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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >The ligand, the metal and the 'Holey'-host: Synthesis, structural and magnetic characterisation of Co(II), Ni(II) and Mn(II) metal-organic frameworks incorporating 4,4 '-dicarboxy-2,2 '-bipyridine
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The ligand, the metal and the 'Holey'-host: Synthesis, structural and magnetic characterisation of Co(II), Ni(II) and Mn(II) metal-organic frameworks incorporating 4,4 '-dicarboxy-2,2 '-bipyridine

机译：配体，金属和“ Holey”-主体：并入4,4'-dicarboxy-2,2'的Co（II），Ni（II）和Mn（II）金属-有机骨架的合成，结构和磁性表征-联吡啶

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摘要

We report herein the single crystal structures of four metal-organic framework complexes incorporating the 4,4'-dicarboxy-2,2'-bipyridine ligand, H(2)dcbp: alpha-[Co(dcbp)(H2O)(2)], 1; beta-[Co(dcbp)(H2O)(2)], 2, [Ni(dcbp)(H2O)(2)], 3 and {[Mn(dcbp)].1/2DEF}, 4 (DEF=diethylformamide). In each complex the ligand is deprotonated giving neutral species with 1:1 stoichiometry that form three-dimensional coordination polymers. Supramolecular isomerism (polymorphism) in 1 and 2 arises from the different ligand connectivity around the octahedral Co(II) centres. The two coordinated water molecules in 1 occupy cis positions, which are trans to the chelating bipyridine nitrogen atoms, leaving the carboxylate oxygen atoms in axial trans positions. In 2 all like donors occupy cis positions. Different modes of carboxylate coordination in 1 and 2 give dissimilar network topologies. A rare example of two interpenetrating 6(4)8(2)-b (quartz-like) chiral networks in 1 results from both dcbp carboxylate groups coordinating in a monodentate fashion to adjacent Co(II) centres, whereas in 2 only one carboxylate group bridges between adjacent Co(II) centres giving rise to a single chiral (10,3)-a net. In 1 and 2 the coordinated water molecules hydrogen bond to the non-coordinated carboxylate oxygen atoms. These interactions give rise to water-carboxylate double helices in 1, and support the coordination network in 2. Strikingly for a pair of dimorphs the crystal densities of 1 and 2 differ by ca. 0.3 g cm(-3) (1.654 vs. 1.940 g cm(-3), respectively). Compound 3 is isomorphous with 1 and likewise features two chiral interpenetrating nets of quartz topology. In 4, chelating bipyridine nitrogen atoms and four carboxylate oxygen atoms from a total of five adjacent dcbp ligands provide distorted octahedral geometry around Mn(II). The carboxylate groups bridge adjacent Mn(II) centres to produce bis-carboxylato chains which cross-link and generate a 3D network that is perforated with channels. The channels are occupied with disordered DEF molecules. The network topology in 4 is quite different to 1-3 and has a (4.6(2))(4(2).6)(4(3).6(6).8(6)) Schlafli notation. Magnetic susceptibility studies performed on 1, 2, {[Mn(dcbp)].1/2DMF} 5 (DMF=dimethylformamide) and {[Mn(dcbp)].2H(2)O) 6 reveal very weak antiferromagnetic coupling between the metal centres in each case.
机译：我们在这里报告的四个金属-有机框架配合物结合4,4'-di羧基-2,2'-联吡啶配体，H（2）dcbp的单晶结构：alpha- [Co（dcbp）（H2O）（2） ]，1; beta- [Co（dcbp）（H2O）（2）]，2，[Ni（dcbp）（H2O）（2）]，3和{[Mn（dcbp）]。1 / 2DEF}，4（DEF =二乙基甲酰胺）。在每个复合物中，配体都被去质子化，从而形成具有1：1化学计量比的中性物质，从而形成三维配位聚合物。 1和2中的超分子异构现象（多态现象）是由八面体Co（II）中心周围不同的配体连通性引起的。 1中的两个配位水分子占据顺式位置，顺式转移到螯合的联吡啶氮原子上，而羧酸盐的氧原子留在轴向反式位置。在2中，所有类似的供体都占据顺位。 1和2中不同的羧酸盐配位模式给出不同的网络拓扑。两个中互穿的6（4）8（2）-b（类石英）手性网络的罕见例子是两个dcbp羧酸盐基团以单齿方式与相邻的Co（II）中心配位，而在2个中只有一个羧酸盐相邻的Co（II）中心之间的组桥形成一个手性（10,3）-网。在1和2中，配位的水分子氢键合到非配位的羧酸氧原子上。这些相互作用在1中产生了水羧酸双螺旋，并在2中支持了配位网络。对于一对双晶型，惊人的是1和2的晶体密度相差约1。 0.3 g cm（-3）（分别为1.654和1.940 g cm（-3））。化合物3同构为1，并且同样具有两个石英拓扑的手性互穿网络。在图4中，来自总共五个相邻dcbp配体的螯合联吡啶氮原子和四个羧酸氧原子在Mn（II）周围提供了扭曲的八面体几何形状。羧酸酯基桥接相邻的Mn（II）中心，以产生双羧基链，该双羧基链交联并生成3D网络，该网络带有通道。通道被无序的DEF分子占据。 4中的网络拓扑与1-3完全不同，并具有（4.6（2））（4（2）.6）（4（3）.6（6）.8（6））Schlafli表示法。对1，2，{[Mn（dcbp）]。1 / 2DMF} 5（DMF =二甲基甲酰胺）和{[Mn（dcbp）]。2H（2）O）6进行的磁化率研究表明，铁氧体之间的反铁磁耦合非常弱金属中心。

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