Exploring the Insertion Chemistry of Tetrabenzyluranium Using Carbonyls and Organoazides

Abstract

The insertion chemistry of U(CH2C6H5)4 (1) was explored with acetone, benzophenone, mesityl azide, and 1-azidoadamantane. Using 2 equiv of acetone affords the double-insertion product U[OC(CH3)2(CH2C6H5)]2(CH2C6H5)2(THF)2 (2), while using 4 equiv results in the tri-inserted enolate product U[OC(CH3)2(CH2C6H5)]3[OC(CH3)CH2](THF)3 (3). Deuterium labeling experiments aided in the assignment of 2 and 3. With 4 equiv of benzophenone, insertion at all U–C bonds is noted, forming U[OC(C6H5)2(CH2C6H5)]4 (4) and the THF adduct U[OC(C6H5)2(CH2C6H5)]4(THF) (4-THF). Addition of 4 equiv of N3Mes to 1 forms the tetrakis(triazenido)uranium(IV) complex U[CH2(C6H5)NNN(Mes)-κ2N1,2][CH2(C6H5)NNN(Mes)-κ2N1,3]3 (5), while the same reaction with 1-azidoadamantane generates the uranium(VI) trans-bis(imido) complex U(NAd)2[CH2(C6H5)NNN(Ad)-κ2N1,3]2(THF) (6). All species were characterized by 1H NMR and infrared spectroscopy, with select examples being structurally characterized using single-crystal X-ray diffraction.