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The magnetic properties and multi-electron reductive reactivity of the bimetallic inverse sandwich La2+ complex salt, [K(18-crown-6)(THF)2][(Cp″2La)2(μ-η6:η6-C6H6)]·THF, 1 (Cp′′ = C5H3(SiMe3)2), originally described by Lappert et al., have been examined. The compound was prepared by reduction of Cp″3La with potassium metal in benzene and crystallographically characterized. Compound 1 can be described as containing two 5d1 La(II) ions bridged by a planar (C6H6)1– benzenide bridged radical monoanion, with fits to its variable-temperature magnetic susceptibility data revealing strong antiferromagnetic exchange coupling, with JLa–C6H6 > |−400 cm–1|. The multi-electron reduction reactivity of 1 was explored in reactions with anthracene, naphthalene, and cyclooctatetraene. Compound 1 reduces anthracene to give Cp″2La(μ-η6:η6-C14H10)K(18-crown-6), 2, which contains a nonplanar anthracenide dianion with an end ring interacting with La(III) and the central ring interacting with potassium. The reaction of 1 with na...

To evaluate the effect of cyclopentadienyl ligand substitution in complexes of new +2 ions of the lanthanides, comparisons in reactivity and spectroscopic and magnetic properties have been made between [K(crypt)][Cp′3Ln], 1-Ln (Cp′ = C5H4SiMe3; crypt = 2.2.2-cryptand; Ln = La, Ce, Pr, and Nd), and [K(crypt)][Cp′′3Ln], 2-Ln [Cp′′ = C5H3(SiMe3)2]. The 2-Ln complexes (Ce, Pr, and Nd) were synthesized by reduction of Cp′′3Ln with potassium graphite in the presence of crypt and crystallographically characterized. The structures and UV–visible spectra of 2-Ln are similar to those of 1-Ln, as expected, but greater thermal stability for 2-Ln, expected from comparisons of 2-U and 1-U, was not observed. The magnetic susceptibilities of 2-Ce and 2-Pr were investigated because those of 1-Ce and 1-Pr did not match simple coupling models for 4fn5d1 electron configurations. The magnetic data of the 2-Ln complexes are similar to those of 1-Ln, which suggests that Ce2+ and Pr2+ complexes with 4fn5d1 electron configuration...