【作者】 张道鹏；

【导师】 姜建壮；

【作者基本信息】 山东大学 ， 无机化学， 2010， 博士

【摘要】 分子磁性的研究是一门涉及化学、物理、材料和生命科学等诸多学科的新兴交叉研究领域,其主要任务是研究和阐明分子体系中自旋载体之间的磁耦合本质,揭示分子磁性与结构的关系,发现和研究复杂的磁现象,设计和合成新的分子基磁材料,如单分子磁体和单链磁体,高相变温度(Tc)磁材料、自旋交叉材料和光-磁、电-磁多功能复合材料。目前,分子磁性研究由于其广阔的应用前景和重要的理论意义,已经得到了全世界科学工作者的密切关注。本论文的主要目的在于通过选择和开发合适的氰根前躯体及各种含有磁性离子的自旋载体,研究他们之间在不同条件下的反应,来合成具有新颖结构的氰根桥联配合物,并对其结构和磁学性质进行详细的研究,以期得到性质优良的分子磁性材料。主要研究内容如下：1.研究了四苯基卟啉及其含有各种取代基的衍生物的锰的配合物,包括-NO2,Cl,MeO-,(CH3)2N-等,与含有两个氰根的构筑单元trans-K[M(L)(CN)2](MⅢ=Fe,Cr,Co；L=bpb2-,bpmb2-)的反应,得到了6个氰根桥联的三核三明治型(MⅢ-MnⅢ-MⅢ)配合物和4个双核FeⅢ-MnⅢ配合物。用元素分析、红外光谱等手段进行了表征,并解析了它们的单晶结构。结构研究表明,四苯基卟啉赤道方向的取代基的电性和体积对于配合物的结构具有明显的影响。磁性研究结果表明,所有氰根桥联FeⅢ-MnⅢ配合物为铁磁耦合,而CrⅢ-MnⅢ配合物中Cr离子与Mn离子间则表现为反铁磁耦合。对于Fe-Mn配合物的低温交流磁化率测量表明,该类配合物的交流磁化率的实部和虚部随温度的变化表现出明显的频率依赖性,说明此类化合物在低温下极可能是单分子磁体。研究了四苯基卟啉锰与trans-[PPh3(PhCH2)][Ru(acac)2(CN)2]的反应,得到了两个一维氰根桥联的RuⅢ-MnⅢ配合物。有意思的是两个配合物中除含有交替的Ru-Mn中性一维链以外,都含有共结晶的大的阳离子([PPh3(PhCH2)]+)和阴离子(ClO4-,PF6-)。对其磁化率和变场磁化强度的研究表明,氰根桥联RuⅢ-MnⅢ之间为铁磁耦合。交流磁化率研究发现,这两个配合物的交流磁化率的实部和虚部在3K以下表现出明显的频率依赖性。对于其磁性的进一步研究表明,在1.6K以下可观察到经典磁体的磁滞行为,从而证明这两个氰根桥联配合物为典型的单链磁体。这也是迄今为止第一例基于锰卟啉的氰根桥联杂自旋单链磁体。2.研究了希夫碱类锰配合物与五氰根或者六氰根构筑单元[Mg(1-CH3im)2(H2O)2Fe(CN)5(1-CH3im)]-H2O, K3[Cr(NO)(CN)5], [Et4N]3[Fe(CN)6], K3[Cr(CN)6]的反应,得到了两个四核氰根桥联的FeⅢ-MnⅢ配合物,两个七核氰根桥联FeⅢ／CrⅢ-MnⅢ配合物和三个氰根桥联二维FeⅢ-MnⅢ,CrⅢ-MnⅢ,CrⅠ-MnⅢ配合物。用元素分析、红外光谱等手段进行了表征,并解析了它们的单晶结构。结构研究表明,希夫碱配体上的取代基的位置,大小和氰根前躯体的电荷以及氰根的数目都对配合物的结构有明显的影响。其中,两个四核配合物的构型为以Fe为中心的“T”型,七核配合物则是以Fe或Cr作为体心的立方盒状构型,两种配合物中分别以ClO4-或[M(CN)6]3-(M=Fe,Cr)作为平衡离子。值得注意的是,在这几个配合物中,离子型配合物单元之间通过锰离子轴向配位水与相邻单元酚氧原子之间的氢键作用形成了一维梯子状双链结构和三维立体网状结构。磁性研究表明,所有氰根桥联Fe-Mn配合物中FeⅢ-MnⅢ之间为铁磁耦合,而CrⅢ-MnⅢ和CrⅠ-MnⅢ之间为反铁磁耦合。由于分子间相对较强的氢键磁性传递作用,使得几个氰根桥联多核配合物在低温时表现出典型的变磁行为。对于几个氰根桥联的二维配位聚合物的磁性研究表明,这几个化合物在低温下也表现出典型的三维反铁磁有序的变磁体行为。3.研究了trans-K[Fe(bpb)(CN)2], trans-K[Fe(bpClb)(CN)2], trans-K[Fe(bpdBrb)(CN)2], K[Ag(CN)2]和K[Au(CN)2]与十五元大环七配位二价锰配合物的反应,得到了9个氰根桥联的FeⅢ-MnⅡ,AgⅠ-MnⅡ,AuⅠ-MnⅡ配合物。用元素分析、红外光谱等手段进行了表征,并解析了它们的单晶结构。结构研究表明,这九个化合物皆为一维氰根桥联单链结构,组成为交替的Fe-Mn或Ag／Au-Mn阳离子型一维链,以阴离子ClO4-,[Ag(CN)2]-或[Au(CN)2]-作为平衡离子。磁性研究表明,Fe-Mn配合物中FeⅢ与MnⅡ之间通过氰根传递的是反铁磁耦合,而Ag／Au-Mn配合物中MnⅡ-MnⅡ间通过[Ag(CN)2]-或[Au(CN)2]-表现出很弱的反铁磁作用。4.设计合成了一个新的氰根前躯体trans-K[FeSalen(CN)2],并且对其结构进行了表征。以其作为氰根构筑单元与Mn(bipy)Cl2, Mn(phen)2Cl2及大环七配位二价锰配合物反应,得到了两个三核,两个一维氰根桥联FeⅢ-MnⅡ配合物。用元素分析、红外光谱等手段进行了表征,并解析了它们的单晶结构。结构研究表明,平面型大环锰配合物更易于形成氰根桥联的一维结构,而对于空间位阻比较大的联吡啶和邻非罗琳配体来说,则更易形成三核配合物。对他们的磁性研究表明,氰根桥联的FeⅢ离子与MnⅡ之间的磁耦合是反铁磁的。研究了trans-K[Fe(bpb)(CN)2],trans-K[Fe(bpmb)(CN)2]和trans-K[Fe(bpClb)(CN)2]与[Mn(acac)2]ClO4的反应,得到了四个氰根桥联FeⅢ-MnⅡ配合物。反应中,MnⅢ被还原为MnⅡ,轴向与两个氰根前躯体的氰根氮原子配位,形成三核夹心型结构。对其磁性研究表明,FeⅢ-MnⅡ之间为表现为反铁磁耦合。本文研究了18个氰根构筑单元与锰卟啉类配合物,锰希夫碱类配合物,平面型大环锰配合物以及其他锰化合物之间的反应,得到了四十多个具有不同结构的氰根桥联异金属配合物。通过用元素分析、红外光谱以及X-射线单晶衍射等手段进行了表征。对所有配合物的结构和磁性进行了详细的研究。为进一步探索氰根桥联配合物的合成,以及有目的的设计合成单链磁体和单分子磁体提供了大量的实验依据和研究思路。更多还原

【Abstract】 The study of molecular magnetism is a new rising research field encompassing chemistry, physics, material science and life sciences, which the main task is to study and elucidate the magnetic coupling nature between the spin-carrier in the molecular system, reveal the correlation of structure and magnetism, find and study the complicated magnetism phenomenon, and design and synthesize new molecular-based magnetic materials, such as single-molecular magnet (SMM), single-chain magnet (SCM), high-Tc magnet, spin-crossover material, photomagnetic materials and elec-magnetic bifunctional materials, et al. It should be worth noting that, due to the wide application foreground and the important theoretical significance, the research of molecular magnetism has attracted intense attention of the molecular magnetism chemist over the world. The main purpose of this dissertation is to select and develop suitable cyanide-containing building blocks and all kinds of magnetic spin-carriers, synthesize cyanide-bridged complexes with novel structures by using them under different reaction conditions, and study their structure and magnetic properties with an aim to obtain excellent molecular magnetic materials. The main research contents are as follows:1. Six cyanide-bridged trinuclear sandwich-type MⅢ-MnⅢ-MⅢ(MⅢ= Fe, Cr, Co) complexes and four binuclear cyanide-bridged FeⅢ-MnⅢcomplexes have been synthesized by the reactions of six cyanide-containing building blocks trans-K[M(L)(CN)2](MⅢ= Fe, Cr, Co; L= bpb2-, bpmb2-) and five manganese(Ⅲ)-porphyrin compounds. All the complexes have been characterized by element analysis, IR spectra and X-ray diffraction. Single structure analysis reveal that both the electronic nature and the steric volume of the substituent groups coming from the equatorial plane of the porphyrin have obvious influence on the structure of the formed cyanide-bridged complexes. Investigation over magnetic properties of these heterometallic complexes reveals the ferromagnetic interaction between MnⅢand FeⅢmagnetic centers and antiferromagnetic coupling between MnⅢand CrⅢ. For the ac magnetic susceptibility measurement of cyanide-bridged FeⅢ-MnⅢcomplexes, there are obvious frequency-dependent out-of-phaseχm’ signals below 3.5 K, along with a clear frequency-dependent decrease in the in-phaseχm’signals, suggesting the SMM behavior of these complexes at low temperature.The trans-[PPh3(PhCH2)][Ru(acac)2(CN)2] has been employed firstly to synthesize cyanide-bridged complexes, and two cyanide-bridged alternated 1:1 RuⅢ-MnⅢcomplexes structurally characterized as single chain containing co-crystallized bulk anions and cations have been successfully assembled from the reaction of this cyanide precursor and [Mn(TPP)(H2O)2]+. Systematic investigation over their magnetic properties reveals the typical single-chain magnet (SCM) behaviors for both of them. To the best of our knowledge, this is the first example of heterobimetallic porphyrin-based SCM.2. A series of seven new cyanide-bridged heterometallic complexes including two tetranuclear FeⅢMnⅢ3 compounds, two heptanuclear MⅢMnⅢ6 (M= Fe, Cr) compounds, and three two-dimensional M-MnⅢ(M= FeⅢ, CrⅢ, CrⅠ) networks have been successfully assembled from four polycyanidemetalates containing five or six cyanide groups and two manganese(Ⅲ) building blocks containing bicompartimental Schiff base ligands. All the complexes have been characterized by element analysis, IR spectra and X-ray diffraction. Single structure analysis reveal that the structure of the tetranuclear FeⅢMnⅢ3 complexes can be characterized as "T"-like, while the structure of the two heptanuclear ones are cage-shaped. The structural difference between these complexes demonstrates the effect of the number of charge and cyanide groups of polycyanidemetlates as well as the position and size of substituted group at the Schiff base ligand on the structure of cyanide-bridged heterometallic complexes. It is worth noting that the cyanide-bridged polynuclear complexes are self-complementary through coordinated aqua ligand from one complex and the free O4 compartment from the neighboring complex, giving supramolecular one-dimensional ladders and three-dimensional networks. Investigation over magnetic properties of all the heterometallic complexes reveals the ferromagnetic interaction between MnⅢand FeⅢmagnetic centers and antiferromagnetic coupling between MnⅢand CrⅢor CrⅠions. Due to the relatively strong intermolecular hydrogen bond interactions, the several polynuclear cyanide-bridged complexes show some characters of metamagnet behavior at low temperature. The three complexes with two-dimensional structure exhibit three-dimensional antiferromagnetic ordering with typical metamagnetic behavior at low temperature. 3. Two mononuclear seven-coordinated macrocycle manganese(Ⅱ) compounds and five dicyanide-containing precursors have been employed as building blocks to assemble cyanide-bridged heterobimetallic complexes, resulting in nine new cyanide-bridged FeⅢ-MnⅡ, AgⅠ-MnⅡand AuⅠ-MnⅡsingle chain complexes. All the complexes have been characterized by element analysis, IR spectra and X-ray diffraction. Single X-ray diffraction analysis reveals their one-dimensional single cyanide-bridged cationic polymeric chain structure consisting of alternating units of [Mn(L)]2+(L represents the fifteen-membered ring ligands) and [Fe(L’)(CN)2]" (L’= bpb2-, bpClb2- or bpdBrb2-) or [Ag/Au(CN)2]- with free CIO4- or [Ag/Au(CN)2]- as balanced anion. Investigation over magnetic properties of these five one-dimensional single chain cyanide-bridged FeⅢ-MnⅡcomplexes reveals the antiferromagnetic magnetic coupling between neighboring FeⅢand Mn" ions through the bridging cyanide group, while very weak antiferromagntic interaction can be found between the MnⅡions bridged by [Ag/Au(CN)2]-in the cyanide-bridged AgⅠ-MnⅡand AuⅠ-MnⅡcomplexes.4. A new cyanide-containing precursor trans-K[Fe(salen)(CN)2]CH3OH (1) has been designed, synthesized and structurally characterized. Two cyanide-bridged trinuclear FeⅢ2MnⅡcomplexes and two one-dimensional cyanide-bridged FeⅢ-Mn" complexes have been successfully assembled from compound 1 and Mn(bipy)Cl2, Mn(phen)2Cl2 or two mononuclear seven-coordinated macrocycle manganeseⅡcompounds. All the complexes have been characterized by element analysis, IR spectra and X-ray diffraction. The structural difference between these complexes reveals that the macrocycle manganese(Ⅱ) compounds are facile for forming one-dimensional complexes, while other organic ligands with large steric volume, such as bipy and phen, are more prone to construct polynuclear complexes. Investigation over magnetic properties of these heterometallic cyanide-bridged FeⅢ-MnⅡcomplexes reveals the overall antiferromagnetic interaction between neighboring FeⅢand MnⅡions through the bridging cyanide group. Four cyanide-bridged trinuclear FeⅢ-MnⅡ-FeⅢcomplexes have been obtained by the reactions of trans-K[Fe(bpb)(CN)2],trans-K[Fe(bpmb)(CN)2], trans-K[Fe(bpClb)(CN)2] and [Mn(acac)2]ClO4. The antiferromagnetic coupling nature between the cyanide-bridged FeⅢion and Mn" ion in these complexes has been found.In this dissertation, eighteen cyanide-containing building blocks have been employed to react with manganese(III)-porphyrin compounds, manganese(III)-Schiff-base compounds, seven-coordinated macrocycle manganese(II) compounds and other manganese(II) compounds, and over forty cyanide-bridged complexes with different structures, including molecular clusters, one-dimensional chain, and two-dimensional network, were successfully synthesized, which have been characterized by element analysis, IR spectra and X-ray diffraction. The magnetic properties of all the complexes have been studied in detail. The results of this dissertation can afford lots of valuable experiment gists and research ideas for the further investigation of the synthesis of cyanide-bridged complexes with novel structural types and the rational design and synthesis of interesting molecular-based magnetic materials, such as SMM and SCM.更多还原