The importance of electrostatic effects in controlling π-facial stereoselectivity in nucleophilic additions to carbonyl compounds: an ab initio MO study of a prototype chelation model

1991 ◽  
Vol 0 (5) ◽  
pp. 327-330 ◽  
Author(s):  
Stephen S. Wong ◽  
Michael N. Paddon-Row
Keyword(s):  
Ab Initio ◽  
Carbonyl Compounds ◽  
Nucleophilic Additions ◽  
Electrostatic Effects ◽  
Ab Initio Mo

An ab initio MO study of conformation structure of nicotinamide and its derivatives

1983 ◽  
Vol 48 (7) ◽  
pp. 1842-1853 ◽  
Author(s):  
Stanislav Böhm ◽  
Josef Kuthan
Keyword(s):  
Ab Initio ◽  
Wave Functions ◽  
Semiempirical Calculations ◽  
Rigid Rotor ◽  
Qualitative Similarity ◽  
Ab Initio Mo ◽  
Experimental Findings

Conformation of nicotinamide (I), 3-carbamoylpyridinium (IIa), 1-methyl-3-carbamoylpyridinium (IIb), and 1-methyl-1,4-dihydronicotinamide (IIIa) has been studied in the rigid rotor approximation on the basis of non-empirical STO-3G wave functions. The rotation barriers decrease in the order: IIIa > I ~ IIb > IIa. When confronted with semiempirical calculations, the conformation curves of molecular energy show a better qualitative similarity to the EHT than to NDDO and particularly to CNDO/2 curves. Relation of the calculated characteristics to experimental findings is discussed.

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