Metal-phenoxyalkanoic acid interactions. Part I. Crystal and molecular structures of diaquabis( p-chlorophenoxyacetato)zinc(II)

Abstract

The crystal structures of diquabis(p-chlorophenoxyacetato)copper(II) ( 1) and diaquabis(phenoxyacetato)zinc(II) ( 2) have been determined by X-ray methods from diffractometer data and refined by least squares to R 03059 ( 1) and 03032 ( 2) for 999 and 1472 `observed' reflections respectively. Crystals of ( 1) are triclinic, space group P 1 with Z = 1 in a unit cell of dimensions a = 7.065(3), b = 13.273(11), c = 5.114(2) Å, α = 93.72(5), β = 103.64(4), γ = 81.63(5)°. The complex has a centrosymmetric tetragonally-distorted octahedral stereochemistry, the coordination sphere consisting of two water oxygens [CuO, 1.960(4) Å] and two carbonyl oxygens [CuO, 1.956(4) Å] from different bidentate phenoxyacetate ligands about the square plane while the axial positions are occupied by two ether oxygens [CuO, 2.406(4) Å]. The water oxygens are tied into a two-dimensional hydrogen-bonded network involving the un-co-ordinated carboxyl oxygens (O⋯O, 2.652 Å) and the co-ordinated carboxyl oxygens with the O(H 2)⋯O distances of 2.164 and 2.708 Å respectively. Compound ( 2) is monoclinic, spacegroup C2 with Z = 2 in a cell of dimensions a = 11.625(3), b = 5.221(1), c = 13.767(4) Å, β = 101.05(5)°. The complex ( 2) possesses a distorted trapezoidal pyramidal stereochemistry involving two water oxygens [ZnO, 1.994(1) Å] and four carboxyl oxygens from phenoxyacetate ligands [ZnO, 2.118(1) Å]. In both structures the phenoxy ligands are essentially planar and have similar distances and angles to those found in the structure fo un-co-rdinated phenoxyacetic acid. Single-crystal and powder diffractionaer X-ray data are also reported for diaquabis(p-chlorphenoxyacetato)zinc(II) (3), which is isostructural with ( 2).