The complexes structures of chromium(III) with ethylglycine and alanine

The reaction of chromium(III) chloride with the amino acid ethylglycine in a 1:1 molar ratio of metal to ligand has been performed. The complex with monodentate coordinated ethylglycine [Cr(CH₃СН₂CH(NH₃)COO)(H₂O)₃Cl₂]Cl∙3H₂O (І) has been synthesized. Interaction of compound (І) with the α-аlanine results in formation of different-ligand complex [Cr(CH₃СН₂CH(NH₃)COO)(СН₃CH(NH₃)COO)(H₂O)₃Cl]Cl₂ (ІІ). The complexes I and II have been analyzed by IR and UV/Vis spectroscopy. Significant difference in wave numbers of carboxylic group valence vibritations (n_as(COO^–)–ν_s(COO^–)=220 cm^–1 for (I) and n_as(COO^–)–ν_s(COO^–)=244 cm^–1 for (II))confirms that both amino aсids are coordinated to Cr³⁺ by oxygen of carboxyl group. Compounds (І–ІІ) have the octahedral structure. Two bands of transition (⁴Т_1g¬⁴A_2g and⁴Т_2g¬⁴A_2g) have been observed in the visible part of the spectrum and one band of transition (⁴Т_1g(Р¬⁴A_2g in UV region. The parameters of crystal field of complexes have been calculated (Dq = 1640 cm^–1, В= 627 cm^–1 and b = 0.61 for (I) and Dq = 1700 cm^–1 В= 553 cm^–1 and b = 0.54 for (IІ)). The computer three-dimension models of complexes (II) has been created. Geometrical parameters of complexes have been calculated at HF/6-31G(D) level of theory