The reduction of Nb₂Cl₆(tmeda)₂ by R₂NLi. Formation of a diamagnetic niobium(II) cluster with short Nb–Nb triple bond and amide C–N bond cleavage

Abstract

Reduction of trivalent Nb₂Cl₆(tmeda)₂ with either lithium diisopropylamide or n-butyllithium yields a novel Nb^II cluster which performs oxidative addition into the amide C–N bond.

References

1. (a) F. A. Cotton, M. P. Diebold and W. J. Roth, J. Am. Chem. Soc., 1987, 109, 5506; (b) F. A. Cotton, M. P. Diebold and W. J. Roth, J. Am. Chem. Soc., 1986, 108, 3538; (c) J. Kohler and A. Simon, Angew. Chem., Int. Ed. Engl., 1986, 25, 996; (d) D. M. Curtis and J. Real, Organometallics, 1985, 4, 940; (e) F. Calderazzo, G. Pampaloni, L. Ricchi, J. Strahle and K. Wurst, J. Organomet. Chem., 1991, 413, 91; (f) F. A. Cotton, J. H. Matonic and C. A. Murillo, J. Am. Chem. Soc., 1997, 119, 7889.
2. C.-E. Laplaza and C.-C. Cummins, Science, 1995, 268, 861; J. S. Frendlich, R. R. Schrock, C. C. Cummins and W. M. Davis, J. Am. Chem. Soc., 1994, 116, 6476; M. Moore, S. Gambarotta, G. Yap, L. M. Liable-Sands and A. Rheingold, Chem. Commun., 1997, 645; P. Berno, S. Hao, R. Minhas and S. Gambarotta, J. Am. Chem. Soc., 1994, 116, 7417; P. Berno and S. Gambarotta, Organometallics, 1994, 13, 2569.
3. Ad hoc synthetic procedures have been developed for niobium and tantalum(v) amides: D. M. Hoffman and S. P. Rangarajan, Polyhedron, 1993, 12, 2899; Y. W. Chao, S. Polson and D. E. Wigley, Polyhedron, 1990, 9, 2709; Y. W. Chao, P. A. Wexler and D. E. Wigley, Inorg. Chem., 1989, 28, 3860; D. C. Bradley, M. B. Hursthouse, A. J. Howes, A. N. M. Jelfs, J. D. Runnacles and M. Thornton-Pett, J. Chem. Soc., Dalton Trans., 1991, 841; W. A. Nugent and R. L. Harlow, J. Chem. Soc., Chem. Commun., 1978, 579; F. Guerin, D. H. McConville and J. J. Vittal, Organometallics, 1995, 14, 3154; F. P. O'Flaherty, R. A. Henderson and D. L. Hughes, J. Chem. Soc., Dalton Trans., 1990, 1087.
4. J. A. M. Canich and F. A. Cotton, Inorg. Chem., 1987, 26, 4236.
5. R. H. Sommerville and R. Hoffmann, J. Am. Chem. Soc., 1979, 101, 3821; J. L. Templeton, W. C. Dorman, J. C. Clardy and R. E. McCarley, Inorg. Chem., 1978, 17, 1263; B. E. Bursten, F. A. Cotton and A. Fang, Inorg. Chem., 1983, 22, 2127.
6. Typically, strong reducing agents such as alkali metals, amalgams or potassium graphite are necessary for obtaining divalent niobium. See for example: M. A. Araya, F. A. Cotton, J. H. Matonic and C. A. Murillo, Inorg. Chem., 1995, 34, 5424; E. Guggloz, M. L. Ziegler, H. Biersack and W. A. Herrmann, J. Organomet. Chem., 1980, 194, 317; M. L. Luetkens, J. C. Huffman and A. P. Sattelberger, J. Am. Chem. Soc., 1983, 105, 4474; T. W. Coffindaffer, I. P. Rothwell, K. Folting, J. C. Huffman and W. E. Streib, J. Chem. Soc., Chem. Commun., 1985, 1519.
7. See for example: M. H. Chisholm, F. A. Cotton, B. A. Frenz, W. W. Reichert, L. W. Shive and B. R. Stults, J. Am. Chem. Soc., 1976, 98, 4469; M. H. Chisholm and W. W. Reichert, J. Am. Chem. Soc., 1974, 96, 1249; D. C. Bradley and M. H. Chisholm, J. Chem. Soc. A, 1971, 1511; M. H. Chisholm, F. A. Cotton, B. A. Frenz, L. W. Shive and B. R. Stults, J. Chem. Soc., Chem. Commun., 1974, 480; J. R. Dilworth, S. J. Harrison, R. A. Henderson and D. R. M. Walton, J. Chem. Soc., Chem. Commun., 1984, 176.
8. Identified by comparison of the cell parameters and analytical data with those of an analytically pure sample: S. G. Bott, D. M. Hoffman and S. P. Rangarajan, Inorg. Chem., 1995, 34, 4305 and references therein.