Nickel(II)–triphenylphosphine complexes of ONS and ONN chelating 2-hydroxyacetophenone thiosemicarbazones

The complexes [Ni(L1)(PPh3)] (1) and [Ni(L2)(PPh3)]·HCl (2) were synthesized by the reaction of [Ni(PPh3)Cl2] and dibasic 2-hydroxyacetophenone-S-R-4-R1-thiosemicarbazones (R/R1: H/CH3, L1H2; CH3/H, L2H2). The ligands and the complexes were characterized using elemental analysis, IR and 1H NMR spectra. In both complexes, the thiosemicarbazone ligands coordinate to nickel(II) by giving two protons. Complex 1 is formed through the phenolate oxygen, azomethine nitrogen and sulfur atoms of L1 and the P atom of a triphenylphosphine ligand. In complex 2, L2 is functional through an ONN donor set, containing a thioamide nitrogen instead of a sulfur atom. X-ray analysis indicated distorted square planar structures for the complexes, and the nickel atoms lie slightly above the planes structured by the donor atoms. In the crystal forms of 1 and 2, some phenyl ring protons of the phosphine ligand give intramolecular hydrogen bonds with the donor atoms of the thiosemicarbazone moiety, namely the phenolate oxygen (in complexes 1 and 2) and N4 nitrogen (in complex 2).

The complexes [Ni(L1)(PPh3)] (1) and [Ni(L2)(PPh3)]·HCl (2), of 2-hydroxy-acetophenone thiosemicarbazones S-R 4-R1-thiosemicarbazones (R/R1: H/CH3, L1; CH3/H, L2) were synthesized and characterized. Complex 1 formed through ONS donor set of the thiosemicarbazone and P atom of triphenylphosphine ligand in monoclinic space group P21/c. Complex 2 consist of the ONN set and P atoms of the ligands, and this complex crystallizes in the triclinic space group P1¯. The donor atoms have taken place in the edges of a slightly deformed square planar, and nickel atom is slightly above the plane. Phospine protons give intramolecular hydrogen bonds with phenolate oxygen and thioamide nitrogen of these thiosemicarbazones.Figure optionsDownload as PowerPoint slideHighlights
► Nickel complexes of ONS and ONN chelating thiosemicarbazones.