The vibration frequencies of [6] cyclacenes (linear, angular and angular-chirai)‎ monoring molecules

Abstract EN

The (3N-6) vibration frequencies and IR-absorption intensities of [6] Cyclacene (linear, angular and angular-chiral) monoring molecules were calculated applying Density Functional Theory (DFT) of the type (B3LYP) and a Gaussian basis (6-311G) method.

Comparison of the results showed that, similar to the polyaromatic hydrocarbons, the following relations hold : vsymmetricCH str.

> vasymmetric CH str.

and, vsymmethc CC str.

> v asymmetric CC str.

i.

e., the following relation hold too, vsymmetric.

CC sir.

(axial.) > vasymmtric.

CC str.

(axial) > vasymmetric.

CC str.

(circumferential) in the linear molecule, where axial are the vertical C-Ca bonds (annular bonds) in the rings and circumferential C-Cc are the outer ring bonds.

The relation for the C- Cstr.

is reversed in the angular and the angular-chiral molecules, since the C-Ca bonds are converted to C-Cc bonds in the angular and angular-chiral cyclacenes.

The results include the assignment of all puckering, breathing and clock-anticlockwise bending vibrations.

They allow a comparative view of the charge density at the carbon atoms too