Copper(II) complex of the 2-pyridinecarbaldehyde aminoguanidine Schiff base: Crystal structure and catalytic behaviour in mild oxidation of alkanes

Article abstract of DOI:10.1016/j.inoche.2017.03.008

The new neutral dichloro-copper(II) Schiff base complex [CuCl₂L]·dmf 2, where L results from condensation of 2-pyridinecarbaldehyde and aminoguanidine, was prepared, while the ligand itself was isolated in its protonated form as the dinitrate salt (H₂L)(NO₃)₂ 1. Extended conjugation is responsible for the planarity of the H₂L^2?+ cation in 1. On coordination, L forms two fused 5-membered chelate rings occupying three equatorial positions of the distorted square pyramidal copper polyhedron in 2. The catalytic investigations disclosed a prominent activity of the copper compound 2 towards oxidation of cyclohexane with hydrogen peroxide in the presence of various promoters (nitric and acetic acids, pyridine and pyrrole), showing overall yields of products (cyclohexanol and cyclohexanone) up to 21% based on the substrate.