DFT Application to the Analysis of Quadrupole Coupling Constant of Aluminum Methyl Chloride Dimers

Abstract

The analysis of the ²⁷Al and ³⁵Cl quadrupole coupling parameters of aluminum methyl chloride dimers were carried out on the basis of the density functional theory (DFT). The available experimental values of quarupole coupling constants were compared with their calculated ones. In this investigation, the correlations were made between calculated ²⁷Al and ³⁵Cl nuclear quadrupole coupling constant,, and dihedral angles <em>q</em>, of dimers. These <em>q</em>s were produced through the ring puckering motions about the hinge line which joins the two bridge atoms. s of ²⁷Al and ³⁵Cl were used as probes for monitoring the departure of the symmetry of these dimers from a high symmetry point group to the lower one. It was also found that the common symmetry point group attributed to aluminum methyl chloride dimers is valid only up to dihedral angle, 20°. After this point, puckering motions can cause further break down of symmetry. Moreover, the replacement of bridged chloride by methyl can apparently decrease c values of ²⁷Al atom. This could be due to the alteration of the orbital density in aluminum atoms.