Formation and Structure of Metal Complexes with the Fungicides Tebuconazole and Propiconazole

Abstract

Divalent copper and zinc complexes with metal:azole ratio 1:2 were readily formed at room temperature with the fungicides tebuconazole and propiconazole. The structure of copper and zinc tebuconazole acetate and zinc cis-propiconazole chloride were examined by X-ray crystallography. In copper tebuconazole acetate, the copper atom lies on a crystallographic inversion center and is coordinated to two triazole and two acetate ligands in a trans arrangement. The two binding tebuconazole N atoms and two close binding acetate O atoms form a square plane. The two remaining acetate O atoms have more distant interactions, thus forming an elongated octahedron around the copper atom. The coordination geometry of zinc tebuconazole acetate is tetrahedral and the metal is bound to two triazole and two acetate ligands. The 243 geometry is distorted from regular owing to the size of the tebuconazole ligands. The butyl chains are less folded than for the copper tebuconazole complex, resulting in a more extended molecule. The coordination geometry of zinc cis-propiconazole chloride is also tetrahedral with the metal atom bonded to two triazole and two chloride ligands.

The extent of tebuconazole leaching from unpainted and painted softwood

“…7,19 Previous studies focusing on TAZ leaching mainly used wood co-treated with copper and other metals; 5-10 however many wooden products, such as windows, are treated with formulations that do not contain metals. Since complexation with a metal has been shown to reduce TAZ leaching rates, [20][21][22] the published results cannot be used to describe metal-free systems. For instance, the natural depletion of TAZ from pine decks co-treated with copper during a ten-month exposure to rain was found to be between 0.8-1.4% of the original amount present in decks.…”

Synergistic actions between tebuconazole ligand and Cu(ii) cation: reasons for the enhanced antifungal activity of four Cu(ii) complexes based on the fungicide tebuconazole

“…Even though the crystal structure of the complex of tebuconazole and copper acetate [CuL 2 (CH 3 COO) 2 ] 2 (L=tebuconazole) has been proposed,22 its antifungal activities against phytopathogens (selected plant fungi) such as Gibberella nicotiancola, Botryosphaeria berengriana, Botryosphaeria ribis and Alternaria solani have not yet been reported, to the best of our knowledge. Interestingly, with variation in anions, complexes were obtained with significant L=tebuconazole).…”

Two novel Co(ii) and Ni(ii) complexes of tebuconazole with enhanced antifungal activities

“…Evans reported the formation and structures of CuAc 2 and ZnAc 2 complexes with tebuconazole and propiconazole. 9 Yang reported the synthesis, controlled release properties and antifungal activities of a series of metal complexes with cis and trans propiconazole. 10 Fujii prepared difenoconazole copper complexes and used them as wood preservatives.…”