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CHPC: 2013 National Meeting and Conference 2–6 December Cape Town International Convention Centre

CHPC: 2013 National Meeting and Conference 2–6 December Cape Town International Convention Centre. +27(0)51 401 2194 | ConradJ@ufs.ac.za | www.ufs.ac.za. Jeanet Conradie. Density Functional Theory calculations with High Performance Computing predicts chemical reactivity.

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CHPC: 2013 National Meeting and Conference 2–6 December Cape Town International Convention Centre

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  1. CHPC: 2013 National Meeting and Conference 2–6 December Cape Town International Convention Centre +27(0)51 401 2194 | ConradJ@ufs.ac.za | www.ufs.ac.za Jeanet Conradie Density Functional Theory calculations with High Performance Computing predicts chemical reactivity.

  2. Catalytic Application 1. Monsanto Process [Rh(CO)2(I)2]- This Study Rh(I)-b-diketonato complexes rate determining 1 electrochemical oxidation 2 substitution 3 chemical oxidation

  3. 2. The complexes

  4. 3. The complexes more electron donating in terms of sum of group electronegativitiescR + cR’ donate electron density via conjugation to Rh cCF3 (3.01) > cCCl3 (2.76) > cCH3 (2.34) > cPh (2.21) > cFc (1.87) (high c) (low c) e- withdrawing e- donating

  5. Experimental: Electrochemical oxidation 4. electrochemical oxidation 3 and 4 electrochemical oxidation 5 electrochemical oxidation 2 electrochemical oxidation 1

  6. 5. (11) (10) (7) more electron donating Experimental: Electrochemical oxidation 1 oxidation one electro-active center more electron donating Rh(I) easier oxidized to Rh(III) J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.

  7. 6. more electron donating Experimental: Electrochemical oxidation 1 oxidation (8) (3) two electro-active centers J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.

  8. 7. more electron donating Experimental: Electrochemical oxidation 1 oxidation (8) (3) (1) has three electro-active centers two electro-active centers J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.

  9. 8. more electron donating Experimental: Electrochemical oxidation 1 oxidation (8) (3) (1) has three electro-active centers two electro-active centers (1) more electron donating Rh(I) easier oxidized to Rh(III) J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.

  10. 9. more electron donating Experimental: Electrochemical oxidation 1 oxidation more electron donating Rh(I) easier oxidized to Rh(III) J.J.C. Erasmus, J. Conradie, Electro Chim. Acta 56 (2011) 9287.

  11. 10. DFT and Electrochemical oxidation 1 Oxidation of Rh(I) to Rh(III) corresponds to the removal of 2 electrons from the highest molecular orbital, the HOMO of the complex. oxidation LUMO HOMO higher energy HOMO – electrons easier removed – easier oxidized more electron donating Rh(I) easier oxidized to Rh(III) Gaussian 09 with B3LYP functional and 6-311G(d,p) basis set for C, H, O, F, P, Fe and Lanl2dz for Rh

  12. 11. DFT and Electrochemical oxidation 1 Oxidation of Rh(I) to Rh(III) corresponds to the removal of 2 electrons from the highest molecular orbital, the HOMO of the complex. oxidation LUMO HOMO higher energy HOMO – electrons easier removed – easier oxidized more electron donating Rh(I) easier oxidized to Rh(III) J. Conradie, Electro Chim. Acta 110 (2013) 718.

  13. Experimental: Electrochemical oxidation 2 12. Fc Rh more electron donating CV data from: Conradie J. and Swarts J.C., Dalton Trans., 2011, 40, 5844-5851

  14. DFT and Electrochemical oxidation 2 13. LUMO -e- -2e- HOMO HOMO-1 • First oxidation: 2e- from HOMO (RhI to RhIII) • Second oxidation: e- from HOMO-1 (Fc to Fc+) CV data from: Conradie J. and Swarts J.C., Dalton Trans., 2011, 40, 5844-5851 DFT: von Eschwege, K.G. and Conradie, J., S. Afr. J. Chem., 2011, 64, 203-209.

  15. DFT and Electrochemical oxidation 2 14. LUMO -e- -2e- HOMO HOMO-1 • First oxidation: 2e- from HOMO (RhI to RhIII) • Second oxidation: e- from HOMO-1 (Fc to Fc+) higher energy HOMO – electrons easier removed – easier oxidized

  16. 15. DFT and Electrochemical oxidation 3 higher energy HOMO electrons easier removed easier oxidized Erasmus, J.J.C. and Conradie, J., Dalton Transactions, 2013, 42, 8655–8666.

  17. 16. DFT and Electrochemical oxidation 4 higher energy HOMO electrons easier removed easier oxidized Ferreira, H., Conradie, M.M. and Conradie, J., Electrochim. Acta, 2013, 113, 519-526.

  18. 17. DFT and Electrochemical oxidation 5 • HOMO on ferrocene • First oxidation: e- from HOMO (Fc to Fc+) CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.

  19. 18. DFT and Electrochemical oxidation 5 • HOMO on ferrocene • First oxidation: e- from HOMO (Fc to Fc+) CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.

  20. 19. DFT and Electrochemical oxidation 5 higher energy HOMO electrons easier removed easier oxidized CV data from: Conradie, J., et. al., Inorg. Chim. Acta., 358, 2005, 2530-2542.

  21. DFT and Electrochemical oxidation: Summary 20.

  22. Experimental: Substitution reactions 21.

  23. Experimental: Substitution reactions 22. substitution 1 substitution 3 substitution 2 • Experimental1DV# and large negative DS#: • associative mechanism involving the formation of a 5-c species. • The FMO Theory simplifies reactions to interactions between frontier orbitals. 1 J.G. Leipoldt, E.C. Steynberg, R. van Eldik, Inorg. Chem. 26 (1987) 3068.

  24. Experimental and DFT: Substitution reaction 1 23. TS • DFT calculated TS: • Associative mechanism • 5-coordinate TS • Rh is electron acceptor (electrophile) • electron withdrawing groups stabilize TS, more reactive HOMO P(OPh)3 HOMO Rh(b)(cod) k2 from J.G. Leipoldt, G.J. Lamprecht and E.C. Steinberg, J. Organomet. Chem. 397 (1990) 239 DFT from Conradie, J. Inorg. Chim. Acta, 2013, 406, 211-216.

  25. Experimental and DFT: Substitution reaction 1 24. lower energy HOMO electrons easier accepted larger substitution k • DFT calculated TS: • Associative mechanism • 5-coordinate TS • Rh is electron acceptor (electrophile) • electron withdrawing groups stabilize TS, more reactive k2 from J.G. Leipoldt, G.J. Lamprecht and E.C. Steinberg, J. Organomet. Chem. 397 (1990) 239 DFT from Conradie, J. Inorg. Chim. Acta, 2013, 406, 211-216.

  26. Experimental and DFT: Substitution reaction 2 25. lower energy HOMO electrons easier accepted larger substitution k k2 from J.G. Leipoldt and E. C. Grobler, Trans. Met. Chem. 11 (1986) 110 and T.G. Vosloo, W.C. Du Plessis, J.C. Swarts, Inorg. Chim. Acta 331 (2002) 188. DFT from Conradie, J. J. Organomet. Chem. 2012, 719, 8-13

  27. Experimental and DFT: Substitution reaction 3 26. lower energy HOMO electrons easier accepted larger substitution k k2 from J.G. Leipoldt, S.S. Basson, J.J.J. Schlebush and, E.C. Grobler Inorg. Chim. Acta., 1982, 62, 113–115. DFT from Conradie, S. Afr. J. Chem; 2013, 66, 54-59

  28. 27. Experimental: Oxidative addition chemical oxidation 2 and 3 chemical oxidation 1

  29. 28. Experimental and DFT: Oxidative addition 1 • DFT calculated TS: • Associative mechanism M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.

  30. 29. Experimental and DFT: Oxidative addition 1 • DFT calculated TS: • Associative mechanism M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.

  31. 29. Experimental and DFT: Oxidative addition 1 • DFT calculated TS: • Associative mechanism • Rh nucleophile • electron donating groups makes Rh more electron rich, i.e more reactive towards o.a. higher energy HOMO electrons easier donated larger oxidative addition k M.M. Conradie, J. Conradie, J. Organomet. Chem. 695 (2010) 2126.

  32. 30. Experimental and DFT: Oxidative addition 1 higher energy HOMO electrons easier donated larger oxidative addition k more electron donating Rh(I) easier oxidized to Rh(III) k2 from: G.J. Van Zyl, G.J. Lamprecht, J.G. Leipoldt, T.W. Swaddle, Inorg. Chim. Acta 143 (1988) 223-227 M.M. Conradie, J.J.C. Erasmus, J. Conradie, Polyhedron 30 (2011) 2345. DFT from Conradie, J., Electrochimica Acta; 2013, 110, 718-725

  33. 31. Experimental and DFT: Oxidative addition 2 2 higher energy HOMO electrons easier donated larger oxidative addition k more electron donating Rh(I) easier oxidized to Rh(III) Erasmus, J.J.C. and Conradie, J., Inorg. Chim. Acta; 2011, 375, 128-134 Erasmus, J.J.C. and Conradie, J., Cent. Eur. J. Chem. 2012, 10(1) 256-566. Erasmus, J.J.C., Conradie, M.M. and Conradie, J., Reac. Kinet. Cat. Lett. 2012, 105(2) 233-249. Erasmus, J.J.C. and Conradie, J., Dalton Transactions, 2013, 42, 8655–8666.

  34. 32. Experimental and DFT: Oxidative addition 3 higher energy HOMO electrons easier donated larger oxidative addition k more electron donating Rh(I) easier oxidized to Rh(III) k2 from:Basson, S. S.; Leipoldt, J. G.; Roodt, A.; Venter, J. A.; van der Walt, T. J. Inorg. Chim. Acta, 1986, 119, 35. Conradie, J., Lamprecht, G.J., Roodt, A. and Swarts, J.C. Polyhedron, 23, 2007, 5075-5087. Conradie, M.M. and Conradie, J. Inorg. Chim. Acta., 2008, 361, 208-218 and 2008, 361, 2285-2295. Stuurman, N.F. and Conradie, J. J Organomet. Chem., 2009, 694, 259-268. Conradie, J. and Swarts, J.C. Organometallics, 2009, 28 (4), 1018-1026. DFT Conradie, J., unpublished

  35. 33. Experimental and DFT: Summary kinetics

  36. 34. Conclusion • The stability/reactivity of the HOMO of [Rh(RCOCHCOR')(XY)] complexes is related to the electronic influence of R and R' on Rh • more electron donating, higher HOMO energy • The energy of the HOMO of [Rh(RCOCHCOR')(XY)] relates to: • experimental electrochemical oxidation potential • experimental substitution kinetic rate constants • experimental oxidative addition kinetic rate constants • Close correlation between the experimental and the theoretical descriptors enable the design of related rhodium complexes with a particular reactivity.

  37. The Chemistry Department at the UFS for available facilities HPC Warehouse Facility of the UFS for computational facilities CTCC and the University of Tromsø for computational facilities The National Research Foundation for financial support +27(0)51 401 2194 | ConradJ@ufs.ac.za | www.ufs.ac.za

  38. Experimental: Chemical- and Electrochemical oxidation and Substitution reactions substitution 2 substitution 1 electrochemical oxidation 3 and 4 electrochemical oxidation 2 electrochemical oxidation 2 electrochemical oxidation 1 chemical oxidation 3 chemical oxidation 1 and 2 substitution 3

  39. DFT and Electrochemical oxidation 1 Experimental parametersrelated to oxidation potentialof [Rh(RCOCHCOR')(P(OPh)3)2] 1oxidation potential (Epa) of Rh 2 kinetic rate constant (k2) of oxidative addition reaction Calculated parameterrelated to oxidation potential of [Rh(RCOCHCOR')(P(OPh)3)2] 3 energy of HOMO (EHOMO) 4 calculated NPA charge on Rh(P(OPh)3)2 Parameters used to describe electron donating power (RCOCHCOR’)- 5 group electronegativity () of R and R’ groups 6 Hammett values (meta) of R and R’ groups 7 pKa of the -diketone (RCOCH2COR’) Empirical relationship describing redox potential 8 Lever ligand parameter Eredox (vs. SHE) = SMX ΣEL + IM (ΣEL=sum of the values of the ligand EL parameter for all the ligands )

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