Structural and Spectroscopic Characterization of a Charge-Separated Uranium Benzophenone Ketyl Radical Complex .

The reaction of [((t-BuArO)3tacn)UIII] (1) with 4,4′-di-tert-butylbenzophenone affords a unique isolable U(IV) ketyl radical species [((t-BuArO)3tacn)UIV(OC•t-BuPh2)] (2) supported by XRD data, magnetization measurements, and DFT calculations. Isolation and full characterization of the corresponding diphenyl methoxide complex [((t-BuArO)3tacn)UIV(OCHt-BuPh2)] (3) is also presented. The one-electron reduction of benzophenone by [((AdArO)3tacn)UIII] (4) leads to a purple U(IV) ketyl radical intermediate [((AdArO)3tacn)UIV(OC•Ph2)] (5). This species is highly reactive, and attempts at isolation were unsuccessful and resulted in methoxide complex [((AdArO)tacn)3UIV(OCHPh2)] (6) from H abstraction and dinuclear paracoupled complex [((AdArO)3tacn)UIV(OCPhPh-CPh2O)UIV((AdArO)3tacn)] (7). [ABSTRACT FROM AUTHOR]