P. S. Sobolev

Quantitative relations holding in coordination of (Tetraphenylporphyrinato)zinc(II) and nucleophilic substitution with anilines

Thermodynamic parameters (ΔG°, ΔS°) of quasi-isoenthalpic coordination of (tetraphenylporphyrinato) zinc(II) with anilines (except for 4-halo derivatives) in chloroform at 273–313 K in the absence of steric factors are linearly related to shifts of their absorption bands in the electronic spectra in reactions with anilines, as well as with logarithms of the stability constants of the complexes, pKa values of the ligands in water, and Hammett substituent constants σ+. Linear relations were also found between thermodynamic and kinetic parameters of some nucleophilic substitution reactions and complex formation of (tetraphenylporphyrinato) zinc(II) with anilines.

Nucleophilicity of Heteroaromatic N-Oxides in Coordination with Zn(II) Tetraphenylporphyrinate and in the Substitution Reactions

Linear correlations have been revealed between thermodynamic and kinetic parameters of the nucleophilic substitution and coordination reactions of zinc(II) tetraphenylporphyrinate with heteroaromatic Noxides in different solvents. Complex formation of zinc(II) tetraphenylporphyrinate with n-donor ligands in chloroform can serve as model system in spectroscopy studies of nucleophilicity and basicity of the compounds capable of the n,ν type complexes formation.

Coordination of zinc tetraphenylporphyrin with pyridine derivatives in chloroform solution and in the solid phase

Coordination of zinc tetraphenylporphyrin with 2-,3-, and 4-halopyridines, pyridin-2-amine, and pyrimidin-2-amine in chloroform has been studied by spectrophotometry. Protonation and complexation of halopyridines and haloanilines with zinc tetraphenylporphyrin are discussed. According to the X-ray diffraction data, enhanced stability of the 2: 2 zinc tetraphenylporphyrin complex with pyrimidin-2-amine in the solid phase and in chloroform solution is likely to be determined by hydrogen bonding between the two ligand molecules involving nitrogen atoms in the pyrimidine ring and amino group.

Crystal structure of molecular complexes of zinc(II) tetraphenylporphyrin with pyridine and quinoline N-oxides

The structure of molecular complexes of zinc(II) tetraphenylporphyrin (Zn-TPP) with 4-methoxy- and trans-2-(4-dimethylaminostyryl)pyridine and 4-methoxy-, 4-nitro, and 4-chloroquinoline N-oxides was studied by X-ray diffraction analysis. Heteroaromatic N-oxides, like aniline derivatives, are coordinated at an angle of 26°–32° to the porphyrin ring plane, whereas pyridine ligands are coordinated almost perpendicularly to this plane. It is suggested that just such coordination peculiarities are responsible for the difference in the thermodynamic parameters of Zn-TPP with pyridine-based ligands (linear relationship between ΔH0 and ΔS0, high heat effect of the process), and N-oxides, aniline derivatives (low ΔH0 values, quasi-isenthalpic processes).

Complex formation between zinc(II) tetraphenylporphyrinate and alkylamines

Zinc(II) tetraphenylporphyrinate in chloroform forms complexes with primary amines containing up to 18 carbon atoms; the complex with n-octylamine is the most stable. Zinc(II) tetraphenylporphyrinate complex with octanol-1 is more stable than those with other alcohols. Reasons for this highest complex stability have been discussed basing on X-ray diffraction data for the n-octylamine complex.

Nucleophilicity of N-Propargylanilines in the Coordination to Zinc Tetraphenylporphyrin in Chloroform

Thermodynamic parameters (ΔG0 and ΔS0) of the isoenthalpic (except for 4-halo derivatives) coordination of (tetraphenylporphyrinato)zinc(II) with anilines in chloroform at 273–313 K linearly correlate with the shift of their electronic absorption maxima in the reaction with anilines, as well as with the logarithms of the stability constants of the complexes, pKa values of the ligands in water, and substituent constants σ+. The 2: 1 complex of (tetraphenylporphyrinato)zinc(II) with p-phenylenediamine was characterized by the X-ray diffraction data

Spatial structure of molecular complexes of zinc(II)tetraphenylporphyrin with pyridine and aniline derivatives

Structure of molecular complexes of zinc(II)tetraphenylporphyrin with 4-dimethylaminopyridine and 4-methoxyaniline has been studied by X-ray diffraction analysis. 4-Dimethylaminopyridine is coordinated almost perpendicular to the porphyrin cycle plane, whereas 4-methoxyaniline is coordinated at lower dihedral angle. The hybridization of aniline nitrogen atom in the crystal depends on donor-acceptor properties and the volume of the substituents in the aromatic ring.

Coordination of secondary and tertiary amines to zinc tetraphenylporphyrin

Stability constants of 46 complexes of zinc(II) tetraphenylporphyrin with primary, secondary, and tertiary amines and thermodynamic parameters of their formation (ΔG0, ΔH0, ΔS0) in chloroform at 283–308 K have been analyzed. Probable factors responsible for enhanced stability of the complexes with ligands containing n-octyl groups are discussed. The X-ray diffraction data for the 1: 1 complex of zinc(II) tetraphenylporphyrin with di-n-octylamine are given.

Crystal structure of hydrobromides of pyridines and quinolines N-oxides

Structures of hydrobromides of quinoline, 4-methylquinoline, pyridine, and 4-methylpyridine N-oxides have been elucidated by means of X-ray diffraction analysis. In contrast to other salts, quinoline N-oxide hydrobromide crystallizes in the form of dimer with two water molecules. The oxygen atom of the organic molecule is coordinated with water protons, and its state is close to sp2-hybridization. In the cases of other hydrobromides, the oxygen atom is strongly bound to the proton of НBr and exhibits sp3-hybridization.

Kinetics of the reaction of N , N -dimethylaniline with 1-bromoalk-2-ynes

Quaternization of N,N-dimethylaniline with propargyl bromide, 1-bromobut-2-yne, and 1-bromooct-2-yne were studied. It was shown that, with the lengthening chain of the substituent at the triple bond, the quaternization rate tends to increase.