C. Janiak
Jul 1, 1993
Citations
0
Influential Citations
18
Citations
Journal
Chemische Berichte
Abstract
Crystallization of potassium fluorenide or 9-tert-butylfluorenide [formed from potassium metal and fluorene or 9-tert-butylfluorene in tetramethylethylenediamine (tmeda)] from a mixture of tmeda, tetrahydrofuran (THF) and diethyl ether yields [K(tmeda)2][C13H9] (1) or {[K(THF)2][μ-C13H8(tBu)][K(tmeda)][μ-C13H8(tBu)]}∞ (2). Compound 1 is a monomeric solvated ion pair with one η5-coordinated fluorenyl and two chelating tmeda ligands and crystallizes in the monoclinic space group C2/c. Compound 1 is an example of polymorphism in organo-potassium compounds, as a polymeric structure of 1 obtained under slightly different crystallization conditions has been reported earlier. Compound 2 forms a polymeric chain with potassium coordinated to two anellated six-membered rings from two bridging 9-tert-butylfluorenyl systems and alternatingly solvated by one chelating tmeda or two THF. The crystal system for 2 is monoclinic, space group P21/c. A comparative AM1 study on the fluorenyl and 9-tert-butylfluorenyl anion suggests a steric origin for the haptotropic potassium shift in 2. 1H- and 13C-NMR data for 1 and 2 as well as for 9-tert-butylfluorene are reported.