Excess electrons in lithium–ethylamine solutions—density, electrical conductivity and EPR studies

Abstract

The density, electrical conductivity and electron paramagnetic resonance (EPR) of the lithium–ethylamine system have been measured as a function of metal concentration and temperature. The obtained data have been discussed with emphasis on the comparison with those of alkali metal–ammonia or –methylamine solutions which have been well studied in view of the metal–nonmetal transition. Although lithium metal was dissolved into ethylamine up to 18–20 mol% metal, the observed conductivity was nonmetallic, dissimilar to the corresponding ammonia and methylamine systems. From the observed spectral linewidth of EPR it has been suggested that the hyperfine interaction with nitrogen nuclei is dominant in the electron spin–spin relaxation in the concentration range studied. The integrated intensity data of EPR have been analyzed in terms of the spin-pairing equilibrium of excess electrons in the solutions. It is concluded that excess electrons in Li–ethylamine solutions are more strongly localized than those in ammonia or methylamine solutions which exhibit electron delocalization with increasing metal concentration.

References

1. W. Weyl, Ann. Phys., 1864, 121, 601.
2. J. C. Thompson, Electrons in Liquid Ammonia, Clarendon, London, 1976.
3. T. Toma, Y. Nakamura and M. Shimoji, Philos. Mag., 1976, 33, 181.
4. M. G. De Backer, E. B. Mkadmi, F. X. Sauvage, J. P. Lelieur, M. J. Wagner, R. Conception, J. L. Eglin, R. E. Guadagnini, J. Kim, L. E. H. McMills and J. L. Dye, J. Am. Chem. Soc., 1994, 116, 6570.
5. H. Matsui, E. Yamada, S. Shimokawa and Y. Nakamura, J. Phys. Chem., 1993, 97, 4284.
6. T. Nozaki and M. Shimoji, Trans. Faraday Soc, 1969, 65, 1489.
7. M. Yamamoto, Y. Nakamura and M. Shimoji, Trans. Faraday Soc., 1971, 67, 2922.
8. E. Swift, Jr., J. Am. Chem. Soc., 1942, 64, 115.
9. O. Terakado, T. Kamiyama and Y. Nakamura, J. Chem. Soc., Faraday Trans., 1998, 94, 867.
10. P. Marshall and H. Hunt, J. Am. Chem. Soc., 1955, 77, 5016.
11. M. Hirasawa, Y. Nakamura and M. Shimoji, Ber. Bunsen-Ges. Phys. Chem., 1978, 82, 815.
12. R. E. Lo, Z. Anorg. Allg. Chem., 1966, 344, 230.
13. J. L. Dye, R. F. Sankuer and G. E. Smith, J. Am. Chem. Soc., 1960, 82, 4797.
14. C. A. Kraus, J. Am. Chem. Soc., 1921, 43, 749, 2529; 1922, 44, 1941.
15. K. F. Herzfeld, Phys. Rev., 1927, 29, 701.
16. N. F. Mott, Philos. Mag., 1961, 6, 287.
17. P. P. Edwards and M. J. Sienko, Phys. Rev. B., 1978, 17, 2525; J. Am. Chem. Soc., 1981, 103, 2967; P. P. Edwards, T. V. Ramakrishnan and C. N. R. Rao, J. Phys. Chem., 1995, 99, 5228.
18. Handbook of Physics and Chemistry, CRC Press, Cleveland, OH, 78th edn., 1997.
19. D. E. O'Reilly, J. Chem. Phys., 1961, 35, 1856.
20. P. P. Edwards, J. Phys. Chem., 1980, 84, 1215.
21. R. Catterall, M. C. R. Symons and J. W. Tipping, in Metal Ammonia Solutions, Butterworths, London, 1970, p. 317.
22. M. Niibe, Y. Nakamura and M. Shimoji, J. Phys. Chem., 1984, 88, 3555.
23. Y. Nakamura, M. Niibe and M. Shimoji, J. Phys. Chem., 1984, 88, 3755.
24. E. Becker, R. H. Lindquist and B. J. Alder, J. Chem. Phys., 1956, 25, 971.
25. C. J. Page, D. C. Johnson, P. P. Edwards and D. M. Holton, Z. Phys. Chem. N.F., 1994, 184, 157.
26. U. Schindewolf, in Physics and Chemistry of Electrons and Ions in Condensed Matter, Reidel, Dordrecht, 1984, p. 361.
27. C. A. Hutchison, Jr. and R. C. Pastor, J. Chem. Phys., 1953, 21, 1959.
28. J. P. Lelieur and P. Rigny, J. Chem. Phys., 1973, 59, 1142.
29. U. Even, R. D. Swenumson and J. C. Thompson, Can. J. Chem., 1977, 55, 2240.