Formation of macrocyclic oligoferrocenes: a matrix-assisted laser desorption ionization mass spectrometric study

Oligomeric ferrocenes were investigated simultaneously by matrix-assisted l aser desorption/ionization time of flight mass spectrometry (MALDI-TOFMS), The oligomers were obtained by the reaction of tetrahydro-4,4,8,8-tetrameth yl-4,8-disila-s-indacene-3a,7a-diyldilithium(Li2L) with FeCl2 . 1.5 THF (TH F = tetrahydrofuran), Depending on the reaction conditions up to ten linear -chain and eleven cyclic ferrocene oligomers with masses between 1139 and 5 071 Da could be detected unambiguously. The most abundant macrocycles conta ined ten and seven iron atoms when the reactions were carried out at -20 an d 25 degrees C, respectively, The chains had cyclopentadienes as end groups and formally resulted from replacing one iron of a cycle by two hydrogens, which corresponds to a mass difference of 54 Da, Copyright (C) 1999 John W iley & Sons, Ltd.