Ring inversion in 1,4,7 cyclononatriene and analogues: Ab initio and DFT calculations and topological analysis.
The multidimensional conformational potential energy hypersurfaces (PEHSs) for cis-cis-cis 1,4,7 cyclononatriene (I), Tribenzocyclononatriene (TBCN) (II), and cis-cis-cis cyclic triglycine (III) were comprehensively investigated at the Hartree-Fock (HF/6-31G(d)) and density functional theory (B3LYP/6-31G(d,p)) levels of theory. The equilibrium structures, their relative stability, and the transition state (TS) structures involved in the conformational interconversion pathways were analyzed. Altogether, four geometries (two low-energy conformations and two transition states) were found to be important for a description of the conformational features of compounds I-III. B3LYP/aug-cc-pvdz//B3lYP/6-31G(d,p) and MP2/6-31G(d,p)//B3LYP/6-31G(d,p) single point calculations predict that the conformational interconversion between crown and twist forms requires 14.01, 26.71, and 17.79 kcal/mol for compounds I, II, and III, respectively, which is in agreement with the available experimental data. A topological study of the conformational PEHSs of compounds I-III was performed. Our results allow us to form a concise idea about the internal intricacies of the PEHSs of compounds I-III, describing the conformations as well as the conformational interconversion process in these hypersurfaces.
Zamora
Miguel A
MA
Departamento de Química, Universidad Nacional de San Luis, Chacabuco 917, 5700 San Luis, Argentina.
Suvire
Fernando D
FD
Enriz
Ricardo D
RD
D000465:Algorithms; D019295:Computational Biology / Q000379:methods*; D003198:Computer Simulation; D008962:Models, Theoretical; D008968:Molecular Conformation; D011789:Quantum Theory; D013237:Stereoisomerism; D013729:Terpenes
C527577:1,4,7 cyclononatriene; D013729:Terpenes