Piotr Garczarek

Synthesis, X-ray characterization, DFT calculations and Hirshfeld surface analysis of thiosemicarbazone complexes of Mn+ ions (n = 2, 3; M = Ni, Cd, Mn, Co and Cu)

Two new pyridine-based heterocyclic thiosemicarbazone ligands and their Ni(II), Cd(II), Mn(II), Co(III) and Cu(II) complexes have been synthesized and characterized by structural, analytical and spectroscopic methods. The monodeprotonated anionic forms of the ligands coordinate in a tridentate fashion via two nitrogen and one sulphur donor atoms to yield seven complexes in which metal centres vary from four-coordinated square planar to six-coordinated distorted octahedral geometries. Single-crystal X-ray crystallography showed that the molecular complexes can aggregate into larger entities depending on the anion coordinated to the metal centre. We have analysed the interesting supramolecular assemblies observed in the solid state of some complexes by means of DFT calculations. These assemblies are formed by a combination of several noncovalent interactions, including chelate ring–π, π–π, and chalcogen bonding interactions, that have been characterized using Baders Theory of “atoms-in-molecules”.

Synthesis, X-ray characterization, DFT calculations and Hirshfeld surface analysis studies of carbohydrazone based on Zn( ii ) complexes

In this manuscript we report the synthesis and X-ray characterization of five complexes of Zn(II) based on a N4O core carbohydrazone ligand (H2L); i.e. {[Zn4(HL)4](CH3OH)4(NO3)4} (1), {[Zn4(HL)4](ClO4)4} (2) {[Zn4(HL)4][Zn(SCN)4](NO3)2} (3) {[Zn(SCN)4](H4L)(CH3OH)2} (4) and {[Zn4(HL)4](NO3)4(H2O)} (5). Structurally characterized tetranuclear Zn(II) complexes, as those reported herein, are scarcely found in the literature. In the crystal structures of several compounds, N–H⋯S hydrogen bonds, anion–π and π–hole interactions are described and analysed by means of density functional theory (DFT) calculations since they play an important role in the construction of three-dimensional supramolecular frameworks. Moreover, the noncovalent interactions have been also analysed using Hirshfeld surface analysis.

Metal–organic and supramolecular lead(II) networks assembled from isomeric nicotinoylhydrazone blocks: the effects of ligand geometry and counter-ion on topology and supramolecular assembly

A new series of six structurally diverse lead(II) coordination compounds was assembled from two isomeric nicotinoylhydrazones as neutral ligands and three Pb(II) salts with different monoanions (chloride, nitrate and thiocyanate) as starting materials. The products were isolated in good yields and were fully characterized, including by single-crystal X-ray diffraction and theoretical methods. Within the six compounds, three feature 2D metal–organic networks, two are 1D coordination polymers, and another one comprises discrete 0D dimeric units. The structures of the latter low dimensional compounds are extendable into 2D supramolecular networks. The topology of the coordination or supramolecular networks is primarily dictated by the geometry of the nicotinoylhydrazone used as a main building block. In contrast, supramolecular interactions are greatly influenced by the choice of the anion in the starting lead(II) salt, which is demonstrated by Hirshfeld surface analysis. In fact, the topological analysis and classification of metal–organic or supramolecular underlying networks in the obtained compounds was performed, disclosed the hcb, 2C1, gek1, SP 1-periodic net (4,4)(0,2) and 3,4L83 topological types; the latter topology was documented for three compounds, including both coordination and supramolecular networks. In the two compounds containing thiocyanate moieties, there are supramolecular contacts between the thiocyanate anions and lead centres. These were shown by DFT calculations to be strong tetrel bonds (−15.3 and −16.7 kcal mol−1) between the σ-hole of the lead atom and the π-system of the thiocyanate S–C bond.

Halide ion-driven self-assembly of Zn(II) compounds derived from an asymmetrical hydrazone building block: a combined experimental and theoretical study

Three Zn(II) complexes, namely mononuclear derivatives [Zn(H2L)2I2]·2CH3OH (1) and [Zn(H2L)2Br2]·2CH3OH (2) and a tetranuclear cyclic compound [Zn4(H2L)4Cl8]·4CH3OH (3) {H2L = p-hydroxybenzaldehyde isonicotinoylhydrazone}, were synthesized using a self-assembly method and fully characterized. Characterization included theoretical methods and single crystal X-ray diffraction. The molecular structures of compounds 1–3 demonstrate the effect of halide ions and the binding mode of H2L on self-assembly. The arrangement of the packing patterns in 1–3 is well explained by various types of non-covalent interactions. Notably, several types of strong H-bonding, C–H⋯O, and π⋯π interactions were also observed, which assist in the formation of 3D supramolecular networks. In the isostructural compounds 1 and 2, a tripod type H-bonding interaction of H2L with the methanol molecules of crystallization was observed. Furthermore, the terminal halide ligands exert H-bonding interactions with the –OH/–NH and –CH moieties of H2L. In all compounds, the supramolecular 3D networks, driven by strong H-bonding interactions, were simplified by topologial analysis. This showed a 6-connected framework with a unique topology in 1 and 2, and an 8-connected framework with bcu topology in 3 (the latter is composed of cyclic tetrazinc(II) cluster units with 2M4-1 topology). In addition, the discussion on coordination geometries and non-covalent interactions was also supported using Hirshfeld surface analysis and DFT calculations.

Chapter 6:Synthesis of Phosphonic Acids and Their Esters as Possible Substrates for Reticular Chemistry

The scope of this chapter is to describe selected group of methods of synthesis of phosphonic acids and their esters which have found use or seems of interest in metal phosphonate chemistry. In the first place some properties of phosphonic group are mentioned. Those are geometry, acidity, and coordination of phosphonic group compared to carboxylic group, as the most frequently used organic group in synthesis of coordination polymers. In the main part of the chapter most popular synthetic methods leading to phosphonic acids and their esters are reviewed. Three fundamental methods are the Michaelis–Arbuzov reaction, catalytic cross-coupling reaction, and the Mannich-type condensation. These methods are presented in terms of substrate and reagent description, reaction scheme and mechanism, examples and a selected procedure Additionally number of other useful reactions leading to P–C bond formation are briefly described. If synthesis leads to an ester, transformation into a phosphonic acid is usually required. Therefore, two methods of such transformation are presented: acidic hydrolysis and transsilylation/methanolysis. This subsection consists of a description with a scheme of reaction. Some spectral characterization of obtained ligands are also considered. The final part of the chapter includes concluding remarks based on a statistical analysis of the use of the described synthetic methods in the past five years.