Design of selective macrocyclic ligands for the divalent first-row transition-metal ions[hair space]

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Judite Costa, Rita Delgado, Michael G. B. Drew and Vitor Félix


Abstract

The protonation constants of H2L1, 3,11-bis(carboxymethyl)-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene and H3L2, 3,7,11-tris(carboxymethyl)-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-triene, and stability constants of complexes formed by these macrocycles with Mg2+, Ca2+, Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+, Ga3+, Fe3+ and In3+ were determined at 25 °C and ionic strength 0.10 mol dm–3 in NMe4NO3. Both compounds are very selective for the divalent first-row transition-metal ions, exhibiting very high stability constants for Cu2+, fairly high values for Ni2+, but sharply decreasing ones for the remaining metal ions of this row. Their complexes with the alkaline-earth or larger metal ions, such as Pb2+, have low stability constants. The crystal structure of [CuL1]·4H2O was determined. The copper atom is encapsulated by the macrocycle in a distorted octahedral environment. The equatorial plane contains the four nitrogen atoms of the tetraaza ring and six-co-ordination is completed via two oxygen atoms of the appended carboxylate groups. The angles at the metal centre are close to the expected values of 90 and 180° for octahedral geometry. Molecular mechanics studies carried out for the cis and the trans octahedral [ML1] complexes were consistent with the structure found in the solid state. For a mean CuII–N distance of 2.01 Å the experimentally observed trans isomer is 6.5 kcal mol–1 more stable than the cis one. On the other hand these calculations suggest that larger ions such as Pb2+, Ca2+ or Mn2+ can be accommodated by the macrocycle in a cis-octahedral environment. However, these ions allow co-ordination numbers higher than six and so other structures ought to be also considered. The low stability constants for metal complexes of Co2+ and Zn2+ indicate that these complexes do not have a trans-octahedral structure, while the molecular mechanics calculations reveal that the cis isomer is not the most stable form. Therefore, other structures with co-ordination numbers lower than six should be considered, implying that one or more donor atoms are not co-ordinated. Stability constants of metal complexes of (L2)3– and EPR studies suggest that not all the donor atoms in this macrocycle are co-ordinated when complexes are formed with first-row-transition divalent metal ions.


References

  1. (a) R. Delgado and J. J. R. Fraústo da Silva, Talanta, 1982, 29, 815 CrossRef CAS; (b) S. Chaves, R. Delgado and J. J. R. Fraústo da Silva, Talanta, 1992, 39, 249 CrossRef CAS.
  2. S. Chaves, A. Cerva and R. Delgado, J. Chem. Soc., Dalton Trans., in 1997, 4181 Search PubMed.
  3. S. Chaves, A. Cerva and R. Delgado, Polyhedron, 1998, 17, 93 CrossRef CAS.
  4. R. Delgado, S. Quintino, M. Teixeira and A. Zhang, J. Chem. Soc., Dalton Trans., 1997, 55 RSC.
  5. J. Costa, R. Delgado, M. C. Figueira, R. T. Henriques and M. Teixeira, J. Chem. Soc., Dalton Trans., 1997, 65 RSC.
  6. S. Chaves, R. Delgado, M. T. Duarte, J. A. L. Silva, V. Felix and M. A. F. de C. T. Carrondo, J. Chem. Soc., Dalton Trans., 1992, 2579 RSC.
  7. A. Riesen, M. Zehnder and T. A. Kaden, (a)Acta Crystallogr., Sect. C, 1988, 44, 1740; (b)Helv. Chim. Acta, 1986, 69, 2074 Search PubMed.
  8. M. K. Moi, M. Yanuck, S. V. Deshpande, H. Hope, S. J. DeNardo and C. F. Meares, Inorg. Chem., 1987, 26, 3458 CrossRef CAS.
  9. M.-R. Spirlet, J. Rebizant, M.-F. Loncin and J. F. Desreux, Inorg. Chem., 1984, 23, 4278 CrossRef CAS.
  10. S. V. Deshpande, S. J. DeNardo, C. F. Meares, M. J. McCall, G. P. Adams, M. K. Moi and G. L. DeNardo, J. Nucl. Med., 1988, 29, 217 Search PubMed; M. K. Moi, C. F. Meares, M. J. McCall, W. C. Cole and S. J. DeNardo, Anal. Biochem., 1985, 148, 249 CrossRef CAS.
  11. S. P. Kasprzyk and R. G. Wilkins, Inorg. Chem., 1988, 27, 1834 CrossRef CAS.
  12. J. Costa and R. Delgado, Inorg. Chem., 1993, 32, 5257 CrossRef CAS.
  13. D. D. Perrin and W. L. F. Armarego, Purification of Laboratory Chemicals, 3rd edn., Pergamon, Oxford, 1988 Search PubMed.
  14. G. Schwarzenbach and H. Flaschka, Complexometric Titrations, Methuen & Co, London, 1969 Search PubMed.
  15. G. Schwarzenbach and W. Biedermann, Helv. Chim. Acta, 1948, 31, 331 CrossRef CAS.
  16. R. Delgado, M. C. Figueira and S. Quintino, Talanta, 1997, 45, 451 CrossRef CAS.
  17. P. Gans, A. Sabatini and A. Vacca, J. Chem. Soc., Dalton Trans., 1985, 1195 RSC.
  18. D. J. Leggett and W. A. E. McBryde, Anal. Chem., 1975, 47, 1065 CrossRef CAS; D. J. Leggett, ibid., 1978, 50, 718 Search PubMed.
  19. D. F. Evans, J. Chem. Soc., 1959, 2003 RSC.
  20. F. Neese, Diploma Thesis, University of Konstanz, June 1993.
  21. W. Kabasch, J. Appl. Crystallogr., 1988, 21, 916 CrossRef CAS.
  22. G. M. Sheldrick, SHELXS 86, in Crystallographic Computing 3, eds. G. M. Sheldrick, C. Krüger and R. Goddard, Oxford University Press, 1985 Search PubMed.
  23. G. M. Sheldrick, SHELXL 93 program for crystal structure refinement, University of Göttingen, 1993.
  24. C. K. Johnson, ORTEP II. A Fortran Thermal-ellipsoid Plot Program for Crystal Structure Illustrations, Report ORNL-5138, Oak Ridge National Laboratory, Oak Ridge, TN, 1976.
  25. A. K. Rappé, C. J. Casewit, K. S. Colwell, W. A. Goddard III and W. M. Skiff, J. Am. Chem. Soc., 1992, 114, 10 024 CrossRef CAS.
  26. CERIUS 2, version 1.6, Molecular Simulations Inc., Cambridge, 1994.
  27. K. P. Balakrishnan, H. A. A. Omar, P. Moore, N. W. Alcock and G. A. Pike, J. Chem. Soc., Dalton Trans., 1990, 2965 RSC.
  28. V. Félix, M. J. Calhorda, J. Costa, R. Delgado, C. Brito, M. T. Duarte, T. Arcos and M. G. B. Drew, J. Chem. Soc., Dalton Trans., 1996, 4543 RSC.
  29. N. W. Alcock, P. Moore and H. A. A. Omar, J. Chem. Soc., Chem. Commun., 1985, 1058 RSC.
  30. E. T. Clarke and A. E. Martell, Inorg. Chim. Acta, 1991, 190, 37 CrossRef CAS.
  31. M. T. S. Amorim, R. Delgado, J. J. R. Fraústo da Silva, M. C. T. A. Vaz and M. F. Vilhena, Talanta, 1988, 35, 741 CrossRef CAS.
  32. M. T. S. Amorim, R. Delgado and J. J. R. Fraústo da Silva, Polyhedron, 1992, 11, 1891 CrossRef CAS.
  33. R. Delgado, Y. Sun, R. J. Motekaitis and A. E. Martell, Inorg. Chem., 1993, 32, 3320 CrossRef CAS.
  34. A. B. P. Lever, Inorganic Electronic Spectroscopy, 2nd edn., Elsevier, Amsterdam, 1984 Search PubMed.
  35. L. Sacconi, F. Mani and A. Bencini, Comprehensive Coordination Chemistry, eds. G. Wilkinson, R. D. Gillard and J. A. McCleverty, Pergamon, Oxford, 1987, vol. 5, pp. 1–137 Search PubMed.
  36. L. Y. Martin, C. R. Sperati and D. H. Busch, J. Am. Chem. Soc., 1977, 99, 2968 CrossRef CAS.
  37. B. J. Hathaway, Coord. Chem. Rev., 1983, 52, 87 CrossRef CAS.
  38. B. J. Hathaway and A. A. G. Tomlinson, Coord. Chem. Rev., 1970, 5, 1 CrossRef CAS.
  39. N. Azuma, Y. Kohno, F. Nemoto, Y. Kajikawa, K. Ishizu, T. Takakuwa, S. Tsuboyama, K. Tsuboyama, K. Kobayashi and T. Sakurai, Inorg. Chim. Acta, 1994, 215, 109 CrossRef CAS.
  40. P. W. Lau and W. C. Lin, J. Inorg. Nucl. Chem., 1975, 37, 2389 CrossRef CAS.
  41. M. J. Maroney and N. J. Rose, Inorg. Chem., 1984, 23, 2252 CrossRef CAS.
  42. B. J. Hathaway, in Comprehensive Coordination Chemistry, eds. G. Wilkinson, R. D. Gillard and J. A. McCleverty, Pergamon, Oxford, 1987, vol. 5, p. 533 Search PubMed.
  43. G. A. McLachlan, G. D. Fallon, R. L. Martin and L. Spiccia, Inorg. Chem., 1995, 34, 254 CrossRef CAS.
  44. I. M. Helps, D. Parker, J. Chapman and G. Ferguson, J. Chem. Soc., Chem. Commun., 1988, 1094 RSC.
  45. F. H. Allen and O. Kennard, Chem. Des. Automat. News, 1993, 8, 31 Search PubMed.
  46. (a) P. Comba and T. W. Hambley, Molecular modeling of inorganic compounds, VCH, Weinheim, 1995, pp. 85–88 Search PubMed; (b) R. D. Hancock, in Prog. Inorg. Chem., 1989, 37, 187 Search PubMed.
  47. P. V. Bernhardt and P. Comba, Helv. Chim. Acta, 1991, 74, 1834 CrossRef CAS.
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