Novel, axially chiral analogues of nickelocene with nickeladibenzofluorenyl ligand

•Axial chirality in metallacyclic analogues of nickelocene and cobaltocene.•Metalocenes with nickeladibenzofluorenyl ligand exhibit paramagnetic properties.•Different behavior of nickeladibenzofluorenyl ligand from nickelafluorenyl ligand.

In this paper we describe the syntheses and characterization of novel axially chiral metallacyclic complexes. Contrary to previously described synthesis of 9-nickelafluorenyllithium complexes, reaction of dilithium ligand afforded nickelacyclic analogue of nickelocene. Similar compounds were obtained after replacing nickelocene with pentamethylcyclopentadienyl nickel and cobalt acetylacetonates. Structural characterization proved to be difficult since all of these compounds exhibit paramagnetic behaviour. Crystal and molecular structures of products were determined by single-crystal X-ray analysis. Electronic properties were investigated using Evans method and DFT calculations.

Graphical abstractThe paper describes the syntheses and characterization of novel metallacycles. Contrary to previously described synthesis of 9-nickelafluorenyllithium complexes, reaction of dilation ligand afforded nickelacyclic analogue of nickelocene. Similar compounds were obtained after replacing nickelocene with pentamethylcyclopentadienyl nickel and cobalt acetylacetonates. Molecular structures of products were determined by single-crystal X-ray analysis.Figure optionsDownload full-size imageDownload as PowerPoint slide