Cyclopentadienyl, indenyl, fluorenyl, and pentamethylcyclopentadienyl complexes of potassium with 18-crown-6

The first 18-crown-6 Lewis base adducts of potassium organometallic compoun ds are described. The mononuclear complexes [KCp(18-crown-6)] (1), [KCp*(18 -crown-6)]. 0.5THF (2a), [KInd(18-crown-6)] (3), [KFl(18-crown-6)]. 0.5tolu ene (4), and [(KFl(18-crown-6)) (KFl(18-crown-6)(THF))] (5) and the binucle ar complex [(KFl(18-crown-6))(2)(DME)] (6) were synthesised and single-crys tal X-fay diffraction analyses were carried out (Cp = cyclopentadienyl, Cp* = pentamethylcyclopentadienyl, Ind = In-denyl, Fl = Fluorenyl). The influe nce of the neutral ligand on the potassium-anion-interaction is discussed i n a comparative study. (C) 1999 Elsevier Science S.A. All rights reserved.