Crystal structure and Hirshfeld surface analysis of 3-cyano-phenyl-boronic acid

A study of the crystal structures, supra-molecular patterns and Hirshfeld surfaces of bromide salts of hypoxanthine and xanthine

Two new crystalline salts, namely, hypoxanthinium bromide monohydrate, C5H5N4O+·Br-·H2O (I) and xanthinium bromide monohydrate, C5H5N4O2 +·Br-·H2O (II), were synthesized and characterized by single-crystal X-ray diffraction technique and Hirshfeld surface analysis. The hypoxanthinium and xanthinium cations in salts I and II are both in the oxo-N(9)-H tautomeric form. The crystal packing of the two salts is governed predominantly by N-H⋯O, N-H⋯Br, C-H⋯Br and O-H⋯Br inter-actions described by R 2 3(9) and R 2 2(8) synthons. The crystal packing is also consolidated by carbon-yl⋯π inter-actions between symmetry-related hypoxanthinium (HX+ ) cations in salt I and xanthinium cations (XA+ ) in salt II. The combination of all these inter-actions leads to the formation of wave- and staircase-like architectures in salts I and II, respectively. The largest contributions to the overall Hirshfeld surface are from Br⋯H/H⋯Br contacts (22.3% in I and 25.4% in II) .

Crystal structure and Hirshfeld surface analysis of 2,4,6,11-tetra-kis-(4-fluoro-phen-yl)-9-oxa-1,5-di-aza-tri-cyclo-[5.3.1.03.8]undeca-ne

The title compound, C32H26F4N2O, crystallizes in the monoclinic space group P21/n with four mol-ecules in the unit cell. The compound was prepared by the NaBH4 reduction of 4,8,9,10-tetra-kis-(4-fluoro-phen-yl)-1,3-di-aza-adamantan-6-one in chloro-form and ethanol as solvent. The piperidine rings exhibit chair and boat conformations, and all four fluoro-phenyl groups are oriented in the equatorial direction. The crystal structure features C-H⋯F hydrogen bonds, C-H⋯π, N-H⋯π and π-π inter-actions. Hirshfeld surface and two-dimensional fingerprint analysis show that van der Waals inter-actions constitute a major contribution to the inter-molecular inter-actions, with H⋯H contacts accounting for 37.9% of the surface.