View PDF Version
 
DOI: 10.1039/A603412H (Paper) Reference Section for: J. Chem. Soc., Perkin Trans. 2, 1997, 833-838

NMR studies of nonplanar porphyrins. Part 1. Axial ligand orientations in highly nonplanar porphyrins

(Note: The full text of this document is currently only available in the PDF Version )

Craig J. Medforth, Cinzia M. Muzzi, Kalyn M. Shea, Kevin M. Smith, Raymond J. Abraham, Songling Jia and John A. Shelnutt

Abstract

The ligand orientations in the nonplanar porphyrin complexes 1a–e and 2a–e have been investigated using molecular mechanics calculations and proton NMR spectroscopy. The minimum energy structures calculated for complexes 1a–e show that the planes of the axial pyridine or imidazole ligands are orientated approximately parallel to the CoIII–Nporphyrin bonds, with the ligand ring planes being perpendicular to each other. For complexes 2a–e, the planes of the axial ligands in the calculated minimum energy structures are orientated along the porphyrin meso carbon axis and the ligand ring planes are perpendicular to each other. Thus, for both series of complexes the planes of the axial ligands are orientated parallel to cavities formed by these very nonplanar porphyrins. Proton NMR studies suggest that structures similar to those obtained from the molecular mechanics calculations are retained in solution. In some complexes, hindered rotation of the axial ligands is also observed. Complexes 1a–e and 2a–e are unusual examples of the porphyrin conformation influencing the orientations of axial ligands and, as such, may be useful as models for studying ligand orientation effects in relation to biological systems.

References

  1. (a) K. M. Barkigia, M. D. Berber, J. Fajer, C. J. Medforth, M. W. Renner and K. M. Smith, J. Am. Chem. Soc., 1990, 112, 8851 CrossRef CAS; (b) K. M. Barkigia, M. W. Renner, L. R. Furenlid, C. J. Medforth, K. M. Smith and J. Fajer, J. Am. Chem. Soc., 1993, 115, 3627 CrossRef CAS.
  2. M. W. Renner, K. M. Barkigia, Y. Zhang, C. J. Medforth, K. M. Smith and J. Fajer, J. Am. Chem. Soc., 1994, 116, 8582 CrossRef CAS.
  3. (a) S. Gentemann, C. J. Medforth, T. P. Forsyth, D. J. Nurco, K. M. Smith, J. Fajer and D. Holten, J. Am. Chem. Soc., 1994, 116, 7363 CrossRef CAS; (b) A. Regev, T. Galili, C. J. Medforth, K. M. Smith, K. M. Barkigia, J. Fajer and H. Levanon, J. Phys. Chem., 1994, 98, 2520 CrossRef CAS.
  4. (a) J. A. Shelnutt, C. J. Medforth, M. D. Berber, K. M. Barkigia and K. M. Smith, J. Am. Chem. Soc., 1991, 113, 4077 CrossRef CAS; (b) L. D. Sparks, C. J. Medforth, M.-S. Park, J. R. Chamberlain, M. R. Ondrias, M. O. Senge, K. M. Smith and J. A. Shelnutt, J. Am. Chem. Soc., 1993, 115, 581 CrossRef CAS.
  5. K. M. Kadish, E. V. Caemelbecke, P. Boulas, F. D'Souza, E. Vogel, M. Kisters, C. J. Medforth and K. M. Smith, Inorg. Chem., 1993, 32, 4177 CrossRef CAS.
  6. W. Jentzen, J. D. Hobbs, M. C. Simpson, K. K. Taylor, T. Ema, N. Y. Nelson, C. J. Medforth, K. M. Smith, M. Veyrat, M. Mazzanti, R. Ramassel, J.-C. Marchon, T. Takeuchi, W. A. Goddard III and J. A. Shelnutt, J. Am. Chem. Soc., 1995, 117, 11 085 CrossRef CAS.
  7. S. Gentemann, C. J. Medforth, T. Ema, N. Y. Nelson, K. M. Smith, J. Fajer and D. Holten, Chem. Phys. Lett., 1995, 245, 441 CrossRef CAS.
  8. (a) J. Fajer, Chem. Ind., 1991, 869 Search PubMed; (b) M. O. Senge, J. Photochem. Photobiol. B:Biol., 1992, 16, 3 CrossRef CAS.
  9. C. J. Medforth, C. M. Muzzi, K. M. Smith, R. J. Abraham, J. D. Hobbs and J. A. Shelnutt, J. Chem. Soc., Chem. Commun., 1994, 1843 RSC.
  10. (a) F. A. Walker, B. H. Huynh, W. R. Scheidt and S. R. Osvath, J. Am. Chem. Soc., 1986, 108, 5288 CrossRef CAS; (b) M. K. Safo, G. P. Gupta, F. A. Walker and W. R. Scheidt, J. Am. Chem. Soc., 1991, 113, 5497 CrossRef CAS; (c) M. K. Safo, G. P. Gupta, C. T. Watson, U. Simonis, F. A. Walker and W. R. Scheidt, J. Am. Chem. Soc., 1992, 114, 7066 CrossRef CAS; (d) M. K. Safo, F. A. Walker, A. M. Raitsimring, W. P. Walters, D. P. Dolata, P. G. Debrunner and W. R. Scheidt, J. Am. Chem. Soc., 1994, 116, 7760 CrossRef CAS.
  11. W. R. Scheidt and Y. J. Lee, Struct. Bonding (Berlin), 1987, 64, 1 CAS.
  12. C. J. Medforth, J. D. Hobbs, M. R. Rodriguez, R. J. Abraham, K. M. Smith and J. A. Shelnutt, Inorg. Chem., 1995, 34, 1333 CrossRef CAS.
  13. D. M. Collins, R. Counryman and J. L. Hoard, J. Am. Chem. Soc., 1972, 94, 2066 CrossRef CAS.
  14. M. O. Senge, T. Ema and K. M. Smith, J. Chem. Soc., Chem. Commun., 1995, 733 RSC.
  15. R. J. Abraham and C. J. Medforth, Magn. Reson. Chem., 1987, 25, 432 CAS.
  16. H. Bang, J. O. Edwards, J. Kim, R. G. Lawler, K. Reynolds, W. J. Ryan and D. A. Sweigart, J. Am. Chem. Soc., 1992, 114, 2843 CrossRef CAS.
  17. R. J. Abraham, J. Fisher and P. Loftus, Introduction to NMR Spectroscopy, Wiley, Chichester, 1988 Search PubMed.
  18. (a) H. Zhang, U. Simonis and F. A. Walker, J. Am. Chem. Soc., 1990, 112, 6124 CrossRef CAS; (b) F. A. Walker and U. Simonis, J. Am. Chem. Soc., 1991, 113, 8652 CrossRef CAS.
  19. M. Nakamura and A. Ikezaki, Chem. Lett., 1995, 733.
  20. A. L. van Geet, Anal. Chem., 1970, 42, 679 CrossRef CAS.
  21. T. Ema, M. O. Senge, N. Y. Nelson and K. M. Smith, Angew. Chem., Int. Ed. Engl., 1994, 33, 1879 CrossRef.
  22. T. Sakurai, K. Yamamoto, N. Seino and M. Katsuta, Acta Crystallogr., Sect. B, 1975, 31, 2514 CrossRef.
  23. K. W. Lauher and J. A. Ibers, J. Am. Chem. Soc., 1974, 96, 4447 CrossRef CAS.
  24. W. R. Scheidt, J. A. Cunningham and J. L. Hoard, J. Am. Chem. Soc., 1973, 95, 8289 CrossRef CAS.
Click here to see how this site uses Cookies. View our privacy policy here.