Salicylimine Nickel Complexes Containing Peripheral N-Heteroaromatic Substituents

O] Salicylimine Nickel Complexes Containing Peripheral N-Heteroaromatic Substituents 

Synthesis of the corresponding neutral [N,O] Ni complexes 86-101 is accomplished by deprotonation with n-butyllithium followed by reaction with bis(triphenylphosphine)phenyl(chloro)nickel [28] (Chart 3.7). Complexes 86-101 are orange solids which are slightly air-sensitive and moderately paramagnetic due to a small tetrahedral distortion of the square planar coordination. However, H and P-NMR gave usually well-resolved spectra, whereas in the C-NMR spectra only in a number of cases useful information could be obtained. 

Figs 3.7 and 3.8 show the X-ray crystal structures of 90 and 91, respectively. Overall, both structures show the expected square planar coordination geometry around the nickel center with more or less orthogonal peripheral N-pyrrolyl and Ni-phenyl substituents. The different axial steric shielding of the metal center by the differently substituted pyrrolyl groups of complexes 90 and 91 is easily appreciated. 

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