WANG Xiao-Juan YIN Jian-Ling CHEN Jing FENG Yun-Long(Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces,Institute of Physical Chemistry,Zhejiang Normal University,Jinhua,Zhejiang 321004,China)

A New 2D Layer Manganese(Ⅱ)Complex Assembled by Flexible 1,4-Benzenebis(thioacetic acid)Ligand:Synthesis,Crystal Structure and Magnetic Property

WANG Xiao-Juan YIN Jian-Ling CHEN Jing FENG Yun-Long＊
(Zhejiang Key Laboratory for Reactive Chemistry on Solid Surfaces,Institute of Physical Chemistry,Zhejiang Normal University,Jinhua,Zhejiang 321004,China)

A new Mn(Ⅱ)complex based on 1,4-benzenebis(thioacetic acid)(H2L),[Mn3L3(phen)2]n(1,phen=1,10-phenanthroline),has been hydrothermally synthesized and characterized by single crystal X-ray diffraction,elemental analysis,IR spectrum,and TG analysis.The structure can be considered as a two-dimensional(2D)layered architecture which consists of linear trinuclear Mn(Ⅱ)units.The magnetic susceptibility data are interpreted with the linear trinuclear law,yielding J and g values of-1.95(5)cm-1and 1.98(1).The exchange integral(J)indicates a weak antiferromagnetic interactions in the linear trinuclear Mn(Ⅱ)unit.CCDC:734943.

Mn(Ⅱ)complex;hydrothermal synthesis;1,4-benzenebis(thioacetic acid);crystal structure;magnetic property

The design and synthesis of novel polymeric complexes has developed rapidly in recent years due to their potential applications in some fields,such as gas storage,size-and shape-selective catalysis,material science,medicineandmagnetochemistry,aswellastheir intriguing variety of architectures and topologies[1-9].In contrast to the great deal of work on hydrothermal synthesis with phenylene diacetate ligands[10-14],there havebeen few reportsofstudieson phenylene dithioacetate ligands[15-17].Hence,we designed a multicarboxylate ligand,1,4-benzenebis (thioacetic acid)(H2L,Scheme 1),on the basis of the 1,4-benzenebisoxyacetate[14,18]and phenylthioacetate[19].The-S-CH2-groups make H2L ligand more flexible in comparison with the corresponding benzene-dicarboxylate, while the existence of the benzene ring also provides a rigid element. Recently, we have synthesized some complexes that contain first row transition metal cationsbridged by H2L and bipyridine analogues ligands[20-21].Moreover,manganese ions not only have versatile coordination behavior but also with well magnetism.Herein, we report the synthesis, structural characterizations and magnetic property of a new Mn(Ⅱ)complex,[Mn3L3(phen)2]n(1).

Scheme 1 Molecular structure of H2L ligand

1 Experimental

1.1 Materials and general methods

All solvents and starting materials for the synthesis were purchased commercially without further purification.H2L was obtained according to a rational procedure by 1,4-benzenebisthiol[17].The complex was obtained under hydrothermal reaction in a 25 mL Tefion-lined stainless steel Parr bomb.Data collection was performed on a Bruker SMART APEXⅡCCD diffractometer with Mo Kα radiation(λ=0.071 073 nm).Elementary analysis was performed on a EuroEA3000 element analyzer.IR spectrum was measured in KBr pellets on a Nicolet 5DX FTIR spectrometer.Thermogravimetric analysis(TGA)was performed at a rate of 10℃·min-1under oxygen stream using a Netzsch STA449C apparatus.The magnetic measurement was carriedoutwithaMPMSSQUID magnetometer Quantum Design SQUID MPMS XL-7 instruments working in the temperature range of 2～300 K at an applied field of 0.1 T.

1.2 Synthesis of[Mn3L3(phen)2]n

A mixture of H2L (0.103 g,0.4 mmol),MnCl2·4H2O (0.079 g,0.4 mmol),1,10-phen (0.040 g,0.2 mmol),and NaOH(0.032 g,0.8 mmol)in H2O(18 mL)was placed in a Tefion-lined stainless steel vessel and heated at 160℃for 72 h,then cooled to room temperature over 3 d.Block pink crystals of 1 were obtained and washed with water,dried in air(yield 48%).Anal.Calcd.for C54H40Mn3N4O12S6(%):C,50.12;H,3.12;N,4.33;S,14.86.Found(%):C,50.08;H,3.08;N,4.45;S,14.69.IR (KBr,cm-1):3 445,2930,1 601,1385,1209,1113,847,736,680,599,488.

1.3 X-ray crystallography

The diffraction data were collected on a Bruker SMART APEXⅡCCD diffractometer equipped with a graphite-monochromatized Mo Kα radiation (λ=0.071 073 nm)at 296(2)K.Intensity data were corrected by Lorentz-polarization factors and empirical absorption.The structure wassolved with direct methods and expanded with difference Fourier techniques.Except the hydrogen atoms on oxygen atoms were located from the difference Fourier maps,the other hydrogen atoms were generated geometrically.All calculations were performed using SHELXS-97[22]and SHELXL-97[23]program package.In the title complex,part of L2-ligands are disordered over two positions in 0.60∶0.40 ratio.Further details for structural analyses are summarized in Table 1,selected bond lengths and angles are listed in Table 2.

CCDC:734943.

Table 1 Crystal data and structure refinement for the complex

Table 2 Selected bond lengths(nm)and angles(°)for the complex

2 Results and discussion

2.1 Crystal structure

Single-crystal X-ray diffraction analysis revealed that the title complex is a 2D layer structure containing linear trinuclear Mn(Ⅱ)units.As shown in Fig.1,it consists of the trinuclear[Mn3(μ2-COO)6]unit,in which Mn(2)atom lies a crystallographic center at(0.25,0.25,0),and is six-coordinated by carboxylic O atoms from six different L2-ligands(Mn(2)-O 0.217 5(2),0.216 2(2),0.216 9(2)nm)to form an octahedral geometry.The Mn(1)is six-coordinated by four O atoms from three L2-ligands(Mn(1)-O 0.248 0(2),0.219 0(2),0.211 5(2),0.209 6(2)nm),and two N atomsfrom one phen molecule(Mn(1)-N 0.222 7(2)and 0.225 8(2)nm)to form a distorted octahedral geometry.Each pair of Mn(Ⅱ) atoms is μ-linked by three carboxylic groups of the individual L2-ligands with Mn(1)…Mn(2)distances of 0.3626(1)nm.The structure is similar to those found in [Mn3(ppei)2(OAc)6][24], [Zn3L3(2,2′-bipy)2][20], and[Co3(OAc)8][25].

Fig.1 Coordination environment of trinuclear Mn(Ⅱ)unit

As illustrated in Fig.2,the trinuclear[Mn3(μ2-COO)6]units are joined by flexible carboxyl O atoms to generate 2D networks.Notably,in this 2D layer,it consists of two kinds of link modes:single-stranded along b axis and double-stranded mode along c axis.To better understand this structure,the linear trinuclear Mn(Ⅱ)units serve as nodes,and the nodes are linked by carboxylic O atoms of L2-ligands,resulting in a 2D(4,4)net in the ab plane.

Fig.2 2D(4,4)net in ab plane

2.2 Magnetic property

From the magnetic point of view,the title complex can be considered as a linear trinuclear Mn(Ⅱ)system.The magnetic behaviourofthe title complex is illustrated in Fig.3 by meansofthe magnetic susceptibility(χmT)vs the temperature(T).The χmT value per Mn3gradually decreases from 12.18 cm3·mol-1·K at 300 K to 4.25 cm3·mol-1·K at 0.85 K.The μeffvalue (9.87μB)at room temperature is smaller thanthat of 10.25μBexpected for three independent Mn(Ⅱ)ions withS=5/2.This result reveals the overall antiferroma-gnetic character of the system.The Heisenberg spin Hamiltonian model for the isotropic magnetic exchange interaction in the linear trinuclear Mn(Ⅱ)unit is given inH=-2Jwhereand the numbering has been employed in Fig.1.Take into account the fact that the magnetic coupling except Mn3unit is weak,using the contributions of intermole-cular force in the fit.Then the temperature dependence of the magnetic susceptibility is given by the equation:

A=35+84e5x+35e-2x+10e-7x+165e10x+84ex+35e-6x+10e-11x+e-14x+286e15x+165e4x+84e-5x+35e-12x+10e-17x+e-20x+455e20x+286e7x+165e-4x+84e-13x+35e-20x+10e-25x+680e25x+455e10x+286e-3x+165e-14x+84e-23x+35e-30x;B=6+8e5x+6e-2x+4e-7x+10e10x+8ex+6e-6x+4e-11x+2e-14x+12e15x+10e4x+8e-5x+6e-12x+4e-17x+2e-20x+14e20x+12e7x+10e-4x+8e-13x+6e-20x+4e-25x+16e25x+14e10x+12e-3x+10e-14x+8e-23x+6e-30x.x=J/(kT).The best-fit parameters obtained:J=-1.95(5)cm-1,g=1.98(1),zJ′=-0.41(1)cm-1,andR=9.8×10-6.The variation of χm-1also is well described by the Curie-Weiss law in the experimental temperature range 2～300 K withC=12.97 cm3·mol-1·K and θ=-25.056 K.The negativeJand θ values further indicate a weak antiferromagnetic interaction in the linear trinuclear Mn3unit.The spin-exchange interaction is comparable to that of the other with the similar structure[26-28].

Fig.3 Plots of the χmTand χm-1(inset)vsTfor the title complex

2.3 Thermogravimetric analysis

To study the stability of the title complex,thermogramimetric analytical (TGA)was performed.The TGA curve exhibits two steps of weight losses(Fig.4).It displays a high thermal stability,as there is no significant weight loss up to 315℃.An initial weight loss of 30.41%occurred between the temperature range of 315～420℃ corresponds to the removal of two phen molecules(calcd 30.63%),The second weight loss of 58.95% (calcd.59.81%)in the range of 480～575 ℃ is consistent with the removal of three L2-ligands.The remaining products may be MnO.

Fig.4 TGA curve of the title complex

In summary,we have successfully synthesized a new Mn(Ⅱ)complex based on 1,4-benzenebis(thioacetic acid)ligand under hydrothermal conditions.It is a 2D layered architecture which consists of linear trinuclear[Mn3(μ2-COO)6]units.Variable temperature magnetic susceptibility indicates the existence of a weak antiferromagnetic interactions in the linear trinuclear unit.

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基于柔性1，4-苯二硫乙酸配體構筑的二維錳配合物的合成、晶體結構及磁性

王曉娟 尹建玲 陳 靜 馮云龍＊

(浙江師范大學物理化學研究所，浙江省固體表面反應化學重點實驗室，金華 321004)

水熱法合成了一個基于1，4-苯二硫乙酸(H2L)柔性配體的Mn(Ⅱ)配合物[Mn3L3(phen)2]n，并通過元素分析，紅外光譜、熱失重和X-射線單晶衍射實驗對其結構進行了表征。結構分析表明，配合物是一個包含三核錳結構單元的二維層面結構。對配合物的變溫磁化率研究表明，在三核錳離子間存在弱的反鐵磁交換作用。

Mn(Ⅱ)配合物；水熱合成；1，4-苯二硫乙酸；晶體結構；磁性

O614.7+11

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：1001-4861(2011)02-0367-05

2010-09-14。收修改稿日期：2010-10-11。

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