Synthesis, characterization, and electrochemical properties of a new series of inorganic and organometallic Co(III) complexes with a Schiff base ligand derived from tyrosine

详细信息	查看全文 | 推荐本文 |

• 作者：Patrizia Siega ; Vi&scaron ; nja Vrdoljak¹ ; Claudio Tavagnacco ; Renata Dreos ; ^{dreos@units.it}
• 关键词：Cobalt complexes ; Schiff base ; ESI-MS spectrometry ; 1H NMR spectroscopy ; UV&ndash ; Vis spectra ; Cyclic voltammetry
• 刊名：Inorganica Chimica Acta
• 出版年：2012
• 期刊代码：40_00201693
• 类别：ch
• 出版时间：30 May, 2012
• 卷：387
• 期：Complete
• 页码：93-99
• 文件大小：493 K

摘要

A new series of inorganic and organometallic cobalt Schiff base complexes containing the tetradentate ligand {[Z-Tyr(3-Ac)-OMe]₂en} derived from the condensation of two equivalents of protected 3-acetyl-l-tyrosine with one equivalent of ethylenediamine has been synthesized. As the amino acids have l configuration, the resulting ligand is chiral. The complexes have been characterized by ¹H and ¹³C NMR, ESI-MS spectrometry and UV-Vis spectroscopy. The UV-Vis spectra recorded in CH₂Cl₂ show an absorption band at about 650 nm, characteristic of penta-coordinated alkylcobalt(III)(salen), but an evident deviation from the Lambert Beer law in the concentration range 0.20-2.0 脳 10^鈭? M suggests some kind of association in this solvent. In coordinating solvent the complexes are hexa-coordinated. The equilibrium constants for pyridine ligation in CH₃OH decrease with increasing electron-donor power of the axial alkyl group. Cyclic voltammetry studies indicate that after the reduction RCo(III)/RCo(II), the complexes decompose giving a Co(I) species that is stable on the CV time scale and can be reoxidized to Co(II) and Co(III) species. Both the E_pa and the E_pc values show that the peak potentials are shifted to more negative values with increasing inductive effect of the axial alkyl group.