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An SCF and CI Study of the 1,3 Shift in the HXCHY⇌XCHYH Isoelectronic Series: X, YCH 2 , NH, and O
Author(s) -
Poirier Raymond A.,
Majlessi Dariush,
Zielinski Theresa J.
Publication year - 1986
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/jcc.540070409
Subject(s) - tautomer , chemistry , basis set , gaussian orbital , computational chemistry , ab initio , proton , bond length , hydrogen bond , molecular geometry , affinities , series (stratigraphy) , molecular orbital , proton affinity , transition state , ab initio quantum chemistry methods , crystallography , molecule , stereochemistry , density functional theory , ion , crystal structure , physics , catalysis , paleontology , protonation , organic chemistry , quantum mechanics , biology , biochemistry
Ab initio molecular orbital calculations at SCF level with the 3‐21G, 6‐31G, and 6‐31G** basis sets and CI level with the 6‐31G basis set have been carried out for an isoelectronic series HXCHY and XCHYH, where X, Y can be CH 2 , NH, and O. Optimized structures (3‐21G and 6‐31G**) for both tautomers and the 1,3 hydrogen shift transition states are reported. The relative stabilities of the isomers and the barriers of the 1,3 shift are discussed in terms of proton affinities and bond orders. It is shown that both the relative stabilities of the tautomers and the relative barrier heights can be explained qualitatively using simple proton affinity arguments and that the barrier heights are quantitatively related to bond orders.