During our attempts to prepare paddlewheel actinide-molybdenum complexes of the type [(X)An-(MesNPR(2))(3)Mo(CO)(3)] (Mes= 2,4,6-trimethylphenyl; X = Cl or I; An = U or Th; R = Pr-i or Ph) we have found that under certain conditions acetonitrile insertion reactions occur to give the heterobimetallic bridging ketimido species [ClAn(mu-MesNP(i)Pr(2))(2)(mu-MesNP(i)Pr(2){mu-NCMe})Mo(CO)(3)] (An = U, 1; Th, 2), [ClAn(mu-MesNPPh(2))(2)(mu-MesNPPh(2){mu-NCMe})Mo-(CO)(3)] (An = U, 3; An = Th, 4), and [IAn(eta(2)-MesNP(i)Pr(2))(mu-MesNP(i)Pr(2)){mu-NC(Me)N(Mes)(PPr2)-Pr-i}Mo(CO)(3)] (An = U, 5; Th, 6). Structural and spectroscopic data confirm the assignment of a ketimido ligand bridging An(W) and Mo(0) centers. The isolation of 1-6 is in contrast to our previously reported preparations of [(X)An(MesNPPh(2))(3)Mo(CO)(3)] (An = U or Th; X= Cl or I; Chem. Commun. 2018, 54, 13515-13518) with the difference in reactivity being attributable to a combination of ancillary phosphino-amide, reaction solvent, and temperature variation. Complexes 1-5 represent the first examples of structurally characterized ketimido-bridged actinide-transition metal linkages and demonstrate the profound differences in reaction outcomes that can occur from relatively minor experimental changes.