Novel approach for the synthesis of chiral organometallic complexes - first series of lithium 2-amino-indenide ligands bearing pendant donor groups and a unique helical bent-zirconocene

A broad series of mono- and bis-2-aminoindenyl ligands, bearing pendant donor sec-amine groups was synthesized via the reaction of indan-2-one with the corresponding secondary mono- and bis-amines: 1-H from pyrrolidine, 2-H from piperidine, 3-H from morpholine, 4-H from thiomorpholine, 5-H from dibenzylamine, 6-H-2 from N,N'-diethyldiaminopropane-1,3, 7-H-2 from piperazine, 8-H-2 from S-(+)-prolinol, 9-H from O-methyl-S-(+)-prolinol, 10-H from O-ethyl-S-(+)-prolinol and 11-H-2 from R-(-)-N-(2-anliinomethyl)-pyrrolidine. Direct metaation of 3-H, 4-H and 9-H by nBuli led to the formation of the corresponding mono-lithiated species 3-Li, 4-Li and 9-Li. Trans-Metaation of 4-Li by ZrCl4 Led to the formation of the presumably monomeric [(eta(5)-4)ZrCl3] 12. Partial hydrolysis of 12 occurred after several attempts to crystallize it and Led to the formation of its 1:1 adduct with the free ligand 4-H, [(eta(5)-4)ZrCl3(mu-N,S-4-H)] 13. Direct metaation of 8-H-2 with [Zr(NEt2)(4)] led to the formation of a chiral bent-zirconocene with a helical structure [eta(5),mu-O-8)(2)Zr] 14. The molecular structure of enantiomericay pure 9-Li was determined using X-ray crystallographic studies. Alternating Li+ and chelating indenyl anions are Linked in infinite chains. The coordination environment of Li+ consists of the eta(5)-bonded five-membered ring of the indenyl fragment, the eta(1)-bonded adjacent ligand and the donor sp(3) nitrogen and oxygen atoms of the chelating side chain.