A Novel Cu(II) Complex with 2,2′-Bipyridyl and L-Methioninate—Synthesis, Characterization, Molecular Structure and Stability

The ternary Cu(II) complex with 2,2′-bipyridyl (bipy) and L-methioninate (L-Met) has been synthesized and characterized by elemental analysis, molar conductivity, UV-Vis spectra, IR spectra and pH-potentiometric titration methods. The structure of the complex [Cu(L-Met) (bipy) (H₂O)]ClO₄ · 3/8H₂O was characterized by the X-ray diffraction analysis. It crystallizes in the triclinic system, space group P1 with four molecules in a unit cell of dimensions, a = 0.7656(2) nm, b = 1.3142(3) nm, c = 2.0596(4) nm, α = 97.70(3)°, β = 97.96(3)°, γ = 94.33(3)°, V= 2.0244(8) nm³, R₁, = 0.0441 and wR₂ = 0.0678. The crystal contains four crystllographically independent [Cu(L-Met) (bipy) (H₂O)]⁺ complexes (Cu1—Cu4), having a distorted square-pyramidal geometry with the same coordinated atoms around each copper center. The base plane is occupied by two nitrogen atoms of one bipy, the amino nitrogen atom and one carboxylate oxygen atom from each independent L-Met moiety, and one water oxygen at an axial position. Cu1 and Cu3 are essentially enantiomers of Cu2 and Cu4. The four molecules are packed with each other by intermolecular hydrogen-bonding and aromatic-ring stacking interactions.