• Ahmet Kilic

      Articles written in Journal of Chemical Sciences

    • Synthesis, spectroscopic and redox properties of the mononuclear NiII, NiII(BPh2)2 containing (B-C) bond and trinuclear CuII-NiII-CuII type-metal complexes of $N,N'$-(4-amino-1-benzyl piperidine)-glyoxime

      Ahmet Kilic Esref Tas Ismail Yilmaz

      More Details Abstract Fulltext PDF

      The novel vic-dioxime ligand containing the 4-amino-1-benzyl piperidine group, $N,N'$-(4-amino-1-benzyl piperidine)-glyoxime, (LH2) has been prepared from 4-amino-1-benzyl piperidine with anti-dichloroglyoxime at -15°C in absolute THF. Mononuclear NiII metal complex has been obtained with 1 : 2 metal/ligand ratio. The NiII complex of this ligand is proposed to be square planar geometry. IR spectra show that the ligand acts in a tetradentate manner and coordinates N4 donor groups of LH2 to NiII ion. The detection of H-bonding (O-H$\cdots$O) in the [Ni(LH))2] (${\rm 1}$) metal complex by IR spectra supported the square-planar MN4 coordination of mononuclear complex. The disappereance of H-bonding (O-H$\cdots$O) in the [Ni(L)2(BPh2)2] (2) complex shows that the BPh$^+_2$-capped groups (BPh$^+_2$ cation formed BPh4 anion) attaches to the main oxime core. MN4 coordination of the [Ni(LH)2] (1) and [Ni(L)2(BPh2)2] (2) metal complexes were also determined by 1H-NMR spectroscopy. In the trinuclear CuII-NiII-CuII metal complexes, the NiII ion centered into the main oxime core by the coordination of the imino groups while the two CuII ions coordinate dianionic oxygen donors of the oxime groups and linked to the ligands of 1,10-phenanthroline, $2,2'$-bipyridine, and $4,4'$-bipyridine. The ligand and their mono and trinuclear metal complexes were characterized by elemental analyses, FT-IR, UV-Vis, 1H and 13C-NMR spectra, magnetic susceptibility measurements, molar conductivity, cyclic voltammetry, mass spectra and X-ray powder techniques. The cyclic voltammetric results show that the cathodic peak potential of [Ni(L)2(BPh2)2] shifted toward more negative value compared to that of [Ni(LH)2], probably due to a decreasing effect of back donation of metal-oxime moieties as a result of the BPh$^+_2$-bridged complex formation. Also, the formation of the trinuclear CuII-NiII-CuII metal complexes caused considerable changes on the CV behaviour of mononuclear [Ni(LH)2] (1) complex. The spectroelectrochemical study of [Ni(L)2(BPh2)2] (2) showed distinctive spectral changes that the intensity of the band (𝜆 = at 364 nm, assigned to $n \to \pi^\ast$ transitions) decreased and a new broad band in low intensity about 460 nm appeared as a result of the reduction of the nickel centered in the oxime core.

    • Synthesis of the Multinuclear Cobaloxime Complexes via Click Chemistry as Catalysts for the Formation of Cyclic Carbonates from Carbon Dioxide and Epoxides

      Ahmet Kilic Armagan Keles Emine Aytar Mustafa Durgun Mahmut Ulusoy

      More Details Abstract Fulltext PDF

      In this study, the structurally similar multinuclear cobaloxime complexes based on dioxime ligands were synthesized and characterized as trinuclear complexes with respect to varied axial groups. The multinuclear cobaloxime complexes were characterized by 1H, 13C-NMR, FT-IR, UV-Vis, LC-MS spectra, melting point and magnetic susceptibility measurements. These multinuclear cobaloxime complexes have been successfully applied to the synthesis of cyclic carbonates from CO2 and epoxides under optimized conditions and with-out using any solvent. All multinuclear cobaloxime complexes obtained by click chemistry are good catalysts for the cycloaddition of CO2 to different epoxides in the presence of pyridine as a co-catalyst. Additionally, the effects of epoxides, bases, temperature, pressure, and time on the yield of cyclic carbonates were investigated.

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