Solvatochromism of Nickel(II) Mixed Chelates Containing Acetylacetonate and Some Cyclic Diamines

Abstract The preparation and spectral behaviors of several chelates of Ni(II) containing acetylacetonate(acac) and an N-alkylated cyclic diamine (N-methyl-1, 4-diazacycloheptane (medach) and N, N'-dimethyl-1, 4-diazacycloheptane (dmdach)) are reported. It was found that the mixed nitrate chelates, [Ni(NO3)(acac)L](L=medach or dmdach), are strongly solvatochromic: in a non-polar solvent they dissolve intact, but they ionize in polar solvents, forming solvated or unsolvated cations ([Ni(acac)L(Solv)2] or [Ni(acac)L]+) and showing different spectra according to the nature of the solvent polarity. Similar phenomena were also observed with the bis-medach nitrate, [Ni (NO3) (medach)2]NO3