Conformational variety of flexible mono-dentate ligands in coordination compounds: influence of π-involving interactions

Abstract

The effect of intermolecular interactions on the conformational variety of flexible mono-dentate ligands in coordination compounds has been investigated through the preparation of two series of mercury(ii) complexes. In this regard, the molecular and structural architecture of eight complexes, [HgCl2(L(amide-Cl))2] (), [HgCl2(L(amide-Br))2] (), [HgBr2(L(amide-Br))2] (), and [HgI2(L(amide-Br))2] (), as the first series and [HgBr2(L(imine-Cl))2] (), [HgBr2(L(imine-Br))2] (), [HgI2(L(imine-Cl))]n (), and [HgI2(L(imine-Br))]n (), as the second series, using two kind of flexible ligands, N-(1-halonaphthalen-4-yl)nicotinamide, L(amide-X), and 4-halo-N-((pyridin-3-yl)methylene)naphthalen-1-amine, L(imine-X), has been studied. Inspection of the packing of these compounds clearly shows the presence of conformational changes in the arrangement of the ligands in each series. Although there are slight differences between the crystal packing of these compounds, it seems that π-involving intermolecular interactions including πnaphπnaph in the first series and πimineπpy/naph in the second series with the cooperation of Hgπpy can lock the ligand conformational variety to a single conformer.

Coordination Polymers with Intramolecular Fluorine-Involved Contacts in Two-Dimensional Sheet Windows

“…So, it can be considered that fluorinated-phenyl rings as hanging groups in the windows are pointed toward the adjacent groups to generate different fluorine-involved intramolecular interactions. Such conformationally flexible mercury complexes containing pyrazineamide ligands have previously been reported in detail by some of us. − …”

“…During our research program aiming at the understanding of the role of intermolecular interactions in the crystal packing of mercury coordination compounds containing pyrazine carboxamide ligands, − we have synthesized, characterized, and investigated a series of designed complexes in the present work, in order to gain a deeper understanding on the crucial role of fluorine-involved interactions in the supramolecular architecture of coordination compounds including fluorinated ligands. In this article, a series of N -(fluorinatedphenyl)-2-pyrazinecarboxamide ligands, L 2‑F , L 2,5‑F , L 3‑F , L 2,3,4‑F , L 3,4,5‑F , L 2,3,4,5‑F , and L 2,6‑F , Scheme , carrying fluorine atoms on the phenyl ring, have been employed for the synthesis of six isostructural two-dimensional polymeric mercury­(II) coordination complexes 1 – 6 and a discrete complex 7 , in order to get insights into the investigation of fluorine-involved interactions on the structural assemblies.…”

Synthesis, characterization, and crystal structure analysis of Zn(II) and Cd(II) coordination compounds containing 4-((pyridin-4-ylmethylene)amino)phenol Schiff-base ligand

“…A variety of supramolecular synthons based on highly directional intermolecular interactions such as hydrogen bonding, halogen bonding, and even weak directional π-stacking interactions have been identified and employed as synthetic vectors for the assembly of metal-containing materials [23,24]. It should be noted that although weak interactions such as π-stacking and non-classical hydrogen bonds are usually regarded as weak intermolecular contacts compared to the classical hydrogen bonds, there is experimental evidence showing these interactions can even affect the coordination geometry of metal complexes [25][26][27][28][29]. Therefore, supramolecular chemists have a large toolbox of functionalities capable of non-covalent interactions at their disposal (supramolecular synthons), which allow them to design the metal-containing building blocks into well-defined supramolecular architecture according to the chemical information encoded in their molecular structure [18,30].…”

Effects of Orthohalogen Substituents on Nitrate Binding in Urea-Based Silver(I) Coordination Polymers

“…Research in the area of coordination polymers has attracted intense interest in recent years due to their rich structural chemistry and their wide range of applications as functional materials. , It is well-known that physical and chemical properties of materials are dictated by the relative orientation and organization of the molecular building blocks. , Therefore, supramolecular chemists have endeavored to control this ordering, so as to fully understand how properties are influenced by the supramolecular assemblies . Previous research clearly revealed that the final supramolecular architecture of metal-containing species is dependent on different determining factors, such as metal and ligand geometries, , counterions, , and the reaction conditions. , Not surprisingly, the judicious selection of organic ligand has been verified to be one of the most important factors in the construction of coordination polymers, because it can not only provide suitable binding sites but can also direct the self-assembly through providing potential interaction sites for generating desired intermolecular interactions. − …”