Although various low-lying energy structures of electron.water clusters, e-(H2O)2.6, have been reported, some of the global minimum energy structures (in particular, for the tetramer and pentamer) are still not clearly characterized yet. Therefore, using high-level ab initio calculations,we have investigated several new low-lying energy conformers in addition to previously reported ones. The lowest energy conformer for the pentamer is found to have a wedge-like structure which has never been studied before. Based on the experimental vertical electron-detachment energies and OH vibrational spectra of the electron.water clusters, we report the most probable structures and their nearly isoenergetic structures. The OH vibrational frequencies of e2(H2O)2.6 and e2HOD(D2O)1.5 are investigated, and are found to be in excellent agreement with the available experimental data. Their O.H stretch frequency shifts are classified in terms of the types of water molecules.