The Chromium(III) Complexes with Ammoniatriacetic Acid. I. The Complexes with Ammoniatriacetic Acid as a Tridentate or Tetradentate Ligand

Abstract The following chromium(III) complexes, each containing ammoniatriacetic acid (ATA) as a tridentate or a tetradentate ligand, were newly prepared: (NH4)3[Cr(ata)2]·4H2O (pale red) (I), NH4[Cr(ataH)2]·2H2O (pink) (II), NH4[Cr(OH)(ata)(H2O)]·2H2O (purple) (III) and NH4[Cr(OH)(ata)(H2O)]·3H2O(green)(IV), where ata is an abbreviated form of N(CH2COO−)3. On the basis of the chemical and thermal analyses and the measurement of electronic absorption spectra, it was considered that the I and II complexes belong to the [Cr·N2·O4] type, III belongs to the [Cr·N·O5] type, and IV to the [Cr·O6] type. The further information on the conductivity in an aqueous solution suggested that the II and III complexes are gradually aquated to form the [Cr·N·O5] and [Cr·O6] types respectively. The X-ray powder diffraction patterns show that all these complexes have crystals of the tetragonal system. The values of the effective magnetic moments for these complexes were 3.7–3.9 B. M., nearly equal to the spin-only magnetic moments of tervalent chromium.