Premium
Stabilization of methyl anions by first‐row substituents. The superiority of diffuse function‐augmented basis sets for anion calculations
Author(s) -
Spitznagel Günther W.,
Clark Timothy,
Chandrasekhar Jayaraman,
Schleyer Paul Von Ragué
Publication year - 1982
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.540030311
Subject(s) - chemistry , substituent , singlet state , ion , basis set , ab initio , lithium (medication) , computational chemistry , gaussian orbital , crystallography , electronic correlation , group (periodic table) , ab initio quantum chemistry methods , stereochemistry , density functional theory , molecule , atomic physics , organic chemistry , physics , medicine , excited state , endocrinology
The entire set of methyl anions, XCH 2 − , substituted by first‐row substituents, Li, BeH, BH 2 , CH 3 , NH 2 , OH, and F, was examined at various ab initio levels. Diffuse orbital‐augmented basis sets, such as 4−31+ G and 6−31+ G *, are needed to describe the energies of these anions adequately. Estimates of proton affinities are further improved by second‐order Møller–Plesset ( MP 2) electron correlation corrections, but relative energies are less affected. The methyl group in the ethyl anion is destabilizing, the amino substituent is borderline, but all other groups are stabilizing. Very large π effects are exhibited by BH 2 and BeH groups; inductive stabilization by the electronegative F and OH groups is less effective. Lithium also is stabilizing, but the best singlet geometry of CH 2 Li − is not planar. A planar CH 2 Li − triplet with a π 1 configuration may be lower in energy.