Study of the different behaviour of thiazolin and thiazin indazole derivatives with palladium(II) acetate

Abstract

The study of the reactivity of the ligands 2-(indazol-1-yl)-2-thiazoline ( 1) and 2-(indazol-1-yl)-1,3-thiazine ( 2) with palladium(II) acetate has allowed the isolation of different compounds. For the thiazolin indazole derivative ( 1) a cyclopalladated compound: (μ-OAc) 2[Pd( k 2- C, N-TnInA)] 2 ( 1a) with a bidentate [C(sp 2,phenyl),N] − ligand and a central “Pd(μ-OAc) 2Pd” unit was obtained. Treatment of the dimeric compound 1a with sodium acetylacetonate produced the mononuclear compound [Pd( k 2- O, O′-acac)( k 2- C, N-TnInA)] ( 1c). The reaction of 1a with LiCl followed by the addition of PPh 3 gave the compound [PdCl(PPh 3)( k 2- C, N-TnInA)] ( 1e) where the acetate groups were replaced by Cl − and PPh 3 ligands, and with the PPh 3 in a cis-arrangement to the metallated carbon atom. The solid-state structure of 1e was determined by single-crystal X-ray diffraction methods. The reaction of 2 with palladium(II) acetate produced, in contrast to ligand 1, the complex cis-[Pd(OAc) 2( k 2- N, N′-TzIn)] ( 2a) with a bidentate [ N, N′] ligand. Compound 2a reacted with LiCl giving cis-[PdCl 2( k 2- N, N′-TzIn)] ( 2b), where the acetate groups were exchanged by chloride ligands. DFT calculations suggest that the most favoured compound obtained from the reaction between 1 and palladium(II) acetate should be the cyclopalladated one, while for 2 the formation of the [ N, N′] coordinated complex is less unfavoured.