Importance of the Type of Bread: Comparing Uranocene, Bis(Phthalocyaninato)Uranium(IV), and Mixed Uranophthalocyanin-ocene

Sandwich complexes usually have two similar ligands interacting with the central metal atom. In this work, a mixed sandwich with two different ligands, termed uranophthalocyanin-ocene U(COT)(Pc) (COT = cyclo-octatetraene^2-; Pc = phthalocyaninato^2-), has been synthesized from the reaction of UPcCl₂·LiCl and K₂COT. The crystal structure is reported, and the variable-temperature solid-state magnetic susceptibility measurements confirm the presence of a U(IV) center. This mixed-sandwich compound was compared to uranocene, U(COT)₂, and bis(phthalocyaninato)uranium(IV), U(Pc)₂, using density functional theory (DFT) and computational bonding analysis (ETS-NOCV). The geometrical structures have been optimized using DFT, and the obtained bond lengths are similar to the experimental results. From the energy decomposition analysis (EDA), it is evident that by replacing carbon atoms with nitrogen atoms, i.e., replacing COT with a Pc ligand, the covalent nature of the molecule increases.