SYNTHESIS OF 3-(2-PYRIDYL)-N-METHYL-1,2,4-TRIAZOLE-5-ACETIC ACID ETHYL ESTER AND THEIR COORDINATION COMPOUNDS WITH Pd(II)

UDC 546.98+547.792+543.429.23

Abstract

Alkylation of 3-(2-pyridyl)-1,2,4-triazole-5-acetic acid  with iodomethane leads to formation of 3-(2-pyridyl)-N¹-methyl-1,2,4-triazole-5-acetic acid ethyl ester (L¹) and 3-(2-pyridyl)-N²-1,2,4-triazole-5-acetic acid ethyl ester (L²). It was also managed to identify the compound ethyl ester 3-(2-pyridyl)-N²-methyl-1,2,4-triazol-5-yl-α-propionic acid (L³) which is the product of alkylation of L² in the methylene group. L^1-3 were used for synthesis of palladium(II) complexes PdL¹Cl₂, PdL²Cl₂ and PdL³Cl₂. The composition and structure of obtained compounds were proposed on the basis of IR and ¹H NMR spectroscopy data and elemental analysis.

IR spectra of synthesized ligands have a lot in common, due to their structure similarity. As a result of coordination all signals in the IR spectra are shifted besides bands of ester groups. ¹H NMR spectra of obtained ligands is bit similar, this is due to their structure. Signals of pyridine ring protons 3-(2-pyridyl)-N¹-methyl-1,2,4-trazole-5-acetic acid ethyl ester shifted to 0.11–0.13 ppm in a weak field in compare with  izomers. N¹–CH₃ signals are shifted to lower field than N²–CH₃, it can be explained by the influence of negative magnetic anisotropy of pyridine ring. Methyl and methylene signals of ester group are located nearly in the same field in L^1–3.

Coordination of all ligands occurs through the nitrogen atom of pyridine ring and N⁴-triazole. In this case all L¹, L² and L³ signals of pyridine  protons suffer shift to a low field. Methyl and methylene signals of ester group almost no shifted what indicate that no coordination through oxygen atom.