Preparation and Characterization of Nickel Complexes with η-Indenyl Ligands Bearing a Pendant Aminoalkyl Chain

The aminoindenyl complexes {Ind(CH 2 ) 3,4 N( t -Bu)H}Ni(PPh 3 )Cl ( 7, 8 ) and {Ind(CH 2 ) 2,3 NMe 2 }Ni(PPh 3 )Cl ( 9, 10 ) have been prepared and characterized by spectroscopy and, in the case of 7 and 9, by X-ray structural studies. Although there is no interaction between the Ni center and the amine moiety of these complexes in the solid state, solution spectra point to a temperature-dependent, intramolecular N→Ni coordination in complex 9 and a more facile, intermolecular interaction in 10 . Abstraction of Cl - from these complexes led to the formation of the cations [{η 3:η 0 -Ind(CH 2 ) 3,4 N( t -Bu)H}Ni(PPh 3 ) 2 ] + and [{η 3:η 1 -Ind(CH 2 ) 2,3 NMe 2 }Ni(PPh 3 )] + ( 11, 12 ). The origin of the observed differences in the reactivities of these complexes is discussed in terms of the lengths of the tether and the nature of the N-substituents.