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Homogeneous Oxidative Coupling Catalysts: Kinetics of the Oxidation of Copper(I) Complexes [(Pyr)nCuX]4 (n = l or 2, Pyr = pyrrolidine, X = Cl, Br or I) by Dioxygen in Aprotic Media
Corresponding Author(s) : M.A. El-Sayed
Asian Journal of Chemistry,
Vol. 25 No. 6 (2013): Vol 25 Issue 6
Abstract
This paper reports the kinetics of oxidation of [(Pyr)nCuX]4 by O2 to form the oxidative coupling catalysts [(Pyr)nCuX]4O2. The mechanism has been described as a pre-equilibrium, K, between tetranuclear copper(I) and incoming dioxygen, which is followed by rate determining step k2. The rates of the reaction are reflected to the core structure of [(Pyr)nCuX]4, faster for cubane structure as for (X = Cl or Br), when compared to step structure as in case of (X = I). The overall reaction is a second-order process, first order in each [(Pyr)nCuX]4 and [O2], with rate constant kon (kon = Kk2) and exothermic DH¹ varying from -4.9 to -15.5 kcal mol-1 and DS¹ varying from -61.3 to -97.8 cal deg-1 mol-1. kon were found to be very sensitive to n value 1 or 2.
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- E.I. Solomon and M.D. Lowery, Science, 259, 1575 (1993).
- N. Kitajima and Y. Moro-oka, Chem. Rev., 94, 737 (1994).
- K. Selmeczi, G. Speier, M. Reglier, M. Giorgi and G. Peinter, Coord. Chem. Rev., 245, 191 (2003).
- M.A. El-Sayed, A.H. Abdel Salam, T.A. El-Zayat, A. El-Dissouky and K.Z. Ismail, Inorg. Chim. Acta, 357, 4057 (2004).
- M.A. El-Sayed, T.S. Kassem, H.A. Abo-Eldahab and A.E. El-Kholy, Inorg. Chim. Acta, 358, 22 (2005).
- M.A. El-Sayed, H.A. El-Wakil, T.S. Kassem, H.A. Abo-Eldahab and A.E. El-Kholy, Inorg. Chim. Acta, 359, 4304 (2006).
- M.A. El-Sayed, A.H. Abdel Salam, H.A. Abo-Eldahab, H.M. Refaat and A. El-Dissouky, J. Coord. Chem., 62, 1015 (2009).
- G. Davies and M.A. El-Sayed, in eds.: K. Karlin and J.A. Zubieta, Inorganic and Biochemical Perspective in Copper Coordination Chemistry, Adenine Press, New York, p. 281 (1983).
- G. Davies and M.A. El-Sayed, Inorg. Chem., 22, 1257 (1983).
- R.N. Keller and H.D. Wycoff, Inorg. Synth., 2, 1 (1946).
- M.A. El-Sayed, Doctoral Dissertation, Northeastern University, USA (1982).
- G. Davies, M.A. El-Sayed and M. Henary, Inorg. Chem., 26, 3266 (1987).
- M.A. El-Sayed, K.Z. Ismail, T.A. El-Zayat and G. Davies, Inorg. Chim. Acta, 217, 109 (1994).
- M.R. Churchill, G. Davies, M.A. El-Sayed, J.P. Hutchinson and M.W Rupich, Inorg. Chem., 21, 995 (1982).
References
E.I. Solomon and M.D. Lowery, Science, 259, 1575 (1993).
N. Kitajima and Y. Moro-oka, Chem. Rev., 94, 737 (1994).
K. Selmeczi, G. Speier, M. Reglier, M. Giorgi and G. Peinter, Coord. Chem. Rev., 245, 191 (2003).
M.A. El-Sayed, A.H. Abdel Salam, T.A. El-Zayat, A. El-Dissouky and K.Z. Ismail, Inorg. Chim. Acta, 357, 4057 (2004).
M.A. El-Sayed, T.S. Kassem, H.A. Abo-Eldahab and A.E. El-Kholy, Inorg. Chim. Acta, 358, 22 (2005).
M.A. El-Sayed, H.A. El-Wakil, T.S. Kassem, H.A. Abo-Eldahab and A.E. El-Kholy, Inorg. Chim. Acta, 359, 4304 (2006).
M.A. El-Sayed, A.H. Abdel Salam, H.A. Abo-Eldahab, H.M. Refaat and A. El-Dissouky, J. Coord. Chem., 62, 1015 (2009).
G. Davies and M.A. El-Sayed, in eds.: K. Karlin and J.A. Zubieta, Inorganic and Biochemical Perspective in Copper Coordination Chemistry, Adenine Press, New York, p. 281 (1983).
G. Davies and M.A. El-Sayed, Inorg. Chem., 22, 1257 (1983).
R.N. Keller and H.D. Wycoff, Inorg. Synth., 2, 1 (1946).
M.A. El-Sayed, Doctoral Dissertation, Northeastern University, USA (1982).
G. Davies, M.A. El-Sayed and M. Henary, Inorg. Chem., 26, 3266 (1987).
M.A. El-Sayed, K.Z. Ismail, T.A. El-Zayat and G. Davies, Inorg. Chim. Acta, 217, 109 (1994).
M.R. Churchill, G. Davies, M.A. El-Sayed, J.P. Hutchinson and M.W Rupich, Inorg. Chem., 21, 995 (1982).