Facile Template Syntheses of Nickel(II) Complexes of Dibenzotetraazaannulenes
Cutler, A.R., Alleyne, C.S., and David Dolphin
NiL (H2L = substituted dibenzotetraazaannulenes) were prepared. In situ condensations of diamines with β-diketones or 1,5-benzodiazepinium salts in the presence of Ni(II) afforded symmetrically substituted macrocycles. Reaction of the [N',N''-(1,3-propanediylidene)bis(1,2-benzenediaminato)]nickel(II) cation with β-diketones or keto acetals gave complexes that could be unsymmetrically substituted on the diimine chelate rings. Complexes with substituents on the benzenoid rings were generally more soluble in organic solvents than complexes substituted on the diimine rings. Hypsochromic shifts in the UV spectra of the complexes correlated with the degree of substitution in diimine-substituted complexes, but not in comparable phenylene-substituted complexes, for which only minor shifts in the UV spectra occurred.