Revealing Coordination Patterns in C5-Cyclic Lithium Organics

Lithium organics with a C 5 perimeter are the most prominent class of compounds in s-block metal organic chemistry to introduce bulky haptotropic bound substituents in organometallic complexes. In this paper we present some coordination patterns. (η 5 -Cp)Li(PMDETA) ( 1 ), (η 5 -Cp)Li(TMEDA) ( 2 ), and (η 5 -Cp)Li(DME) ( 3 ) reveal the electron-releasing capacity of the donor base: The better the density supply from the base, the longer the Li···Cp center distance. The donor base DIGLYME gives the solvent-separated ion pair (SSIP) [(DIGLYME) 2 Li][(η 5 -Cp) 2 Li] ( 4 ). The contact ion pair (η 2 -Ind)Li(PMDETA) ( 5 ) shows an unprecedented strong C–H···π interaction of a PMDETA methyl group to the center of the C 6 perimeter of an indenyl anion. {(η 5 -Ind)Li(μ-DME)Li(η 5 -Ind)} ( 6 ) is a unique DME-bridged dimer, while [(DIGLYME) 2 Li][Ind] ( 7 ) crystallizes as a SSIP.