[en] The low-temperature magnetic susceptibilities of [(CH3)4COT]2U, [(C6H5)4COT]2U, and [(C6H5)COT]2U are reported. These measurements are consistent with the calculation of Hayes and Edelstein but are in contradiction with the results of Amberger, Fischer, and Kanellakopulos. Furthermore, it is shown that the empirical parameters of the latter authors fail to give a diamagnetic ground state for Pu(COT)2 as found experimentally