Internal rotation in some organic molecules containing methyl, amino, hydroxyl, and formyl groups

1972 ◽  
Vol 25 (8) ◽  
pp. 1601 ◽  
Author(s):  
L Radom ◽  
WA Lathan ◽  
WJ Hehre ◽  
JA Pople
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Internal Rotation ◽  
Molecular Orbital ◽  
Organic Molecules ◽  
Experimental Information ◽  
Molecular Orbital Theory ◽  
Orbital Theory ◽  
Moderate Agreement ◽  
Theoretical Results

Ab initio molecular orbital theory is used to study internal rotation in 20 organic molecules of the types X-Y, X-CH2-Y, X-SH-Y, X-O-Y, and X-CO-Y-where X and Y are methyl, amino, hydroxy, or formyl groups. In some of these molecules, internal rotation about two bonds is possible. The theoretical results are generally in moderate agreement with available experimental data and, in addition, lead to a number of predictions for molecules for which experimental information is lacking.

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.

A Model Theoretical Study for Alkylation in Benzimidazoles: ab initio Electrostatic Potentials

1979 ◽  
Vol 32 (1) ◽  
pp. 11 ◽  
Author(s):  
AL Hinde ◽  
L Radom ◽  
M Rasmussen
Keyword(s):  
Experimental Data ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Electrostatic Potential ◽  
Molecular Electrostatic Potential ◽  
Theoretical Study ◽  
Molecular Orbital Theory ◽  
Frontier Orbital ◽  
Orbital Theory ◽  
Controlled Processes

Ab initio molecular orbital theory is used to study the protonation of benzimidazole anions. Both kinetically and thermodynamically controlled processes are considered for the unsubstituted and for NH2, NO2 and CN substituted systems. Extensive use is made of molecular electrostatic potential (m.e.p.) maps to predict kinetically preferred sites of protonation. Predictions made on this basis are consistent with experimental data on alkylation of these and closely related systems. In contrast, other approaches based on theoretical charges or frontier orbital coefficients do not correlate well with the experimental results.

The Heat of Formation of Formaldimine

1992 ◽  
Vol 45 (1) ◽  
pp. 285 ◽  
Author(s):  
BJ Smith ◽  
JA Pople ◽  
LA Curtiss ◽  
L Radom
Keyword(s):  
Ab Initio ◽  
Molecular Orbital ◽  
Heat Of Formation ◽  
Molecular Orbital Theory ◽  
Orbital Theory

Ab initio molecular orbital theory at the G 2 level has been used to predict new values for the heat of formation of formaldimine (CH2=NH): ?Hfº0 = 94 ±10 kJ mol-1 and ?Hfº298 = 86 ±10 kJ mol-1.

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