Crystallographic and/or magnetic properties of neutral and cationic uranium(IV) sandwiched phthalocyanine complexes

Abstract

Neutral and cationic U(IV) sandwiched phthalocyanine (Pc) complexes were prepared. The neutral species, UPc2, was obtained by the reaction of UCl4 and phthalonitrile, and the [UPc2][BF4] crystals were grown by electrolysis. The structures of the complexes were determined crystallographically. A U(IV) ion has two 5f electrons, which carry a magnetic moment localized at the U sites, making the complex magnetically active. The magnetic susceptibility measurement of UPc2 revealed that the system was paramagnetic with local magnetic moments down to 2 K, but these magnetic moments were suppressed, possibly by a ligand field effect. The paramagnetism was also confirmed by the magnetization curve without hysteresis. The cationic complex, [UPc2][BF4] crystalized in a tetragonal structure with the space group P4nc, in which the UPc2 molecules stacked along the tetragonal c-axis. The structure was similar to that of [LnPc2][BF4], but with distinct disorder in the stacking plane. The stabilities of the crystal and molecular structures and the electronic configurations of UPc2 and [UPc2][BF4] were evaluated via the ab initio calculations that included the multiconfigurational nature of the actinide element.