Mono-cyclononatetraenyl lanthanide complexes.

The synthesis of the first half-sandwich complexes based on the cyclononatetraenyl (Cnt = CH) ligand ([Ln(-Cnt)(-BH)(thf)] (Ln = La, Ce)) is reported. The title compounds were obtained from the reaction of [Ln(BH)(thf)] and [K(Cnt)]. Further solvation of [Ln(-Cnt)(-BH)(thf)] with tetrahydrofuran (THF) resulted in a reversible decoordination of the Cnt ring and the formation of the ionic species [Ln(-BH)(thf)][Cnt]. Removal of THF from [La(-Cnt)(-BH)(thf)] gave the polymeric compound [La(-BH)(-BH)(-Cnt)].