Emission-Tunable B←N Lewis Pair-Functionalized Naphthalenes.

Herein, we simultaneously synthesized three different double B←N Lewis pair-functionalized naphthalenes including the asymmetric BNNY and BNNO and the mirror-symmetric BNNR, via a one-pot method. The annulation modes of the B←N Lewis pairs and the substituents on the boron atoms efficiently tune the molecular frontier orbitals and emission colors. α-Position fusion leads to a significant enhancement of the HOMO energy level and a decrease in the HOMO-LUMO gap, while the electron-withdrawing groups attached to the boron atom make the LUMO energy level more stable.

Radical anions of 1,1-azoliumdithiocarboxylates.

The 1,1-azoliumdithiocarboxylate cAAC-CS (1a) was prepared and its redox chemistry was evaluated and compared to NHC based dithiocarboxylates IDipp-CS (1b) and IMes-CS (1c). Radical anions [carbene-CS]˙ were prepared by metallic reduction as the potassium or magnesium ion complexes [K(18-crown-6)(cAAC-CS)] (2a), [K(18-crown-6)(NHC-CS)] (NHC = IDipp: 2b, IMes: 2c), and [Mg(NacNac)(cAAC-CS)] (3) and extensively characterized (SC-XRD, EPR, UV/VIS/NIR, DFT). These complexes represent the first examples of isolated radical anions of 1,1-dithiolenes.

Cross-Coupling of NHC/CAAC-Based Carbodicarbene: Synthesis of Electron-Deficient Diradicaloids.

Herein, we report nickel(0)-catalyzed cross-coupling reactions of NHC/CAAC-based carbodicarbene (NHC = -heterocyclic carbene and CAAC = cyclic(alkyl)(amino)carbene) with different aryl chlorides, bromides, and iodides. The resulting aryl-substituted cationic carbodicarbene derivatives are prone to one-electron oxidation yielding radical-dications, which, depending on the aryl motif employed, follow different modes of radical-radical dimerization and constitute an entry point to carbon/nitrogen- and nitrogen/nitrogen-centered diradicaloids. Subsequently, this coupling strategy was strategically applied to the synthesis of -phenylene- and ,-biphenylene-bridged carbon/carbon-centered electron-deficient diradicaloids.

Tuning Electron Transfer Coupling and Exchange Interaction in Bis-triarylamine Radical Cations and Dications by Bridge Electron Density.

The influence of the electron density of a bridge connecting two redox centers on both the intervalence hole transfer and the magnetic superexchange was investigated in a series of bridged bis-triarylamine mono- and dications. In this series, the bridge was 2,7-fluorenyl, where the bridge electron density was modified by substituents at the 9-position. For the mixed-valence monocations, the observation of both an intervalence charge transfer (IVCT) band and an absorption band associated with an electron transfer from the bridging fluorene to the triarylamine radical cation centers allowed determination of the electron transfer couplings in the framework of the three-state generalized Mulliken-Hush theory.

The forgotten borole: synthesis, properties and reactivity of a 1-boraindene.

The chemistry of unsaturated boron heterocycles, including five-membered boroles, continues to attract substantial interest. Herein, we report the synthesis of 1,2,3-triphenyl-1-boraindene, a benzene-fused borole, and examine its Lewis acidic, electrophilic, and antiaromatic properties relative to non-fused and bis-benzannulated boroles (9-borafluorenes). Reactivity studies with organic azides reveal that the boraindene behaves similarly to other boroles, undergoing ring expansion to a BN-naphthalene through insertion of a nitrogen atom.