二咪唑基苯及硫酸根構筑的鈷配位聚合物的合成、晶體結構和磁性質

陳滿生曾巨瀾張春華鄺代治鄧奕芳聶 雪

(1功能金屬有機材料湖南省普通高等學校重點實驗室，衡陽師范學院化學與材料科學系，衡陽 421008)

(2長沙理工大學化學與生物工程學院電力與交通材料保護湖南省重點實驗室，長沙 410004)

二咪唑基苯及硫酸根構筑的鈷配位聚合物的合成、晶體結構和磁性質

陳滿生1,2曾巨瀾＊,2張春華＊,1鄺代治1鄧奕芳1聶 雪1

(1功能金屬有機材料湖南省普通高等學校重點實驗室，衡陽師范學院化學與材料科學系，衡陽 421008)

(2長沙理工大學化學與生物工程學院電力與交通材料保護湖南省重點實驗室，長沙 410004)

由溶劑熱法合成了鈷化合物[Co(dib)(SO4)](1)(dib=1，4-二咪唑基苯)，并對其進行了元素分析、IR及X-射線衍射法表征。晶體結構表明：配合物1屬于單斜晶系，C2/c空間群。配合物1是由橋聯配體1，4-二咪唑基苯連接成二維層狀結構，該二維層被硫酸根離子拓展成三維層柱狀結構。配合物1的磁性測試研究表明它具有弱反鐵磁性。

鈷配合物；晶體結構；柱層狀；磁性質

0 Introduction

In recent years,many interest has been devoted to the development of rational synthetic routes to novel one-,two- and three-dimensional crystal frameworks,due to their potential applications in many areas such as ion-exchange,nonlinear optics,molecular sieves,gas storage,catalysis,magnetism,and so on[1-9].However,the control of synthesis of supramolecularcompounds is stilla fascinating challenge.Our strategy in this approach is using the organic functional ligand 1,4-di(1-imidazolyl)benzene(dib),which is very similar to the 4,4′-bipyridine,a few structures is known to date[10-14].In order to further investigate the dib ligand with organic carboxylate ligands on the coordiantion architectures and related properties,herein we report the synthesis,crystal structure and magnetic property ofa new 3D coordination compound,namely[Co(dib)(SO4)](1).

1 Experimental

1.1 Materials and instruments

The regents were used as commercial sources without further purification.Elemental analyses were performed on a Perkin-Elmer 240C elemental analyzer.The ligand dib was prepared as reported previously[15].The IR spectra were recorded on Bruker Vector22 FT-IR spectrophotometer using KBr discs.Thermogravimetric analyses were performed on a simultaneousSDT 2960 thermalanalyzerunder nitrogen with a heating rate of 10 ℃·min-1.Magnetic measurements for complex 1 in range of 1.8～300 K were performed on a MPMS-SQUID magnetometer at a field of 2 kOe on crystalline samples in the temperature settle mode.The diamagnetic contributions of the samples were corrected by using Pascal′s constants.

1.2 Synthesis of the compound 1

Complex1 wassynthesized bysolvothermal method in a 16 mL Teflon-lined autoclave by heating a mixture containing CoSO4·7H2O (29.9 mg,0.1 mmol),HCOONa(13.7 mg,0.2 mmol),and dib(20.1 mg,0.1 mmol)dissolved in 8 mL DMF and heated at 120 ℃ for 4 d.Block red single crystals of 1 were collected by filtration and washed by water and ethanol for several times with a yield of 45%(based on dib).Anal.Calcd.for C24H20CoN8O4S(%):C 50.05;H 3.48;N 19.46;found (%):C 50.11;H 3.39;N 19.40.IR(KBr pellet,cm-1):3 319(s),1 531(s),1 500(w),1448(w),1313(w),1267(m),1109(s),1070(s),962(w),938(m),824(m),738(m),650(m),618(m).

1.3 X-ray crystallography

The X-ray diffraction measurement for 1 was performed on the Bruker Apex-II CCD diffractometer with graphite-monochromated Mo Kα radiation (λ=0.071 075 nm)at room temperature.The data were integrated by using the SAINT program[16],which also did the intensity corrections for Lorentz and polarization effect.An empirical absorption correction was applied using the SADABS program[17].The structures were solved by direct methods using the program SHELXS-97 and all the non-hydrogen atoms were refined anisotropically on F2by the full-matrix leastsquares technique using the SHELXL-97 crystallographic software package[18-19].Crystal data and structure refinement parameters are listed in Table 1.The selected bond lengths and bond angles are given in Table 2.

CCDC:878879.

Table 1 Crystal data and structure parameters for complex 1

Continued Table 1

Table 2 Selected bond lengths(nm)and bond angle(°)

2 Results and discussion

2.1 Structure description

The dib reacted with CoSO4·7H2O under solvothermal conditions to give complex 1.Single-crystal X-ray diffraction study reveals 3D of 1 that crystallizes in space group C2/c.The coordination environment around the Co（Ⅱ）in complex 1 is shown in Fig.1.The central Co （Ⅱ） atom is located in a slightly distorted octahedron coordination environment:four N atoms (N1,N1A,N1B,N1C)from four dib ligands in the equatorial plane and the other two O atoms (O1 and O1A)from water molecules in axes sites.The Co-O bond-distances are the same distance of 0.206 83(12)nm,and Co-N bond-distances are 0.214 67(13)and 0.21578(13)nm.Then the cobalt ions are bridged by dib ligands to form a 2D infinite layer structure[Co(dib)]n(Fig.2).It is noteworthy that these layers are further connected by SO42-anions extend it into the three-dimensional (3D)layerpillared architecture(Fig.2),which is entirely different from the reported complexes[10-11].To further understand this 3D structure of 1,the Co（Ⅱ）center is considered as the nodes,the topology of 2,calculated by TOPOS[20],is a uniform 3D 6-connected pcu as shown in Fig.3.

2.2 IR,TG and Magnetic Property

The infrared spectra of the title complexes have been recorded and some important assignments are shown above.No strong IR band from-COOH appeared at nearly 1 660 cm-1,indicating that the formate ligands are not existed in it,and peaks at 1 109,1 070 and962 cm-1could be assigned to characteristic peaks of SO42-.These IR results are coincident with the crystallographic structural analyses.The results of thermogravimetric analyses (TGA)indicate that no weight loss is found before 380℃in compound 1,and above this temperature,the structure collapsed due to the liberation of the organic ligands dib.

The magnetic susceptibilities were measured on a crystalline sample of 1 in the temperature range from 1.8 to 300 K under 2 kOe using a SQUID magnetometer.At room temperature,the observed χMT value is 4.37 emu·K·mol-1,which is slightly larger than the expected value of 3.75 emu·K·mol-1corresponding to two Co（Ⅱ）(S=3/2)ions bridged by SO42-anion with the Co…Co distances of ca.0.59 nm (Fig.4).Upon cooling from 300 to 100 K the values of χMT decrease slowly,and then rapidly reach a value of 3.57 emu·K·mol-1at 1.8 K.The χM-1versus T plot follows the Curie-Weiss law with C=2.77 emu·K·mol-1,θ=-2.89 K.The negative θ value suggests that there is a weak antiferromagnetic interaction among cobalt（Ⅱ）atoms transferred through SO42-anion.

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Synthesis,Crystal Structure and Magnetic Properties of Cobalt Coordination Compound Constructed from 1,4-Di(1-imidazolyl)benzene and Sulfate

CHEN Man-Sheng1,2ZENG Ju-Lan＊,2ZHANG Chun-Hua＊,1KUANG Dai-Zhi1DENG Yi-Fang1NIE Xue1
(1Key Laboratory of Functional Organometallic Materials of Hengyang Normal University,College of Hunan Province,Department of chemistry and Materials Science,Hengyang,Hunan 421008,China)
(2Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation,School of Chemistry and Biological Engineering,Changsha University of Science and Technology,Changsha 410004,China)

A cobalt coordination polymers[Co(dib)(SO4)](1)was obtained by solvothermal assembly of CoSO4·7H2O with sodium formate in the presence of N-donor ligands,namely 1,4-di(1-imidazolyl)benzene(dib).Compound 1 crystallizes in monoclinic system,space group C2/c with a=1.972 26(7)nm,b=0.977 0(3)nm,c=1.1839 6(4)nm,β=96.479(2)°,V=2.266 8(13)nm3,Z=4,C24H20N8CoO4S,Mr=575.47,Dc=1.686 g·cm-3,μ=0.903 mm-1,F(000)=1 180,Rint=0.018 3,R=0.024 6,wR=0.072 6.Single-crystal X-ray diffraction analysis revealed that each dib ligand in turn uses its two imidzole groups to connect two metal centers,then the two-dimensional(2D)layer is formed.On the other hand,the 2D layers are further connected by sulfate to give a three-dimensional(3D)pcu topologic structure.In addition,the magnetic property of complex 1 has been investigated in the temperature range of 1.8～300 K,and the results show the weak antiferromagnetic interactions between Co（Ⅱ）ions bridged by sulfate.CCDC:878879.

Co（Ⅱ）complex;crystal structure;layer-pillared;magnetic property

O614.81+2

A

1001-4861(2012)08-1775-04

2011-12-25。收修改稿日期：2012-03-22。

國家自然科學基金(No.21003014)，湖南省科技計劃(No.2010FJ3167)，湖南省教育廳創新平臺開放基金(No.11K009)和長沙理工大學電力與交通材料保護湖南省重點實驗室開放基金(No.2012CL07)資助項目。

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