Synthesis and Crystal Structure of the Novel Binuclear Copper Complex Cu2（C5 H 5 N）2（C8 H 7 O2）4*

LI Li，CHEN Fan，YAN Chen-ting，NI Sheng-liang

（Faculy of Life Science，Huzhou Teachers College，Huzhou 313000，China）

Synthesis and Crystal Structure of the Novel Binuclear Copper Complex Cu2（C5H5N）2（C8H7O2）4*

LI Li，CHEN Fan，YAN Chen-ting，NI Sheng-liang

（Faculy of Life Science，Huzhou Teachers College，Huzhou 313000，China）

Reactions of thefreshly prepared Cu（OH）2·y H2O precipitate，2-methyl benzoic acid with pyridinein C2H5OH／H2O （1∶1，v／v）afforded Cu2（C5H5N）2（C8H7O2）4（1）.Thecentrosymmetric binuclear compound was structurally characterized by X-ray diffraction methods.In the crystal，four 2-methyl benzoate anions form a cage around two Cu atoms in a syn-syn configuration，two pyridine molecules are apically bonded to the Cu atoms，which show a square-pyramidal coordination geometry.The molecular packing forms a puckered pseudo-hexagonal closepacked framework in（010）.CCDC：856726.

binuclear copper；2-mehyl benzoate complex；crystal structure

0 Introduction

Binuclear copper complexes are very significant in catalytic reactions and coordination chemistry.Of course，copper complexes have shown some unordinary chemical properties in such diverse areas as homogenous，oxygen transfer，and oxidative addition［1］.Recently years，2-methyl benzoato ligands have been actively utilized as construction units to obtain many supramolecularcomplexes［2～4］.To gain an insight into the correlation between the structure and properties of 2-methyl benzoatate binuclear copper complex，we have reported the binuclear copper complex Cu2（C5H5N）2（C8H7O2）4（2），which structure is asymmetric with p-1 space group［5］.Different from 2，herein，we are interested in self-assemblies of Cu2＋ions with 2-methyl benzoate and pyridine，further report the synthesis and structure of Cu2（C5H5N）2（C8H7O2）4（1）in detail，as shown in Fig.1.

1 Experimental Section

SynthesisDropwise addition of 2.0 ml of 1.0 M aqueous NaOH to a stirred aqueous solation of CuCl2·2H2O （0.1705 g，1.0 mmol）in 3 ml H2O produced a blue precipitate，Cu（OH）2·y H2O，which was centrifuged and washed with water until no chroride anions were detected in the supernatant.Theblue precipitate was added to a mixed solution of 2-methyl benzoic acid（0.2725 g，2.0 mmol）and pyridine（0.0791g，1.0 mmol）in 30 ml C2H5OH／H2O（1∶1，v／v）.The solution was stirred and filtered.The blue solution（p H＝5.13）was allowed to stand at room temperature.Slow evaporation during several days afforded green block crystals.Yield：41%based on initial CuCl2·2H2O.

CharacterizationSuitable single crystals were selected under a polarizing microscope and fixed with epoxy cement on respective fine glass fibers，which were then mounted on a Rigaku R-Axis Rapid IP X-ray diffractometer with graphite-monochromated Mo Karadiation（λ＝0.71073）for cell determination and subsequent data collection.The reflection intensities in theθrange 3.04～25.00°were collected at 293 K using thewscan technique.The employed single crystals exhibit no detectable decay during the data collection.The data were corrected for Lp and absorption effects.The SHELXS–97［6］and SHELXL–97［7］programs were used for structure solution and refinement.The structures were solved by using direct methods.Subsequent difference Fourier syntheses enabled all non-hydrogen atoms to be located.After several cycles of refinement，all hydrogen atoms associated with carbon atoms were geometrically generated，and the rest of the hydrogen atoms were located from the successive difference Fourier syntheses.Finally，all non-hydrogen atoms were refined with anisotropic displacement parameters by the full-matrix least-squares technique and hydrogen atoms with isotropic displacement parameters set to 1.2 times ofthe values for the associated heavier atoms，1.5 times H atached methyl group.Detailed information about the crystal data and structure determination is summarized in Table 1.

Table 1 Crystallographic and experimental data for 1

2 Results and Discussions

In the title centrosymmetric dinuclear compound，Cu2（C5H5N）2（C8H7O2）4，exhibits as a cage-like structure，as shown in Fig.2.Four 2-methylbenzoate anionic ligands form a cage around two Cu atoms in a syn-syn configuration，two pyridine N atoms are apically bonded to the Cu atoms.The metallic Cu—Cu＃1bond length is 2.646（5），comparing the Van der waals radii of copper（2.32），and the metallic Cu—Cu bond is substantially longer to the Cu—Cu separation in（1），which would expect the presence of weak orbital interaction.Each Cu atom is displaced from the basal plane of the four cage carboxylates by 0.210，towards the apical N atom.

The Cu—O bond lengths of the cage carboxylates vary between 1.996（5）～1.971（5），the Cu—N bond distances is 2.154（6to the pyridine molecule show aca 0.2increase.The adjacent O—Cu—O bond angles and N—Cu—O bond angles are all in the normal range 88.8（2）～98.5（2）°［8］.Selected interatomic distances and bond angles are given in Table 2.

In the crystal，there are no typical hydrogen bonds or arylπ－πpackinginteractions，the molecules are assembled into one-dimension chains extending along theb direction，and the supermolecular chains are further constructed puckered pseudo-hexagonal close-packed framework structure in （010）by van der waals interactions，as shown in Fig.3.

Table 2 Selected interatomic distances（and bond angles（°）for 1

Table 2 Selected interatomic distances（and bond angles（°）for 1

les Cu—N1 2.154（6） O1—Cu—O2 167.8（2） O1—Cu—O3 89.6（2）Interatomic distances bond ang Cu—O1 1.966（5） O2—Cu—O3 89.7（2） O1—Cu—O4 88.8（2）Cu—O3 1.969（5） O2—Cu—O4 89.3（2） O3—Cu—O4 167.6（2）Cu—O2 1.969（5） O1—Cu—N1 97.5（2） O2—Cu—N1 94.6（2）Cu—O4 1.971（5） O3—Cu—N1 98.5（2） O4—Cu—N1 93.9（2）

3 Supplementraty Data

Crytallographic data（excluding structure factors）for the structure in this paper have been deposited with Cambride Crytallographic Data Centre as Supplementraty publication no.CCDC：856726 （Cu2（C5H5N）2（C8H7O2）41）.Copies of the data can be obtained，free of charge，on application to CCDC，12 Union Road，Cambriage CB2 1EZ，UK（fax：＋44 1223 336033 or e-mail：deposit＠ccdc.cam.ac.uk）.

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新型雙核銅配合物Cu2（C5H5N）2（C8H7O2）4的合成及結構

李 黎，陳 帆，嚴晨婷，倪生良

（湖州師范學院 生命科學學院，浙江 湖州313000）

新制備的Cu2（C5H5N）2（C8H7O2）4加入到溶有2-甲基苯甲酸、吡啶的C2H5OH／H2O （1∶1，v／v）混合溶劑中反應，得到新的雙核銅配合物Cu2（C5H5N）2（C8H7O2）4晶體，結構經X-衍射法表征.晶體結構中，四個苯甲酸離子羧基八個O原子經syn-syn式橋連二個Cu原子成燈籠狀，在軸向分別由二個吡啶分子N配位而形成四方錐形幾何結構.分子間沿（010）方向，形成折疊假性的六邊形緊密堆積結構.配合物CCDC號：856726.

雙核銅；2-甲基苯甲酸配合物；晶體結構

O614.121 Document code：A Article ID：1009-1734（2012）01-0049-04

date：2011-12-06

s：This research is partially supported by The 9thHuzhou Teachers College Undergraduate Research Project（2011-92）.

Biography：LI Li，undergraduate of class 090911，faculty of life science，Huzhou Teachers College，engages in syntheses and crystal structure of organic-metal complexes.