Synthesis and Characterization of a Novel Tetranuclear 5f Compound: A New Synthon for Exploring U(IV) Chemistry

In the course of structurally characterizing previously reported complexes based on the 1,2-bis­(dimethylphosphino)­ethane)) (dmpe) ligand ([(dmpe)2UCl4] (1) and [(dmpe)2UMe4] (2)), we find that adjusting the U/dmpe ratio leads to an unprecedented species. Whereas the use of two or three equivalents of dmpe relative to UCl4 produces 1 as a blue-green solid, the use of a 1:1 dmpe/UCl4 stoichiometry yields [(dmpe)4U4Cl16]·2CH2Cl2·(3·2CH2Cl2) as a green solid. In turn, 3 is used to prepare a mixed-chelating ligand complex featuring the bidentate ligand 4,4′-dimethyl-2,2′-bipyridine (dmbpy), [(dmpe)­(dmbpy)­UCl4] (4). The measured magnetic susceptibilities for 1–4 trend toward nonmagnetic ground states at low temperatures.