Crystal structure of bis(ethylenediamine)cuprate ethylenediaminetetraacetate-zinc(II) tetrahydrate

Abstract

Nickel, copper, and zinc atoms (M) are good complexing agents relative to ethylenediamine (En) and to Edta (H4L). The nickel and copper atoms are coordinated in a series of dinuclear complexes containing both ligands (L 4and En) only by L 4or by En: Ni2(L)(En).4H20 [1], Niz(L)(En)z.4HzO [2], Cu2(En)9.(L).6H20 [3] The formation of the mixed dinuclear complex, Cu~(L)(En)2.2H20, in which both copper atoms are coordinated with En and L 4was established on the basis of chemical and spectral data [4, 5]. In the study of the competitive complexation of Ni, Cu, and Zn in aqueous solutions containing only the L 4ligand or both L 4and En, we examined ZnCu(L).6H~O (I), ZnNi(L).6H2:) (II), and CuNi(L)(En)~.nH~O, where n = 2 (III) [6] and n 4 (IV) [7]. In the present work, we give the x-ray diffraction data for ZnCu(L)(En)2-4H20 (V) and atomic coordinates of ZnM(L).6H20, where M Cu (I) and Ni (II), which were omitted in our previous communication [8]. The unit cell parameters for monoclinic crystals of V are as follows: a = 10.356(3), b = 11.849(6), c = 10.082(2) A,/~ = 104.570(3) ~ V = 1197(1) A s, deale = 1.69 g/cm 3, Z = 2, space group P21. The exposure of the monocrystal was carried out on a CAD-4/SDP-t55 automatic diffractometric system using AMoK a radiation, graphite monochromator, and o,,--(n/6)20 scanning. A total of 3834 reflections were measured, of which 2283 reflections had I > 3o(I). Treatment of the experimental data and the structural calculations were carried out using the ENX-SDP program. The structure was solved by the heavy atom method. The coordinates of the nonhydrogen atoms and then the hydrogen atoms were determined from successive electron density maps. The refinement was carried out anisotropically for the nonhydrogen atoms and isotropically for the hydrogen atoms taking account of secondary extinction (c = 3.3617x10 -7) and a unified weighting scheme (w i = 1), R = 0.046, R w -0.050, and S = 0.729. The coordinates of the nonhydrogen atoms in I, II, and V are given in Table 1. The hydrogen atom coordinates in V are given in Table 2. The hydrogen atoms were not determined in the structures of I and II. Complexes V and IV are isostruetural. The structure of V consists of neutral binuclear [ZnL--CuEnz.HzO] complexes and water of crystallization molecules. As in IV, the Cu atom is coordinated by En, while the L 4ligand coordinates the Zn atom. The structure of the ZnL and CuEnz.HzO fragments is ordinary (see Fig. 1). No significant differences were observed in the bond lengths and angles in V and IV. The equatorial plane in the distorted octahedron of the Zn atom is formed by 03, 05, O7, and N5 while the axial apices are occupied by Ol and N6. The distortion of the octahedron is characterized by the following parameters: the equatorial plane is tetrahedrally distorted and the mean deviation of the atoms is +0.113 A. The zinc atom extrudes from the equatorial plane by 0.174 A toward O1. The bond angles are significantly distorted: O3ZnO5, 86.9(3); O3ZnN5, 80.9(3); O5ZnO7, 91.0(3); O7ZnN5, 100.3(3); O1ZnN6, 157.5(2)*. The equatorial plane of the copper square bipyramid is formed by the nitrogen atoms of the ethylenediamine rings E 1 and E 2. The water molecule in the bipyramid is closer the ideal axial position than O1. The OwlCuN(1-4) bond angles are 89.7,87.7, 87.6, and 89.7(3)*, while the OICuN(I-4) bond angles are 94.1, 96.0, 88.7, and 86.4(3)* The OICuOwl bond angle is 174.9(3)*.