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The tris(cyclopentadienyl) yttriumcomplexes Cp3Y(THF),CpMe3Y(THF), Cp″3Y, Cp″2YCp, and Cp″2YCpMe[Cp = C5H5, CpMe= C5H4Me, Cp″ = C5H3(SiMe3)2] have been treated with potassium graphite in the presenceof 2.2.2-cryptand to search for more stable examples of complexesfeaturing the recently discovered Y2+ion first isolatedin [K(18-crown-6)][Cp′3Y] and [K(2.2.2-cryptand)][Cp′3Y], 1-Y(Cp′ = C5H4SiMe3). Reduction of the tris(cyclopentadienyl)complexes generates dark solutions like that of 1-Y, and the EPR spectra contain doublets with gvalues between 1.990 and 1.991 and hyperfine coupling constantsof 34–47 gauss that are consistent with the presence of Y2+. [K(2.2.2-cryptand)][Cp″2YCp], 2-Y, was characterizable by X-ray crystallography. Reductionof the Cp″3Gd, Cp″2GdCp, and Cp″2GdCpMecomplexes containing the larger metal gadoliniumwere also examined. In each case, dark solutions and EPR spectra likethat of [K(2.2.2-cryptand)][Cp′3Gd], 1-Gd, were obtained, and [K(2.2.2-cryptand)][Cp″2GdCp], 2-Gd, was crystallographicallycharacterizable. None of the new yttrium and gadolinium complexesdisplayed greater stability than 1-Yand 1-Gd. Exploration of this reduction chemistrywith indenyl ligands did not give evidence for +2 complexes. The onlydefinitive information obtained from reductions of the CpIn3Ln (CpIn= C9H7, Ln= Y, Ho, Dy) complexes was the X-ray crystal structure of {K(2.2.2-cryptand)}2{[(C9H7)2Dy(μ–η5:η1-C9H6)]2}, a complex containing the first example of the indenyl dianion,(C9H6)2–, derived from C–Hbond activation of the (C9H7)1–monoanion. Density functional theory analysis of these results providesan explanation for the observed hyperfine coupling constants in theyttrium complexes and for the C–H bond activation observedfor the indenyl complex. [ABSTRACT FROM AUTHOR]