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Equilibria between Nonclassical and Classical Boron Compounds, Competition between Aromaticity in Two and Three Dimensions
Author(s) -
Michel Holger,
Steiner Dirk,
Wočadlo Sigrid,
Allwohn Jürgen,
Stamatis Nicolaos,
Massa Werner,
Berndt Armin
Publication year - 1992
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199206071
Subject(s) - aromaticity , benzene , boron , ring (chemistry) , carborane , chemistry , chemical shift , computational chemistry , competition (biology) , thermodynamics , stereochemistry , organic chemistry , physics , molecule , ecology , biology
Carborane 1 and organoborane 2 are in equilibrium in solution. This is deduced from the temperature dependence of the position of the 11 B and 13 C NMR signals of 1 (R = t Bu or mesityl). An estimation of the thermodynamic parameters shows that the energy difference between 1 and 2 (1–2 kcal mol −1 ) is significantly less than for the parent compounds without a fused benzene ring (37.5 kcal mol −1 ). A possible explanation is that two‐dimensional aromaticity is lost in the transition from 2 to 1 .