Spin-orbit configuration-interaction calculations have been carried ou
t on actinide complexes using relativistic core potentials and contrac
ted Gaussian atomic orbitals. At present, this type of calculation giv
es moderate-accuracy results on ground states and excited states and o
n a number of molecular properties. Our previous work on uranocene has
been continued with protactinocene, neptunocene, and plutonocene, giv
ing the patterns of low-lying f --> f states and higher-lying f --> d
and pi --> d states. Accurate magnetic moment values are obtained from
these wavefunctions. The U@C-60 and U@C-28 complexes show extensive m
ixing of pi orbitals with both 6d and 5f orbitals. The lower states of
U@C-28 are of pif and f(2) character with the ground state appearing
to be a pif state with mainly singlet character.