Crystal structure of bis(μ2-tetrabromophthalato-κ2 O 1:O 2)bis[aqua(N,N,N′,N′-tetramethylethane-1,2-diamine-κ2 N,N′)copper(II)]

In the title complex, [Cu2(C8Br4O4)2(C6H16N2)2(H2O)2], the CuII cation is chelated by a tetramethylethane-1,2-diamine ligand and coordinated by a water molecule as well as bridged by two tetrabromophthalate anions in a distorted O3N2 trigonal–bipyramidal geometry. The two symmetry-related tetrabromophthalate anions bridge the two CuII cations, forming a centrosymmetric dinuclear complex in which the Cu⋯Cu separation is 5.054 (2) Å. Intramolecular classic O—H⋯O hydrogen bonds and weak C—H⋯O hydrogen bonds occur in the dinuclear molecule. In the crystal, the molecules are linked by weak C—H⋯Br and C—H⋯O interactions into supramolecular chains propagating along the b-axis direction.


S1. Introduction
The self-assembly of metal complexes with benzene-multicarboxylate ligands remains an active area in coordination chemistry especially with copper due to the very wide structural diversity and interesting properties in magnetism, hostguest systems, porous material (Ene et al., 2009;Dorazco-González et al., 2013;Liang et al., 2004). Dinuclear copper(II) compounds have been used in magnetism, as biomimetic active sites in bioinorganic chemistry and in the design and synthesis of metallic networks (Lu et al., 2004). Herein we present a dinuclear copper complex synthesised by selfassembly between copper perchlorate, a aliphatic diamine (tmen) and a bulky benzendicarboxylate (tetrabromophthalate).
The tittle compound represents the first example of copper complex with tetrabromophthalate.

S2.1. Synthesis and crystallization
Blue deep suitable crystals for diffraction X-ray were grown directly from solution by slow evaporation during 5 days.

S2.2. Refinement
Water H atoms were placed in a difference Fourier map and positional parameters were refined, U iso (H) = 1.2U eq (O).
Other H atoms were placed in calculated positions with C-H = 0.98-0.99 Å and refined in riding mode, U iso (H) = 1.2U eq (C) for methylene H atoms and 1.5U eq (C) for methyl H atoms.

S3. Results and discussion
The reaction between the aqua-complex [Cu(tmen)(H 2 O) x ](ClO 4 ) 2 and potassium salt of tetrabromophthalate in mixture ethanol gives the title compound in good yield (>94 %) as blue suitable crystals for X ray diffraction. The single-crystal X-ray analysis reveals that the compound is a neutral dinuclear centro-symmetric copper (II) complex which crystallizes in monoclinic crystal system, space group P21/n ( Figure 1). The asymmetric unit contains a five-coordinate copper atom [Cu(N 2 O 3 )] with two sites occupied by diamine and three sites by oxygen atoms from two carboxylate groups and one molecule of water. The Addison tau-parameter has been used to describe the distortion around coordination geometry, τ = (difference between two largest angles/60 for five-coordinated metal centers allows the distinction between trigonal-supporting information bipyramidal (ideally τ = 1) and square-pyramidal (ideally τ = 0). In this context, the coordination geometry of complex is distorted trigonal-bypiramide, τ = 0.68. The distance Cu ··· Cu is 5.054 (2) Å and a macrocycle is formed by 14 atoms containing two TBr-phthalate-bridge ligands. The combination of copper(II) with multi-carboxylic acids has formed one of the largest subgroups in metal-organic compounds and despite this there are few examples of coordination complex with 1,2,3,4,-tetrahalogenated benzenes among these only with tetrachlorophthalate have been reported (Hong & You, 2004;Yang et al., 2002). The present compound represents the first example with tetrabromophthalate.

Figure 1
The structure with displacement ellipsoids drawn at the 30% probability level and H atoms shown as small spheres of arbitrary radii.

Figure 2
View of interactions in the crystal.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq