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First‐Principles Molecular Dynamics Evaluation of Thermal Effects on the NMR 1 J Li,C Spin–Spin Coupling
Author(s) -
de la Lande Aurélien,
Fressigné Catherine,
Gérard Hélène,
Maddaluno Jacques,
Parisel Olivier
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601108
Subject(s) - methyllithium , molecular dynamics , dimer , coupling constant , spin (aerodynamics) , monomer , computational chemistry , coupling (piping) , chemistry , ether , carbon 13 nmr , chemical physics , materials science , thermodynamics , physics , stereochemistry , organic chemistry , polymer , quantum mechanics , metallurgy
Car–Parrinello (CP) molecular dynamics were applied to sample conformations of various models of organolithium aggregates which are chosen to estimate 1 J Li,C NMR coupling constants. The results show that the deviations from the values computed using static (optimized) geometries are small provided no large‐amplitude motions occur within the timescale of the simulations. In the case of the vinyllithium dimer, for which rotation of the vinyl chain is observed, this approach allows analysis of the various contributions to the experimentally measured constants. For the trisolvated methyllithium monomer, partial decoordination of solvating dimethyl ether is observed and results in a significant shift of 1 J Li,C . All these results highlight that a varied physicochemical machinery is hidden behind general empirical formulas, such as the Bauer–Winchester–Schleyer rule used experimentally.