Synthesis, structural and spectroscopic properties of a new Schiff base ligand N,N′-bis(trifluoromethylbenzylidene)ethylenediamine |
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Authors: | Mohammad Hossein Habibi Morteza Montazerozohori Ross W. Harrington |
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Affiliation: | a Chemistry Department, University of Isfahan, Isfahan 81746-73441, Iran b Chemistry Department, Yasouj University, Yasouj 75914-353, Iran c School of Natural Science(Chemistry), Newcastle Upon Tyne NE1 7RU, UK |
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Abstract: | The Schiff base compound, N,N′-bis(trifluoromethylbenzylidene)ethylenediamine (C18H14F6N2) (1), CF3C6H4CHNCH2CH2NCHC6H4CF3 has been synthesized by adding a solution of ethylenediammine (en), 0.1 mmol in chloroform to 4-(trifluoromethyl)-benzaldehyde, CF3C6H4CHO (0.2 mmol) and the product was crystallized in ethanol with the mp, 109.2 °C and 75% yield. The crystal structure was investigated by a single-crystal X-ray diffraction study at 150 K. The compound crystallizes in monoclinic space group, P21/c with a = 9.295(3), b = 5.976(5), c = 15.204(9) Å and α = 90°, β = 96.56(5)° and γ = 90°. The crystal structure is stabilized by intermolecular C H · · · F hydrogen bonds. The asymmetric unit contains only one-half of the molecule related to the center of symmetry coinciding with C(1)-C(1′) and as a whole, the title molecule is in the staggered conformation. The phenyl rings and the C N imine bonds are co-planar. The infrared spectrum showed a sharp peak at 1640 cm−1 which is typical of the conjugated C N stretching and strong peaks at 800-1400 cm−1 regions are due to the C-C and C-H stretching modes. Electronic absorption spectra exhibits strong absorption in the UV region (240 nm wavelength) which have been ascribed to , and electronic transitions. The 1H NMR spectra showed three distinct peaks at 2.5, 7.8 and 8.5 ppm which are assigned based on the splitting of resonance signals and are clearly confirmed by the X-ray molecular structure. The aromatic protons appear at about 7.8 ppm and the imine protons at 8.5 ppm. The sharp singlet at about 3.95 ppm is assigned to the CH2-CH2 protons. Mass spectra of the titled compound showed the molecular ion peak at m/e 372 (M+), and fragments at m/e 353 (M-F), 342 (M-2F), 200 (M-CF3C6H4CHN), 186 (M-CF3C6H4CHNCH2). |
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Keywords: | Schiff base Ethylenediamine Trifluorobenzaldehyde Crystal structure N,N&prime -Bis(trifluoromethylbenzylidene)ethylenediamine |
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