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G2 ab initio calculations on three‐membered rings: Role of hydrogen atoms
Author(s) -
Alcamí M.,
Mó O.,
Yáñez M.
Publication year - 1998
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/(sici)1096-987x(19980715)19:9<1072::aid-jcc8>3.0.co;2-n
Subject(s) - single bond , cyclopropane , electronegativity , chemistry , bond length , bond order , bond energy , ring (chemistry) , crystallography , delocalized electron , ring strain , ab initio quantum chemistry methods , computational chemistry , bent bond , ab initio , sextuple bond , group (periodic table) , molecule , crystal structure , organic chemistry
G2 ab initio calculations on all ABX three‐membered rings (TMRs) that can be derived from cyclopropane by systematic substitution of the (SINGLE BOND)CH 2 groups by (SINGLE BOND)NH or (SINGLE BOND)O groups have been performed. Our results show that the decrease in the A(SINGLE BOND)B bond length as the electronegativity of X increases is significantly larger than that found for the corresponding acyclic analogs. In general, a systematic substitution of the (SINGLE BOND)CH 2 groups of cyclopropane by (SINGLE BOND)NH or (SINGLE BOND)O groups implies significant geometric changes that are not reflected in a parallel change of the corresponding conventional ring strain energy (CRSE). When the electronegativity of the groups forming the TMR increases the effect on the CRSE of the system is small, although the charge delocalization inside the ring decreases. The near constancy of the CRSE along the series can be explained in terms of the charge redistribution of the system where the (SINGLE BOND)CH 2 groups play a crucial role. There are, however, significant changes in the hydrogenation energies of the TMR investigated; our results show that, when in an ABX three‐membered ring, the electronegativity of X increases the hydrogenation energy of A(SINGLE BOND)B bond decreases and vice versa. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 1072–1086, 1998