Conformational disorder in 4-(5,5′-dibromo-2′-chloro-4,4′-bipyridyl-2-yl)benzaldehyde: role of π–π and halogen interactions

Energetic analysis of the molecular packing of 5,5′-dibromo-2,2′-bis[4-(methylsulfanyl)phenyl]-4,4′-bipyridine: the role of π–π and halogen interactions

The crystal packing of the title compound, C24H18Br2N2S2, is rationalized using the PIXEL method, which allows a separation of the intermolecular interaction energy into Coulombic, polarization, dispersion and repulsion contributions. Infinite (\overline{1}01) molecular planes are formed through π–π stacking and other minor interactions, including a Br...S contact, with the σ hole of the Br atom pointing towards the S-atom lone pair. The title compound has crystallographically imposed twofold symmetry, with the twofold axis at the mid-point of the central C—C bond.

Double N-arylation reaction of polyhalogenated 4,4'-bipyridines. Expedious synthesis of functionalized 2,7-diazacarbazoles

Unusual 2,7-diazacarbazoles were prepared in one step from readily available tetra-halogenated 4,4'-bipyridines by using a double N-arylation reaction in the presence of the Pd-XPhos catalyst system. Moderate to good yields were obtained in this site-selective Buchwald-Hartwig double amination. The functionalization of these tricyclic derivatives was performed by using Pd-catalyzed cross-coupling reactions such as the Stille and Suzuki couplings. Two compounds were analyzed by X-ray diffraction and show π-π stacking involving the diazacarbazole moieties and the phenyl rings of functionalized groups.