Pyrazabole formation by thermolysis of the free acid of the hydrotris(pyrazolyl)borate ion

Abstract

Thermolysis of the free acid of the hydrotris(pyrazolyl)borate ion resulted in one of three product pyrazaboles, depending on the reaction conditions. Melting the acid alone afforded 4,8-trans-(pz)HB(µ-pz)₂BH(pz) (pz = C₃H₃N₂), whilst doing so in the presence of ZrCl₄ resulted in the cis isomer. Melting the acid in a damp HCl atmosphere afforded, on alkaline work-up, the novel oxo-bridged dimeric pyrazabole [(pz)B(µ-pz)₂BO(pz)]₂. The crystal structures of all three pyrazaboles have been determined, and procedures for obtaining each compound in the pure state are described.

References

1. S. Trofimenko, J. Am. Chem. Soc., 1966, 88, 1842.
2. S. Trofimenko, J. Am. Chem. Soc., 1967, 89, 3165.
3. K. Niedenzu and S. Trofimenko, Top. Curr. Chem., 1986, 131, 1.
4. K. Niedenzu and H. Nöth, Chem. Ber., 1983, 116, 1132.
5. T. G. Hodgkins and D. R. Powell, Acta Crystallogr., Sect. C, 1992, 48, 1260.
6. W. J. Layton, K. Niedenzu, P. M. Niedenzu and S. Trofimenko, Inorg. Chem., 1985, 24, 1454.
7. K. Niedenzu and P. M. Niedenzu, Inorg. Chem., 1984, 23, 3713.
8. C. P. Brock, K. Niedenzu, E. Hanecker and H. Nöth, Acta Crystallogr., Sect. C, 1985, 41, 1458.
9. R. A. Kresiński, T. A. Hamor, C. J. Jones and J. A. McCleverty, J. Chem. Soc., Dalton Trans., 1991, 603.
10. R. A. Kresiński, C. J. Jones and J. A. McCleverty, Polyhedron, 1990, 9, 2185.
11. R. A. Kresiński, unpublished work.
12. E. K. Davies, SNOOPI, Chemical Crystallography Laboratory, University of Oxford, 1982.
13. J. Bielawski, M. K. Das, E. Hanecker, K. Niedenzu and H. Nöth, Inorg. Chem., 1986, 25, 4623.
14. N. W. Alcock and J. F. Sawyer, Acta Crystallogr., Sect. B, 1974, 30, 2899.
15. M. Yalpani, R. Boese and R. Koster, Chem. Ber., 1990, 123, 1275.
16. F. H. Allen and O. Kennard, Chem. Des. Autom. News, 1993, 8, 1 and 31.
17. C. M. Clarke, M. K. Das, E. Hanecker, J. F. Mariategui, K. Niedenzu, H. Nöth and K. R. Warner, Inorg. Chem., 1987, 26, 2310.
18. V. O. Atwood, D. A. Atwood, A. H. Cowley and S. Trofimenko, Polyhedron, 1992, 11, 711.
19. E. Hanecker, T. G. Hodgkins, K. Niedenzu and H. Nöth, Inorg. Chem., 1985, 24, 459.
20. E. M. Holt, S. L. Tebben, S. L. Holt and K. J. Watson, Acta Crystallogr., Sect. B, 1977, 33, 1986.
21. L.-Y. Hsu, J. F. Mariategui, K. Niedenzu and S. G. Shore, Inorg. Chem., 1987, 26, 143.
22. E. M. Holt, S. L. Holt, K. J. Watson and B. Olsen, Cryst. Struct. Commun., 1978, 7, 613.
23. M. Yalpani, R. Boese and R. Koster, Chem. Ber., 1990, 123, 713.
24. M. K. Das, K. Niedenzu and H. Nöth, Inorg. Chem., 1988, 27, 1112.
25. F. Jakle, T. Priermeier and M. Wagner, Organometallics, 1996, 15, 2033.
26. S. Asslani, R. Rahbarnoohi and B. L. Wilson, Inorg. Nucl. Chem. Lett., 1979, 15, 59.
27. D. L. Reger, M. E. Tarquini and L. Lebioda, Inorg. Chem., 1983, 22, 1064.
28. D. L. Reger, M. E. Tarquini, R. Mahtab and L. Lebioda, Inorg. Chem., 1986, 25, 2046.
29. D. L. Reger and M. E. Tarquini, Inorg. Chem., 1982, 21, 840.
30. S. Trofimenko, Inorg. Synth., 1970, 12, 115.
31. J. A. Darr, S. R. Drake, M. B. Hursthouse and K. M. A. Malik, Inorg. Chem., 1993, 32, 5704.
32. G. M. Sheldrick, SHELXS 86, Program for the Solution of Crystal Structures, University of Göttingen, 1976.
33. G. M. Sheldrick, SHELXL 93, Program for Crystal Structure Refinement, University of Göttingen, 1993.
34. N. Walker and D. Stuart, Acta Crystallogr., Sect. A, 1983, 39, 158.