We have investigated the structures and the properties of polyaminoborane oligomers by using ab initio computational tools including dynamic electron correlation effects. It turned out that the PBEO/6-31G(2d) method provides a good agreement between experimental and theoretical structures. The key data include geometries, rotational profiles, infrared spectra, vertical excitation energies, atomic charges, and dipole moments. The variations of these properties upon conformation changes are studied. Our results are compared to available experimental measurements.