Synthesis and characterisation of some nickel(II) β-ketoamines and their adducts with 2,2'-bipyridine and 1,10-phenanthroline

A series of nickel(11) beta-ketoimine complexes, {Ni[CH3C(O)CHC(CH3)NR](2), R = CH3, C4H9}, and ketoiminates, {Ni[CH3C(O)CH(CH3)C(-N(CH2)(n)N-)C(CH3)CHC(O)CH3], n = 2, 6, 8, 91, and their adducts with 2,2-bipyridine (bipy) and 1,10-phenanthroline (phen) have been synthesized and characterized using elemental analyses, magnetic susceptibility, conductivity, infrared and electronic spectral measurements. The ketoimine ligands coordinate to the nickel atom in a bidentate fashion using the N2O2 chromophore. A range of stereochemistries was observed for the nickel(II) ketoiminates from four-coordinate tetrahedral and square-planar geometry to six-coordinate octahedral geometry. Conductivity measurements indicate that the compounds are non-electrolytes. The influence of bridging chain lengthening on the adopted geometry is discussed and possible structures for the compounds are suggested.