The discovery of slow relaxation of the magnetization and quantum effects in the single-molecule magnet (SMM) Mn12-ac in 1993 has inspired both physicist and chemist alike. A main hindrance to possible practical applications of SMMs is the blocking temperature, below which one molecule behaves as a magnet, which is too low. Recently it was found that the two N2(3-) radical-bridged rare-earth complexes Dy2N2(3-) and Tb2N2(3-) posses the highest known blocking temperatures of 8.3 and 14 K, respectively. We here propose INS experiments on these clusters in order to determine the strength of the magnetic anisotropy and exchange interactions, where the latter is, as suggested by previous magnetic susceptibility data, remarkably high for 4f metal ions.