Dimers of highly π-loaded organoimido d1 metal radicals of niobium, tantalum, molybdenum, tungsten, and rhenium: the context of the cyclopentadienyl imido ligand analogy

The reductive generation and dimerisation of highly π-loaded and coordinatively unsaturated d1 imido metal radicals of the type [Cp2M(NR)] (M=Nb, Ta), [CpM(NR)2] (M=Mo, W), and [Re(NR)3] is described. Their dinuclear spin-coupled complexes are characterized by crystal structure determinations and their bonding situation is discussed with reference to the cyclopentadienyl imido ligand analogy.