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A Rhenium–Cyclohexane Complex with Preferential Binding of Axial CH Bonds: A Probe into the Relative Ability of CH, CD, and CC Bonds as Hyperconjugative Electron Donors?
Author(s) -
Lawes Douglas J.,
Darwish Tamim A.,
Clark Timothy,
Harper Jason B.,
Ball Graham E.
Publication year - 2006
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.200600313
Subject(s) - cyclohexane , chemistry , hyperconjugation , rhenium , proton , crystallography , electron , stereochemistry , molecule , inorganic chemistry , organic chemistry , physics , quantum mechanics
Which bonds bind better? According to NMR experiments with the alkane complex [CpRe(CO) 2 (cyclohexane)] at low temperatures, complexation with an axial proton is preferred over that through an equatorial one by about 1.5 kJ mol −1 . Calculations support this order of binding energies. The preference is proposed to be due to stronger electron donation through hyperconjugation from a CH bond than from a CC bond.