A theoretical research on the low-energy structures, binding energies, and Raman spectra of the (N-2)(n) (n = 3-6) complexes has been systematically explored. Similar to the water trimer, the energetically lowest-lying structure of the nitrogen molecule trimer is a C-3h-symmetric cyclic structure. However, different from the water tetramer and pentamer being simple ring structures, the lowest-lying structures of the tetramer and the pentamer are pyramidal structures with C-3 and C-4 symmetry. Additionally, the hexamer prefers the C-i-symmetric bipyramidal structure rather than the prism structure that is the most stable of the water hexamer. Moreover, the binding energy and the Raman spectrum for each complex are also predicted. (C) 2003 Elsevier Science B.V. All rights reserved.