Kinetics and Mechanism of trans-[Cr(cyca)(OH)F]+Complex Oxidation by [Fe(CN)6]3- Ion in Strongly Alkaline Aqueous Solutions

• Autorzy: Katafias A. , Impert O. , Kita P. , Wrzeszcz G. , Dominiak D.
• Języki publikacji: EN

Abstrakty

EN

Oxidation of the trans-[Cr(cyca)(OH)F]+ complex, where cyca = meso-5,5,7,12,14- hexamethyl-1,4,8,11-tetraazacyclotetradecane, by [Fe(CN)6]3- ion in strongly alkaline media has been studied. A long-lived intermediate chromium(V) species was detected basing on the EPR signal at giso = 1.986. The hyperfine structure of the main EPR signal is consistent with the d1-electron interactions with four equivalent or nearly equivalent nitrogen nuclei and [CrV=O(cycaox)]3+ formula, where cycaox = oxidized cyca, can be postulated for the intermediate CrV complex. Kinetics of the rate limiting stage - electron transfer from the chromium(III) complex - has been studied in details applying an excess of the reductant and [OH-] at ionic strength equal 2.0 M. The rate law: -d[FeIII] dt = d[CrIV] dt = 0,5k cb K[OH-] 1+ 0,5(K-1)[OH-] [CrIII][FeIII] is consistent with an outer-sphere electron transfer from the conjugate base (cb) of the reductant formed in a preequilibrium (K) step. Reactivity of the deprotonated chromium(III) complex is characterized by kcb 298 = 9.7,deltaH#= (44.1š 0.5) kJ_mol-1, deltaS# = (-78.0 š 2.0) JxK-1xmol-1 and the preequilibrium step -by K298 = 0.237, delta H0 = (11.5 š 1.8) kJ_mol-1, delta S0 = (26.6 š 5.8) JxK-1xmol-1.

Słowa kluczowe

EN

chromium(IV); chromium(V); electron transfer from a tetraazamacrocyclic chromium(III); hexacyanoferrate(III); kinetics

• Wydawca: Polskie Towarzystwo Chemiczne
• Czasopismo: Polish Journal of Chemistry
• Rocznik: 2006
• Tom: Vol. 80, nr 6
• Strony: 931--941
• Opis fizyczny: Bibliogr. 24 poz., rys.

Twórcy

autor

Katafias A.

autor

Impert O.

autor

Kita P.

autor

Wrzeszcz G.

autor

Dominiak D.

• Department of Chemistry, N. Copernicus University, 87-100 Torun, ul. Gagarina 7, Poland

Bibliografia

• 1. Roat-Malone R.M., Bioinorganic chemistry, J. Wiley & Sons, Inc., Hoboken, New Jersey 2002, p. 278.
• 2. Vincent J.B., Acc. Chem. Res., 33, 503 (2000).
• 3. Vincent J.B., Polyhedron, 20, l (2001).
• 4. Szabłowicz M. and Kita E., Transition Met. Chem., 29, 762 (2004).
• 5. Levina A. and Lay P.A., Coord. Chem. Rev., 249, 281 (2005).
• 6. Ford P.C. and Wecksler S., ibid., 249, 1382 (2005).
• 7. DeRosa F., Bu X. and Ford P.C., Inorg. Chem., 44, 4157 (2005).
• 8. Venkataramanan N.S., Kuppuraj G. and Rajagopal S., Coord. Chem. Rev., 249, 1249 (2005).
• 9. Barnard P.J., Levina A. and Lay P.A., Inorg. Chem., 44, 1044 (2005).
• 10. Gez S., Luxenhofer R., Levina A., Codd R. and Lay P.A., ibid., 44, 2934 (2005).
• 11. Levina A., Codd R., Foran G.J., Hambley T.W., Maschmeyer T., Masters A.F. and Lay P.A., ibid., 43,1046(2004).
• 12. Gonzakz J.C., Daier V., Garcia S., Goodman B.A., Atria A.M., Sala L.F. and Signorella S., Dalton Trans., 2288 (2004).
• 13. Weeks C.L., Levina A., Dillon C.T., Turner P., Fenton R.R. and Lay P.A.Inorg. Chem., 43, 7844
• 14. Premsingh S., Venkataramanan N.S., Rajagopal S., Mirza S.R, Vairamani M., Rao P.S. and Yelavan K., ibid.t 43, 5744 (2004).
• 15. Pestovsky O. and Bakac A., Dalton Trans., 556 (2005).
• 16. Bendix J., Birk T. and Weyhermuller T., ibid., 2737 (2005).
• 17. Chatłas J., Impert O., Katafias A., Kita P. and Wrzeszcz G., Transition Met. Chem., 29, 634 (2004).
• 18. Katafias A., Impert O., Kita P. and Wrzeszcz G., ibid., 29, 855 (2004).
• 19. Madej E., Monsted O. and Kita R, Dalton Trans., 2361 (2002).
• 20. Dominiak D., Impert O., Katafias A. and Kita R, Microsymposium on "Kinetic methods of studies on reactions mechanisms in solutions", Poznań, Poland 2004 and 2005.
• 21. DulingD.R.,J.. Magn. Reson., B104, 105 (1994).
• 22. http://alfred.niehs.nih.gov/pest.html
• 23. Goodman B.A. and Raynor J.B., Adv. Inorg. Chem. Radiochem., 13, 135 (1970).
• 24. Headlam H.A. and Lay P.A., Inorg. Chem., 40, 78 (2001).