We have carried out muSR experiments on [Co(NH3)6]Cl3 and [Co(ND3)6]Cl
3. At 293 K, all the muons implanted into the complexes were in the di
amagnetic state. The observed Gaussian-type muon spin relaxation funct
ion proved that the internal magnetic field was caused by nuclear dipo
le moments of the atoms in the complexes. In addition, another exponen
tial-type muon spin relaxation function was observed in [Co(ND3)6]Cl3
below 50 K.