Reactivity studies on lanthanum and cerium hydrido metallocenes

Alkyl complexes [η5-1,3-(Me3C)2C5H3]2Ln(CH2C6H4-o-NMe2) (Ln = La 1 and Ce 2) react with 9-borabicyclo[3.3.1]nonane (9-BBN) in THF to afford the lanthanum boroxide complex [η5-1,3-(Me3C)2C5H3]2La(μ-OBC8H14)(THF) (3) and cerium boroxide complex [η5-1,3-(Me3C)2C5H3]2Ce(μ-OBC8H14)(THF) (4). However, the reaction of alkyl complexes [η5-1,3-(Me3C)2C5H3]2Ln(CH2C6H4-o-NMe2) with cyclohexene oxide followed by the addition of 9-BBN resulted in the formation of ring-opened products [η5-1,3-(Me3C)2C5H3]2Ln(OC6H11)(THF) (Ln = La 5 and Ce 6) concomitant with C8H14BCH2C6H4N(CH3)2 release, indicating that lanthanum and cerium hydride complexes formed in situ by treating alkyl complexes with 9-BBN may be the reactive species. Therefore, further studies on the reactivity of lanthanum and cerium hydride complexes generated in situ were carried out. The reaction of lanthanum and cerium hydride complexes with Me3SiCl provided lanthanide chloride complexes [η5-1,3-(Me3C)2C5H3]2LnCl (Ln = La 7and Ce 8) as well as Me3SiH. Each lanthanide hydride complex reduces phenazine and white phosphorus to produce {[η5-1,3-(Me3C)2C5H3]2Ln}2(μ-η3:η3-C12H8N2) (Ln = La 9 and Ce 10) and {[η5-1,3-Me3C)2C5H3]2Ln}3P7 (Ln = La 11 and Ce 12), respectively. All the new compounds were characterized by various spectroscopic methods, and their solid-state structures were further confirmed by single-crystal X-ray diffraction analyses.