Solvated electrons: electron paramagnetic studies of solutions of lithium in ethylamine *

Abstract

Lithium metal dissolves in ethylamine to give stable blue solutions the EPR spectra of which showed the presence of a singlet assigned to solvated electrons, together with a nine-line spectrum assigned to Li⁺_solv–e^–_solv ion pairs. The hyperfine splitting of ca. 2.5 G is assigned to four equivalent ¹⁴N nuclei. There is no detectable coupling to lithium nuclei. In the region of 50% diglyme there is extensive displacement of two of the four amine ligands. Thus, in addition to the solvated electron centres, two ion pairs were detected, one showing hyperfine coupling to four ¹⁴N nuclei and one to two ¹⁴N nuclei. The hyperfine splitting remained constant at ca. 2.5 G. This result strongly supports a model in which it is the lithium ligands that give rise to coupling in the ion pairs. The diglyme displaces two amines at a time. There was no increase in the singlet, so the displacement of the second pair of amine ligands is not favourable.

References

1. M. C. R. Symons, Chem. Soc. Rev., 1976, 5, 337; F. S. Dainton, Chem. Soc. Rev., 1975, 4, 323.
2. H. F. Hameka, G. W. Robinson and C. J. Maesden, J. Phys. Chem., 1987, 91, 3150.
3. T. R. Tuttle and P. GraceVa, J. Phys. Chem., 1971, 75, 843.
4. W. Weyl, Pogg. Ann., 1864, 121, 601; 123, 350.
5. C. A. Krauss, J. Am. Chem. Soc., 1908, 30, 1323.
6. R. Catterall, M. C. R. Symons and J. W. Tipping, J. Chem. Soc. A, 1967, 1234.
7. K. Bar-Eli and T. R. Tuttle, J. Chem. Phys., 1964, 40, 2508.
8. R. Catterall, M. C. R. Symons and J. W. Tipping, Pure Appl. Chem., 1970, 317.
9. T. Griffiths and M. C. R. Symons, Mol. Phys., 1960, 3, 90.
10. R. Catterall, M. C. R. Symons and J. W. Tipping, J. Chem. Soc. A, 1966, 1529.
11. R. Catterall and P. P. Edwards, J. Phys. Chem., 1975, 79, 3010.
12. R. Catterall and M. C. R. Symons, J. Chem. Soc., Dalton Trans., 1972, 139.
13. W. T. Cronenwett and M. C. R. Symons, J. Chem. Soc. A, 1968, 2991.