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

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 ?, of dimers. These ?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 ? values of 27Al atom. This could be due to the alteration of the orbital density in aluminum atoms.