Synthesis and characterization of copper(II), nickel(II), cadmium(II), cobalt(II) and zinc(II) complexes with 2-Benzoyl-3-hydroxy-1-naphthylamino-3-phenyl-2-propen-1-on

Turk J Chem 25 (2001) , 181 – 185. c TÜBİTAK Synthesis and characterization of copper(II), nickel(II), cadmium(II), cobalt(II) and zinc(II) complexes with 2-Benzoyl-3-hydroxy-1-naphthylamino-3-phenyl-2propen-1-on Mehmet SÖNMEZ Department of Chemistry, Faculty of Sciences, University of Yüzüncü Yıl, 65080 Van-TURKEY Received 15.06.1998 Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) complexes of 2-Benzoyl-3-hydroxy-1-naphthylamino-3-phenyl2-propen-1-on, which is a derivative of carboxamide, were prepared and characterized by elemental, spectral and magnetic methods. Based on the analytical results, electronic and infrared spectral data and magnetic susceptibility measurements, suitable structures have been proposed. The formation of the complexes in solution was investigated conductometrically. 2-Benzoyl-3-hydroxy-1-naphthylamino-3phenyl-2-propen-1-on was found to be a bidentate ligand coordinating through enolic oxygen and amide nitrogen. The complexes of Co(II) and Ni(II) are proposed to have an octahedral structure, while Cd(II), Cu(II) and Zn(II) are suggested to possess a square-planar environment in the complexes. Introduction The binding of metal ions to amide groups has been a subject of increasing interest over the past two decades largely because many of these reactions provide simple models for much more complex metalpeptide systems and enzymes1 . The interaction of different metal ions with diversely substituted amides has been intensively studied2−5 . We are interested in studying the coordinating properties of an amide group containing compounds and the biological activity of their complexes6−9 . In this paper we report the preparation and characterization of 2-Benzoyl-3-hydroxy-1-naphthylamino-3-phenyl-2-propen-1-on complexes with Cu(II), Ni(II), Co(II), Zn(II) and Cd(II). Experimental The chemicals used were all of Merck and Aldrich or chemically pure grade. Preparation of ligand. Dibenzoylaceticacit-N-carboxymethylamide was synthesized according to the literature method.10 The ligand was prepared from Dibenzoylaceticacit-N-carboxymethylamide with 1naphthylamin (1:1) under reflux in the presence of toluene for 3h. The product was crystallized from hot ethanol. The structure of the ligand was characterized by elemental analysis, IR, NMR and X-ray studies11 . 181 Synthesis and characterization of copper(II), nickel(II)..., M. SÖNMEZ In the ligand, the hydroxy groups are involved in O-H. . . .O intramolecular hydrogen bonds11 . Yield was 161 mg (41%). Anal Calcd for ligand (C26 H19 NO3 ): C, 79.42; H, 4.83; N, 3.56; Found C, 79.73; H, 5.04, N, 3.40 1 H-NMR (CDCl3 ): δ 11.57 (s, NH), 7.07-8.25(m, arom.H) 13 C-NMR (CDCl3 ): δ 188.99, 200.61 (C=O), 172.32-105.95 (arom.C). Synthesis of complexes. The metal acetate salt (2 mmol) in the case of Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) was dissolved in 10-15 ml of methanol. To this, 4 mmol of ligand in chloroform (30 ml) was added slowly, with constant stirring. The mixture was refluxed for 1-2h. The Cu(II), Ni(II), Co(II), Zn(II) and Cd(II) complexes separated out were filtered and washed thoroughly with water, ethanol and hexane and then air-dried. Physical measurements. IR spectra were recorded on a Shimadzu 435V-04 spectrophotometer using KBr pellets in the 4000-400 cm−1 range. The electronic spectra were recorded on a Pye-Unicam u.v.vis spectrophotometer model UV2-100 over the 200-900 nm range. A Gouy balance was used to determine the magnetic moments of the powdered samples, employing Hg(II) tetrathiocyanatocobaltate(II) as a calibrant. Diamagnetic corrections were made from the Pascal’s constants. Molar conductances of all the compounds were determined in CHCl3 (10−3 M) at room temperature using a Jenway Model 4070 conductivity meter. Elemental analyses were performed at the Microanalytical Laboratory, University of Erciyes, Kayseri. NMR spectra were recorded on a Varian A-60 1 H-NMR spectrophotometer. Results and Discussion All the complexes are non-hygroscopic and stable at room temperature. The Co(II), Cu(II), Ni(II), Cd(II) and Zn(II) complexes are insoluble in common organic solvents but are soluble in DMSO, DMF and CHCl3 . The analytical data of the complexes are presented in Table 1. The molar conductances of the solutions of the compounds in CHCl3 (1 mM) are in the range (Table 1) 3.3-4.3 Ω−1 cm2 mole−1 . These values are lower than those expected for an electrolyte12 . These observations suggest that all the compounds are non-electrolytes in CHCl3 (1.10−3 M) at room temperature. Table 1. Elemental Analysis and Some Physical Properties of the Chelates. Complexes Colour [Cu(L)2 ]H2 O Olive green Light yellow Light green Dull white Yellow [Co(L)2 2H2 O] [Ni(L)2 2H2 O] [Zn(L)2 ]3H2 O Cd(L)2 ]3H2 O ∗ Ω−1 cm2 mole−1 Λm∗ in CHCl3 4.3 M.P. (Dec.)◦ C 219 Yield (%) 87 3.3 220 78 3.5 120 81 4.1 192 64 3.6 167 78 Found (Calc.) % C H N 71.84 4.30 3.24 (72.09) (4.39) (3.30) 68.61 4.69 2.90 (68.18) (4.80) (3.05) 66.83 4.71 3.24 (66.89) (4.92) (3.00) 68.71 4.80 3.11 (69.06) (4.64) (3.09) 68.26 4.41 3.03 (67.88) (4.15) (3.06) The IR values of the complexes studied are presented in Table 2. The IR spectrum of the ligand shows three strong bands at 3250 ν(NH), 1620-1680 ν(C=O) and 1560 cm−1 ν(C-N) +δ(N-H) amide vibrations. 182 Synthesis and characterization of copper(II), nickel(II)..., M. SÖNMEZ The IR spectra of the complexes do not show the characteristic stretching frequency of the NH group at 3250 cm−1 . The ν(C=O) groups and enolic carbonyl oxygen (C=O) at 1620-1680 cm−1 frequency found in the IR spectra of the ligand show a shift in the spectra of complexes. The following evidence supports the coordination through the enolic carbonyl oxygen (C=O) and the (NH) amide. Table 2. Important IR bands (cm−1 ) and Magnetic Moments (µef f : B.M.) Compounds L [Cu(L)2 ]H2 O [Co(L)2 2H2 O] [Ni(L)2 2H2 O] [Zn(L)2 ]3H2 O [Cd(L)2 ]2H2 O ν (H2 O)/ ν (OH) 3500 860 850 3480 3510 ν (NH) ν (C=O) ν (CN) ν (C-O) ν (M-N) ν (M-O) µeff (B.M.) 3250 1620-l680 1600 1590 1600 1580 1600 1140 1070 1090 1085 1070 1100 1560 1560 1540 1520 1530 1540 495 500 480 470 510 440 420 470 420 450 1.93 4.75 3.10 Diam. Diam. The IR spectra of all the complexes show two absorption bands in the far infrared region, 420-440 cm−1 and 480-520 cm−1 , which are assignable to ν(M-O)and ν(M-N) vibrations, respectively13 . The IR spectra of all the complexes show new absorption bands in the region 3300-3500 cm−1 indicating the presence of water molecules. The existence of the water molecules inside the coordination sphere of the complexes Co(II) and Ni(II) is suggested on the basis of IR studies. In addition, the band at 860 cm−1 in the IR spectra of Co(II) and Ni(II) complexes suggests that water molecules are coordinated to metal ions13. DMSO was used as a deuterated solvent to measure the 1 H NMR spectra of the metal chelates except those of Cu(II), Co(II) and Ni(II). The 1 H NMR spectra show multiplets o (...truncated)