Two Derivatives of Lithium Isodicyclopentadienide: [(1,2,3,3a,7a-η)-4,5,6,7-Tetrahydro-4,7-methanoindenido](N,N,N',N'-tetramethylethylenediamine)lithium and Bis(1,4,7,10-tetraoxacyclododecane)lithium(1+) Bis[(1,2,3,3a,7a-η)-4,5,6,7-tetrahydro-4,7-methanoindenido]lithate(1–)

Selective crystallization of a solution of lithium isodicyclopentadienide, (isodiCp)Li, in dry thf or diethylether under argon has produced two lithium complexes: (isodiCp)Li(TMEDA), [Li(C₁₀H₁₁)(C₆H₁₆N₂)], (4), and [Li(12-crown-4)₂]⁺.[Li(isodiCp)₂]⁻, [Li(C₈H₁₆O₄)₂] [Li(C₁₀H₁₁)₂], (5). In 4 the Li⁺ ion is coordinated to the two nitrogen atoms of the disordered TMEDA and is η⁵-coordinated to the Cp ring of the isodiCp ligand. The Li—Cp-ring centroid distance is 1.906 (7) Å. In 5 there are two independent half-molecules of the anion and one molecule of the cation in the asymmetric unit. In each anion, the Li⁺ ion occupies a crystallographic inversion center and is η⁵-coordinated to the two Cp rings of two isodiCp ligands. The Cp rings are in a staggered arrangement, as required by the inversion center. The Li—Cp-ring centroid distances for the two anions are 1.987 (3) and 2.008 (3) Å. In the cation of 5, the Li⁺ ion is coordinated to two 12-crown-4 ligands, one of which is disordered. Both 4 and 5 exhibit exo coordination of the Li⁺ ion to the isodiCp ligand, with a resultant slight endo bending of this ligand.

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