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A family of cyclic phosphine‐disiloxane featuring peri‐substituted naphthyl(Nap)/acenaphthyl(Ace) scaffolds has been prepared and fully characterized including X‐ray structure, which enables a detailed structural analysis. This straightforward synthesis takes advantage of both ortho‐ and peri‐substitution of Nap/Ace‐substituted phosphine oxides. The synthetic method allows diversifying the polycyclic aromatic platform (Nap and Ace) as well as the Si substituents (Me and Ph). Despite a strong steric congestion, the P‐atom remains reactive toward oxidation or coordination. In particular, Au(I) complex could be prepared. All the compounds display absorption/luminescence in the UV‐Vis range. Surprisingly, the P‐trivalent derivatives display unexpected luminescence in the green in solid‐state. [ABSTRACT FROM AUTHOR]

Investigations based on NMR spectroscopy, mass spectrometry, and DFT calculations shed light on the metallic species generated in the rhodium-catalyzed asymmetric [2+2+2] cycloaddition reaction between diynes and isocyanates with the chiral phosphate TRIP. The catalytic mixture comprising [{Rh(cod)Cl}2], 1,4-diphenylphosphinobutane (dppb), and Ag( S)-TRIP actually gives rise to two species, both having an effect on the stereoselectivity. One is a rhodium(I) complex in which TRIP is a weakly coordinating counterion, whereas the other is a bimetallic Rh/Ag complex in which TRIP is a strongly coordinating X-type ligand. [ABSTRACT FROM AUTHOR]

The photophysical and chiroptical properties of a novel, chiral helicene‐NHC−Re(I) complex bearing an N‐(aza[6]helicenyl)‐benzimidazolylidene ligand are described, showing its ability to emit yellow circularly polarized luminescence. A comparative analysis of this new system with other helicene‐Re(I) complexes reported to date illustrates the impact of structural modifications on the emissive and absorptive properties. [ABSTRACT FROM AUTHOR]

We report the straightforward synthesis of unprecedented electron‐acceptors based on dicationic P‐containing PAHs (Polycyclic Aromatic Hydrocarbons) based on copper mediated radical approach. In these systems, two phosphoniums are connected through various PAHs backbones. The impact of π‐extension on both the optical and redox properties is investigated using a joint experimental (UV/Vis absorption, fluorescence and cyclic voltammetry) and theoretical approach (TD‐DFT calculations). Finally, (spectro)‐electrochemical studies prove that these compounds possess three redox states and EPR studies confirm the in situ formation of an organic radical delocalized on the PAH backbone. [ABSTRACT FROM AUTHOR]

Strontium and calcium (alkaline earth: Ae) olefin complexes stabilised by secondary Ae⋅⋅⋅F−C and β-agostic Ae⋅⋅⋅H−Si interactions are presented. Olefin coordination onto the alkaline earths is plain in the solid state, and it is thermodynamically favoured over the coordination of THF. The existence of the Ae⋅⋅⋅olefin interactions is corroborated by solution NMR data and DFT computations. The coordination mode of the olefin varies with steric effects and, if enforced, olefin dissociation can be compensated by the other non-covalent interactions, as supported by DFT computations. [ABSTRACT FROM AUTHOR]

Mono‐ and di‐boranil‐substituted helicenes were prepared by BF2‐borylation of the corresponding anils, readily synthesized by condensation of 2‐amino‐ and 2,15‐diamino‐helicenes with 4‐(diethylamino)salicylaldehyde. After enantiomeric resolution using HPLC, their chiroptical properties including circularly polarized fluorescence in solution and in PMMA films were investigated and rationalized with the help of NMR, X‐ray and quantum‐chemical calculations. [ABSTRACT FROM AUTHOR]

Abstract: N‐Aryl‐N‐methyl‐2‐tert‐butyl‐6‐methylaniline derivatives exhibit a rotationally stable N−C axially chiral structure and the rotational barriers around an N−C chiral axis increased with the increase in electron‐withdrawing character of para‐substituent on the aryl group. X‐ray crystal structural analysis and the DFT calculation suggested that the considerable change of the rotational barriers by the electron effect of para‐substituents is due to the disappearance of resonance stabilization energy caused by the twisting of para‐substituted phenyl group in the transition state. This structural property of the N−C axially chiral anilines was employed to reveal a new acid‐decelerated molecular rotor caused by the protonation at the remote position (remote proton brake). [ABSTRACT FROM AUTHOR]