Structural and spectroscopic characterization of a charge-separated uranium benzophenone ketyl radical complex

Article abstract of DOI:10.1021/ja801007q

The reaction of [((^t-BuArO)₃tacn)U^III] (1) with 4,4′-di-tert-butylbenzophenone affords a unique isolable U(IV) ketyl radical species [((^t-BuArO)₃tacn)U^IV (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)U^IV(OCT^t-BuPh ₂)] (3) is also presented. The one-electron reduction of benzophenone by [((^AdArO)₃tacn)U^III] (4) leads to a purple U(IV) ketyl radical intermediate [((^AdArO)₃tacn)U ^IV(OC?Ph₂)] (5). This species is highly reactive, and attempts at isolation were unsuccessful and resulted in methoxide complex [((^AdArO)₃tacn)U^IV(OCHPh₂)] (6) from H abstraction and dinuclear paracoupled complex [((^AdArO) ₃tacn)U^IV(OCPhPh-CPh₂O)U^IV(( ^AdArO)₃tacn)] (7).