научная статья по теме SYNTHESIS AND CRYSTAL STRUCTURE CHARACTERIZATION OF SUPRAMOLECULAR COMPLEX [CD2(BIPY)2(L)2(H2O)2] · 9H2O (H2L = 2,2-BIPYRIDYL-6,6-DICARBOXYLIC ACID) Химия

КООРДИНАЦИОННАЯ ХИМИЯ, 2010, том 36, № 10, с. 755-759

УДК 541.49

SYNTHESIS AND CRYSTAL STRUCTURE CHARACTERIZATION OF SUPRAMOLECULAR COMPLEX [Cd2(Bipy)2(L)2(H2O)2] • 9H2O (H2L = 2,2'-BIPYRIDYL-6,6'-DICARBOXYLIC ACID)

© 2010 E. J. Gao*, Z. Wen, M. C. Zhu, Y. Wang, F. C. Liu, L. Wang, M. Su, Y. X. Zhang, T. D. Sun, S. H. Liu, X. N. Gao, and Y. Zhang

Coordination Chemistry Laboratory, ShenyangUniversity of Chemical Technology, Shenyang, Liaoning 110142, P.R. China *E-mail: ejgao@yahoo.com.cn Received December 14, 2009

In the complex [Cd2(Bipy)2(L)2(H2O)2] • 9H2O, the center atom Cd(II) presents a seven-coordinated pentagonal bipyramidal geometry with seven coordination bonds, four Cd—N bonds, and three Cd—O bonds. X-ray structural analysis shows that nineteen water molecules formed a large water cluster, the cluster and the composition connected to form 2D plane areolar framework and 3D zigzag networks structure through n—n-stacking and hydrogen bonding. This composition in the previous report is rare.

INTRODUCTION

Supramolecular compounds constructed from weak interactions, such as hydrogen bond, n-n-stack-ing, C—H—O, ion—n interaction, and hydrophobing interactions. The supramolecular compounds have become the new focus of crystal engineering, catalysis, molecular recognition, etc. [1]. Carboxylic acid ligands have versatile types and coordination modes. They are perfect to be used to reveal the supramolecu-lar chemistry of a metal—carboxylic acid system [2].

Cadmium is a typical toxic metal. After entering the body, it needs a long metabolic period and can change the biological molecules conformation, such as protein, and nucleic acid.

Many compositions about cadmium have been reported. Most ofthem belong to single molecular structure [3, 4]. Our laboratory have synthesized supramolecular complexes, such as Cd(Phen)2(Mal), Cd2(Phen)4(Bmal)4 • 3H2O, Cd(HPdc)(Phen)(NO3)(H2), Cd2(Phen)2(Adip)(NO3)2, [Cd2(Phen)4(p-Phth)(H2O)2](p-Phth) • 10H2O, and so on [2, 5-7].

By using 2,2'-bipyridyl-6,6'-dicarboxylic acid (H2L), and bipyridyl as ligands, we successfully synthesized a novel mononuclear complex [Cd2(Bipy)2(L)2(H2O)2] • 9H2O (I).

EXPERIMENTAL

Materials. Cadmium nitrate (analytically pure, Beijing 57601 chemical plant), H2L and bipyridyl (analytically pure, Sinopharm Chemical Reagent Co., Ltd), KOH and absolute ethyl alcohol (analytically pure, Xinhua reagent factory of Shenyang, China), and distilled water were used.

Synthesis of complex I. H2L (as the second ligand) (0.2862 g) and 100 ml H2O were charged into a flask, then a small portion of KOH was added under stirring to let the H2L dissolve fully.

Complex I was synthesized under the normal temperature condition. Cd(NO3)2 ■ 4H2O (0.31 g, 1 mmo1) was dissolved into 100 ml ofwater, then 100 ml of an aqueous solution containing bipyridyl (0.20 g, 1 mmol) was added and stirred for about 4 h under nature surroundings, then the second ligand was added, the pH was adjusted to 7 with HCl and KOH, and stirring was carried out for 12 h. The crystalloid product was collected by filtration.

IR (v, cm-1): 3396 v(O-H), 3077 v(=C-H), 1620 v(C=O), 1373 v(C-N).

For C44H46 N8O19Cd2

anal. calcd, %: C, 43.47; H, 3.81; N, 9.22. Found, %: C, 43.51; H, 3.76; N, 9.19.

X-ray structure determination. The crystal determination ofI was carried out on a Bruker Smart CCD X-ray single-crystal diffractometer (monochromate Mo^a radiation, X = 0.71073 A) by using an ® scan technique in a range of1.67° < 0 < 25.00° at 294(2) K. The structure was solved by direct methods using the SHELXL-97 program package [8-10]. All the collected points were used in the structure analysis. All non-hydrogen atoms were determined with successive difference Fourier maps. All hydrogen atoms were located at the calculated positions. The crystal data and structure refinement for I are given in Table 1. Selected bond lengths and bond angles are listed in Table 2.The coordinates of the atoms and thermal parameters were deposited with

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Table 1. Crystallographic data and details of the experiment and refinement of the C44H46N8O19Cd2 complex

Parameter Value

Formula weight 1215.688

Crystal system, space group Triclinic PI

Unit cell dimensions:

a, A 11.985(4)

b, A 13.602(5)

c, A 17.229(6)

a, deg 88.0(0)

P, deg 73.52(0)

Y, deg 70.58(0)

V, A3 2534.58(583)

Z 2

Pcalcd g cm-3 1.56905

^ mm-1 6.222

9 range for data collection, deg 1.24 < 9 < 26.23

Limiting indices -14 < h < 12, -16 < k < 16, -17 < l < 21

Reflections collected/unique I > 2ct(T) 10522/7457 (Rint = 0.0551)

Completeness, % 73.1

Number of refined parameters 680

Goodness-of-fit on F2 0.945

Final R indices (I > 2ct(I)) Rx = 0.0871, wR2 = 0.2219

R indices (all data) R1 = 0.1387, wR2 = 0.2469

Ap(max) and Ap(min), e A-3 1.994 and -0.761

the Cambridge Crystallographic Data Centre (no. 756795; deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).

RESULT AND DISCUSSION

The coordination mode of the crystal structure of I is the following:

In the graphic charts of complex, the center atom Cd(II) presents a seven-coordinated pentagonal bipyramidal geometry. Coordination bonds are formed with four nitrogen atoms and three oxygen atoms. Two of the four nitrogen atoms come from the Bipy ligand, the other two nitrogen atoms come from the L2-ligand, and two of the three oxygen atoms come from two carboxyls of the L2- ligand. The last oxygen atom comes from the water molecule.

Due to different environments, the complexes formed two molecules, and they exhibit structural isomerism (Fig. 1). The bond with the same bonding mode has different bond distances. In Table 2, the Cd-O, Cd-N, C-O, and C-N distances show the discipline. The angles with the same mode are different. The bond distance and bond angles related to Cd(II) are similar to those found in other Cd(II) complexes, and other bond distances and bond angles are within normal statistical errors [11, 12].

The complex molecules with structural isomerism and water molecules formed the complex unit mainly through the hydrogen bonding interaction. The nine water molecules (O(11)-O(19)) formed a large water cluster with the oxygen atoms which come from ligands and bound water molecules (O(2), O(3), O(5), O(6), O(7), O(8) come from L and (O(9), O(10) come from bound water molecules) (Fig. 2). These water molecules linked by the hydrogen bonding between them. They also interact with oxygen atoms coming from the -COO- of pyridine dicarboxylic acid of the complexes through hydrogen bonding. The hydrogen bonding takes shape of four-membered, five-mem-bered, and six-membered ring structure. These rings according to certain rules formed a certain regularity of the cluster. Each of two clusters units adjacent through oxygen atoms come from -COO- of the pyridine dicarboxylic acid molecule. Two adjacent complexes connected through n-n stacking (3.794 A) of bi-pyridyl and hydrogen bonding (O(3)-O(10)) (Fig. 3) [13-15]. The complexes and water molecules outspread in the space in this connection mode and formed the 3D structure (Fig. 4). So, the complexes

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Table 2. Selected bond lengths and bond angles in complex I

Bond d, Â Bond d, Â

Cd(1)-0(10) 2.283(8) C(11)-0(2) 1.285(18)

Cd(1)-N(6) 2.346(10) C(12)-N(4) 1.342(16)

Cd(1)-N(8) 2.368(11) C(16)-N(4) 1.355(14)

Cd(1)-N(7) 2.370(9) C(17)-N(3) 1.361(16)

Cd(1)-N(5) 2.373(9) C(21)-N(3) 1.350(15)

Cd(1)-O(8) 2.484(8) C(22)-0(3) 1.227(14)

Cd(1)-O(6) 2.487(8) C(22)-0(4) 1.266(13)

Cd(2)-O(9) 2.314(8) C(23)-N(5) 1.345(16)

Cd(2)-N(1) 2.330(11) C(27)-N(5) 1.380(14)

Cd(2)-N(3) 2.369(9) C(28)-N(6) 1.328(14)

Cd(2)-N(2) 2.370(11) C(32)-N(6) 1.326(16)

Cd(2)-N(4) 2.376(12) C(33)-0(6) 1.258(16)

Cd(2)-O(4) 2.413(9) C(33)-0(5) 1.284(15)

Cd(2)-O(2) 2.504(9) C(34)-N(8) 1.368(15)

C(1)-N(1) 1.334(18) C(38)-N(8) 1.363(14)

C(5)-N(1) 1.324(18) C(39)-N(7) 1.338(16)

C(6)-N(2) 1.363(19) C(43)-N(7) 1.354(16)

C(10)-N(2) 1.326(17) C(44)-0(8) 1.245(14)

C(11)-0(1) 1.259(17) C(44)-0(7) 1.272(15)

Angle ro, deg Angle ro, deg

0(10)Cd(1)N(6) 96.8(3) 0(9)Cd(2)N(1) 95.8(4)

0(10)Cd(1)N(8) 90.6(3) 0(9)Cd(2)N(3) 98.0(3)

N(6)Cd(1)N(8) 142.7(3) N(1)Cd(2)N(3) 146.8(4)

0(10)Cd(1)N(7) 102.1(3) 0(9)Cd(2)N(2) 166.4(4)

N(6)Cd(1)N(7) 144.4(3) N(1)Cd(2)N(2) 70.8(4)

N(8)Cd(1)N(7) 67.4(3) N(3)Cd(2)N(2) 92.4(3)

0(10)Cd(1)N(5) 166.9(3) 0(9)Cd(2)N(4) 95.1(3)

N(6)Cd(1)N(5) 70.9(3) N(1)Cd(2)N(4) 140.5(4)

N(8)Cd(1)N(5) 101.9(4) N(3)Cd(2)N(4) 67.8(3)

N(7)Cd(1)N(5) 86.5(3) N(2)Cd(2)N(4) 96.9(4)

0(10)Cd(1)0(8) 90.9(3) 0(9)Cd(2)0(4) 86.6(3)

N(6)Cd(1)0(8) 82.8(3) N(1)Cd(2)0(4) 82.2(4)

N(8)Cd(1)0(8) 133.7(3) N(3)Cd(2)0(4) 68.7(3)

N(7)Cd(1)0(8) 67.1(3) N(2)Cd(2)0(4) 89.1(3)

N(5)Cd(1)0(8) 83.3(3) N(4)Cd(2)0(4) 136.3(3)

0(10)Cd(1)0(6) 83.0(3) 0(9)Cd(2)0(2) 82.6(3)

N(6)Cd(1)0(6) 77.8(3) N(1)Cd(2)0(2) 77.0(4)

N(8)Cd(1)0(6) 66.9(3) N(3)Cd(2)0(2) 134.6(3)

N(7)Cd(1)0(6) 134.1(3) N(2)Cd(2)0(2) 96.3(4)

N(5)Cd(1)0(6) 98.2(3) N(4)Cd(2)0(2) 66.9(3)

0(8)Cd(1)0(6) 158.8(3) 0(4)Cd(2)0(2) 155.4(3)

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C(36)

Fig. 1. Molecular structure showing the local geometry around the metal center and ligands.

O(3) ^0(10) »O(6)

« #0(8) 0(17),» 0(5) 0(9) ®0(2)

'■-0(14^ ф0(7) • • /

1 0(16) *0ш) -'*0(18)

_-0(15) ; *0(19)

0(16) -J

10(15)

^bi ■. V 1 u у л 1 \

™ -ф0(18) ф--- ; ---^0(14) w

/ è0(-9^-0(5^W0(17) 0(7)® -

Ю(2) J •0(8)^.....«0(3)

( ) «0(6> ™0(10)

Fig. 2. 0rganic-water 2D framework formed by hydrogen bonding.

Fig. 3. Framework structure formed by n—п-stacking and hydrogen bonding.

КООРДИНАЦИОННАЯ ХИМИЯ том 36 № 10 2010

SYNTHESIS AND CRYSTAL STRUCTURE CHARACTERIZATI0N

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Fig. 4. The 3D zigzag networks structure formed through n-n-stacking and hydrogen bonding.

formed the 2D structure and 3D structure through n—n stacking and hydrogen bonding between molecules.

Attentively, we have observed complexes of structural

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