Thermal properties of ligands, salts and metal complexes of linear oligopyrroles
摘要:
The effect of structure on the thermal properties of dipyrrolylmethanes, dipyrrolylmethenes, bis (dipyrrolylmethenes), their salts, and chelates is analyzed proceeding from the results of thermogravimetric analysis. The common tendency is a decrease in the thermal stability of compounds with a disturbed symmetry of alkyl substitution of ligands and with a higher degree of their alkylation, with the increased size of alkyl substituents, with the nitrogen atom in the five-member cycles replaced by S or O. The opposite effect occurs at the change in the mode of attaching methylene spacer in going from 2,2'- to 3,3'-bis(dipyrrolylmethenes). The effects of the themostabilization of the ligands of linear oligopyrroles in the composition of chelates and HBr salts are evaluated quantitatively.
Trends in formation and stability of homo- and heteroligand d-metal complexes with 2,2′-dipyrrolylmethenes in dimethylformamide
摘要:
The reactions of symmetric and nonsymmetric alkyl-substituted 2,2'-dipyrrolylmethenes with Cu(II), Ni(II), Co(II), Zn(II), Cd(II), and Hg(II) acetates in dimethylformamide solutions at 298.15 K were studied. The formation of hetero- and homoligand complexes was observed in the systems studied depending on the concentration conditions and the nature of the complexing metal. The stepped and complete constants of formation for metal complexes were determined. The key trends of the influence of the metal and ligand nature on the stabilization of the complexes were established.