Experimental and Theoretical Investigations of Complex Formation of Substituted Phenylazo-Derivatives of Methylphloroglucinol

Using spectrophotometric titration technique, the processes of complex formation of some phenylazo-derivatives of methylphloroglucinol (MPG) containing hydroxo-, nitro- and nitroso-substituents were studied. The spectral criteria of neutral and ionized forms of the organic ligands in their different tautomeric forms were determined.It was detected that the complex formation is accompanied by formation of one or two chelate cycles which involve azo- or nitroso-fragments and neighboring OH-groups of the organic ligands. Different types of coordination lead to different changes in the electronic absorption spectra.The DFT-B3LYP modeling of a Ni(II) complex of α-hydroxyphenylazo MPG established the most probable coordination mode of the organic ligand: tridentate chelating dianion, distorted square coordination of Ni-cations including one water molecule.  The theoretical results are in a good accordance with the experimental data

Experimental and Theoretical Investigations of Complex Formation of Substituted Phenylazo-Derivatives of Methylphloroglucinol

Using spectrophotometric titration technique, the processes of complex formation of some phenylazo-derivatives of methylphloroglucinol (MPG) containing hydroxo-, nitro- and nitroso-substituents were studied. The spectral criteria of neutral and ionized forms of the organic ligands in their different tautomeric forms were determined.It was detected that the complex formation is accompanied by formation of one or two chelate cycles which involve azo- or nitroso-fragments and neighboring OH-groups of the organic ligands. Different types of coordination lead to different changes in the electronic absorption spectra.The DFT-B3LYP modeling of a Ni(II) complex of α-hydroxyphenylazo MPG established the most probable coordination mode of the organic ligand: tridentate chelating dianion, distorted square coordination of Ni-cations including one water molecule.  The theoretical results are in a good accordance with the experimental data

Synthesis and studies of complex compounds of carboxyl-derivatives of methylphloroglucinol with metals

Ten new complexes of 2,4,6–trihydroxy-3-methyl benzoic acid (methylphloroglucinol, L1) and 2,4,6–trihydroxy benzoic acid (phloroglucinol, L2) are isolated in the solid state, and their formulae were detected.The spectroscopic methods indicate that the coordination of  L1 and L2 to the metallic ions occurs through one of the O-atom of the deprotonated carboxylic group and an O atom of the non-deprotonated neighboring hydroxy-group (bidentate chelating coordination). The schemes of the structure of complexes are proposed.The complex formation in solution is studied, and formation constants are calculated. It is shown that for the metal complexes of the 1st transitional series, the formation constants for the complexes are arranged as Mn(II) < Co(II) < Ni(II) < Cu(II) > Zn(II). The obtained results correlate with the Irving-Williams Series

catena-Poly[ammonium [aquabis(μ-2,3,5,6-tetraoxo-4-nitropyridin-4-ido)argentate(I)]]

In the title compound, {(NH4)[Ag(C5HN2O6)2(H2O)]}n, the AgI cation is seven-coordinated and is surrounded by four oxo O atoms of the 2,3,5,6-tetraoxo-4-nitropyridin-4-ide species [Ag—O = 2.3848 (19), 2.4931 (18), 2.5361 (18) and 2.573 (2) Å], two nitro O atoms [Ag—O = 2.644 (2) and 2.661 (2) Å], and one water molecule [Ag—O = 2.3133 (19) Å]. The pyridin-4-ide mono-anions act as polydentate bridging ligands and form a three-dimensional network that is stabilized through O—H...O and N—H...O hydrogen bonds involving the coordinating water molecule and the imide function as donator groups. The ammonium cations are located in the cavities of the framework and are also involved in hydrogen bonding to O atoms of the ligand

The Spectroscopic and theoretical investigations of complex formation of (3E,3'E)-7,7'-(carbonylbis(azanediyl))bis(3-(2-(2-hydroxyphenyl)hydrazono)-4-oxo-3,4-dihydronaphthalene-2-sulfonic acid) with metal cations

A novel azo-dye  was isolated by a diazo-coupling reaction and characterized by the elemental analysis, mass spectra, IR and UV-VIS spectroscopy. The processes of complex formation of H4L with some mono-, bis-, and trivalent metal cations were studied by spectrophotometric titration and theoretical modeling. The NBO effective charge calculations indicate a strong covalent character of the coordination bonds at complexation

3.2.1. Synthesis, crystal and molecular structure of catena-(bis(µ1-oxalic acid)-µ3-hydrogen oxalate-di-aqua-sodium(I)).

The crystal and molecular structure of catena-(bis(µ- oxalic acid)-µ-hydrogen oxalate-di-aqua-sodium(I)) was detected by X-Ray analysis. The compound crystallizes in the triclinic space group P-1, with a(Å) 6.2378(12); b(Å) 7,1115(14); c(Å) 10.489(2); α(°) 94.65(3); β(°) 100.12(3); γ(°) 97.78(3). The sodium cation in the title compound is eight coordinated and forms a square antiprism. It is surrounded by two molecules of oxalic acid, one hydrogen oxalate anion and one water molecule. Both oxalic acid and hydrogen oxalate anion act as polydentate bridging ligands. Centrosymmetric sodium cations are bounded by hydrogen oxalate anions through a system of H bonds involving the molecules of oxalic acid. In the lattice, the 3D structure stabilized by H bonds is formed

Crystal structure of chlorido{1-(2,3-dimethyl-5-oxido-1-phenyl-1H-pyrazol-2-ium-4-yl-κO)-2-[3-methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-ylidene-κO]hydrazin-1-ido-κN1}copper(II) from laboratory X-ray powder data

In the title compound, [Cu(C21H19N6O2)Cl], the CuII atom is in a slightly distorted square-planar coordination involving two O atoms from the pyrazolone rings [Cu—O = 2.088 (10) and 1.975 (10) Å], an N atom of the azo group [Cu—N = 2.048 (13) Å] and a chloride anion [Cu—Cl = 2.183 (5) Å]. The organic anions act as tridentate chelating ligands. The molecules stack in columns along the c axis