The Influence of the Steric Factor on the Structure of Indium(III) Iodide Complexes based on Substituted -Iminobenzoquinones

A series of substituted -iminobenzoquinones (6-((2,6-di--propylphenyl)imino)-2,4-(2,4,4-trimethylpentan-2-yl)cyclohexa-2,4-dien-1-one (L), 4-(-butyl)-6-((2,6-di--propylphenyl)imino)-3-methoxycyclohexa-2,4-dien-1-one (L) and 6-((2,6-di--propylphenyl)imino)-3-methoxy-4-(2,4,4-trimethylpentan-2-yl)cyclohexa-2,4-dien-1-one (L)) were used to synthesize indium(III) iodide complexes containing the redox-active ligand in its neutral form. The -iminobenzoquinone L was synthesized for the first time. It was found that the structure of the obtained complexes depends on the degree of steric shielding of the carbonyl oxygen atom in the initial -iminobenzoquinone. The sterically hindered ligand L forms a 1 : 1 adduct with InI (complex (L)InI (I)). The absence of a substituent at the 2-position of the -iminobenzoquinone ring promotes the formation of bis-ligand ionic derivatives {[(L)]InI}InI} (II) and {[(L)]InI}InI} (III). The molecular structures of L and complexes I - 0.5 toluene, II - toluene · 0.5 hexane were determined by X-ray diffraction analysis (CCDC № 2440874 (L), 2440875 (I · 0.5 toluene), 2440876 (II · toluene · 0.5 hexane)). The optical and electrochemical properties of the initial -iminobenzoquinones and indium(III) complexes based on them were studied. It is shown that activating complexation contributes to a significant enhancement of the oxidative properties of L, L and L.