Calculation of Nuclear Quadrupole Parameters in Imidazole Derivatives and Extrapolation to Coenzyme B12. A Theoretical Study

1999 ◽  
Vol 103 (40) ◽  
pp. 8618-8627 ◽  
Author(s):  
Maricel Torrent ◽  
Djamaladdin G. Musaev ◽  
Keiji Morokuma ◽  
Shyue-Chu Ke ◽  
Kurt Warncke
Keyword(s):  
Theoretical Study ◽  
Coenzyme B12 ◽  
Imidazole Derivatives ◽  
Quadrupole Parameters ◽  
Nuclear Quadrupole

Stabilization of the adenosyl radical in coenzyme B12 – a theoretical study

2004 ◽  
Vol 386 (1-3) ◽  
pp. 174-178 ◽  
Author(s):  
Nicole Dölker ◽  
Feliu Maseras ◽  
Per E.M. Siegbahn
Keyword(s):  
Theoretical Study ◽  
Coenzyme B12

Effect of Intermolecular Hydrogen Bonding on the Nuclear Quadrupole Interaction in Imidazole and its Derivatives as Studied by ab initio Molecular Orbital Calculations

2000 ◽  
Vol 55 (1-2) ◽  
pp. 315-322
Author(s):  
Nobuo Nakamura ◽  
Hirotsugo Masui ◽  
Takahiro Ueda
Keyword(s):  
Hydrogen Bond ◽  
Ab Initio ◽  
Molecular Orbital ◽  
Quadrupole Interaction ◽  
Bond Distance ◽  
Nuclear Quadrupole Interaction ◽  
Basis Sets ◽  
Molecular Orbital Calculations ◽  
Imidazole Derivatives ◽  
Nuclear Quadrupole

Ab initio Hartree-Fock molecular orbital calculations were applied to the crystalline imidazole and its derivatives in order to examine systematically the effect of possible N-H---N type hydrogen bond-ing on the nuclear quadrupole interaction parameters in these materials. The nitrogen quadrupole coupling constant (QCC) and the asymmetry parameter (η) of the electric field gradient (EFG) were found to depend strongly on the size of the molecular clusters, from single molecule, to dimer, trimer and to the infinite molecular chain, i.e., crystalline state, implying that the intermolecular N-H -N hydrogen bond affects significantly the electronic structure of imidazole molecule. A certain correla-tion between the QCC of 14N and the N-H bond distance R was also found and interpreted on the basis of the molecular orbital theory. However, we found that the value of the calculated EFG at the hy-drogen position of the N-H group, or the corresponding QCC value of 2 H, increases drastically as R-3 when R is shorter than about 0.1 nm, due probably to the inapplicability of the Gaussian basis sets to the very short chemical bond as revealed in the actual imidazole derivatives. We suggested that the ob-served N-H distances in imidazole derivatives should be re-examined.

Sign in / Sign up

Export Citation Format

Share Document