Half-Sandwich Cerium and Lanthanum Dialkyl Complexes: Synthesis, Structure, and Reactivity Studies.

Cerium and lanthanum dialkyl complexes [η-1,2,4-(MeC)CH]Ln(CHCH--NMe) (Ln = Ce and La ), supported by a tri-butylcyclopentadienyl ligand, have been successfully synthesized. Studies demonstrate that these complexes possess diverse reactivity toward various small molecules. For example, the reaction of complexes and with diphenyl dichalcogenides PhEEPh (E = S, Se) results in the formation of lanthanide thiolates [(η-1,2,4-(MeC)CH)Ln(SPh)(μ-SPh)] (Ln = Ce and La ) and selenolates [(η-1,2,4-(MeC)CH)Ln(SePh)(μ-SePh)] (Ln = Ce and La ), concomitantly releasing PhE(CHCH--NMe). Furthermore, complexes and , upon reaction with dibenzyl disulfide, yield tetranuclear rare-earth metallomacrocyclic compounds {[(η-1,2,4-(MeC)CH)Ln(μSCHCH)](μ-η:η-SCHCH)} (Ln = Ce and La ). This reaction may involve a process of σ-bond metathesis and C-H activation. While the reaction of and with dibenzyl diselenide in the presence of LiCHCH-o-NMe leads to the formation of lanthanide-lithium selenido clusters [(η-1,2,4-(MeC)CH)La(μ-SeCHCH)](μ-Se)[μ-SeLi(THF)] (Ln = Ce and La ). Meanwhile, lanthanide selenido clusters [(η-1,2,4-(MeC)CH)La(μ-SeCHCH--NMe)](μ-Se) (Ln = Ce and La ) can be obtained by treating and with elemental selenium in a 1:2 molar ratio. Additionally, the treatment of and with benzoxazole generates ring-opening/C-C coupling/C-N coupling products {(η-1,2,4-(MeC)CH)La[μ-OCH--N═CHN(CH(CHCH--NMe)CH--O]} (Ln = Ce and La ). All new compounds were characterized by various spectroscopic methods, and their solid-state structures were confirmed by single-crystal X-ray diffraction analyses.