Thermodynamic and kinetic study of Copper(II) Complexes with N-methylene(phenylphosphinic) Derivatives of Cyclen and Cyclam
| Authors | |
|---|---|
| Year of publication | 2001 |
| Type | Article in Periodical |
| Magazine / Source | Polyhedron |
| MU Faculty or unit | |
| Citation | |
| Field | Inorganic chemistry |
| Keywords | polyazamacrocycles phosphinic acids; cyclen and cyclam derivatives; copper(II) complexes; potentiometry; kinetics; stability constants |
| Description | Equilibria of Cu(II) with newly synthetised ligands H4L1 and H4L2 were investigated by the glass electrode potentiometry at 25 degrees of Celsius and I = 0.1 M KNO3. A simple chemical model with metal:ligand molar ratio 1:1 was found in the systems. Presence of main species , CuL1 (log Beta = 20.37(4)) and CuL2 (log Beta = 17.19(2)) was also confirmed by MALDI-TOF/MS. The dissociation kinetics of the complexes was followed by spectrophotometry and mechanism of the dissociation was proposed. Activation parameters (activation enthalpy and entropy) of the dissociation were estimated. For Cu(II)-H4L1 system, the complex dissociation starts after protonization of phosphinic pendant arms and its mechasnism is similar to the decomplexation of [Cu(cyclen)]2+. The complex with H4L2 is kinetically much less stable and the proton transfer from phosphinic pendant arm to the azacycle plays a significant role in the reaction mechanism. |
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