Kinetics and mechanism of water substitution in the low-spin Fe(II) complex of 4-octasulfophenylpyrazinoporphyrazine.
The substitution reaction of the axial-coordinated water by pyridine, pyrazine and 4-CN-pyridine in the low-spin Fe(II) complex of octasulfophenyltetrapyrazinoporphyrazine was studied. Kinetic and thermodynamic parameters for the different reaction steps of the process were determined. On the basis of NMR data and spectrophotometric titrations, a pronounced non-equivalence of the two coordinated N-donor ligands was observed. The substitution of water by pyridine and 4-CN-pyridine is shown to include the formation of a precursor outer-sphere complex, whereas substitution by pyrazine follows a limiting dissociative mechanism.
Kudrik
Evgeny V
EV
Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany. vaneldik@chemie.uni-erlangen.de
Van Eldik
Rudi
R
Makarov
Sergei V
SV
D005296:Ferrous Compounds / Q000737:chemistry*; D007700:Kinetics; D047028:Macrocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011719:Pyrazines / Q000138:chemical synthesis / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D014867:Water / Q000737:chemistry
C500569:4-octasulfophenylpyrazinoporphyrazine; D005296:Ferrous Compounds; D047028:Macrocyclic Compounds; D009942:Organometallic Compounds; D011719:Pyrazines; D011725:Pyridines; D014867:Water