Crystal structure of di­aqua­(μ2-tri­ethyl­ene­tetra­minehexa­acetato)­dizinc tetra­hydrate

Huan Liu; Li-Ping Lu

doi:10.1107/S2056989015002108

. 2015 Feb 7;71(Pt 3):m55–m56. doi: 10.1107/S2056989015002108

Crystal structure of diaqua(μ₂-triethylenetetraminehexaacetato)dizinc tetrahydrate

Huan Liu ^a, Li-Ping Lu ^a,^*

PMCID: PMC4350722 PMID: 25844206

Abstract

The reaction of ZnO and triethylenetetraminehexaacetic acid (H₆TTHA) in aqueous solution after refluxing yields the binuclear title compound, [Zn₂(C₁₈H₂₆N₄O₁₂)(H₂O)₂]·4H₂O. There is a centre of symmetry in the [Zn₂(H₂TTHA)(H₂O)₂] molecule in the crystalline state. Both Zn^II ions are octahedrally surrounded and bound by an N₂O₃ donor set from the H₂TTHA⁴⁻ anion and a water molecule; the N atoms are cis and the water molecule is trans to an N atom. The Zn⋯Zn separation is 7.562 (1) Å. An intramolecular C—H⋯O interaction is observed and both carboxylate H atoms are disordered over two adjacent sites. In the crystal, the components are linked by O—H⋯O and C—H⋯O hydrogen bonds generating a three-dimensonal network.

Keywords: Crystal structure, binuclear Zn^II complex, triethylenetetraminehexaacetic acid, crystal structure

Related literature

For general background to the complexes of triethylenetetraminehexaacetic acid, see: Long et al. (2003 ▸); Lu & Zhu (2014 ▸); Mondry & Starynowicz (1998 ▸); Ouyang et al. (2007 ▸); Sethi et al. (2012 ▸); Shi et al. (2006 ▸); Song et al. (2003 ▸); Thompson et al. (1998 ▸); Wang et al. (2003 ▸); Wullens et al. (1996 ▸). For related structures, see: Carlson et al. (2010 ▸); Qian et al. (2013 ▸). graphic file with name e-71-00m55-scheme1.jpg

Experimental

Crystal data

[Zn₂(C₁₈H₂₆N₄O₁₂)(H₂O)₂]·4H₂O
M _r = 729.26
Triclinic,
a = 7.1330 (14) Å
b = 8.7013 (16) Å
c = 11.979 (2) Å
α = 103.969 (2)°
β = 101.052 (2)°
γ = 100.882 (3)°
V = 686.2 (2) Å³
Z = 1
Mo Kα radiation
μ = 1.84 mm⁻¹
T = 298 K
0.28 × 0.22 × 0.20 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2000 ▸) T _min = 0.627, T _max = 0.710
3582 measured reflections
2384 independent reflections
2080 reflections with I > 2σ(I)
R _int = 0.057

Refinement

R[F ² > 2σ(F ²)] = 0.034
wR(F ²) = 0.089
S = 0.99
2384 reflections
190 parameters
H-atom parameters constrained
Δρ_max = 0.49 e Å⁻³
Δρ_min = −0.76 e Å⁻³

Data collection: SMART (Bruker, 2000 ▸); cell refinement: SAINT (Bruker, 2000 ▸); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: SHELXTL/PC (Sheldrick, 2008 ▸); software used to prepare material for publication: SHELXTL/PC.

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S2056989015002108/hb7351sup1.cif

e-71-00m55-sup1.cif^{(25.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989015002108/hb7351Isup2.hkl

e-71-00m55-Isup2.hkl^{(117.1KB, hkl)}

Click here for additional data file.^{(1.3MB, tif)}

. DOI: 10.1107/S2056989015002108/hb7351fig1.tif

A view of the structure of the title complex with displacement ellipsoids drawn at the 50% probability level. Dash open line indicates hydrogen bonding interaction.

Click here for additional data file.^{(1.8MB, tif)}

. DOI: 10.1107/S2056989015002108/hb7351fig2.tif

The packing diagram of the title compound, Zn dark green C gray, N blue,H light green, O red.

CCDC reference: 1046672

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths ().

Zn1O7	2.003(2)
Zn1O1	2.063(2)
Zn1O3	2.112(2)
Zn1O5	2.130(2)
Zn1N1	2.150(2)
Zn1N2	2.243(2)

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Table 2. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
C9H9BO1	0.97	2.54	3.198(4)	125
C2H2AO8ⁱ	0.97	2.52	3.476(4)	168
C5H5BO4ⁱⁱ	0.97	2.48	3.428(4)	166
O7H71O1ⁱⁱⁱ	0.82	1.91	2.720(3)	169
O7H72O8	0.82	1.83	2.627(3)	164
O8H81O2ⁱⁱⁱ	0.82	1.94	2.747(4)	166
O8H82O9	0.82	1.96	2.734(4)	157
O9H91O5^iv	0.82	2.33	3.074(4)	151
O9H92O6^v	0.82	2.33	3.033(4)	144

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) ; (iv) ; (v) .

Acknowledgments

This work was supported financially by the National Natural Science Foundation of China (grant No. 21171109), SRFDP (grant No. 20121401110005), the Natural Science Foundation of Shanxi Province of China (grant No. 2011011009–1) and the Research Project supported by Shanxi Scholarship Council of China (grant No. 2013–026).

supplementary crystallographic information

S1. Introduction

Triethylenetetraminehexaacetic acid(H₆TTHA), a multidentate ligand having ten potential coordinating sites (six oxygen atoms and four nitrogen atoms), can play an important role in the self-assembly of chelating metals. It can be employed as a structure-directing agent to form main group metal complexes(Wullens et al., 1996, Thompson et al., 1998), transition-metal complexes(Song et al., 2003, Long et al., 2003, Qian et al., 2013, Carlson et al., 2010, Sethi et al., 2012), lanthanide complexes(Wang et al., 2003, Mondry & Starynowicz, 1998) and 3d–4f coordination polymers(Ouyang et al., 2007, Shi et al., 2006). To our knowledge, Zn(II) ions strongly inhibits many protein tyrosine phosphatases(Lu & Zhu, 2014). As part of the ongoing study of metal complexes inhibiting protein tyrosine phosphatases, the aim of us is to synthesize new zinc complexes employing polyamino polycarboxylic acids to form stable and soluble complexes. In this contribution, crystal structure of a binuclear zinc(II) complex of H₂TTHA is reported.

S2. Experimental

S2.1. Synthesis and crystallization

All chemicals were of reagent grade, commercially available and used without further purification. A mixture of H₆TTHA (0.050 g, 0.10 mmol) and ZnO (0.016 g, 0.20 mmol) in 50 mL of deionized water in a flask was refluxed for 6 h. The clear solution was cooled to room temperature and filtered. The colorless filtrate was set aside at room temperature for three weeks. The title complex crystal was obtained as colourless blocks with yield 45%. Elemental Analysis(%): Cald. C 29.73, H 4.99, N 7.70; found C 29.52, H 5.05, N 7.57. Selected IR(KBr, cm^-1): ν(O—H) 3445s, ν(C=O) 1732s, δ(O—H) 897m.

S2.2. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. H atoms attached to C of the title complex were placed in geometrically idealized positions with Csp³—H = 0.97Å and with Uiso(H) = 1.2Ueq(C). The carboxyl H4 and H6 atoms are each located close to a crystallographic inversion centre between pairs of symmetry equivalent atoms of O4 and O6. Both H atoms were thus refined as 50% occupied. The O—H distances were constrained to be 0.82 Å and Uiso= 1.5Ueq(O). H atoms attached to O(water) atoms were located from difference Fourier maps; their bond lengths were idealized to 0.82 Å and they were refined using a riding model, with Uiso(H) = 1.5Ueq(O).

S3. Results and discussion

The molecular structure and the crystal packing are depicted in Figures 1 and 2, respectively. Selected bond lengths and bond angles are listed in Table 1. The Zn(II) ion has a six-coordinate pseudo-octahedral environment with two N and three O atoms from ligand H₂TTHA anion as well as one water molecule. The complete binuclear molecule exists a centre of symmetry locating on the midpoint of bond C9—C9ⁱ (Symmetry code i -x, 2-y, 2-z). The distance of both Zn(II) ions in the complex is 7.562 (1) Å. The distance of Zn—O(water) is 2.003 (2) Å, which is the shortest in all coordinate bonds of the title complex, while Zn—O bond lengths are in the range of 2.063 (2) to 2.130 (2) Å, and the Zn—N bond lengths are 2.150 (3) and 2.243 (2) Å, respectively. All the geometrical features compare very well with those in some similar structures, such as [Zn(H₂O)₆][Zn₂(H₂O)₂(TTHA)].4H₂O(Carlson et al., 2010), [Co₂(H₂TTHA)(H₂O)₂].4H₂O(Qian et al., 2013).

In the structure of the title complex, numerous intermolecular hydrogen bonds (O—H···O; Table 3) play an important role in stabilizing the structure and linking ions and solvent water molecules. Additional nonclassical C—H···O hydrogen bonds (Table 3) occur in the structure, with C—H···O angles in the range 125–168° and C···O distances between 3.198 (4) and 3.476 (4) Å.