RT Journal Article
T1 Karplus Equation for 3 JHH Spin-Spin Couplings with Unusual 3 J(180°) < 3 J(0°) Relationship
A1 Contreras, Ruben
A1 Suardíaz Delrío, Reynier
A1 Pérez, Carmen
A1 Crespo-Otero, Rachel
A1 San Fabián, Jesús
A1 García de la Vega, José
AB Vicinal 3JHH coupling constants for monosubstituted ethane molecules present the unusual relationship 3JHH (180°) < 3JHH (0°) when the substituent contains bonding and antibonding orbitals with strong hyperconjugative interactions involving bond and antibond orbitals of the ethane fragment. This anomalous behavior is studied as a function of the substituent rotation for three model systems (propanal, thiopropanal, and 1-butene) at the B3LYP/TZVP level. The consistency of this level of theory to study this problem is previously established using different ab initio methods and larger basis sets. The origin of the unusual 3JHH(180°) − 3JHH(0°) relationship is attributed to simultaneous σ/π hyperconjugative interactions σCα—Hα → π*Cc═X, and σCα—Cβ → π*Cc═X. These interactions depend on the substituent rotation and their effects are different for 3JHH(180°) than for 3JHH(0°). The modelization carried out shows an increase of those effects as the substituent changes from weaker (CH═CH2) to stronger (CH═S) electron acceptor π*C═X.
PB American Chemical Society
SN 1549-9618
YR 2008
FD 2008
LK https://hdl.handle.net/20.500.14352/93092
UL https://hdl.handle.net/20.500.14352/93092
LA eng
NO R. H. Contreras, R. Suardíaz, C. Pérez, R. Crespo-Otero, J. San Fabián, and J. M. García de la VegaJournal of Chemical Theory and Computation 2008 4 (9), 1494-1500DOI: 10.1021/ct800145h
NO Ministerio de Ciencia, Innovación y Universidades (España)
NO Universidad de Buenos Aires
NO Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina)
DS Docta Complutense
RD 6 abr 2025