Ceric Cyclopentadienides Bearing Alkoxy, Aryloxy, Chlorido, or Iodido Co-Ligands.

A series of heteroleptic tris(cyclopentadienyl) Ce complexes has been isolated and crystallographically characterized, revealing the broad accessibility of such organocerium(IV) compounds. The oxidation of complexes Cp Ce(thf) and Cp' Ce(thf) (Cp =C H Me, Cp'=C H SiMe ), bearing monosubstituted electron-poor cyclopentadienyl ligands, with 0.5 equivalents of 1,4-benzoquinone or C Cl gave the cerium(IV) hydroquinolate complexes Cp Ce(OC H O)CeCp and Cp' Ce(OC H O)CeCp' , or the chloride complexes Cp CeCl and Cp' CeCl, respectively; the iodide complex Cp' CeI was obtained from the reaction of Cp' Ce(thf) with elemental iodine. The behavior of Cp' CeCl in salt metathesis protocols employing alkali metal amides or alkyl, alkoxide, and aryloxide reagents was investigated, which gave rise to the robust and isolable cerium(IV) alkoxide Cp' Ce(OtBu). Trivalent [Cp' CeCl] was synthesized by AlMe →Cl exchange utilizing Cp' Ce(AlMe ) and AlMe Cl. The reactivity of [Cp' CeCl] towards the oxidants Ph CCl, C Cl , 1,4-benzoquinone, and I has been assessed, and has provided useful information on Ce /Ce redox deactivation pathways. In addition to X-ray structure analysis, all the complexes were characterized by NMR, DRIFT (diffuse reflectance IR Fourier transform), and UV/Vis spectroscopy as well as elemental analysis. The tetravalent compounds were further analyzed for their magnetic susceptibility by using Evans' method.