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Origins of relative acidity: First and second period hydrides
Author(s) -
Laidig Keith E.,
Streitwieser Andrew
Publication year - 1996
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(19961130)17:15<1771::aid-jcc7>3.0.co;2-m
Subject(s) - deprotonation , chemistry , period (music) , relaxation (psychology) , proton , computational chemistry , total energy , ion , hartree–fock method , atomic physics , inorganic chemistry , quantum mechanics , organic chemistry , physics , social psychology , psychology , acoustics , displacement (psychology) , psychotherapist
The origins of the trends of relatively acidity across and between the first and second period hydrides (BH 3 , CH 4 , NH 3 , H 2 O, HF, AIH 3 , SiH 4 , PH 3 , H 2 S, and HCl) were investigated using molecular and subsystem quantum mechanics at the Hartree‐Fock (HF)/6–31 + + G ** //HF/6–31 + + G ** level of theory. The total deprotonation energies, Δ E acid , are interpreted in terms of three component processes: Δ E 1 ; deprotonation without electronic and nuclear relaxation; Δ E 2 , electronic relaxation within the acid geometry; and Δ E 3 , nuclear relaxation. Δ E 1 is given from the electrostatic potential at the acidic proton, Δ E 3 + Δ E 2 (= Δ E * ) is given from the calculated energy of the conjugate anion at the acid geometry. The increased acidity across a given period is shown to be already mostly an inherent property of the acid. © 1996 by John Wiley & Sons, Inc.