The structures and vibrational frequencies of CI2-helium clusters have been studied using the path integral molecular dynamics method combined with the discrete-variable-representation approach. It is found that the Cl-2-helium clusters form clear shell structures comprised of rings around the Cl-2 bond. The vibrational frequencies calculated show a monotonically increasing red shift with an increase in cluster size. It can be concluded that the first solvation shell and its density around T-shaped configurations play the most important role in the observed frequency shifts. (C) 2002 Elsevier Science B.V. All rights reserved.