode par comparaison avec celles necessaires pour d'autres bromations electrophiles. Mots-cles : bromures d'arenes, bromation aromatique, N-bromo-succinimide. [Traduit par la Redaction], Introduction Bromoarenes are important intermediates for synthesis, specifically as useful substrates in metal-mediated aryl-coupling chemistry. (1-3) Since the late 1950s, (4) there has been considerable interest in N-bromosuccinimide (NBS) as [...]

The surface-supported corannulene (COR)-[C.sub.60] host-guest complexes are formed by deposition of [C.sub.60] onto a COR lattice on Cu(110). The studies have shown that the bistability has originated from a subtle interplay between homo- and heteromolecular interactions.

An experimental plan is developed for measuring the effective hydrogen/deuterium steric kinetic effect (KIE), which is based on greater bowl depth and barrier to bowl inversion in sym-1,3,5,7,9-pentamanisyl-corannule when compared to corannulene. The results have shown the usefulness of the N-heterocyclic carbene (NHC) ligand even for the coupling reaction with multichlorides.

An efficient method is described to prepare symmetric 7,8,9,10-substituted fluoranthenes from the reaction of peri-diynes and alkynes catalyzed by Wilkinson's complex. The crystal structure of indenocorannulenes have helped in understanding the bowl-shaped geometry of these compounds and this new synthetic method has occurred under neutral conditions.

The photorefractive properties of the hole-transporting polymer poly(siloxane)-triarylamine-based composites doped with photorefractive chromophore 4-di(2-methoxyethyl)aminobenzylidene malononitrile (AODCST). The results indicate that the composite exhibited good chromophore orientational mobility.

Research has been conducted on the persistent oxidation dications from fluoranthene-PAHs. Results indicate the charge delocalization mode and tropicity in the resulting nonalternant dications.

Quantum mechanical designs for planar delocalized cyclooctatetraene are discussed.

Research into structure/energy correlation of bowl depth and inversion barrier in corannulene derivatives is presented. The energy profile of an individual corannulene derivative was found to fit a mixed quartic/quadratic function.

The thermal envelope-flip manifold is elucidated as a two-stage inversion process base on ab initio computational methods.

Absolute chemical shielding tensors computed by ab initio quantum mechanical methods have been converted into the more common empirical delta(TMS) values using a set of reference linear correlations. Significant differences between computed and experimental values are analyzed with respect to chemical dynamics. It is shown that unreliable predictions for experimental delta(TMS)values are provided by simple deviations between computed (super 1)H nuclear magnetic resonance shift values for TMS and test nuclei.

A study on pi-sigma-pi through-bond coupling was conducted to determine if bond coupling can significantly increase C-C bond lengths. Ab initio calculations, such as restricted Hartree-Fock techniques, were used to predict molecular geometries and orbital energy trends. Structural analysis reduced the significance of classical pi-sigma-pi conjugation conflicts focused on bond lengthening. However, significant effects of stabilizing filled/empty pi-sigma-pi were evident during bond cleavage.

The postulate that bicyclic annelations are generally effective at inducing bond localization in the aromatic compound annulene is tested using fyran adducts of dimethyldihydropyrene. Results show a large down-field shift in the internal methyl signals when one adduct is compared with another, indicating bond localization in the former. Moreover, ab initio computations not showing dynamic electron correlation is found to be inadequate in modeling annulene's molecular structure.

A study was conducted on the synthesis of trioxatricornan-based macrocyclophanes. Nuclear magnetic resonance solution studies and computational analysis showed that methylene group replacement through an oxygen atom in the linkers of macrocyclophane radically transforms solution conformation from an extended structure with a vacant interior to a collapsed structure.

The bond length of C2h in 1,2-diphenylethane is 1.54 angstroms, as obtained from high-level split valence ab initio calculations. Using the novel electronic interactions, an anomalously short Csp3-Csp3 (central) bond for 1,2-diphenylethane and a few derivatives is reflected more likely showing experimental displacement of parameters than an actual anomaly because this violates the conception of average molecular geometry.

Several derivatives of endo-1-Cr were synthesized, and the dynamic stereochemistry of endo-(starphenylene) chromium tricarbonyl, endo-1-Cr, was analyzed through NMR spectroscopic techniques. Ab initio calculations and NMR experimental findings prove the existence of impaired rotation around the metal-arene bond and intramolecular metal-arene migration chemistry. The first molecules to show smooth metal-arene exchange and comparatively impaired tripod rotation are the derivatives of endo-(starphenylene) chromium tricarbonyl (endo-1-Cr)t-10.