Structure of 2,2′-(5-tert-butyl-1,3-phenylene)bis(1-pentyl-1H-benzimidazol-3-ium) tetrachloridomercurate(II)

In the title salt, (C34H44N4)[HgCl4], the [C34H44N4]2+cations and [HgCl4]2−anions are linked by N—H...Cl hydrogen bonds. One of the twon-pentyl side chains was refined as disordered over two sets of sites, with occupancies of 0.733 (18) and 0.267 (18). The geometry around the HgIIatom in the [HgCl4]2−anion is distorted tetrahedral, with bond angles ranging from 98.16 (3) to 120.68 (3)°. In the [HgCl4]2−anion, there are two short Hg—Cl bonds [2.4120 (9) and 2.4171 (11) Å], one intermediate Hg—Cl bond [2.4716 (12) Å] and one long Hg—Cl bond [2.6579 (13) Å] for the Cl atom involved in a trifurcated hydrogen bond as an acceptor, including two N—H...Cl...H—N interactions as well as one C—H...Cl interaction. There are several C—H...Cl interactions, with C...Cl distances ranging from 3.492 (3) to 3.796 (3) Å. These link the cations and anions into a zigzag chain along thec-axis direction. In addition, there are Cl...Cl halogen bonds, as well as π–π interactions, with centroid-to-centroid distances of 3.4765 (18) Å, which link one of the two benzimidazole moieties into dimeric units.

X-ray structure analysis of 3-chloro-7-hydroxy-4- methyl-chroman-2-one

The title compound crystallizes in the monoclinic space group P21/c, with unit cell parameters a=7.7203(3), b=14.0481(4), c=8.9066(3) Å, â=112.858(5)º, V= 890.11(5) Å3 and Z = 4. The structure has been solved by direct methods and the final R-factor is 0.0433 for 2832 unique reflections. The molecule, as such, is planar and the planarity is confirmed by the magnitude of dihedral angles between the two rings. Extensive Hydrogen-bonding has been observed and chlorine atom is responsible for the formation of trifurcated hydrogen-bond. Trifurcated hydrogen-bond plays a significant role in the design and synthesis of molecules having drug implications.

Infrared Spectra of the Ammonium Ion in Crystals. II. The Ammonium Ion in Trigonal Environments, with a Consideration of Hydrogen Bonding

Infrared spectra of polycrystalline (NH4)2GeF6, β-(NH4)2SiF6, and (NH4)2Pb(SO4)2 have been recorded at room and liquid-nitrogen temperatures. The N—D stretching and bending fundamentals of the isotopically dilute NH3D+ ion in these compounds have been studied with particular attention. The occurrence of N—D stretching doublets and bending triplets, of approximate intensity ratios 1:3 and 2:3:3 respectively, confirms the C3v symmetry of the ammonium ion and suggests that the isotopic dilution technique will prove useful as a diagnostic tool for ascertaining site symmetries of the ammonium ion. The spectra are consistent with non-rotating ammonium ions. The frequencies of dilute NH3D+ ions suggest that for the ammonium ion in (NH4)2Pb(SO4)2 a trifurcated hydrogen bond is stronger than a normal hydrogen bond.