Alkali metal fluorenides

Several types of supramolecular self-assembly are found in indenyl and fluorenyl complexes of the alkali metals. It has recently become possible for the first time to elucidate the crystal structures of unsolvated lithium indenide, [LiC9H7] , 26, and sodium fluorenide, [NaCoHgjn, 27 [24]. The crystal structure of 26 closely resembles that of unsolvated lithium cyclopentadienide because it also consists of a polymeric multidecker array in which the Li atoms are symmetrically coordinated by two rj -cyclopentadienyl rings of the indenyl ligands. In contrast, unsolvated sodium fluorenide, 27, forms a two-dimensional supramolecular structure in the solid state (Figure 7.3). In this unusual coordination polymer both the five- and six-membered rings of the fluorene system participate in coordination to sodium via and rj -interactions, respectively. 

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