STRUCTURE OF THE BIS(CYCLOHEXYLACETOACETATO)NICKEL(II) COMPLEX WITH N,N-DIETHYLNICOTINAMIDE.

• Datum: 2026
• Hauptverfasser: Shtokvysh, Olherd, Dyakonenko, Viktoriya, Koval, Lyudmila
• Format: Artikel
• Sprache: Englisch
• Veröffentlicht: V.I.Vernadsky Institute of General and Inorganic Chemistry 2026
• Online Zugang: https://ucj.org.ua/index.php/journal/article/view/766
• Назва журналу: Ukrainian Chemistry Journal

A new coordination compound of Ni(II) with cyclohexylacetoacetate and N,N-diethylnicotinamide was synthesized and characterized by IR spectroscopy and X-ray analysis. The IR spect­rum exhibits intense broad absorption bands corresponding to the stretching vibrations of the C=O and C=C bonds conjugated within the chelate ring (1625, 1502 cm⁻¹), as well as other absorption bands characteristic of β-dicarbonyl complexes, in particular a sharp band at 775 cm⁻¹ attributed to the out-of-plane bending vibration of the C–H bond in the chelate ring. In the high-frequency region of the spectrum, there are signals of stretching vibrations of the C-H bonds of alkyl groups (2855–2990 cm–1) and weak signals of stretching vibrations of the C-H of the pyridine ring (3080–3110 cm–1). The absorption bands of the amide group (νС=О 1620–1650 cm–1) and the pyridine ring (νС=С, νС=N 1500–1600 cm–1) of N,N‑diethylnicotinamide overlap with the vibration bands of the chelate rings and cannot be unambiguously assigned. The medium-intensity band at 1300 cm⁻¹, present in both the free ligand and the complex, is assigned to C–N stretching vibrations of the amide group. The low-intensity bands in the 600–400 cm⁻¹ region are assigned to Ni–N and Ni–O vibrations. According to X-ray data, the crystal system of NiL2NK2 complex is monoclinic, space group P21/с, a = 7.0360(15) Å, b = 13.233(4) Å, c = 23.619(5) Å, α = γ = 90º,  β = 93.301(12)º. The structure corresponds to the formula [Ni(C10H15O3)2(C10H14N2O)2] and represents a mononuclear complex located in a special position relative to the inversion center. The cent­ral Ni atom has a O4N2 distorted octahedral environment. The axial positions of the coordination polyhedron are occupied by the nitrogen atoms of the pyridine ring of N,N‑diethylnicotinamide. The molecules of chelating ligands, coordinated through oxygen atoms, occupy an equatorial position with a trans configuration relative to each other. In the crystal, the complex molecules are bound by weak C-H…π interactions and form layers in the (001) plane, alternating with each other. The structure of the coordination polyhedron of the described compound is similar to the structure of adducts of β-dicarbonyl complexes of d‑metals with pyridine.