Nuclear quadrupole coupling constants (chi) of Al-27, Cl-35 and Br-81 in AlX3, monomers as well as Al2X6 (X = Cl, Br) dimers are calculated at the RHF/6-311G* and B3LYP/6-311G* levels, using GAUSSIAN 98 package. Correlations are made between chi and dihedral angles theta, of Al2X6. These thetas are produced through the ring puckering motions about the hinge line which joins the two bridge halogens (X-b). Nuclear quadrupole coupling constants of,Cl-35, Br-81 and Al-27 are used as probes for monitoring the departure of the symmetry of Al2X6 from a high symmetry point group D-2h to a lower one. The chis of chlorine nuclei of AlCl3 differ significantly from those of Al2Cl6. These differences appear negligible for AlBr3 in comparison to Al2Br6. This work demonstrates the considerable sensitivity of nuclear quadrupole resonance in distinguishing between Al2X6 conformers. This is in comparison to the usage of energy differences which is customarily employed. (C) 2003 Elsevier Science B.V. All rights reserved.