Cerium compounds

The value of E⦵(Ce4+/Ce3+) varies widely depending on conditions due to the relative ease of complexation and hydrolysis with various anions, although +1.72 V is representative.

[1] Cerium forms all four trihalides CeX3 (X = F, Cl, Br, I) usually by reaction of the oxides with the hydrogen halides.

[1] Cerium(IV) oxide ("ceria") has the fluorite structure, similarly to the dioxides of praseodymium and terbium.

[10] Cerium(III) and terbium(III) have ultraviolet absorption bands of relatively high intensity compared with the other lanthanides, as their configurations (one electron more than an empty or half-filled f-subshell respectively) make it easier for the extra f electron to undergo f→d transitions instead of the forbidden f→f transitions of the other lanthanides.

[11] Cerium(III) sulfate is one of the few salts whose solubility in water decreases with rising temperature.

[12] Due to ligand-to-metal charge transfer, aqueous cerium(IV) ions are orange-yellow.

[16] The 4f electron in cerocene, Ce(C8H8)2, is poised ambiguously between being localized and delocalized and this compound is also considered intermediate-valent.

[17] Alkyl, alkynyl, and alkenyl organocerium derivatives are prepared from the transmetallation of the respective organolithium or Grignard reagents, and are more nucleophilic but less basic than their precursors.