Solvatochromism and structure of acetylacetonatocopper(II) complexes with N,N'-dipropyl-,N,N,N',N'-tetrapropyl-, and N,N- and N,N'- diisopropylethylenediamines

Article abstract of DOI:10.1246/bcsj.71.2621

Seven copper(II) complexes of the general formula [Cu(acac)(diam)]X were prepared, where acac and diam stand for acetylacetonate and one of the diamines in the title, and X- for a bulky univalent anion, respectively. Their solvatochromism was compared with that of the corresponding complexes with N,N,N',N'-tetramethylethylenediamine and related diamines, to see the effect of their bulky N-alkyl groups. X-ray crystal analyses showed that the perchlorates of N,N'- and N,N-diisopropyl complexes are apparently 6- and 5- coordinated, respectively, in their crystals, although their ClO₄^- ions are held extremely weakly and are easily driven out by solvent molecules in solution, leading to their solvatochromism. The Cu-N and Cu-O(acac) bond distances in the former, 199.5(4)/202.4(5) and 190.6(4)/190.1 (4) pm, respectively, are similar to each other, while the Cu-N(isopropyl)₂ distance, 206.4(9) pm, in the latter is notably longer than the Cu-NH₂ distance, 196(1) pm.