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Reaction pathways for model II–VI precursors: A computational study
Author(s) -
Cundari Thomas R.,
Fu Wentao
Publication year - 1999
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/(sici)1097-461x(1999)71:1<47::aid-qua5>3.0.co;2-m
Subject(s) - adduct , chemistry , alkoxide , alkyl , hydride , thermochemistry , reductive elimination , computational chemistry , yield (engineering) , kinetic energy , medicinal chemistry , stereochemistry , thermodynamics , organic chemistry , metal , catalysis , physics , quantum mechanics
A computational study of the reactions of model II–VI precursors, MH 2 (M=Zn, Cd, Hg) and H 2 E (E=O, S, Se, Te), is reported. The present computations yield several results of relevance to OMVPE of II–VI materials from MR 2 /ER 2 ′precursors. Adduct formation is feasible at low temperatures, in line with recent experiments, but not at higher temperatures common in II–VI OMVPE. Calculations suggest that adducts are most likely to form after elimination has resulted in replacement of hydride with hydroxide ligands (in our model) or alkyl with alkoxide ligands (in larger models). The overall reaction MH 2 +2 H 2 E→M(EH) 2 is generally more favorable, kinetically and thermodynamically, for lighter metals and heavier elements. On the basis of calculated thermodynamic and kinetic quantities, we conclude that the preferred pathway from reactants (MH 2 +2 H 2 E), except for M=Hg and E=Te, to an M(EH) 2 intermediate is by way of a 1:2 adduct (or a similar portion of the potential energy surface in the absence of a bound adduct) followed by two successive H 2 eliminations, in preference to the alternative in which adduct formation and H 2 elimination occur in succession. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 71: 47–56, 1999