Cerium(III) and Cerium(IV) Bis(n8-pentalene) Sandwich Complexes: Synthetic, Structural, Spectroscopic, and Theoretical Studies

The Ce(III) anionic bis(pentalene) sandwich complex K[Ce{C 8H4(SiiPr3-1,4)2} 2] (1) has been prepared by treatment of CeCl3 with K 2[C8H4(SiiPr3-1,4) 2] and crystallographically characterized as its 18-crown-6 complex. Oxidation of 1 with Ag[BPh4] affords the neutral, formally Ce(IV) sandwich complex [Ce{C8H4(SiiPr 3-1,4)2)2] (2), whose molecular structure has also been determined. The electronic structure of 2 has been investigated in detail by a combination of magnetic studies, K-edge XANES measurements, gas-phase photoelectron spectroscopy, and density functional calculations.