Structure and Geometry of Carbenes

For an introduction to the structures and reactions of carbenes, see (a) Liebman, J. F. Simons, J. in Liebman, J. F. Greenberg, A., Eds. Molecular Structure and Energetics, Volume 1 Chemical Bonding Models VCH Publishers Deerfield Beach, FL, 1986 p. 51 (b) Moss, R. A. Jones, M., Jr., in Jones, M., Jr. Moss, R. A., Eds. Reactive Intermediates, Vol. 2 John Wiley Sons New York, 1981 (c) Kirmse, W. Carbene Chemistry Academic Press New York, 1964 Gilchrist, T. L. Rees, C. W. Carbenes, Nitrenes and Arynes Appleton-Century-Crofts New York, 1969 (d) Mine, J. Divalent Carbon Ronald Press New York, 1964 Bertrand, G. in Moss, R. A. Platz, M. S. Jones, M., Jr., Eds. Reactive Intermediate Chemistry John Wiley Sons Hoboken, NJ, 2004 chapter 8 (e) Jones, M., Jr. Moss, R. A. in Moss, R. A. Platz, M. S. Jones, M., Jr., Eds. Reactive Intermediate Chemistry John Wiley Sons Hoboken, NJ, 2004 chapter 7. 

The terms singlet and triplet arose from experiments in which singlet states gave emission at only one wavelength in certain spectroscopic experiments, while triplet states gave three lines (i.e., emission at three wavelengths). The distinction between singlet and triplet states will be especially important in the discussion of photochemistry (Chapter 12). 

Calculated potential energy surface for the lowest triplet state of methylene. (Adapted from reference 143.) 

Rate constants for rearrangements of alkylfluorocarbenes are about an order of magnitude lower than those of the alkylchiorocarbenes Moss, R. A. Ho, G.-J. Liu, W.J. Am. Chem. Soc. 1992, 114,959. 

Dichlorocarbene can be used to functionalize single-walled nanotubes Hu, H. Zhao, B. Hamon, M. A. Kamaras, K. Itkis, M. E. Haddon, R. C. /. Am. Chem. Soc. 2003,125,14893. Lavallo, V. Canac, Y. Donnadieu, B. Schoeller, W. W. Bertrand, G. Science 2006, 312, 722. A QTAIM analysis suggested that the mechanism of stabilization may be more complicated Johnson, L. E. DuPre, D. B. /. Phys. Chem. A 2007, 111, 11066. 

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