Aluminum(III), gallium(III), and indium(III) 4-hydroxyacridinato complexes

4-Hydroxyacridine (HAcr) is an O,N-chelating ligand whose coordination chemistry toward group 13 M(III) ions has received little attention. The molecular structure of HAcr consists of a 2,3-disubstituted-8-hydroxyquinoline; thus, in order to compare 8-hydroxyquinoline (HQ), 2-methyl-8-hydroxyquinoline (HMeQ'), and 2,3-disubstituted-8-hydroxyquinoline (HAcr) for steric and/or electronic influence, HAcr chelating ability toward the Al(III), Ga(III), and In(III) triad has been investigated. Irrespective of the nature of M(III), only complexes containing two equivalents of deprotonated HAcr are obtained. This article describes the synthesis and characterization of different series of bis-chelated pentacoordinated (Acr)2MY (M = Al, Ga, In; Y = Cl, Br, I, NCS, N3) or (Acr)2MZ (M = Ga or In; HZ = C6H5OH, C6H13OC6H4OH, C6H5COOH, or C6H13OC6H4COOH) six-coordinate neutral (Acr)2In(acac) (H(acac) =acetylacetone), or ionic [(Acr)2In(N,N)][CF3SO3] (N,N = 2,2'-bipyridine or 1,10-phenanthroline) complexes. These results significantly contribute to elucidating the complexation capability of HAcr.