Synthesis of New Glyoxime Derivatives, Characterization and Investigation of Their Complexes with Co(II), Ni(II), and Cu(II) Metals and Thermal Studies

Abstract

1 The complexes prepared from vic -dioximes were extensively used for various purposes owing to their high stability, including model compounds for vitamin B 12 or trace metal analysis [1][2][3]. The ligands and their metal complexes also played a significant role in the domains of stereochemistry, structure isomerism, spectroscopy, model systems of biochemical interest, cation exchange and ligand exchange chromatography, analytical chemistry, catalysis, stabilizers, polymers, pigments, and dyes [4].The chemistry of oxime/oximato metal complexes has been developed actively since the time of the first synthesis, e.g., preparation of nickel(II) dimethylglyoximate, and recognition of the chelate five-membered character of this complex by Chugaev [5]. Coordinated oxime ligands and oxime complexes display an impressively rich variety of reactivity modes, which lead to unusual types of chemical compounds [6]. Some recently reviewed data show that oximes, although being classical ligands [7], display a variety of reactivity modes unusual even for the modern coordination chemistry [8,9].vic -Dioximes and monooximes are amphoteric materials containing weak acidic OH groups and basic C=N groups. The geometrical isomers of vic -dioximes and their derivatives, depending on the position of the OH groups in the molecule, are syn , anti and amphi structures [10]. Usually, the stability order of these is anti > amphi > syn configuration [11] but there are some exceptions [12].In our previous studies, we presented the synthesis and characterization of various transition metal complexes of novel vic -dioximes [13][14][15][16][17][18][19][20]. In the present paper, we report the synthesis and characterization of 1 The text was submitted by the authors in English.new vic -dioxime ligands morpholineglyoxime ( H 2 L 1 ) and piperidineglyoxime ( H 2 L 2 ) and their mononuclear complexes with Co 2+ , Ni 2+ , and Cu 2+ ions. EXPERIMENTALThe preparation of anti -chloroglyoxime has been described previously [21]. All the reagents used were purchased from Merck, Fluka or Sigma Company and are chemically pure.Elemental analyses (C, H, N) were performed on a LECO-932 CHNSO elemental analyses apparatus. IR spectra were recorded on a Mattson 1000 FT-IR spectrometer as KBr pellets. 1 H and 13 C NMR spectra were recorded on a Bruker GmbH Dpx-400 MHz High Performance Digital FT-NMR spectrometers (in DMSO-d 6 ). Electronic spectra were obtained on a Shimadzu 1240 UV spectrometer. Magnetic susceptibilities were determined on a Sherwood Scientific Magnetic Susceptibility balance (Model MK1) at room temperature using Hg[Co(SCN) 4 ] as a calibrate; diamagnetic corrections were calculated from Pascal's constants. Melting points were determined on a Gallenkamp melting point apparatus. Molar conductance of the vic -dioxime ligands and their transition metal complexes were determined at room temperature using a CMD 750 WPA conductivity meter. TGA curves were recorded on a Shimadzu TG-50 thermobalance.Synthesis of morpholineglyoxime (H 2 L 1 ). A solution o...