Reactions of a Uranium(III) Complex with N-Heterocycles to Form Diuranium(IV) Ketimides.

The chemistry of the classical uranium(III) complex [U(N″)] N″ = {N(SiMe}) is well-developed; however, there have been surprisingly few studies of its reactivity toward -heterocycles. Here, we report the separate reactions of [U(N″)] with pyrazine, 4-azido-pyridine, and the methylene transfer agent -(9,10-dihydro-9,10-epiminoanthracen-11-yl)methanimine (CHNCH) to give the respective diuranium(IV) products [{U(N″)}(μ-NCHN-1κ,2κ')] (), [{U(N″)}(μ-NCHN-1κ,2κ')] (), and [{U(N″)}(μ-NCHN-1κ,2κ')] (). The solid-state structures of complexes and respectively revealed bent U-N═C angles of 167.6(5) and 155.3(4)°, short U-N bond lengths of 2.070(5) and 2.104(4) Å, and diagnostic C═N distances of 1.297(7) and 1.364(7) Å. A combination of structural, spectroscopic, magnetic, and quantum-chemical calculations was required to confidently assign U(IV) ions exclusively in complexes - and to prove that and are ketimides rather than iminyls or nitrenes. Together, this study underscores the need for comprehensive analysis for the correct interpretation of the electronic structures of actinide complexes.