Synthesis and structural characterisation of novel nickelaindenyl and nickelafluorenyl compounds: Differences in the bonding modes of nickelacyclic rings

New binuclear nickelacyclic compounds 1 (η5-pentamethylcyclopentadienyl)(η3-(1-(η5-pentamethylcyclopentadienyl))-1-nickelafluorenyl)nickel and 2 (η5-pentamethylcyclopentadienyl)(η3-(1-(η5-pentamethylcyclopentadienyl))-2-phenyl-3-ethyl-1-nickelaindenyl)nickel were synthesised in reactions of dilithioorganic compounds with Cp∗Ni(acac) and characterised by high resolution mass spectrometry, magnetic moment determination and X-ray single crystal analysis. The bonding mode of the central nickel atom to the nickelaindenyl and nickelafluorenyl ligands was not η5 like in the previously described analogues of nickelocene but half way between η3 and η5.