Main group (IIIA or 13) complexes of benzohydroxamic acid and the crystal structure of tris(benzohydroxamato)indium(III)

Abstract

A series of tris(benzohydroxamato)metal(III) complexes has been prepared and characterized wherein the metals are aluminum, gallium, and indium. The complexes are synthesized in high yield from aqueous solution. The indium complex, as its ethanol solvate In(C₇H₆NO₂)₃•C₂H₅OH, has been studied by single crystal X-ray diffraction. The crystals are monoclinic with a = 11.091(2), b = 18.065(3), c = 12.861(2) Å, β = 105.55(1)°, Z = 4, and space group P2₁/n. The structure was solved by Patterson and Fourier methods and was refined by full-matrix least-squares procedures to R = 0.038 and R_w = 0.037 for 2579 reflections with I ≥ 3σ(I). Bond lengths and angles in the compound were normal, although there is a strong In—O(C) interaction; the arrangement of the three ligands is mer. There is extensive hydrogen bonding involving all possible donors. All three complexes have been studied by mass spectrometry, and by infrared and nuclear magnetic resonance (¹H, ²⁷Al) spectroscopies. Parallel studies have been attempted with acetohydroxamic acid.