Higher Extended Hypervalent Bonds

The linear bond in 12 Br4 is analyzed by the 6c 8e model. Linear Br-Se-Br 3c-4e bonds in 1 Br2 interact mutually to give 12 Br4, which contains the linear alignment of the six Se2Br4 atoms. The linear bond in 12 Br6 is analyzed 

Akiba (ed), Chemistry of Hypervalent Compounds, Wiley-VCH, New York, 1999. 

Hayes and J.C. Martin, Sulfurane chemistry, in Organic Sulfur Chemistry Theoretical and Experimental Advances, F. Bernardi, LG. Csizmadia and A. Mangini (eds), Elsevier Scientific, Amsterdam, 1985, Chapter 8 (b) J. Bergman, L. Engman and J. Siden, Tetra- and higher-valent (hypervalent) derivatives of selenium and tellutium, in The 

Chemistry of Organic Selenium and Tellurium Compounds, vol 1, S. Patai and Z. Rappoport (eds), Wiley, New York, 1986, Chapter 14 (c) KJ. Irgolic, The Organic Chemistry of Tellurium, Gordon and Breach Science Publishers, New York, 1974. 

Drabowicz, Hypervalent Sulfuranes as Transient and Isolable Structures Occurrence, Synthesis, and Reactivity in ref 5 (Chapter 7), Wiley-VCH, New York, 1999 (b) N. Furukawa and S. Sato, Structure and Reactivity of Hypervalent Chalcogen Compounds Selenurane (Selane) and Tellurane (Tellane) in ref 5 (Chapter 8), Wiley-VCH, New York, 1999 (c) D. Lentz and K. Seppelt, The SF5, -SeF5, and -TeF5 Groups in Organic Chemistry in ref 5 (Chapter 10), Wiley-VCH, New York, 1999. 

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The hypervalent chalcogen chemistry has been developed to higher coordinated species with various ligands,7 10 where TBP changes to square pyramidal (SP) or octahedral (Oh), etc. Additional atomic orbitals of E, such as an 5-orbital, may operate to stabilize the structures.10b The concept is also extended over linear a-bonds constructed by m ( > 4) atoms with n electrons (extended hypervalent bonds mc-ne (in > 4)).11 14 The approximate molecular orbital model for mc-ne (m > 4) is also exhibited in Scheme la, exemplified by 4c-6e. 

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