Hg(II) complexes of 4-phenyl-5-(3-pyridyl)-1,2,4-triazole-3-thione and 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione and a Ni(II) complex of 5-(thiophen-2-yl)-1,3,4-oxadiazole-2-thione: Synthesis and X-ray structural studies

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• 作者：A. Bharti^a ; M.K. Bharty^a ; ^{mkbharty@bhu.ac.in} ; S. Kashyap^b ; U.P. Singh^b ; R.J. Butcher^c ; N.K. Singh^a ; ^{singhnk_bhu@yahoo.com}
• 关键词：Oxadiazole complexes ; Triazole complex ; Mixed ligand complexes ; Hg(II) and Ni(II) complexes ; Intermolecular and intramolecular hydrogen bonding
• 刊名：Polyhedron
• 出版年：2013
• 出版时间：13 February, 2013
• 年：2013
• 卷：50
• 期：1
• 页码：582-591
• 全文大小：1429 K

文摘

Three new mixed ligand complexes, [Hg(en)(4-pptt)₂] (2) {4-pptt = 4-phenyl-5(3-pyridyl)-1,2,4-triazole-3-thione}, [Hg(en)(4-pot)₂] (3) {4-pot = 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione} and [Ni(en)₂(5-thot)₂] (4) {5-thot = 5-(thiophen-2-yl)-1,3,4-oxadiazole-2-thione}, have been prepared containing en as a co-ligand. It is observed that 5-(pyridine-4-carbonyl) hydrazine carbodithioic acid methyl ester undergoes cyclization during complexation with Hg(II) in the presence of ethylenediamine and formed complex 3 containing 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione. The metal complexes have been characterized with the aid of elemental analyses, IR, magnetic susceptibility and single crystal X-ray studies. The ligand 4-pptt (1) and complexes 2, 3 and 4 crystallize in the monoclinic system, space group P21/n, P21/c, P121/c1 and P21/n respectively. The ligand is present in the deprotonated thiol form in complexes 2 and 3, and is bonded covalently through sulfur, while in complex 4 the ligand 5-(thiophen-2-yl)-1,3,4-oxadiazole-2-thione is present as the thione form and is bonded to Ni(II) through the oxadiazole nitrogen. Complex 4 shows quasi-reversible redox behavior assignable to a Ni²⁺/Ni³⁺ one electron transfer. The photoluminescence properties indicate that the complexes are fluorescent materials with maximum emissions at 433, 376 and 465 nm for complexes 2, 3 and 4 at excitation wavelengths of 293, 273 and 327 nm, respectively. All the complexes contain extended hydrogen bonding that provides a supramolecular framework.