Comparison of carbon-silicon hyperconjugation at the 2- and 4-positions of the N-methylpyridinium cation.
[structure: see text] N-Methyl-2-trialkylsilylmethylpyridinium cations 6a-c and 4-trialkylsilylmethylpyridinium cations 5a-c were prepared and investigated using (29)Si and (13)C NMR and single-crystal X-ray crystallography. Systematic differences in the (29)Si chemical shifts and (29)Si-(13)C one-bond coupling constants for these cations suggested that the Si-CH(2) bond interacts more strongly at the 2-position of the electron-deficient pyridinium ring than at the 4-position. This result is supported by the X-ray structures of the pyridinium cations 5b and 6b.
Hassall
Kathryn
K
School of Chemistry, The University of Melbourne, Parkville VIC 3010, Melbourne, Australia.
Lobachevsky
Sofia
S
White
Jonathan M
JM
D002244:Carbon / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry; D002412:Cations / Q000737:chemistry; D018360:Crystallography, X-Ray; D007554:Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008956:Models, Chemical; D015394:Molecular Structure; D011726:Pyridinium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*
D002247:Carbon Isotopes; D002412:Cations; D007554:Isotopes; D011726:Pyridinium Compounds; C014677:1-methylpyridinium; D002244:Carbon; D012825:Silicon