Ab initio/DFT/GIAO-CCSD(T) calculational study of the t-butyl cation: comparison of experimental data with structures, energetics, IR vibrational frequencies, and 13C NMR chemical shifts indicating preferred C(s) conformation.
The C(s) conformation of the tert-butyl cation 3 was established to be the preferred global energy minimum using a combination of ab initio, DFT, and CCSD(T) methodology with correlation-consistent basis sets. The potential energy surface of methyl rotation involving the C(3v), C(s), and C(3h) forms, however, in accord with previous studies, is quite flat. The computed IR absorptions of 3 indicate that it has the greatest degree of electron donation from C-H bonds into the C(+)-C bonds. The experimental (13)C NMR chemical shifts also agree very well with the experimental data.
Rasul
Golam
G
Loker Hydrocarbon Research Institute and Department of Chemistry, University of Southern California, University Park, Los Angeles, California 90089-1661, USA.
Chen
Jonathan L
JL
Prakash
G K Surya
GK
Olah
George A
GA
D002073:Butanes / Q000737:chemistry*; D002247:Carbon Isotopes; D002412:Cations / Q000737:chemistry; D003198:Computer Simulation; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D008956:Models, Chemical; D015394:Molecular Structure; D011789:Quantum Theory; D012015:Reference Standards; D013055:Spectrophotometry, Infrared; D013816:Thermodynamics; D014732:Vibration
D002073:Butanes; D002247:Carbon Isotopes; D002412:Cations