научная статья по теме SYNTHESIS AND CHARACTERIZATION OF A NOVEL COORDINATION POLYMER {[MN(L)(PHEN)2] · 2H2O}N Химия

Текст научной статьи на тему «SYNTHESIS AND CHARACTERIZATION OF A NOVEL COORDINATION POLYMER {[MN(L)(PHEN)2] · 2H2O}N»

КООРДИНАЦИОННАЯ ХИМИЯ, 2011, том 37, № 6, с. 437-441

УДК 541.49

SYNTHESIS AND CHARACTERIZATION OF A NOVEL COORDINATION

POLYMER {[Mn(L)(Phen)2] • 2H2O}„

© 2011 E. J. Gao*, S. H. Liu, T. D. Sun, L. Lin, R. S. Wang, Y. X. Zhang, M. Su, and M. Zhang

Coordination Chemistry Laboratory, Shenyang University of Chemical Technology, Shenyang, Liaoning 110142, P.R. China

*E-mail: ejgao@yahoo.com.cn Received July 5, 2010

A novel coordination polymer {[Mn(L)(Phen)2] • 2H2O}„ (I) has been synthesized by the reaction of Mn(CH3COO)2, 2,2'-bipyridine-5,5'-dicarboxylic acid (HL) and 1,10-phenanthroline (Phen). The structure of the complex was charactered by single-crystal X-ray diffractometry. The unit cell parameters for complex I: a = 11.796(3), b = 17.837(5), c = 15.081(4) Á; P = 101.804(5)°; V= 3106.0(15) Á3; Z = 4; space group C2/c. The Mn(II) atom is coordinated by four nitrogen atoms from two Phen molecules and two oxygen atoms from two molecules L with a distorted octahedral geometry. Complex was dibridged by the L ligand forming a 1D infinite chain. Intramolecular weak interactions, such as hydrogen bonds and n---n-stacking, were found in the title complex, and 3D supramolecular framework was constructed by intermolecular weak interactions mentioned above.

INTRODUCTION

The metal manganese is an important life-supported element and plays a key role in the course of photosynthesis and the formation of superoxide dismutase [1]. To our knowledge, many Mn(II) complexes have been reported, but those with pyrazine and its carboxylic derivates as ligands are relatively less [2, 3]. The Mn(II) complex synthesized by us is mainly a bipyridyl dicarboxylic acid system. The carboxyl group is of good flexibility and has a variety of coordination modes [4], which not only enhances the structural stability of the complex, but also compensates with positive charge of the metal cation slowing the counterion effect [5]. In addition, Phen has strong coordination ability and biological activity, which are widely used in synthesis and research of transition metal complexes [6, 7]. Based on the structure of transition metal complexes, a novel coordination polymer {[Mn(L)(Phen)2] • 2H2O}„ (I) has been synthesized by the reaction of Mn(CH3COO)2, 2,2'-bipyridine-5,5'-di-carboxylic acid (HL) and 1,10-phenanthroline (Phen) using the evaporation method at room temperature, and its structure was characterized.

EXPERIMENTAL

Materials and measurements. All chemicals of reagent grade quality were obtained from commercial sources and used without further purification, unless otherwise noted. Elemental analyses (C, H, N) were performed on a model Finnigan EA 1112 apparatus. IR spectra were recorded as KBr pellets on a Nicolet IR-470 instrument.

Synthesis of complex I. In the experiment, L was dissolved in an aqueous KOH solution. An aqueous Mn(CH3COO)2 solution (10 mmol, 10 ml) was mixed with an aqueous solution of L (10 mmol, 10 ml), and the pH value was adjusted to 7.85 with 1 M KOH. After stirring at room temperature for about 4 h, 10 ml of water containing Phen (10 mmol, Vethanol: VH2o = 1 : 4) was added to the above mixture. The resultant solution was stirred continuously for another 4 h, and then the pH value was stable at 7.56. At last, the mixture was filtrated and about 30 ml of a clear brown-red filtrate was obtained, which was kept at room temperature and evaporated. After two weeks, slightly yellow transparent crystals were obtained.

For C36H26N6O6Mn

anal. calcd., %:C, 62.34; H, 3.78; N, 12.14; Mn, 7.92. Found, %: C, 62.30; H, 3.84; N, 12.13; Mn, 7.89.

IR spectrum (v, cm-1): 3385 s, 1584 s, 1400 s, 1241 m, 1021 m, 839 s, 783 s.

X-ray crystal determination. Structure measurement of the complex was performed on a Bruker Smart 1000 CCD X-ray single-crystal diffractometer with Mo^Ta radiation (X = 0.71073 A) at 273 K. The intensity data were obtained in a range of 2.10° < 9 < 25.10° by using a scan technique. The corrections for the Lp factor and an empirical absorption correction were applied. The structure was resolved by a direct method using SHELXS-97 [8, 9]. All the non-hydrogen atoms were determined with successive difference Fourier syntheses and refined by full-matrix least squares on F2 (SHELXL-97). All hydrogen atoms were located at the calculated positions.

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Table 1. Crystal data and structure refinement for complex I

Parameter Value

Formula weight 693.57

Crystal system, space group Monoclinic, C2/c

Unitcell dimensions:

a, A 11.796(3)

b, A 17.837(5)

c, A 15.081(4)

P, deg 101.804(5)

V, A3 3106.0(15)

Z 4

Crystal size, mm 0.10 x 0.08 x 0.06

9 Range for data collection, deg 2.10° < 9 < 25.10°

Limiting indices -13 < h < 14, -16 < k < 21, -17 < l < 17

Reflections collected/unique, I > 2ct(T) 7560/2746 (Rtat = 0.1284)

Completeness, % 99.2

Parameters 222

Goodness-of-fit on F2 1.031

Pcalcd g cm-3 1.483

F(000) 1428

Absorption coefficient, mm-1 0.485

Final R indices (I > 2ct(I)) R1 =0.0573, wR2 = 0.1398

R indices (all data) R1 = 0.1769, wR2 = 0.1904

APmax and Apmin e AT3 1.321 and -1.004

Crystal data and structure refinement details are summarized in Table 1. Selected bond lengths and bond angles are listed in Table 2. Supplementary material has been deposited with the Cambridge Crystallographic Data Centre (no. 777737; deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).

RESULTS AND DISCUSSION

The basic structure of is shown in Fig. 1. For complex I, Mn(II) is coordinated by four nitrogen atoms from two Phen ligands and two oxygen atoms from two L ligands, with a slightly distorted octahedral geometry. In the equatorial plane, the bond lengths of Mn(1)-O(1) is 2.107(3), Mn(1)—N(2) 2.294(4) A, the bond angles N(2)#1Mn(1)N(2), O(1)#1Mn(1)O(1), and O(1)#1Mn(1)N(2) are respectively 95.51(17)°, 97.07(18)°, and 88.03(13)°. In the axial direction, the N(1)Mn(1)N(1)#1 bond angle is 158.75(17)°, O(1)Mn(1)N(2) is 157.64(13)°. Moreover, the bond lengths of Mn(1)-N(1) are 2.344(4) A, which is longer than the bond length Mn(1)-O(1) and Mn(1)-N(2) in the equatorial plane. The bond lengths above are in accordance with the bond lengths range of Mn—N and Mn-O in other coordination compounds [10, 11]. Therefore, the Mn atom is in the distorted octahedral environment. In addition, bond lengths of C(18)-O(2) 1.223(6) and C(18)-O(1) 1.272(5) A are almost equal, showing that the deprotonated HL coordinated with Mn2+ ion in the monodentate mode [12].

Complex I dibridged by L ligand forms a 1D infinite chain shown in Fig. 2. In the structure of L, the two pyri-

Table 2. Selected bond lengths (A) and bond angles (deg)*

Bond d, A Bond d, A

Mn(1)-O(1) 2.107(3) C(12)-N(1) 1.302(7)

Mn(1)-N(2) 2.294(4) C(13)-N(3) 1.324(6)

Mn(1)-N(1) 2.344(4) C(14)-N(3) 1.341(5)

C(1)-N(2) 1.310(6) C(18)-O(2) 1.223(6)

C(5)-N(2) 1.370(5) C(18)-O(1) 1.272(5)

C(9)-N(1) 1.362(5)

Angle ro, deg Angle ro, deg

O(L4)Mn(1)O(1) 97.07(18) O(2)C(18)O(1) 125.3(5)

O(1)Mn(1)N(2^) 88.03(13) O(2)C(18)C(17) 119.3(4)

O(1)Mn(1)N(2) 157.64(13) O(1)C(18)C(17) 115.4(4)

N(2A)Mn(1)N(2) 95.51(17) C(12)N(1)C(9) 118.1(4)

O(1^)Mn(1)N(1) 108.06(12) C(12)N(1)Mn(1) 126.6(3)

O(1)Mn(1)N(1) 86.23(12) C(9)N(1)Mn(1) 115.0(3)

N(2A)Mn(1)N(1) 93.96(13) C(1)N(2)Mn(1) 125.4(3)

N(2)Mn(1)N(1) 71.52(14) C(5)N(2)Mn(1) 116.3(3)

N(1)Mn(1)N(1A) 158.75(17) C(18)O(1)Mn(1) 127.8(3)

* Coordinates of atom A: —x + 1, y, -z + 1/2.

KOOP^HH^HOHHAtf XHMH3 TOM 37 № 6 2011

Fig. 1. Unit structure of the coordination polymer {[Mn(L)(Phen)2] • 2^O}B (all hydrogen atoms are omitted for clarity; coord-nates of atoms: A: — x, —1 + y, 0.5 — z ; B: —1 — x, —y, —z ; C: x, —y, 0.5 + z.

fr * *

w w 4k

Fig. 2. 1D polymeric chain of the coordination {[Mn(L)(Phen)2] • 2H2O}B.

dine rings with 180° twist are still in the same plane leading to the two N atoms of bipyridine rings in the opposite direction, which can make the structure of the complex more stable [13]. There are hydrogen bonds in the complex, shown in Fig. 3, where O(1w)—H—C(6), O(1w)—H—C(18), O(1w)—H—O(1), O(1w)—H—O(2), O(1w)—H—O(1w) hydrogen bond lengths O—C and O-O are 3.514(7), 3.470(7), 2.931(6), 2.984(6), 3.755(8) Á, respectively, all in line with the bond length range of hydrogen bonds [14—16]. This intermolecular force is much weaker than coordination bonds, but it plays a stable role in construction of molecules [17].

There are also n—n-stacking interactions between one py-ridine rings and Phen (the center-to-center distance is 3.697, 3.751 A), meeting the range of n—n-stacking [18]. The three-dimensional structure ofcomplex I is shown in Fig. 4.

ACKNOWLEDGMENTS

We gratefully acknowledge the Natural Science Foundation of China (no. 20971090), the Natural Science Foundation of Liaoning Province (no. 20052014), the Foundation of Educational Department of Liaoning

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O(l) C(18) 0(2)

S .V

ZVb' /&>

C(6)0(1w).

\

0(2) C(18) O(l)

Fig. 3. Intermolecular hydrogen bond interactions.

Province (no. 20060679), the Foundation of Liaoning Bai Qian Wan Talents Program (no. 2008921054).

REFERENCES

1. Wang, K., Bioinorganic Chemistry, Beijing: Tsinghua University Press, 1988, p. 3 (in Chinese).

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3. Pierre-Alain, M., Werner, M., Helen, S.V., and Clire, W, Inorg. Chem. Acta, 1994, vol. 219, p. 161.

4. Chen, X.M. and Tong, M.L., Chin. Univ. Chem, 1997, vol. 12, p. 24.

5. Boskovic, C., Brechin, E.K., Streib, W.E., et al., J. Am. Chem. Soc., 2002, vol. 124, no. 14, p. 3725.

6. Gao, E.J., Chen, M.S., Yu, Y, and Sun, YG., Chin. J. Struct. Chem., 2007, vol. 26, no. 1, p. 59.

7. Gao, E.J., Liu, Q.T., and Duan, LY, Russ. J. Coord. Chem., 2007, vol. 33, no. 2, p. 120.

8. Sheldrick, G.M., SHELXS-97, Program for Crystal Structure Solution, Gottingen (Germany): Univ. of Gottingen, 1997.

9. Sheldrick, G.M., SHELXS-97, Program for Crystal Structure Refinement, Gottingen (Germany): Univ. of Gottingen, 1997.

10. Sun,

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