Structures and Properties of Ternary Copper(II) Complexes Involving a Halogen Substituted Phenylalanine and 2,2′-Bipyridine. Intermolecular Interactions between Halo and Organic Groups

Structural and spectroscopic studies have been performed on the ternary Cu(II) complexes containing 4-halophenylalanines (XPhe) (X = I or Br) and 2,2′-bipyridine (bpy). The absorption spectra of the 1 : 1 : 1 Cu(bpy)(XPhe) systems exhibited a single d–d peak at 605—608 nm (pH 6—7), and the band centered at ca. 320 nm due to the charge transfer interaction between the substituted phenyl ring and bpy was observed in the difference spectra in the near ultraviolet region. Three complexes with XPhe, [Cu(bpy)(DL-IPhe)(NO3)] (1), [Cu(bpy)(DL-BrPhe)(NO3)] (2), and [Cu(bpy)(L-IPhe)]ClO4 (3) were isolated as crystals, and the structures were determined by the X-ray diffraction method. Complex 1 crystallizes in the monoclinic space group, P21/n, with four molecules in a unit cell of dimensions a = 5.292(1), b = 27.315(8), c = 13.848(2) A, β = 90.05(2)°. Complex 2 also crystallizes in the monoclinic space group, P21/n, with four molecules in a unit cell of dimensions a = 5.293(5), b = 27.18(1), c = 13.540(6) A, β = 9...