Hydrogen bond synthons affect the coordination geometry of d10-metal halide complexes: synthetic methods, theoretical studies, and supramolecular architectures

The tendency of the pyrazine nitrogen atom to form hydrogen bond supramolecular synthons affects the coordination geometry of new d10-metal halide complexes which have been prepared by solution-based methods in comparison with solid-state reactions.

The combination of halogen and hydrogen bonding: a versatile tool in coordination chemistry

4-Iodo-N-(4-pyridyl)benzamide (INPBA) and four derived coordination complexes were synthesized in order to explore the combination of halogen and hydrogen bonding interactions in coordination chemistry.

Solid-state supramolecular architectures of a series of Hg(ii) halide coordination compounds based on hydroxyl-substituted Schiff base ligands

Herein, six Hg(ii) coordination compounds containing Schiff base ligands were synthesized, characterized and studied using geometrical and Hirshfeld analyses as well as theoretical calculations.

Lone pair⋯π interaction versus σ-hole appearance in metal-bonded halogens

Three complexes of N-(2,5-diluorophenyl)-2-pyrazine carboxamide and ZnX₂ have been synthesized. The crystal structures reveal that in all three coordination compounds, metal-bound halides have interacted with π systems through a negative electrostatic region.

Sonochemical synthesis, characterization, and effects of temperature, power ultrasound and reaction time on the morphological properties of two new nanostructured mercury(II) coordination supramolecule compounds

Two new mercury(II) coordination supramolecular compounds (CSCs) (1D and 0D), [Hg(L)(I)₂]_n (1) and [Hg₂(L')₂(SCN)₂]·2H₂O (2) (L=2-amino-4-methylpyridine and L'=2,6-pyridinedicarboxlic acid), have been synthesized under different experimental conditions. Micrometric crystals (bulk) or nano-sized materials have been obtained depending on using the branch tube method or sonochemical irradiation. All materials have been characterized by field emission scanning electron microscope (FESEM), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Single crystal X-ray analyses on compounds 1 and 2 show that Hg²⁺ ions are 4-coordinated and 5-coordinated, respectively. Topological analysis shows that the compound 1 and 2 have 2C1, sql net. The thermal stability of compounds 1 and 2 in bulk and nano-size has been studied by thermal gravimetric (TG), differential thermal analyses (DTA) for 1 and differential scanning calorimetry (DSC) for 2, respectively. Also, by changing counter ions were obtained various structures 1 and 2 (1D and 0D, respectively). The role of different parameters like power of ultrasound irradiation, reaction time and temperature on the growth and morphology of the nano-structures are studied. Results suggest that increasing power ultrasound irradiation and temperature together with reducing reaction time and concentration of initial reagents leads to a decrease in particle size.

Coordination chemistry of mercury(ii) with 2-pyridylnitrones: monomers to polymers

The coordination chemistry of mercury(ii) halides, HgX₂, X = Cl, Br, I, with N-methyl-α-(2-pyridyl)nitrone, L1, and N-t-butyl-α-(2-pyridyl)nitrone, L2, is reported. The structures of 1 : 1 complexes [HgX₂L], X = Cl, L = L1; X = Br, L = L2, 2 : 1 complexes [(HgX₂)₂L], X = Br or I, L = L1; X = Cl or I, L = L2, and a unique compound [(HgBr₂)₅(L2)₃] have been determined. In the 1 : 1 and 1 : 2 complexes, the ligand L1 adopts the anti conformation, and is either monodentate or bridging, while the ligand L2 adopts the syn conformation and acts as a chelate ligand. In the compound [(HgBr₂)₅(L2)₃] the ligand L2 is present in both syn-chelate and anti-bridging bonding modes. Secondary intermolecular bonding, involving OHg or XHg interactions, can lead to association of the molecular compounds to form polymers of several kinds. In solution, the complexes are labile and the crystalline products do not necessarily reflect the reaction stoichiometry.

Influences of temperature, power ultrasound and reaction time on the morphological properties of two new mercury(II) coordination supramolecular compounds

Nanoparticles of two new coordination compounds, [Hg₂(L)₂(Br)₄]_n (1) and [Hg(L')(SCN)₂] (2), (L=2-amino-4-methylpyridine, L'=2,6-pyridinedicarboxlic acid), have been synthesized by use of a sonochemical process and characterized by scanning electron microscopy (SEM), field emission scanning electron microscopy(FESEM), X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) spectroscopy and elemental analyses. The single crystal X-ray data of compounds 1 and 2 imply that the Hg(II) ions are four and five coordinated, respectively. Topological analysis shows that 1D and 0D coordination networks of 1 and 2 can be classified as underlying nets of topological types 2C1 and 1,3M4-1, respectively. The thermal stability of compounds has been studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The role of temperature, reaction time and ultrasound irradiation power on the size and morphology of "nano-structures" 1 and 2, has been investigated. Results claim that an increase of temperature, sonication power and decrease in reaction time leads to a decrease of particle size.

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

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.

The role of intermolecular interactions involving halogens in the supramolecular architecture of a series of Mn(ii) coordination compounds

This study reveals the role of halogen-involving interactions in structural changes of supramolecular assemblies of manganese(ii) complexes including N-(4-halo)phenyl picolinamide ligands.

Ultrasonic-assisted synthesis and structural characterization of two new nano-structured Hg(II) coordination polymers

Two new Hg(II) coordination polymers containing N,N'-Bis-pyridin-3-ylmethylene-naphtalene-1,5-diamine ligand were synthesized by conventional and sonochemical methods, characterized by spectroscopic techniques (FT-IR and elemental analysis), and their X-ray crystallographic structures were determined. The crystal packing and supramolecular features of these coordination polymers were studied using geometrical analysis and Hirshfeld surface analysis. The crystal structure analysis revealed that H⋯H contacts, C-H⋯π and C-H⋯X (X = Cl for 1 and X = Br for 2) hydrogen bonding interactions are strong enough to govern the supramolecular architecture. The BFDH analysis helps us to compare the predicted morphology to that obtained under ultrasonication. This study may provide further insight into discovering the role of weak intermolecular interactions in the context of nano-supramolecular assembly.

The role of weak hydrogen and halogen bonding interactions in the assembly of a series of Hg(ii) coordination polymers

A series of eight new Hg(ii) complexes based on the L^4-X ligands, where L is (E)-4-halo-N-(pyridin-4-ylmethylene)aniline, were synthesized and characterized and their supramolecular crystal structures were studied by different geometrical and theoretical methods.

Effect of robust π–π stacking synthon on the formation of mercury coordination compounds; an unusual pseudo-square planar geometry

In this study, three Hg(ii) complexes, [HgCl₂(L2-naph)]_n, 1, [HgBr₂(L2-naph)]_n, 2 and [HgI₂(L2-naph)₂], 3 where L2-naph is N-(naphthalene-2-yl)pyrazine-2-carboxamide ligand have been synthesized and characterized.