Barriers to internal rotation in CF3CFCl2, CF3CHCl2, CF3CF2Br, CF3CF2Cl, CF3CH2Br, and CF3CH2Cl: fluorine-19 and proton dynamic NMR studies; ab initio molecular orbital barrier calculations

1992 ◽  
Vol 96 (23) ◽  
pp. 9225-9232 ◽  
Author(s):  
Jacques A. Brunelle ◽  
Leo J. Letendre ◽  
Eugen E. Weltin ◽  
Jay H. Brown ◽  
C. Hackett Bushweller
Keyword(s):  
Ab Initio ◽  
Internal Rotation ◽  
Molecular Orbital ◽  
Dynamic Nmr ◽  
Nmr Studies ◽  
Barriers To Internal Rotation

Ab initio studies on amides: acetamide, N-methylformamide and N-methylacetamide

1982 ◽  
Vol 35 (6) ◽  
pp. 1071 ◽  
Author(s):  
L Radom ◽  
NV Riggs
Keyword(s):  
Ab Initio ◽  
Internal Rotation ◽  
Molecular Orbital ◽  
Basis Sets ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Methyl Group ◽  
Barriers To Internal Rotation ◽  
Reported Data

Ab initio molecular orbital theory with the STO-3G and 4-31G basis sets has been used to investigate the geometries, preferred conformations, and barriers to internal rotation for acetamide, N-methylformamide and N-methylacetamide. Results are compared with corresponding previously reported data for formamide. For acetamide, the preferred conformation has the methyl group staggered with respect to the N-C bond whereas for N-methylformamide the methyl group is eclipsed with respect to this bond. Both N-methylformamide and N-methylacetamide prefer a Z-arrangement, i.e. methyl cis to C=O about the N-C bond. Experimentally determined barriers to internal rotation about the N-C bond generally lie within the range spanned by the STO-3G and 4-31G estimates.

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