Tris(2-ethyl-1H-imidazole-κN 3)(terephthalato-κO)zinc(II)

The title compound, [Zn(C8H4O4)(C5H8N2)3], has a neutral monomeric structure in which one terephthalate dianion and three 2-ethyl-1H-imidazole ligands coordinate to the ZnII ion in a distorted tetrahedral geometry. The methyl group of one of the ethyl groups is disordered over two positions with occupancies of 0.66 (2) and 0.34 (2). In the crystal structure, molecules are linked into a three-dimensional hydrogen-bonded network by intermolecular N—H⋯O interactions involving the uncoordinated carboxylate O atoms.

The title compound, [Zn(C 8 H 4 O 4 )(C 5 H 8 N 2 ) 3 ], has a neutral monomeric structure in which one terephthalate dianion and three 2-ethyl-1H-imidazole ligands coordinate to the Zn II ion in a distorted tetrahedral geometry. The methyl group of one of the ethyl groups is disordered over two positions with occupancies of 0.66 (2) and 0.34 (2). In the crystal structure, molecules are linked into a three-dimensional hydrogenbonded network by intermolecular N-HÁ Á ÁO interactions involving the uncoordinated carboxylate O atoms.
The title compound is a monomeric zinc(II) complex (Fig. 1). The Zn II center is four coordinated by three monodentate 2-ethyl-1H-imidazole ligands and by a monodentate terephthalate group, forming a distorted tetrahedral N3,O geometry.
The N-H···O hydrogen bonds (Table 2) formed between three uncoordinated 2-ethyl-H-imidazole N atoms and two uncoordinated carboxylate O atoms, resulted in a three-dimensional hydrogen-bonded network.

S3. Refinement
The methyl C atom, C18, in one of the ethyl groups is disordered over two positions (C18A and C18B) with refined occupancies of 0.66 (2) and 0.34 (2). The C17-C18A and C17-C18B distances were restrained to 1.53 (1) Å. The displacement parameters of the disordered C atoms were also restrained to be approximately isotropic. The aromatic [C-H = 0.93 Å and U iso (H) = 1.2U eq (C)] and methylene H atoms [C-H = 0.96 Å and U iso (H) = 1.5U eq (C)] were included in the refinement in the riding-model approximation.  The molecular structure of the title compound, showing the atomic numbering and 30% probability displacement ellipsoids. For clarity, H atoms have been omitted. Only the major disorder component is shown.

Tris(2-ethyl-1H-imidazole-κN 3 )(terephthalato-κO)zinc(II)
Crystal data where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.001 Δρ max = 0.51 e Å −3 Δρ min = −0.28 e Å −3 Absolute structure: Flack (1983), 2826 Friedel pairs Absolute structure parameter: 0.049 (15) Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.  (7) 0.057 (7) 0.028 (6) 0.054 (7) Geometric parameters (Å, º)