RESUMEN
Modern Density Functional Theory models are now suitable for many molecular and condensed phase studies. The study of noncovalent interactions, a well-known drawback, is no longer an insurmountable obstacle through design and empirical corrections. However, using empirical corrections as in the DFT-D methods might not be an all-in-one solution. This work uses a simple system, X2 -H2 O with X = Cl or Br, with two different interactions, halogen-bonded (XB) and hydrogen-halogen (HX), to investigate the capability of current density functional approximations (DFA) in predicting interaction energies with eight different exchange-correlation functionals. SAPT(DFT) provides, for all the studied cases, better predictions than the widely used supermolecular approach. In addition, the components of the interaction energy suggest where some of the shortcomings originate in each DFA. The analysis of the functionals used confirms that PBE0 and ω-B97X-D have a physically correct behavior. Using SAPT(DFT) and PBE0, and ω-B97X-D, we obtained the interaction energy of Cl2 and Br2 inside different clathrate cages and satisfactorily compared with wavefunction results; hence, the lower and upper limits of this value are defined: Cl2 @512 , -5.3 ± 0.3 kcal/mol; Cl2 @512 62 , -5.5 ± 0.1 kcal/mol; Br2 @512 62 , -7.6 ± 1.0 kcal/mol; Br2 @512 63 , -10.6 ± 1.0 kcal/mol; Br2 @512 64 , -10.9 ± 0.8 kcal/mol.
RESUMEN
Halogen bonding is a noncovalent interaction that has attracted great attention because of its importance in several areas, such as photonics, nonlinear optics, pharmaceutical products, supramolecular engineering, biochemistry, protein-ligand complexes, and polymer interactions. In this context, we describe the synthesis, molecular structure, supramolecular arrangement, and theoretical calculations of five dibromonitrobenzene derivatives, which present different halogen atoms substituted. The solid-state characterization was carried out by X-ray diffraction with the contribution of Hirshfeld surfaces for analysis of molecular interactions. The frontier molecular orbital, molecular electrostatic potential, and quantum theory of atoms in molecules were carried out at the M06-2X/6-311+G(d,p) level of theory. Those observed halogen interactions indicate the crystalline solid-state stabilization for the dibromonitrobenzene derivatives.
RESUMEN
Previous studies by Desiraju and co-workers have implicated the acidic hydrogen atoms of cubane as a support network for hydrogen bonding groups. Herein we report a detailed structural analysis of all currently available 1,4-disubstituted cubane structures with an emphasis on how the cubane scaffold interacts in its solid-state environment. In this regard, the interactions between the cubane hydrogen atoms and acids, ester, halogens, ethynyl, nitrogenous groups, and other cubane scaffolds were cataloged. The goal of this study was to investigate the potential of cubane as a substitute for phenyl. This could be achieved by analyzing all contacts that are directed by the cubane hydrogen atoms in the X-ray crystal structures. As a result, we have established several new cubane interaction profiles, such as the catemer formation seen in esters, the preferences of halogen-hydrogen contacts over direct halogen bonding, and the stabilizing effects caused by the cubane hydrogen atoms interacting with ethynyl groups. These interaction profiles can then be used as a guide for designing cubane bioisosteres of known materials and drugs containing phenyl moieties.
RESUMEN
The asymmetric unit of the title co-crystalline adduct, 1,3,6,8-tetra-aza-tri-cyclo[4.4.1.13,8]dodecane (TATD)-4-iodo-phenol (1/2), C8H16N4·2C6H5IO, comprises a half mol-ecule of the aminal cage polyamine plus a 4-iodo-phenol mol-ecule. A twofold rotation axis generates the other half of the adduct. The components are linked by two inter-molecular O-Hâ¯N hydrogen bonds. The adducts are further linked into a three-dimensional framework structure by a combination of Nâ¯I halogen bonds and weak non-conventional C-Hâ¯O and C-Hâ¯I hydrogen bonds.
RESUMEN
After reporting the structure of a new polymorph of 1,3,5-trifluoro-2,4,6-triiodobenzene (denoted BzF3I3), C6F3I3, (I), which crystallized in the space group P21/c, we perform a comparative analysis with the already reported P21/n polymorph, (II) [Reddy et al. (2006). Chem. Eur. J. 12, 2222-2234]. In polymorph (II), type-II I...I halogen bonds and I...π interactions connect molecules in such a way that a three-dimensional structure is formed; however, the way in which molecules are connected in polymorph (I), through type-II I...I halogen bonds and π-π interactions, gives rise to an exfoldable lamellar structure, which looks less tightly bound than that of (II). In agreement with this structural observation, both the melting point and the melting enthalpy of (I) are lower than those of (II).
RESUMEN
In the title compound, C21H17N3OSe, the dihedral angles between the central five-membered ring and the C- and N-bound rings are 17.89â (10) and 42.35â (10)°, respectively, indicating the mol-ecule is twisted. The dihedral angle between the Se-bound rings is 85.36â (10)°. A close intra-molecular Seâ¯O contact of 2.8507â (13)â Å is noted. In the crystal, C-Hâ¯O, C-Hâ¯N and C-Hâ¯π inter-actions lead to the formation of supra-molecular layers parallel to (011); these stack with no specific inter-molecular inter-actions between them.
RESUMEN
Two independent mol-ecules, A and B, comprise the asymmetric unit of the title compound, C20H21N3OSe. While the benzene ring directly bound to the central triazole ring is inclined to the same extent in both mol-ecules [dihedral angles = 40.41â (12) (mol-ecule A) and 44.14â (12)° (B)], greater differences are apparent in the dihedral angles between the Se-bound rings, i.e. 74.28â (12) (mol-ecule A) and 89.91â (11)° (B). Close intra-molecular Seâ¯N inter-actions of 2.9311â (18) (mol-ecule A) and 2.9482â (18)â Å (B) are noted. In the crystal, supra-molecular chains along the a axis are formed via O-Hâ¯N hydrogen bonding. These are connected into layers via C-Hâ¯O and C-Hâ¯N inter-actions; these stack along (01-1) without directional inter-molecular inter-actions between them.
RESUMEN
In the title compound, C23H21N3Se, the C-bound phenyl ring is almost coplanar with the central five-membered ring [dihedral angle = 2.84â (10)°], but the N-bound benzene ring is inclined [dihedral angle = 47.52â (10)°]. The dihedral angle between the Se-bound rings is 69.24â (9)°. An intra-molecular Seâ¯N inter-action of 3.0248â (15)â Å is noted. In the crystal, C-Hâ¯π inter-actions connect mol-ecules into double layers that stack along the a axis with no directional inter-actions between them.