Divalent Metal-Complexes of 2-Fluorophenoxyacetic Acid - the Crystal-Structures of 2-Fluorophenoxyacetic Acid, Tetraaquabis(2-Fluorophenoxyacetato)Zinc(II) Dihydrate and Aquabis(2-Fluorophenoxyacetato)Bis(Pyridine)Copper(II)

Abstract

The crystal structures of 2-fluorophenoxyacetic acid ( oflpaH ) and the metal complexes aquabis (2-fluorophenoxyacetato) bis (pyridine)copper(II) (1) and tetraaquabis (2-fluorophenoxyacetato)zinc(II) dihydrate (2) have been determined by X-ray diffraction and refined to residuals R 0.036, 0.041, 0.025 for 641, 863 and 1505 observed reflections respectively. The acid crystallizes in a monoclinic cell, space group P2₁/c with a 6.207(2), b 19.363(8), c 6.999(2) Ǻ, β 114.81(2)° and Z 4. The molecules form planar, centrosymmetric , hydrogen-bonded cyclic dimers [O...O, 2.618(4)Ǻ]. Complex (1) is orthorhombic, space group P2cb with two molecules in a cell of dimensions a 5.621 (2), b 17.218(7), c 13.288(6)Ǻ while (2) is monoclinic, space group P2₁/c, a 6.597(2), b 5.279(2), c 30.079(10) Ǻ, β 94.65(3)°; with Z 2. Complex (1) has square-pyramidal geometry with the basal plane containing two trans related carboxyl oxygens [Cu-O, 1.944(4)Ǻ] and two trans related pyridine nitrogens [Cu-N, 2.030(5)Ǻ]. A water molecule occupies the apex of the square pyramid [Cu-O_W, 2.199(8)Ǻ]. Complex (2) has octahedral geometry with the MO₆ octahedron containing two trans related carboxyl oxygens [Zn-O, 2.122(2)Ǻ] and four water oxygens [Zn-O_W, 2.069(2), 2.085(2)Ǻ]. Preliminary X-ray data also confirm that the magnesium(II) and manganese(II) complexes of 2-fluorophenoxyacetic acid are isomorphous with (2) but different from the cobalt(II) derivative.