The aim of this paper is to elucidate the role played by the bosonic/fermionic character of N He atoms solvating a Br-2(X) molecule. To this end, an adiabatic model in the molecular stretching coordinate is assumed and the ground energy levels of the complexes are searched by means of Hartree (or Hartree-Fock) Quantum Chemistry calculations for He-4 (or He-3) solvent atoms. Simulations of vib-rotational Raman spectra point at the spin multiplicity as the main feature responsible for the drastic difference in the rotational structures of molecules embedded in boson or fermion helium drops as already observed by the experiments of Grebenev [S. Grebenev, J. P. Toennies, and A. F. Vilesov, Science 279 (1998) 2083]. (C) 2004 American Institute of Physics.