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Reductive Reactivity of the Organolanthanide Hydrides, [(C5Me5)2LnH]x, Leads to ansa-Allyl Cyclopentadienyl (η5-C5Me4CH2−C5Me4CH23)2- and Trianionic Cyclooctatetraenyl (C8H7)3- Ligands

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journal contribution
posted on 02.07.2008 by William J. Evans, Benjamin M. Schmiege, Sara E. Lorenz, Kevin A. Miller, Timothy M. Champagne, Joseph W. Ziller, Antonio G. DiPasquale, Arnold L. Rheingold
The reductive reactivity of lanthanide hydride ligands in the [(C5Me5)2LnH]x complexes (Ln = Sm, La, Y) was examined to see if these hydride ligands would react like the actinide hydrides in [(C5Me5)2AnH2]2 (An = U, Th) and [(C5Me5)2UH]2. Each lanthanide hydride complex reduces PhSSPh to make [(C5Me5)2Ln(μ-SPh)]2 in ∼90% yield. [(C5Me5)2SmH]2 reduces phenazine and anthracene to make [(C5Me5)2Sm]2(μ-η33-C12H8N2) and [(C5Me5)2Sm]2(μ-η33-C10H14), respectively, but the analogous [(C5Me5)2LaH]x and [(C5Me5)2YH]2 reactions are more complicated. All three lanthanide hydrides reduce C8H8 to make (C5Me5)Ln(C8H8) and (C5Me5)3Ln, a reaction that constitutes another synthetic route to (C5Me5)3Ln complexes. In the reaction of [(C5Me5)2YH]2 with C8H8, two unusual byproducts are obtained. In benzene, a (C5Me5)Y[(η5-C5Me4CH2−C5Me4CH23)] complex forms in which two (C5Me5)1- rings are linked to make a new type of ansa-allyl-cyclopentadienyl dianion that binds as a pentahapto−trihapto chelate. In cyclohexane, a (C5Me5)2Y(μ-η81-C8H7)Y(C5Me5) complex forms in which a (C8H8)2- ring is metalated to form a bridging (C8H7)3- trianion.