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Protonation of coordinated 2-methylpyrazine and 4,4′-bipyridine as a probe of π-donor potential of ruthenium(II) polyaminopolycarboxylate complexes

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Summary

The proton dissociation pKa data for RuII(hedta)(LH) and Ru II2 (ttha)(LH)2 complexes were measured by the spectrophotometric titration mid-point method using the difference in the MLCT spectra for the protonated and deprotonated complexes with L=2-methylpyrazine (2-Mepz) and 4,4′-bipyridine (4,4′-bpy). The pK ′a s were as follows at 22° C, μ=0.10 (NaCl): Ru(hedta)(2-MepzH), 3.45; Ru2(ttha)(2-MepzH)2, 3.25; Ru(hedta)(4,4′-bpyH), 4.5; Ru2(ttha)(4,4′-bpyH)2, 4.51. The two series (2-Mepzversus 4,4′-bpy) lead to a divergent prediction of the ability of RuII (polyaminopolycarboxylates) to serve as π-donor metal centers in comparison with RuII(NH3) 2+5 . The results with 4,4′-bpy ligation, where the site of protonation is more isolated from electrostatic effects of the ruthenium center, appear to give the more correct interpretation, consistent with their capacity to make good π-complexes with olefins and pyrimidine nucleobases, that RuII(polyaminopolycarboxylates) are better π-donor metal centers than Ru(NH3) 2+5 ·ΔpK*, the difference between ground state and excited state pK ′a s, are used to establish the π-donating order of RuII(polyaminopolycarboxylates) as compared to Ru(NH3) 2+5 and Ru(CN) 3−5 . The π-donor effect of the ruthenium(II) center in Ru II2 (ttha)(1,3-butadiene) 2−2 is observed to influence the ligand electronically up to five bonds away from the site of metallation.

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References

  1. P. Ford, D. P. Rudd, R. G. Gaunder and H. Taube,J. Am. Chem. Soc.,90, 1187 (1968).

    Article  CAS  Google Scholar 

  2. C. R. Johnson and R. E. Shepherd,Inorg. Chem.,22, 1117 (1983).

    Article  CAS  Google Scholar 

  3. H. E. Toma and E. Stadler,Inorg. Chem.,24, 3085 (1985).

    Article  CAS  Google Scholar 

  4. M. G. Elliott, S. Zhang and R. E. Shepherd,Inorg. Chem.,28, 3036 (1989).

    Article  CAS  Google Scholar 

  5. S. Zhang and R. E. Shepherd,Inorg. Chem.,27, 4712 (1988).

    Article  CAS  Google Scholar 

  6. S. Zhang, L. A. Holl and R. E. Shepherd,Inorg. Chem.,29, 1012 (1990).

    Article  CAS  Google Scholar 

  7. S. Zhang and R. E. Shepherd,Inorg. Chim. Acta,163, 237 (1989).

    Article  CAS  Google Scholar 

  8. S. Zhang, Ph.D. Thesis, University of Pittsburgh (USA), 1991.

  9. S. Zhang and R. E. Shepherd, submitted toInorg. Chim. Acta, 1991. (b) S. Zhang and R. E. Shepherd, submitted toInorg. Chem., (1991).

  10. S. Zhang and R. E. Shepherd,Transition Met. Chem., in Press (1991).

  11. R. E. Shepherd, A. Proctor, W. W. Henderson and T. K. Myser,Inorg. Chem.,26, 2440 (1987).

    Article  CAS  Google Scholar 

  12. S. Zhang and R. E. Shepherd,Inorg. Chim. Acta, in press (1991).

  13. R. E. Shepherd, S. Zhang, P. Dowd, G. Choi, B. Wilk andInorg. Chem. Acta,174, 149 (1990).

    Article  Google Scholar 

  14. M. G. Elliott and R. E. Shepherd,Inorg. Chem.,27, 3332 (1988).

    Article  CAS  Google Scholar 

  15. A. A. Diamantis and J. V. Dubrawski,Inorg. Chem.,20, 1142 (1981).

    Article  CAS  Google Scholar 

  16. T. Matsubara and C. Creutz,Inorg. Chem.,18, 1956 (1979). (b) T. Matsubara and C. Creutz,J. Am. Chem. Soc.,100, 6255 (1978).

    Article  CAS  Google Scholar 

  17. Characterization is described in the experimental section. This work was previously reported; S. Zhang, T. K. Myser and R. E. Shepherd, 10th Central Regional American Chemical Society Meeting, Columbus, Ohio, June 25, 1987.

  18. W. R. McWinnie and J. D. Miller,Adv. Inorg. Chem. Radiochem,12, 135 (1969). (b) D. N. Lawson and G. Wilkinson,J. Chem. Soc. 1900 (1965). (c) L. L. Merritt and E. D. Schroeder,Acta Cryst. 9, 801 (1956). (d) R. J. W. LeFevre,J. Chem. Soc. 1773 (1963). (e) C. W. M. Cureton, R. F. A. Guinman and A. I. J. Vogel,J. Chem. Soc., 1188 (1962).

    Google Scholar 

  19. G. Jackson and G. Porter,Proc. R. Soc. London, Ser. A,260, 13 (1961).

    Article  CAS  Google Scholar 

  20. J. Sen and H. Taube,Acta Chem. Scand. Ser. A,A33, 125 (1979).

    Article  Google Scholar 

  21. D. K. Lavallee and E. B. Fleischer,J. Am. Chem. Soc.,94, 2583 (1972).

    Article  CAS  Google Scholar 

  22. M. S. Ram and A. Haim,Inorg. Chem.,30, 1319 (1991).

    Article  CAS  Google Scholar 

  23. C. R. Johnson and R. E. Shepherd,Inorg. Chem.,22, 2439 (1983).

    Article  CAS  Google Scholar 

  24. S. Siddiqui, W. W. Henderson and R. E. Shepherd,Inorg. Chem.,26, 3101 (1987).

    Article  CAS  Google Scholar 

  25. S. Zhang and R. E. Shepherd,Inorg. Chim. Acta, in press (1991).

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Authors and Affiliations

  1. Department of Chemistry, University of Pittsburgh, 15260, Pittsburgh, Pennsylvania, USA

    Songsheng Zhang & Rex E. Shepherd

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  1. Songsheng Zhang
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  2. Rex E. Shepherd
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Zhang, S., Shepherd, R.E. Protonation of coordinated 2-methylpyrazine and 4,4′-bipyridine as a probe of π-donor potential of ruthenium(II) polyaminopolycarboxylate complexes. Transition Met. Chem. 17, 199–203 (1992). https://doi.org/10.1007/BF02910836

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  • DOI: https://doi.org/10.1007/BF02910836

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