Preparation of Heterobimetallic Ketimido-Actinide-Molybdenum Complexes

During our attempts to prepare paddlewheel actinide-molybdenum complexes of the type [(X)An(MesNPR2)3Mo(CO)3] (Mes= 2,4,6-trimethylphenyl; X= Cl or I; An = U or Th; R = iPr or Ph) we have found that under certain conditions acetonitrile insertion reactions occur to give the hetero-bimetallic bridging ketimido species [ClAn(µ-MesNPiPr2)2(µMesNPiPr2{µ-NCMe})Mo(CO)3] (An = U, 1; Th, 2), [ClAn(µ-MesNPPh2)2(µMesNPPh2{µ-NCMe})Mo(CO)3] (An = U, 3; An = Th, 4), and [IAn(η2-MesNPiPr2)(µMesNPiPr2){µ-NC(Me)N(Mes)PiPr2}Mo(CO)3] (An = U, 5; Th, 6). Structural and spectroscopic data confirms the assignment of a ketimido ligand bridging An(IV) and Mo(0) centers. The isolation of 1-6 is in contrast to our previously reported preparations of [(X)An(MesNPPh2)3Mo(CO)3] (An = U or Th; X= Cl or I; Chem. Commun. 2018, 54, 1351513518) 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.