Abstract
Abstract The MM2 force field has been extended so as to deal with periplanone B and nitroxides by using empirical relationships which enable us to derive the MM2 stretching (ks) and bending force (kb) constants systematically. The stretching force constants (ks) could be correlated well with the bond order (N) and equilibrium bond length (r0) by the equation ks = a(N/r03) + b. Three different sets of parameters (a, b) were assigned to the bonds, which were classified according to the atoms forming the bonds. The bending force constants (kb) could be estimated by the equation , where ks1 and ks2 are the stretching force constants of the bonds which comprise the bond angle. The angle types were classified into six groups in the MM2 force field. After assigning ks and kb, the torsional parameters (V1, V2, V3) were determined so as to reproduce the ab initio conformational energies and structural data of the model compounds for the periplanone B and nitroxides. The MM2 calculations using the parameters thus obtained reproduced the experimental structures and conformational energies of periplanone B and the spin adducts of nitrone spin traps correctly.
Published Version
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