Complexes of nickel(II) carboxylates with pyridine and cyclam: crystal structures,mesomorphisms, and thermoelectrical properties |
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| Authors: | Norbani Abdullah Suhana Mohd Said Yanti Yana Halid Megat Muhammad Ikhsan Megat Hasnan Naima Sharmin Siti Amira Mat Hussin |
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| Institution: | 1. Faculty of Science, Department of Chemistry, University of Malaya, Kuala Lumpur, Malaysianorbani7@gmail.com;3. Faculty of Engineering, Department of Electrical Engineering, University of Malaya, Kuala Lumpur, Malaysia;4. Faculty of Science, Department of Chemistry, University of Malaya, Kuala Lumpur, Malaysia |
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| Abstract: | Nickel(II) carboxylates Ni(CH3(CH2)14COO)2(H2O)2] (1) and Ni(C6H5COO)2(H2O)2] (2) were obtained from reactions of NiCl2·6H2O with CH3(CH2)14COONa and C6H5COONa, respectively. Complex 1 reacted with pyridine (pyr) to form Ni(CH3(CH2)14COO)2(pyr)2(H2O)2] (3) and Ni2(μ2-H2O)(CH3(CH2)14COO)4(pyr)4] (4) in the same reaction mixture, and reacted with cyclam to form an ionic complex, Ni(CH3(CH2)14COO)(cyclam)(H2O)]CH3(CH2)14COO·4H2O (5). In contrast, 2 reacted with cyclam to form Ni(C6H5COO)2(cyclam)] (6). Finally, 6 reacted with p-(hexadecyloxy)pyridine (L) to form an ionic complex, Ni(cyclam)(L)2](C6H5COO)2 (7). Complexes 3–6 were single crystals. All complexes have octahedral Ni(II) center(s) and were magnetic. Complexes with cyclam as co-ligand were more thermally stable than those with pyridine and its derivative, L. Complexes 3 and 4 were mesomorphic after partial loss of water and/or pyridine ligands on heating. The ionic complexes 5 and 7 were not mesomorphic, but showed good thermoelectrical behavior with negative Se values in CHCl3 (?0.28 mV K?1 for 5; -0.39 mV K?1 for 7) and positive Se values in C2H5OH (+0.25 mV K?1 for 5; +0.20 mV K?1 for 7). |
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| Keywords: | Nickel(II) carboxylates pyridine cyclam mesomorphism thermoelectricity |
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