Synthesis, Structural Characterization, and Reactivity of Lanthanacarboranes Incorporating “Carbons-Adjacent” <i>n</i><i>ido</i>- and <i>a</i><i>rachno</i>-Carborane Anions of the C₂B₁₀ System

Group 1 salts of “carbons-adjacent” carborane anions of the C2B10 system are useful synthons for the production of other metallacarboranes. Treatment of [{μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10}2Na4(THF)6]n (2) with 2 equiv of LnCl3 gave the novel half-sandwich lanthanacarboranes [η6-{μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10}Yb(NC5H5)3{Na(NC5H5)2}0.5]2(μ-Cl) (4) and [η6-{μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10}]LnCl(THF)3 (Ln = Nd (5), Er (6), Y (7)), which represent the first lanthanacarboranes containing a terminal Ln−Cl bond in the C2B10 systems. The chloro group in these complexes can be substituted by other moieties, leading to the isolation of [η6-{μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10}]Nd[(μ-H)3BH](THF)3 (8) and [η6-{μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10}]Y(η5-C5H5)(THF) (9), respectively. Reduction of 6 or 7 with excess Li metal afforded the full-sandwich lanthanacarboranes {η6-[μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10]2Ln}{Li5(THF)10} (Ln = Er (11), Y (12)). Treatment of 6 with excess Na metal generated the full-sandwich lanthanacarborane cluster [{η6-[μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10]2Er}{Na5(THF)6}]4 (13). These full-sandwich complexes were also prepared from the reaction of [{μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10}Li4(THF)6]2 (3) with LnCl3. Their Gd analogue {η6-[μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10]2Gd}{Li5(THF)9} (10) was prepared via a “one-pot” interaction between μ-1,2-[o-C6H4(CH2)2]-1,2-C2B10H10 (1), excess Li metal, and GdCl3. All complexes were fully characterized by various spectroscopic data and elemental analyses. Complexes 4, 6, 8, 10, 11, and 13 were subjected to single-crystal X-ray analyses.