Home

About

Advanced Search

Browse by Discipline

Scientific Societies

E-print Alerts

Add E-prints

E-print Network
FAQHELPSITE MAPCONTACT US


  Advanced Search  

 
Blue-Shifted and Red-Shifted Hydrogen Bonds in Hypervalent Rare-Gas FRg-H,,,Y Igor V. Alabugin* and Mariappan Manoharan
 

Summary: Blue-Shifted and Red-Shifted Hydrogen Bonds in Hypervalent Rare-Gas FRg-H,,,Y
Sandwiches
Igor V. Alabugin* and Mariappan Manoharan
Department of Chemistry and Biochemistry, Florida State UniVersity, Tallahassee, Florida 32306-4390
Frank A. Weinhold
Theoretical Chemistry Institute, Department of Chemistry, UniVersity of Wisconsin-Madison,
Madison, Wisconsin 53706
ReceiVed: January 19, 2004; In Final Form: March 12, 2004
Increased F-
[Rg-H]+
resonance contribution provides an efficient mechanism for the Rg-H bond
repolarization in the hypervalent 3c,4e-F-Rg-H,,,Y complexes, where Rg is a rare gas atom. This effect
which parallels the effect of rehybridization in classic 2c,2e chemical bonds, decreases the population of the
*(Rg-H) orbitals and increases the covalent Rg-H bond order leading to Rg-H bond contraction. The
origin of this electronic reorganization can be ascribed to competition of two hyperconjugative donors for the
same *(Rg-H) acceptor. As donor Y approaches the H atom of an FRgH moiety, the n(Y) f *(H-Rg)
interaction becomes stronger, whereas the n(F) f *(Rg-H) interaction becomes weaker in an asynchronous
process. For weaker donors Y and longer Y,,,H distances, breaking of the Rg-F covalent bond proceeds
faster than formation of the H-Y bond. As a result, both the *(Rg-H) population and the Rg-H distance
decrease thus accounting for the blue-shift in such H-bonded complexes. However, when Y is a moderately

  

Source: Alabugin, Igor - Department of Chemistry and Biochemistry, Florida State University

 

Collections: Chemistry; Biology and Medicine