View PDF Version
 
DOI: 10.1039/A706003C (Paper) Reference Section for: J. Chem. Soc., Dalton Trans., 1998, 249-254

Complexes of lithium tetrahydroaluminate with N,N,N′,N′-tetramethylethane-1,2-diamine (tmen). Crystal structures of [{Li(tmen)(AlH4)}2] and [Li(tmen)2][AlH4] and the use of the 6Li-{1H} nuclear Overhauser effect to study LiAlH4 and LiBH4 in donor solvents

(Note: The full text of this document is currently only available in the PDF Version )

Mbolatiana M. Andrianarison, Anthony G. Avent, Miles C. Ellerby, Ian B. Gorrell, Peter B. Hitchcock, J. David Smith and David R. Stanley

Abstract

Two crystalline complexes (1∶1 and 1∶2) of LiAlH4 with N,N,N′,N′-tetramethylethane-1,2-diamine (tmen) have been isolated. A crystal structure determination of the 1∶1 complex showed that it formed centrosymmetrical dimers in which [AlH4]– anions and [Li(tmen)]+ cations are linked by µ-hydrogen bridges. Bond lengths and angles within the non-planar eight-membered rings are Al–H 1.55(3), Li–H 1.99(3) Å, H–Li–H 131(1) and H–Al–H 112(1)° and the exocyclic Al–H distance was 1.53(4) Å. Cryoscopic data indicated that the dimeric structure with Li–H–Al bridges was preserved in benzene solution and measurements of the 6Li-{1H} nuclear Overhauser effect (NOE) showed the presence of Li[hair space][hair space]· · ·[hair space][hair space]H–Al interactions. The 1∶2 adduct [Li(tmen)2][AlH4] 2, which crystallised with an ionic NaCl structure, was converted into 1 by heating under vacuum at 120 °C. The NOE measurements on solutions of 2 in benzene showed the presence of Li[hair space][hair space]· · ·[hair space][hair space]H–Al interactions even when a large excess of tmen was present. Aluminium-bound hydrogen was shown to be near to lithium in solutions of LiAlH4 in diethyl ether, tetrahydrofuran, mono- and di-glyme [MeO(CH2)2O(CH2CH2O)nMe, n = 0 or 1]. The NOE measurements on solutions of LiBH4 in Et2O and NMR spectra of partially deuteriated species suggested the formation of contact ion pairs, with Li[hair space][hair space]· · ·[hair space][hair space]H4B interactions which were fluxional on the NMR time-scale.

References

  1. See, for example, A. R. Barron and G. Wilkinson, Polyhedron, 1986, 5, 1897 Search PubMed; B. M. Bulychev, Polyhedron, 1990, 9, 387 CrossRef CAS and refs. therein.
  2. Comprehensive Organic Synthesis, eds. B. M. Trost and I. Fleming, Pergamon, Oxford, 1991, vol. 8 Search PubMed.
  3. E. C. Ashby, F. R. Dobbs and H. P. Hopkins, J. Am. Chem. Soc., 1975, 97, 3158 CrossRef CAS.
  4. E. C. Ashby, F. R. Dobbs and H. P. Hopkins, J. Am. Chem. Soc., 1973, 95, 2823 CrossRef CAS.
  5. A. E. Shirk and D. F. Shriver, J. Am. Chem. Soc., 1973, 95, 5904 CrossRef CAS.
  6. S. V. Sigalova, I. P. Romm, E. N. Gur'yanova, R. R. Shifrina, E. S. Shcherbakova, L. N. Margolin, L. P. Ivanov and A. I. Gorbunov, J. Gen. Chem. USSR., 1989, 59, 301.
  7. S. Heřmánek, O. Křiž, J. Plešek and T. Hanslík, Chem. Ind. (London), 1975, 42 CAS.
  8. H. Nöth, Z. Naturforsch., Teil B, 1980, 35, 119 Search PubMed.
  9. H. Nöth, R. Rurländer and P. Wolfgardt, Z. Naturforsch., Teil B, 1981, 36, 31 Search PubMed.
  10. V. P. Tarasov, V. I. Privalov, A. A. Gorbik and S. I. Bakum, Sov. J. Coord. Chem. (Engl. Transl.), 1985, 11, 935 Search PubMed.
  11. A. G. Avent, C. Eaborn, M. N. A. El-Kheli, M. E. Molla, J. D. Smith and A. C. Sullivan, J. Am. Chem. Soc., 1986, 108, 3854 CrossRef CAS.
  12. See, for example, W. Bauer, in Lithium Chemistry A Theoretical and Experimental Overview, eds. A.-M. Sapse and P. von R. Schleyer, Wiley, New York, 1995, ch. 5 Search PubMed; H. Balzer and S. Berger, Chem. Ber., 1992, 125, 733 Search PubMed and refs. therein.
  13. J. A. Dilts and E. C. Ashby, Inorg. Chem., 1970, 9, 855 CrossRef CAS.
  14. C. Eaborn, I. B. Gorrell, P. B. Hitchcock, J. D. Smith and K. Tavakkoli, Organometallics, 1994, 13, 4143 CrossRef CAS.
  15. A. Heine and D. Stalke, Angew. Chem., Int. Ed. Engl., 1992, 31, 854 CrossRef; R. J. Wehmschulte, J. J. Ellison, K. Ruhlandt-Senge and P. P. Power, Inorg. Chem., 1994, 33, 6300 CrossRef CAS.
  16. M. G. Gardiner, S. M. Lawrence and C. L. Raston, Inorg. Chem., 1995, 34, 4652 CrossRef; 1996, 35, 1349.
  17. D. R. Armstrong, W. Clegg, H. M. Colquhoun, J. A. Daniels, R. E. Mulvey, I. R. Stephenson and K. Wade, J. Chem. Soc., Chem. Commun., 1987, 630 RSC.
  18. K. Semenenko, A. L. Dorosinskii and É. B. Lobkovskii, J. Struct. Chem. (Engl. Transl.), 1973, 14, 700 Search PubMed.
  19. J. L. Atwood, K. D. Robinson, C. Jones and C. L. Raston, J. Chem. Soc., Chem. Commun., 1991, 1697 RSC.
  20. N. Sklar and B. Post, Inorg. Chem., 1967, 6, 669 CrossRef.
  21. D. B. Collum, Acc. Chem. Res., 1992, 25, 448 CrossRef CAS.
  22. D. A. Horne, J. Am. Chem. Soc., 1980, 102, 6011 CrossRef CAS.
  23. A. E. Shirk and D. F. Shriver, J. Am. Chem. Soc., 1973, 95, 5901 CrossRef CAS.
  24. B. D. James, B. E. Smith and R. H. Newman, J. Chem. Soc., Chem. Commun., 1974, 294 RSC; B. E. Smith, B. D. James and R. M. Peachey, Inorg. Chem., 1977, 16, 2057 CrossRef CAS.
  25. I. A. Oxton, A. G. McInnes and J. A. Walter, Can. J. Chem., 1979, 57, 503 CAS.
  26. V. P. Tasarov, S. I. Bakum, V. I. Privalov and Yu. A. Buslaev, Dokl. Akad. Nauk SSSR, 1982, 266, 1423 Search PubMed; V. P. Tasarov, S. I. Bakum, V. I. Privalov, Yu. A. Buslaev and A. M. Kuznetsov, Koord. Khim., 1983, 9, 822 Search PubMed.
  27. D. Barr, K. B. Hutton, J. H. Morris, R. E. Mulvey, D. Reed and R. Snaith, J. Chem. Soc., Chem. Commun., 1986, 127 RSC.
  28. A. Weissberger(Editor), Techniques of Organic Chemistry, 2nd edn., Interscience, London, 1957, vol. 3, Part II, p. 365 Search PubMed.
  29. G. M. Sheldrick, SHELXS 86, University of Göttingen, 1986.
  30. G. M. Sheldrick, SHELXL 93, University of Göttingen, 1993.
Click here to see how this site uses Cookies. View our privacy policy here.