Metal–phenoxyalkanoic acid interactions. Part 13. Copper(II)–(2-chlorophenoxy)ethanoic acid complexes. Crystal and molecular structures of catena-tetra-µ-[(2-chlorophenoxy)ethanoato-O,O′]-dicopper(II), catena-(2-aminopyrimidine-N,N′)-tetra-µ-[(2-chlorophenoxy)ethanoato-O,O′]-dicopper(II), and 1,2,2,2,2-penta-aqua-tetra-µ-[(2-chlorophenoxy)-ethanoato-O,O′]-copper(II)calcium(II)

Abstract

The crystal structures of three copper(II) complexes of (2-chlorophenoxy)ethanoic acid have been determined by X-ray diffraction. Anhydrous [{Cu₂(O₂CCH₂OC₆H₄Cl-2)₄}_n](1) is monoclinic, a= 11.587(3), b= 5.084(2), c= 29.600(6)Å, β= 103.76(2)°, Z= 2, space group P2₁/c. The adduct [{Cu₂(O₂CCH₂OC₆H₄Cl-2)₄(ampym)}_n](ampym = 2-aminopyrimidine)(2) is triclinic, a= 17.543(5), b= 13.344(5), c= 8.459(3)Å, α= 77.89(3), β= 81.43(3)°, γ= 87.61(3)°, Z= 2, space group P. [CaCu(O₂CCH₂OC₆H₄Cl-2)₄(H₂O)₅](3) is orthorhombic, a= 13.800(4), b= 8.426(3), c= 32.558(10)Å, Z= 4, space group C222₁. (1), (2), and (3) were refined to residuals of 0.051, 0.060, and 0.046 for 1 752, 3 399, and 1 042 observed reflections respectively. All three complexes have tetracarboxylate bridged dimer systems [Cu–Cu, 2.583(2)Å(1); 2.700(3), 2.730(3)Å(2); and Ca–Cu, 3.480(3)Å(3)]. In both (1) and (2), the centrosymmetric dimer units are extended into polymer structures via axial groups which in (1) are carboxyl oxygens from adjacent dimer units while in (2) they are the meta-related nitrogens of the pyrimidine rings. Complex (3) is monomeric with ‘half’ the dimer comprising a conventional CuO₄(OH₂) unit, the other ‘half’ being an eight-co-ordinate CaO₄(OH₂)₄ unit, with two-fold rotational symmetry.