Coordination properties of beta-alanine: new complexes with some transition metals: cobalt(II), nickel(II) and copper(II).

The neutral six-coordinated tetragonal Co(\u3b2-ala)2\u20222H2O complex(\u3b2-ala\u2002=\u2002NH2CH2CH2COO 12) was prepared. In this complex \u3b2-alanine acts as an O,N-chelating agent, as in the known Cu(\u3b2-ala)2\u20226H2O and Ni(\u3b2-ala)2\u20223H2O complexes. We also prepared some complexes of a type that is new for \u3b2-alanine, with stoichiometries such as M(\u3b2-alaH)2X2, M(\u3b2-alaH)4(ClO4)2 (M\u2002=\u2002Co and Ni), Cu(\u3b2-alaH)3(ClO4)2, and Cu(\u3b2-alaH)Cl2 in which the ligand acts as a zwitterion and coordinates toward the carboxy group as a formally neutral ligand. The possibility of formulating the complexes as H2[M(\u3b2-ala)2X2] is discussed. The electronic spectra and the magnetic moments of the halide complexes are in accord with pseudo-tetrahedral, octahedral, and tetragonal stereochemistry for the cobalt(II), nickel(II), and copper(II) ions, respectively, while those of the perchlorate complexes are in accord with pseudooctahedral stereochemistry. The \u3b2-alanine hydrohalide salts and the bis(\u3b2-alaninium)tetrachlorocuprate complex were also prepared and are discussed