Solvothermal Synthesis of Oxamate-Based Helicate: Temperature Dependence of the Hydrogen Bond Structuring in the Solid

International audienceSolvothermal synthesis has been successfully tested as a new synthetic method towards the formation of oxamate-based coordination compounds. The reaction of 1,3-benzenedioxamic acid (H4mpba) with divalent metal ions has afforded the dinuclear compounds TBA2[Co2(H2mpba)3].2DMF.5H2O (1a), (HNEt3)2[Co2(H2mpba)3].6DMF.5H2O (1b), TBA2[Ni2(H2mpba)3].2DMF.2.5H2O (2) and (HNEt3)2[Co2(H2mpba)3] (3). Although the 3:2 ligand to metal ratio is known for the (mpba) 4-ligand under bench conditions these complexes are the first examples of oxamate-based helicate. Furthermore, crystalographic studies show a temperature-dependent hydrogen bond structuring that leads to racemic or chiral hexagonal 3D networks

Antiferromagnetic interactions in copper(II) mu-Oxalato dinuclear complexes: The role of the counterion

We report the preparation, crystal structure determination, magnetic properties and DFT calculations of five oxalato-bridged dicopper(II) complexes of formula [Cu-2(bpy)(2-)(H2O)(2)(C2O4)](CF3SO3)(2) (1), [Cu-2(bpy)(2)(C2O4)](PF6)(2) (2), [Cu-2(bpy)(2)(C2O4)](ClO4)(2) (3), [Cu-2(bpy)(2)Cl-2(C2O4)]center dot H2O (4) and [Cu-2(bpy)(2)(NO2)(2)(C2O4)] (5) (bpy = 2,2'-bipyridine and C2O42-= oxalate). Compounds 1, 2, 4 and 5 crystallize in the monoclinic system and 3 crystallizes in the triclinic system. The oxalate ligands in 1-5 adopt the bis-bidentate coordination mode and the two bpy molecules act as terminal ligands. The coordination of the counterions and the surroundings of the copper(II) ions differentiate the five compounds. The four nearest neighbours of copper(II) in 1-4 are roughly in the plane of the CuC2O4Cu framework, whereas they are in an almost perpendicular plane in 5. Using the isotropic Hamiltonian H = -JS(1)center dot S-2, where S-1 and S-2 are the spin quantum operators for Cu-1 and Cu-2; J is -384 cm(-1) for 1, -392 cm(-1) for 2 and -387 cm(-1) for 3, slightly decreasing to -328 cm(-1) for 4 and falling to -14 cm(-1) for 5. The influence of the anions on the magnetic properties of this family of compounds is explained by the changes in the overlap of the magnetic orbitals through the oxalate bridge. DFT calculations reproduce well the experimental values of J and provide an illustration of the magnetic orbitals

A cyanide and hydroxo-bridged nanocage: a new generation of coordination clusters

International audienceCombining serendipitously-formed hydroxo-clusters, [CoII3(OH)(piv)4(L)]+ (where L = MeCN or Hpiv), with assembling cyanide building block, [FeIII(Tp)(CN)3]−, has led to an unprecedented architecture where polymetallic cobalt clusters and blocked tris-cyanide iron complexes define the apexes of a unique magnetic cubic nanocage

Combining Cyanometalates and Coordination Clusters: An Alternative Synthetic Route toward Original Molecular Materials

International audienceWith the discovery of molecules or molecule-based compounds that can display blocked magnetization, magnetic ordering or switchable magnetic bistability, the research efforts devoted to molecular magnetic materials have considerably increased over the past two decades, fully exploiting the advantages of the bottom-up approach. 1-4 This research field focuses on promising properties for potential technological applications such as information storage, quantum computing and spintronics at the molecular scale, but it also provides fundamental insights into original quantum phenomena. 5,6 Coordination chemists have developed efficient synthetic tools for the preparation of interesting magnetic systems

Design, Self-Assembly, and Molecular Structures of 3D Copper(II) Capsules Templated by BF4- Guest Anions

International audienceThe synthesis of two 3D M2L4 copper(II) capsules, [BF4⊂(CH3CN)2Cu2(L1)4][BF4]3 (1) and [BF4⊂(BF4)2Cu2(L1)4][BF4] (2), by using 1,3-(benzimidazol-1-ylmethyl)-2,5-dimethoxy-4,6-dimethylbenzene (L1) as a semirigid exobidentate ligand and [Cu(CH3CN)4][BF4]2 as a metallobrick is reported. Single-crystal X-ray diffraction studies show the encapsulation of a BF4- anion in 1 and 2. Moreover, 2 displayed three coordinated BF4- anions, which is rare in supramolecular coordination host-guest chemistry. Remarkably, in both metallocages the weakly coordinated BF4- anion acts as a template and interacts with the metal center through a weak Cu···F contact. (\textcopyright Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009

Conformation and crystal packing sensitivity to substitution of thioxo- and oxo-tetrazane derivatives

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