Bis[3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)picolinato]nickel(II) tetrahydrate
In the title complex, [Ni(C11H9ClN3O2)2]·4H2O, the Ni atom is coordinated by four N atoms and two O atoms derived from two tridentate 3-chloro-6-(3,5-dimethyl-1H-pyrazol-1-yl)picolinate ligands. The cis-N4O2 donor set defines a distorted octahedral geometry. In the crystal structure, the complex and water molecules are linked by O—H⋯O hydrogen bonds.
Bis[3‐chloro‐6‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl‐κN2)picolinato‐κ2N,O]cobalt(II) 2.5‐hydrate
In the title compound, [Co(C11H9ClN3O2)2]·2.5H2O, the CoII atom, which lies on a twofold rotation axis, is coordinated by four N atoms and two O atoms from two ligands in a distorted octa­hedral geometry. In the crystal structure, mol­ecules are linked together by inter­molecular O—H⋯O hydrogen bonds.
Redox Properties of Tetraphenylporphyrin Complexes
The redox-properties of tetraphenylporphyrin-complexes were studied as a function of substituents on the phenyl group. Electron-withdrawing chlorine substituents cause a rise of approximately 100 mV for the first ligand oxidation and electron-donating methoxy-substituents cause a decrease of about the same magnitude. The redox-properties of the central metal ion are much less sensitive to these substituents. The Fe3+/Fe2+ transition on the other hand, is seen to depend on the anion used. Taking these effects into account a tentative mechanism is proposed for the oxidation-behaviour of μ-oxo-bis (tetraphenyl)porphyrin-iron(III).