The N-(1-phenylethyl)dithiocarbamate anion. Electronic transitions, ultraviolet and CD spectra, and reversible formation of its ammonium salts

Abstract

The UV and CD spectra of tetrabutylammonium (S )-N-(1-phenylethyl)dithiocarbamate (3c) have been recorded in acetonitrile and in absolute ethanol. In the dithiocarbamate anion, the sulfur lone pairs are expected to interact to give a low-energy symmetric combination (n₊) and an antisymmetric combination (n_–) with the higher energy. The UV spectrum was interpreted with the aid of CNDO/S calculations, and the CD spectrum with calculations by the Schellman matrix method. The CD spectrum contains a medium-strong positive band at 230 nm, which lacks a counterpart in the UV spectrum and was initially tentatively assigned to the n₊→π₁* transition. However, the theoretical calculations predict a negative sign for this band, and consequently no assignment for the 230 nm band can be given at present.

Except for the 230 nm band, the calculations predict correct signs and qualitatively correct intensities for the CD bands between 200 and 400 nm in a narrow range of orientations of the 1-phenylethyl group with respect to the dithiocarbamate ion, and it is expected that the favoured conformation falls in this conformational range.

Similar studies of (S )-(1-phenylethyl)ammonium (S )-N-(1-phenylethyl)dithiocarbamate (3a) and triethylammonium (S )-N-(1-phenylethyl)dithiocarbamate (3b) failed because these salts decompose in solution with ultimate formation of carbon disulfide. This decomposition has been studied by UV spectroscopy, and a mechanism has been proposed.

References

1. M. J. Janssen, The electronic structure of organic thione compounds, Thesis, Utrecht University, 1959.
2. M. J. Janssen, Recl. Trav. Chim. Pays-Bas, 1960, 79, 454.
3. M. J. Janssen, Recl. Trav. Chim. Pays-Bas, 1960, 79, 464.
4. M. J. Janssen, Recl. Trav. Chim. Pays-Bas, 1960, 79, 1067.
5. L. Fälth, U. Håkansson and J. Sandström, J. Mol. Struct. (THEOCHEM), 1989, 185, 239.
6. A. Mannschreck, A. Talvitie, W. Fischer and G. Snatzke, Monatsh. Chem., 1983, 114, 101.
7. K. Rang, R. Isaksson and J. Sandström, J. Chem. Soc., Perkin Trans. 2, 1996, 1493.
8. K. Rang, F.-L. Liao, J. Sandström and S.-L. Wang, Chirality, 1997, 9, 568.
9. Deltagraph Pro 3, Copyright 1993 DeltaPoint, Inc., Harris Court, Monterey, CA 93940, USA.
10. C. Guimon, D. Gombeau and G. Pfister-Guillouzo, Tetrahedron, 1973, 29, 3399.
11. K. Nishimoto and N. Mataga, Z. Phys. Chem., 1957, 12, 335.
12. J. Albertsson, Å. Oskarsson, K. Ståhl, C. Svensson and I. Ymén, Acta Crystallogr., Sect. B, 1980, 36, 3072.
13. Å. Oskarsson and I. Ymén, Acta Crystallogr., Sect. C, 1983, 39, 66.
14. I. Ymén, Acta Crystallogr., Sect. C, 1983, 39, 570.
15. I. Ymén, Acta Crystallogr., Sect. C, 1983, 39, 874.
16. I. Ymén, Acta Crystallogr., Sect. C, 1984, 40, 33.
17. The program is available from Instar Software, IDEON Research Park, SE 223 70, Lund, Sweden.
18. U. Burkert and N. L. Allinger, Molecular Mechanics, ACS Monograph 177, Am. Chem. Soc., Washington D.C., 1982.
19. M. J. S. Dewar, E. G. Zoebisch, E. F. Healy and J. J. P. Stewart, J. Am. Chem. Soc., 1985, 107, 3902.
20. Wavefunction, Inc., 18401 Von Karman Avenue, Irvine, CA 92612, USA.
21. P. M. Bayley, E. B. Nielsen and J. A. Schellman, J. Phys. Chem., 1969, 73, 228.
22. E. B. Nielsen and J. A. Schellman, Biopolymers, 1971, 10, 1559.
23. V. Madison and J. A. Schellman, Biopolymers, 1972, 11, 1041.
24. V. Rizzo and J. A. Schellman, Biopolymers, 1984, 23, 435.
25. J. Sandström, in Circular Dichroism: Principles and Applications, ed. K. Nakanishi, N. Berova and R. W. Woody, VCH, New York, 1994, p. 443.
26. J. R. Platt, J. Chem. Phys., 1949, 17, 484.
27. U. Berg and J. Sandström, Acta Chem. Scand., 1960, 20, 689.
28. G. C. Pimentel, J. Am. Chem. Soc., 1957, 79, 3323 and references therein.
29. A. Z.-Q. Khan, R. Isakson and J. Sandström, J. Chem. Soc., Perkin Trans. 2, 1987, 491.
30. E. U. Condon, W. Altar and H. Eyring, J. Chem. Phys., 1937, 5, 753.
31. I. Tinoco, Jr., Adv. Chem. Phys., 1962, 4, 113.
32. J. A. Schellman, Acc. Chem. Res., 1968, 1, 144.
33. N. Harada and K. Nakanishi, in Circular Dichroic Spectroscopy—Exciton Coupling in Organic Stereochemistry, Oxford University Press, Oxford, 1983.
34. K. Rang, J. Sandström and C. Svensson, Can. J. Chem., 1998, 76, 811.
35. U. Berg, T. Liljefors, C. Roussel and J. Sandström, Acc. Chem. Res., 1985, 18, 80.
36. U. Berg and J. Sandström, Adv. Phys. Org. Chem., 1989, 25, 1.
37. M. Langgård and J. Sandström, J. Chem. Soc., Perkin Trans. 2, 1976, 435.
38. M. Kajtar, J. Kajtar, Z. Majer, M. Zewdu and M. Hollosi, Spectrochim. Acta, Part A, 1992, 48, 87.
39. H. Christen and E. Kloster-Jensen, Helv. Chim. Acta, 1973, 56, 1752.
40. Methoden der Organischen Chemie (Houben-Weyl), E4, George Thieme Verlag, Stuttgart, 1983, p. 458, and references therein.