Structure and bonding in metallocenes and oligomers

  • Eluvathingal D. Jemmis
  • A. Chandrasekhar Reddy
Special Issue on Modern Trends in Inorganic Chemistry


The structural variations observed as a function of the number of valence electrons, the metals and the rings present in tripledecker and tetradecker sandwiches have been studied by the extended Huckel method. In tripledecker complexes the electron count varies from 26 electrons to 34 electrons depending on the magnitude of the interactions (8a e). With the njckel complex, CpNiCpNiCp+1, the e′1 antibonding interaction, (8c), is not very high so that the presence of electrons in these orbitals do not affect the stability of the complex. With the vanadium complex, CpVC6H6VCp, the e′1, interaction (8c), is substantial so that 30-valence electron complexes are preferred with the transition metals on the left side of the periodic table. With P6, P5 and As5 complexes the ″a2, (8e), also becomes very strong. This leads to a 28-valence electron closed shell structure. The distortion of the As5 ring in CpMoAs5MoCp is attributed to the presence of three electrons in the degenerate HOMOs. In tetradecker complexes 46-valence electron complexes are found to have highly antibonding degenerate HOMOs which lead to a distorted structure where the two end CpMCp units slip away from the central metal in a direction perpendicular to the original metal-metal axis (7). The extent of antibonding interactions is maximum when the M’ is a late transition metal and M is an early transition metal of the periodic table. With appropriate metals it is possible to have a symmetric 46-valence electron tetradecker complex. Calculations on a series of CpCo(C3B2H5)M’(C3B2H5)CoCp, where M’ = Cr, Mn, Fe, Co, Ni, Cu and Zn reproduced the experimental structural trends. The variation in total energies has been traced predominantly to the energy difference between the valence orbitals of the metal atoms and the π and σ MOs of the ring. The bent geometry of CpCo(C3B2H5)Sn(C3B2H5)CoCp is caused by factors similar to those which operate in making CpSnCp a bent metallocene.


Metallocenes tripledecker tetradecker pentadecker sandwich compounds one-dimensional sandwich compounds molecular orbitals Jahn-Teller distortion slip distortion 


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  1. Albright T A and Hoffmann R 1978Chem. Ber. 11 1578CrossRefGoogle Scholar
  2. Davis J H, Sinn E Jr and Grimes R N 1989J. Am. Chem. Soc. 111 4776CrossRefGoogle Scholar
  3. Fujimoto H and Hoffmann R 1974J. Phys. Chem. 78 1167CrossRefGoogle Scholar
  4. Hoffmann R 1963J. Chem. Phys. 39 1397CrossRefGoogle Scholar
  5. Hoffmann R and Lipscomb W N 1962J. Chem. Phys. 36 3179, 3489Google Scholar
  6. Hoffmann R, Swenson J R and Wan C-C 1973J. Am. Chem. Soc. 95 7644CrossRefGoogle Scholar
  7. Jemmis E D and Reddy A C 1988Organometallics 7 1561, and references thereinCrossRefGoogle Scholar
  8. Jemmis E D and Reddy A C 1990J. Am. Chem. Soc. (in press), and references thereinGoogle Scholar
  9. Jutzi P, Kohl F, Hoffmann P, Kruger C and Tsay Y-H 1980Chem. Ber. 113 757CrossRefGoogle Scholar
  10. Kuhlmann T, Roth S, Roziere J and Siebert W 1985Angew. Chem. 97 88CrossRefGoogle Scholar
  11. Lauher J W, Elian M, Summerville R H and Hoffmann R 1976J. Am. Chem. Soc. 98 3219CrossRefGoogle Scholar
  12. Rheingold A L, Foley M J and Sullivan P J 1982J. Am. Chem. Soc. 104 4727CrossRefGoogle Scholar
  13. Scherer O J 1987Nachr. Chem. Tech. Lab 35 1140Google Scholar
  14. Scherer O J, Schwalb J, Swarowsky H, Wolmershauser G, Kaim W and Gross R 1988aChem. Ber. 121 443CrossRefGoogle Scholar
  15. Scherer O J and Swarowsky H 1987Angew. Chem. Int. Ed. Engl. 26 1153CrossRefGoogle Scholar
  16. Scherer O J, Swarowsky M and Wolmershauser G 1988bAngew. Chem. Int. Ed. Engl. 27 405CrossRefGoogle Scholar
  17. Scherer O J, Wiedemann W and Wolmershauser G 1989J. Organomet. Chem. 361 C11-C14CrossRefGoogle Scholar
  18. Siebert W 1985Angew. Chem., Int. Ed. Engl. 24 943CrossRefGoogle Scholar
  19. Veillard A 1986Quantum chemistry: The challenge of transition metals and coordination chemistry (New York: D Reidel)Google Scholar
  20. Werner H and Salzer A 1972Inorg. Met-Org. Chem. 2 239CrossRefGoogle Scholar
  21. Wadepohl H, Pritzkow H and Siebert W 1982Organometallics 2 1899CrossRefGoogle Scholar
  22. Wilkinson G, Stone F G A and Abel E W 1982Comprehensive organometallic chemistry (Oxford: Pergamon)Google Scholar

Copyright information

© Indian Academy of Sciences 1990

Authors and Affiliations

  • Eluvathingal D. Jemmis
    • 1
  • A. Chandrasekhar Reddy
    • 1
  1. 1.School of ChemistryUniversity of HyderabadHyderabadIndia

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