Synthesis and characterization of new unsymmetrical 鈥榮ide-off鈥?tetra and hexa coordinate homobinuclear Cu(II) and heterobinuclear Cu(II)-Zn(II) complexes: Magnetic, electrochemical and kinetic studies

详细信息	查看全文 | 推荐本文 |

• 作者：K. Shanmuga Bharathi^a ; ^b ; S. Sreedaran^c ; A. Kalilur Rahiman^d ; V. Narayanan^a ; ^{vnnara@yahoo.co.in}
• 关键词：Unsymmetrical &lsquo ; Side-off&rsquo ; complexes ; Homo and hetero binuclear ; Magnetic properties ; Electrochemistry ; Catalytic activity
• 刊名：Spectrochimica Acta Part A ; Molecular and Biomolecular Spectroscopy
• 出版年：2012
• 期刊代码：99_13861425
• 类别：ch
• 出版时间：August, 2012
• 卷：94
• 期：Complete
• 页码：334-339
• 文件大小：475 K

摘要

A new class of phenol based unsymmetrical side-off tetra and hexa coordinate homobinuclear Cu(II) and heterobinuclear Cu(II)-Zn(II) complexes have been synthesized and characterized by elemental and spectral analysis. The electronic spectra of all the complexes show 鈥淩ed shift鈥?in LMCT band, for the ligand H₂L² compared to that of the ligand H₂L¹ due to the relatively higher electron donating nature of their substitutents. The homobinuclear Cu(II) complexes (1 and 2) illustrate an antiferromagnetic interaction (渭_eff: 1.58 and 1.60 BM) at 298 K with a broad EPR signal. Variable temperature magnetic moment study of the binuclear copper (II) complexes shows that the extent of antiferromagnetic coupling is greater in the case of H₂L² complexes than H₂L¹ complexes (鈭? J values: 192 cm^鈭? and 184 cm^鈭? respectively). The heterobinuclear Cu(II)-Zn(II) complexes (3 and 4) have a magnetic moment value close to the spin only value with four hyperfine EPR signals. Electrochemical studies of the complexes reveal that all the binuclear complexes show two irreversible one-electron transfer reduction waves in the cathodic region. There is an 鈥渁nodic shift鈥?in the first reduction potential of the complexes, of the ligand H₂L¹ when compared to that of the ligand H₂L² due to the presence of relatively higher electron donating N-substituents in the later case than in the former case. The catecholase activity of the complexes reveals that the homobinuclear Cu(II) complexes show higher catalytic activity than the corresponding heterobinuclear Cu(II)-Zn(II) complexes. In the hydrolysis of 4-nitrophenylphosphate, the heterobinuclear Cu(II)-Zn(II) complexes show better catalytic activity than the corresponding homobinuclear Cu(II) complexes.