Novel Pd(II) coordination compounds involving 2-[(2-hydroxyphenyl)methylene]hydrazine-N-(2-propenyl)-carbothioamide as a ligand or pro-ligand: Synthesis, crystal structures and analytical application

Novel palladium(II) complexes with a thiourea derivative 2-[(2-hydroxyphenyl)methylene]hydrazine-N-(2-propenyl)-carbothioamide have been synthesized and characterized by single crystal X-ray diffraction, IR, UV–Vis, 1H and 13C NMR spectroscopy. Depending on synthesis conditions the ligand could be coordinated to the metal ion as a neutral molecule or mono-/bianion forming complexes Pd(H2L)Cl (I), Pd(HL)H3L (II), Pd(HL′)Cl (III). The different coordination of two ligand molecules realize in the complex (II), where one carbothioamide molecule coordinates in a tridentate manner being in the thiol form and another one binds to the metal by the sulfur of the thioureide group in a monodentate manner being in the thione tautomeric form. The compound (III) is synthesized in the acidic medium that causes the cyclization of the allyl fragment of carbothioamide. The selected ligand also reacts with Pd(II) as a dibasic acid to yield an anionic complex [Pd(HL)Cl]−, which is isolated as a salt of the astraphloxin basic dye, [Pd(HL)Cl][AF]. The last one is used for developing a procedure for selective extraction of Pd2+ from aqueous solutions containing a mixture of platinum metals.

Graphical abstractNovel palladium(II) complexes with a thiourea derivative have been synthesized and characterized. An analytical procedure for selective extraction of Pd2+ from aqueous solutions has been developed.Figure optionsDownload full-size imageDownload as PowerPoint slide