A DFT study of the isostructural compounds [UO2L5]n− with n=3-5 and linear [Cp2UL5]m− with m=1-3 has been carried out for two different anionic ligands. Structurally stable structures are obtained for all systems. The coordination competition between cyanide (CN−) and isocyanide (NC−) as well as between cyanate (OCN−) and isocyanate (NCO−) has been studied in the uranyl case. A clear preference for cyanide and isocyanate complexes is reported. The coordination of five ligands in the equatorial plane is rationalised by the analysis of the MO diagram of both systems. Moreover, the qualitative comparison of the two MO diagrams shows a high similarity in agreement with the isolobality concept. The existence of linear [Cp2UL5]− organometallic U(VI) complexes is thus proposed, as well as the possibility of obtaining complexes of both types for U(VI) and U(V) with OCN− ligands. In addition, the U(IV) linear metallocene is calculated to be stable for the latter ligand.