(C(5)Me(4)H)(3)U, 1, reacts with 1 equiv of NO to form the first f element nitrosyl complex (C(5)Me(4)H)(3)UNO, 2. X-ray crystallography revealed a 180° U-N-O bond angle, typical for (NO)(1+) complexes. However, 2 has a 1.231(5) Å N═O distance in the range for (NO)(1-) complexes and a short 2.013(4) Å U-N bond like the U═N bond of uranium imido complexes. Structural, spectroscopic, and magnetic data as well as DFT calculations suggest that reduction of NO by U(3+) has occurred to form a U(4+) complex of (NO)(1-) that has π interactions between uranium 5f orbitals and NO π* orbitals. These bonding interactions account for the linear geometry and short U-N bond. The complex displays temperature-independent paramagnetism with a magnetic moment of 1.36 μ(B) at room temperature. Complex 2 reacts with Al(2)Me(6) to form the adduct (C(5)Me(4)H)(3)UNO(AlMe(3)), 3.
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