Synthesis and Molecular Structure of (η5-C5Me5)2Hf(H)(NHMe). Structural Evidence for Nitrogen-to-Hafnium π-Donation

Organometallics

Volumn 7, Issue 6, 1988, Pages 1309-1312

  Hillhouse, Gregory L ^a   Bulls, A Ray ^b   Santarsiero, Bernard D ^b   Bercaw, John E ^b  

^a UNIVERSITY OF CHICAGO   (United States)

^b CALIFORNIA INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 33845280489     PISSN: 02767333     EISSN: 15206041     Source Type: Journal    
DOI: 10.1021/om00096a012     Document Type: Article

References (9)

1. Hillhouse, G. L.; Bercaw, J. E. Organometallics 1982, 1, 1025. Hillhouse, G. L.; Bercaw, J. E. J. Am. Chem. Soc. 1984, 106, 5472. Roddick, D. M.; Fryzuk, M. D.; Seidler, P.F.; Hillhouse, G. L.; Bercaw, J. E. Organometallics 1985, 4, 97.
2. For a good discussion of orbital constraints and symmetry requirements of the bent metallocene derivatives, see: Lauher, J. W.; Hoffmann, R. J. Am. Chem. Soc. 1976, 98, 1729.
3. Cardin, D. J.; Lappert, M. F.; Ras ton, C. L. Chemistry of Organo-Zirconium and-Hafnium Compounds; Ellis Horwood Ltd.: West Sussex, 1986. Wailes, P. C.; Coutts, R. S. P.; Weigold, H. Organometallic Chemistry of Titanium, Zirconium, and Hafnium; Academic: New York, 1974. Marsella, J. A.; Moloy, K. G.; Caulton, K. G. J. Organomet. Chem. 1980, 201, 389.
4. 2) system show structure A to be 0.51 eV more stable than B. A is 0.87 eV more stable than a third hypothetical structure having a pyramidal amido group. Hoffman, D.; Hoffmann, R., private communication.
5. 6b and the following approximated intramolecular distances: Hf-N = 2.04 Å; Hf-H = 1.90 Å; N-C = 1.47 Å; C-H = 1.09 Å; N-H = 1.02 Å. Angles were 120° about N and tetrahedral about the amido methyl. These calculations showed severe intramolecular nonbonded contacts (<0.6 Å) between the amido Me hydrogens and ring Me hydrogens for A; these close contacts were considerably relieved by rotation about the Hf-N bond and were minimized in the B conformation having the amido Me directed toward the hydride ligand (i.e., R' = Me and R" = H), the closest Me-Me contact being 2.1 Å; this was better than the B conformation that has R' = H and R" = Me (here the closest Me-Me contact was 1.2 Å), Miller, G. J., private communication. Wolczanski, P. T.; Threlkel, R. S.; Santarsiero, B. D. Acta Crystallogr. Sect. C: Cryst. Struct. Commun. 1983, C39, 1330.
6. 2 have been described. Bortolin, R.; Patel, V.; Munday, I.; Taylor, N. J.; Carty, A. J. J. Chem. Soc., Chem. Commun. 1985, 456.
7. 2b Similar observations have been made for related dimethylamido complexes of Th and U: Fagan, P. J.; Manriquez, J. M.; Vollmer, S. H.; Day, C. S.; Marks, T. J. J. Am. Chem. Soc. 1981, 103, 2206.
8. 11b Pauling, L. The Nature of the Chemical Bond, 3rd ed.; Cornell University Press: Ithaca, NY, 1960. Erker, G.; Fromberg, W.; Atwood, J. L.; Hunter, W. E. Angew. Chem., Int. Ed. Engl. 1984, 23, 68.
9. Lappert, M. F.; Power, P. P.; Sanger, A. R.; Srivastava, R. C. Metal and Metalloid Amides; Ellis Horwood Ltd.: West Sussex, 1980. Lappert, M. F.; Patil, D. S.; Pedley, J. B. J. Chem. Soc., Chem. Commun. 1975, 830.