Semiexperimental equilibrium structure for the C6 backbone of cis-1,3,5-hexatriene; structural evidence for greater pi-electron delocalization with increasing chain length in polyenes.
J Phys Chem A
; 113(9): 1864-8, 2009 Mar 05.
Article
em En
| MEDLINE
| ID: mdl-19196001
ABSTRACT
Twenty-five microwave lines were observed for cis-1,3,5-hexatriene (0.05 D dipole moment) and a smaller number for its three (13)C isotopomers in natural abundance. Ground-state rotational constants were fitted for all four species to a Watson-type rotational Hamiltonian for an asymmetric top (kappa = -0.9768). Vibration-rotation (alpha) constants were predicted with a B3LYP/cc-pVTZ model and used to adjust the ground-state rotational constants to equilibrium rotational constants. The small inertial defect for cis-hexatriene shows that the molecule is planar, despite significant H-H repulsion. The substitution method was applied to the equilibrium rotational constants to give a semiexperimental equilibrium structure for the C(6) backbone. This structure and one predicted with the B3LYP/cc-pVTZ model show structural evidence for increased pi-electron delocalization in comparison with butadiene, the first member of the polyene series.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Polienos
/
Elétrons
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
J Phys Chem A
Assunto da revista:
QUIMICA
Ano de publicação:
2009
Tipo de documento:
Article
País de afiliação:
Estados Unidos