научная статья по теме A NEW COMPLEX OF MN(II) WITH HIGHLY FLEXIBLE BIS-TRIAZOLE LIGAND 1,2-BIS(1,2,4-TRIAZOLE-1-YL)ETHANE: SYNTHESIS AND CRYSTAL STRUCTURE Химия

Текст научной статьи на тему «A NEW COMPLEX OF MN(II) WITH HIGHLY FLEXIBLE BIS-TRIAZOLE LIGAND 1,2-BIS(1,2,4-TRIAZOLE-1-YL)ETHANE: SYNTHESIS AND CRYSTAL STRUCTURE»

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A NEW COMPLEX OF Mn(II) WITH HIGHLY FLEXIBLE Ms-TRIAZOLE LIGAND 1,2-£/s(1,2,4-TRIAZOLE-1-YL)ETHANE: SYNTHESIS AND CRYSTAL STRUCTURE © 2011 X. X. Wu, B. Ding*, R. N. Chang, H. A. Zou, and Z. Z. Zhou

Tianjin Key Laboratory of Structure and Performance for Functional Molecule, College of Chemistry, Tianjin Normal

University, Tianjin 300387, P.R. China *E-mail: qsdingbin@yahoo.com.cn Received July 14, 2010

Using a highly flexible ligand 1,2-bis(1,2,4-triazole-1-yl)ethane (L), the one-dimensional (1D) chain polymer [[Mn(L)(Cl)2(H2O)2]B (I) has been synthesized and structurally characterized. The crystal crystallizes in the monoclinic system, space group C2/c, a = 12.507(4), b = 8.812(3), c = 12.662(4) Á, P = 115.474(6)°, Z =4. The X-ray analysis shows that I has the three- dimensional (3D) supramolecular network featuring 1D channel along the crystallographic y axis via intermolecular O—H--N interactions.

INTRODUCTION

The design and construction of metal-organic coordination polymers (MOFs), based on the interaction of metal ions with bridging ligands, is an area of intense current interest not only due to their intriguing and versatile structures, but also to their interesting properties as new functional materials of versatile potential applications [1,2]. The generation of MOFs rest on various parameters, such as coordination enviroments of the metal ion, ligand, position, and type of functional groups on the ligands, temperature, reaction time, pH, etc. [3—5].

Neutral organic ligands containing rigid or flexible spacers, such as 4,4'-bipyridine, 1,2-bis(4'-py-ridyl)ethane, 1,2-bis(4-pyridyl)propane and many others, have been used to generate a rich variety of metal-organic architectures with different metal ions by various reaction procedures. 1,2-Bis(1,2,4-triazole-1-yl)ethane (L) or 1,4-bs(triazol-1-ylmethyl)benzene represent another class of N-donor organic linkers for constructing coordination polymers. With two methylene sp3-carbon atoms, the L ligand is highly flexible and can assume variable trans and gauche conformations:

These ligands can produce architectures quite different from those obtained or pyridyl-based ligands [6]. For the L ligand, a variety of silver and cadmium compounds have been reported [7], while the Mn(II) compounds are less reported.

Recently we reported a series of Zn and Cd 1,2-bis(1,2,4-triazole-1-yl)ethane complexes exhibiting the anion variation make different supramolecular structure and the self-assembly of CdN4O2 polyhedra from 2D to 1D [8]. As the continuation of this work, using the self-assembly highly flexible L ligand, we isolated a novel 1D single-chain Mn(II) compound in which the L ligand adopts the gauche conformations. Furthermore it is in-

teresting that 1D microporous supramolecular channel can be found in the complex I.

EXPERIMENTAL

The triazole ligands L were synthesized according to the literature method [9]. All other starting reagents were of A.R. grade and used as purchased. Analyses of C, H, and N were determined on a PerkinElmer 240 elemental analyzer. The IR spectrum was recorded as KBr discs on a Shimadzu IR-408 infrared spectrophotometer in the 4000-600 cm-1 range.

Synthesis of I. An ethanol solution (10 ml) of L (2.0 mmol) was added to an aqueous solution (10 ml) of

Table 1. Crystallographic data and experimental details for complex I

Parameter Value

M 326.06

System Monoclinic

Space group C2/c

a, Â 12.507(4)

b, Â 8.812(3)

c, Â 12.662(4)

ß, deg 115.474(6)

V, Â3 1259.9(7)

Z 4

Pcalcd g/cm3 1.719

^(Mo^a), mm-1 1.472

/(000) 1432

Crystal size, mm 0.40 x 0.22 x 0.20

9 range, deg 2.93-27.10

Index ranges -11 < h < 16

-11 < k < 10

-15 < l < 16

Measured reflections 3720

Independent reflections 1388

Observed reflections (I > ct(I)) 1388

GOOF for F2 1.094

R index (I > 2a(I)) R1 = 0.0241; wR2 = 0.0573

R index (all data) R1 = 0.0321, wR2 = 0.0608

Residual electron density 0.296 and -0.242

(max/min), e Â-3

MnCl2 ■ 6H2O (1.0 mmol) with stirring. The filtrate was refluxed for 1 h. The colorless crystals of I suitable for X-ray diffraction were obtained by evaporation of the filtrate. The yield was 40% (based on Mn(II) salts).

For C6Hi2N6O2Cl2Mn

anal. calcd., %: C, 22.10; H, 3.71; N, 25.78. Found, %: C, 22.18; H, 3.75; N, 25.92.

IR (v, cm-1): 3320 vA(H2O), 1530 v(C=N).

Table 2. Selected bond distances (A) and angles (deg) for I

Bond d, À Bond d, À

Mn(1)-O(1) 2.2312(15) Mn(1)-Cl(1) 2.5160(8)

Mn(1)-N(1) 2.2515(15)

Angle ro, deg Angle ro, deg

O(1)Mn(1)N(1) 90.35(6) N(1)Mn(1)Cl(1) 89.42(4)

O(1)Mn(1)Cl(1) 90.17(5)

X-ray crystal determination. The data were collected on a Bruker Smart-1000-CCD area detector using graph-ite-monchromated MoA^ radiation (X = 0.71073 A). The structure was solved by a direct method and subsequent Fourier difference techniques and refined using a full-matrix least-squares procedure on F2 with anisotropic thermal parameters for all non-hydrogen atoms (SHELXS-97 and SHELXL-97) [10]. Hydrogen atoms were added geometrically and refined with riding model position parameters and fixed isotropic thermal parameters. Crystal data collection and refinement parameters are given in Table 1. Selected bond distances and angles are listed in Table 2. Supplementary material has been deposited with the Cambridge Crystallographic Data Centre (no. 274713; deposit@ccdc.cam.ac.uk or http:// www.ccdc.cam.ac.uk).

RESULTS AND DISCUSSION

Figure 1a reveals that in I the Mn2+ ion is six-coordinated to two L ligands, two chloride atoms, and two aqua ligands. The axial Mn—Cl diatances (2.516 Á) are much longer than the Mn—N and Mn—O distances (2.268 and 2.252 Á), indicative of a distorted octahedral environment with the axis elongated. Each Mn2+ ion is linked by two ligands to two neighboring Mn2+ ions, affording the 1D chain as shown in Fig. 2. The Mn-Mn distance is 6.331 Á, and the ligand adopts the gauche mode to link two neighboring Mn2+ ions. As shown in Fig. 3, the oxygen atoms ofthe aqua ligand and the nitrogen atoms from the ligand generate the intermolecular hydrogen bond, and the corresponding bond length is 2.923 Á. It is interesting that in the 3D supramolecular structure ofI the 1D microporous supramolecular channels can been found along the y axis.

For complex I, there is a broad band at 3320 cm-1, which is mainly attributed to the coordinated water molecules. For I the strong absorption bands at ca. 1530 and 1250 cm-1 can be assigned to the triazole ring stretching vibrations. The triazole out-of-plane ring absorption is

KOOP,3HHAUHOHHAH XHMH3 tom 37 № 6 2011

A NEW COMPLEX OF Mn(II) WITH HIGHLY FLEXIBLE

431

Fig. 1. Perspective view of the coordination chromophore of complex I.

Fig. 2. View of the 1D single-chain structure of complex I.

Fig. 3. View of the supramolecular channel in the 3D supramolecular structure along the y axis in complex I.

КООРДИНАЦИОННАЯ ХИМИЯ том 37 № 6 2011

observed at about 629 cm 1 [11]. These results are in agreement with the X-ray result.

ACKNOWLEDGMENTS

This present work was supported financially by Tianjin Educational Committee (no. 20090504) and Natural Science Foundation of Tranjin (09JCYBJC7900).

REFERENCES

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9. Torres, J., Lavandera, J.L., Cabildo, P., et al., J. Hetero-cycl. Chem., 1988, vol. 25, p. 771.

10. Sheldrick, G.M., SHELXL-97, Program for the Solution of Crystal Structures; SHELXL-97, Program for the Refinement of Crystal Structures, Göttingen (Germany): Univ. of Göttingen, 1997.

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