Synthesis, structure and spectral characteristics of Ni(II), Pd(II) and Zn(II) complexes with N-(2-pyridinyl)morpholine-4-carbothioamide

A series of novel zinc(II), nickel(II) and palladium(II) complexes with a thiourea derivative (N-(2-pyridinyl)morpholine-4-carbothioamide) (HL) and its oxidation product (N-(2-pyridinyl)morpholine-4-carboxamide) (HL′) have been synthesized and characterized by single crystal X-ray diffraction study, IR, UV–Vis, 1H and 13C NMR spectroscopy. It has been shown that under synthesis conditions, HL coordinates in a thiol tautomeric form leading to formation of mononuclear complexes cis-[ML2], where two ligand molecules are coordinated to metal ions via pyridinyl nitrogen and imidothiolic sulfur in a bidentate manner with the formation of six-membered chelate metallocycles. It has been found that utilizing different conditions nickel complexes are able to crystallize in two polymorphic modifications, which differ solely in the mode of intermolecular interactions. It has been shown that a mixed-ligand complex Ni(C10H13N3O2)2(C2H5SO4)2 can be obtained by reaction of Ni(NO3)2 with reaction by-products (pyridine-containing carboxamide and monoethyl sulfate) formed in selected synthesis conditions.

A series of novel Zn(II), Ni(II) and Pd(II) complexes (1–5) with a thiourea derivative (N-(2-pyridinyl)morpholine-4-carbothioamide) and its oxidation product (N-(2-pyridinyl)morpholine-4-carboxamide) have been synthesized and characterized by single crystal X-ray diffraction study, IR, UV-Vis, 1H and 13C NMR spectroscopy. It has been shown that two ligand molecules are coordinated to metal ions on trans- or cis-position via pyridinyl nitrogen and imidothiolic sulfur in a bidentate manner with the formation of six-membered chelate metallocycles.Figure optionsDownload as PowerPoint slideHighlights
► The possibility of carbothioamide oxidation is shown.
► Polymorphic modifications of Ni and Pd complexes are obtained.
► Crystal structures of synthesized complexes are discussed.