Isotope effects in one-bond spin-spin coupling constants A computational study on XHn (n = 2 - 4) molecules

STEPHAN P. A. SAUER; PATRICIO F. PROVASI

WARSAW

Conferencia; VI th Symposium on Nuclear Magnetic Resonance in Chemistry, Physics and Biological Sciences; 2010

Institute of Organic Chemistry Polish Academy of Sciences

Motivation - Experimental study of isotope effects on 1JC-H in methane by Bennett, Raynes and Anderson [Spectrochim Acta 45A, 821 (1989)]: from CH4 to CH3D: the secondary isotope effect1JC-H in CH3D - 1JC-H in CH4 = -0.356 Hz is much larger than the primary isotope effect (γH/γD) 1JC-D in CH3D - 1JC-H in CH4 = -0.071 Hz- Theoretical study of the geometry dependence of 1JC-H in CH4 by Raynes, Geertsen and Oddershede [CPL 197, 516 (1992)]: 1JC-H varies more with changes in the bond length of the other C-H bond than of its own C-H bond.- Effect is called unexpected differential sensitivity (UDS)- UDS is not observed in uncorrelated calculations.