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A 3-D metal-organic coordination polymer based on pyrazine-2,3-dicarboxylic acid (pzdcH₂) formulated as {[Mn(pzdc)(H₂O)₂] · 2H₂O}n (1), was obtained by the treatment of MnCl₂ · 6H₂O with pzdcH₂, 8-hydroxy quinoline (8-HQ), and 2-amino-4-methyl pyridine (ampy). In this study, we describe the synthesis, elemental analysis, IR spectroscopy, TG analysis, and single X-ray diffraction. The X-ray single crystal structure reveals that the chemical environment around each Mn(II) is a distorted octahedral by participating one nitrogen, five oxygens from three (pzdc)²⁻ and two water molecules, O₅MnN. The centrosymmetric 1-D ladder-like structure of 1 is bridged by oxygens of (pzdc)²⁻, and Mn-pzdc-Mn bonds are the rungs for our ladder structure. In the crystal structure, intermolecular O-H ··· O hydrogen bonds result in the formation of a supramolecular structure, effective for the stabilization of the structure. The thermal decomposition of 1 indicates that it is quite thermally stable. The protonation constants of ampy, 8-HQ and pzdcH₂ as the building blocks of proton transfer systems including pzdcH₂-ampy and pzdcH₂-8-HQ and the corresponding stability constants of these systems were determined by potentiometric study. The stoichiometry and stability constants of complexes of pzdcH₂-ampy and pzdcH₂-8-HQ with Mn²⁺ were investigated by this method in aqueous solution. The results obtained from solution study are comparable with the solid state results.

Heterometallic oxides are used as materials in many applications, e.g. from ferroelectrics to superconductors. Making these compounds usually requires high temperatures and long reaction times. Molecular precursors may contribute to render their processing shorter and accessible at lower temperatures, thus cheaper in energy and time. In this review article, different approaches toward oxide materials will be shown, starting with homometallic clusters and coordination polymers and highlighting recent results with heterometallic single source precursors. On the way to the latter, we came across many exciting results which themselves allowed applications in different fields. This work will give an overview on how these fields were brought together for the current mixed metallic compounds as precursors for heterometallic oxides.

The syntheses of H₂-phbpz, [Cu₂(phbpz)]·2DEF·MeOH (CFA-2) and [Ag₂(phbpz)] (CFA-3) (H₂-phbpz = 3,3′,5,5′-tetraphenyl-1H,1′H-4,4′-bipyrazole) compounds and their crystal structures are described. The Cu(I) containing metal–organic framework CFA-2 crystallizes in the tetragonal crystal system, within space group I4₁/a (no. 88) and the following unit cell parameters: a = 30.835(14), c = 29.306(7) Å, V = 27 865(19) ų. CFA-2 features a flexible 3-D three-connected two-fold interpenetrated porous structure constructed of triangular Cu(I) subunits. Upon exposure to different kinds of liquids (MeOH, EtOH, DMF, DEF) CFA-2 shows pronounced breathing effects. CFA-3 crystallizes in the monoclinic crystal system, within space group P2₁/c (no. 14) and the following unit cell parameters: a = 16.3399(3), b = 32.7506(4), c = 16.2624(3) Å, β = 107.382(2)°, V = 8305.3(2) ų. In contrast to the former compound, CFA-3 features a layered 2-D three-connected structure constructed from triangular Ag(I) subunits. Both compounds are characterized by elemental and thermogravimetric analyses, single crystal structure analysis and X-ray powder diffraction, FTIR- and fluorescence spectroscopy. Preliminary results on oxygen activation in CFA-2 are presented and potential improvements in terms of framework robustness and catalytic efficiency are discussed.

A new series of ligands in which nicotinic acid was linked to different monomethyloligoethers and their corresponding silver complexes were prepared. The crystal structures of the silver compounds were investigated to determine the effect of increasing flexibility of the ligands on coordination to the metal ion and crystal packing. We observed the formation of one-dimensional coordination polymers for the shortest ligand derived from monoethylene glycol, the formation of stacks for the diethylene-glycol-based ligand with silver triflate, and even a helical structure for the triethylene-glycol-derived ligand complex. The three ligands, ([C₉H₁₁O₃N] (L1), [C₁₁H₁₅O₄N] (L2), and [C₁₃H₁₉O₅N] (L3)), and the four new complexes, [Ag(L1)₂(NO₃)] (1), [Ag(L1)₂(SO₃CF₃)] (2), [(Ag(L2)₂(SO₃CF₃)] (3), and [Ag(L3)₂]PF₆ (4)), are presented in this paper along with an analysis of their structural features.

Reaction of commercially available tetraethylene glycol with different alkaline earth metal halides affords tetraethylene glycol complexes with different coordination numbers at the metal ion and structural features; depending on the ionic radius of the metal ion, one or two ligand molecules will be coordinated to the metal ion. In this article we will first present complexes with Mg²⁺([Mg(C₈H₁₈O₅)(H₂O)₂]Cl·I) (1), Ca²⁺([Ca(C₈H₁₈O₅)·3H₂O]Cl₂ (2), [Ca(C₈H₁₈O₅)(H₂O)₂]I₂ (3), [Ca(C₈H₁₈O₅)(H₂O)₃]I₂·H₂O (4), ([Ca(C₈H₁₈O₅)(H₂O)₃]Cl·I) (5),Sr²⁺ ([Sr(C₈H₁₈O₅)(H₂O)₄]Cl₂ (6), [Sr(C₈H₁₈O₅)₂]I₂·CHCl₃) (7) and Ba²⁺ ([Ba(C₈H₁₈O₅)₂]I₂) (8). Secondly we will show preliminary tests for the combustion of some selected compounds and their thermal decomposition behavior. Furthermore, selected compounds were evaporated by MOCVD (metal organic chemical vapor deposition) to evaluate their capacity as future single source precursors for oxide materials.

A 3-D metal-organic coordination polymer based on pyrazine-2,3-dicarboxylic acid (pzdcH₂) formulated as {[Mn(pzdc)(H₂O)₂] · 2H₂O}n (1), was obtained by the treatment of MnCl₂ · 6H₂O with pzdcH₂, 8-hydroxy quinoline (8-HQ), and 2-amino-4-methyl pyridine (ampy). In this study, we describe the synthesis, elemental analysis, IR spectroscopy, TG analysis, and single X-ray diffraction. The X-ray single crystal structure reveals that the chemical environment around each Mn(II) is a distorted octahedral by participating one nitrogen, five oxygens from three (pzdc)²⁻ and two water molecules, O₅MnN. The centrosymmetric 1-D ladder-like structure of 1 is bridged by oxygens of (pzdc)²⁻, and Mn-pzdc-Mn bonds are the rungs for our ladder structure. In the crystal structure, intermolecular O-H ··· O hydrogen bonds result in the formation of a supramolecular structure, effective for the stabilization of the structure. The thermal decomposition of 1 indicates that it is quite thermally stable. The protonation constants of ampy, 8-HQ and pzdcH₂ as the building blocks of proton transfer systems including pzdcH₂-ampy and pzdcH₂-8-HQ and the corresponding stability constants of these systems were determined by potentiometric study. The stoichiometry and stability constants of complexes of pzdcH₂-ampy and pzdcH₂-8-HQ with Mn²⁺ were investigated by this method in aqueous solution. The results obtained from solution study are comparable with the solid state results.

Heterometallic oxides are used as materials in many applications, e.g. from ferroelectrics to superconductors. Making these compounds usually requires high temperatures and long reaction times. Molecular precursors may contribute to render their processing shorter and accessible at lower temperatures, thus cheaper in energy and time. In this review article, different approaches toward oxide materials will be shown, starting with homometallic clusters and coordination polymers and highlighting recent results with heterometallic single source precursors. On the way to the latter, we came across many exciting results which themselves allowed applications in different fields. This work will give an overview on how these fields were brought together for the current mixed metallic compounds as precursors for heterometallic oxides.

The multitopic ligand O,O′-bisnicotinic acid tetraethylene glycol, L, was designed for the coordination of two distinct types of metal ions. In this work, we describe how the O-donor part of L is used to coordinate to alkaline earth metal ions and that the N-donor atoms of L bind to group 11 elements. This makes L a suitable ligand for the combination of both metal ion types within the same compound. This concept will be exemplified by highlighting the pure Ca²⁺ complexes, a Cu⁺-coordination polymer network, as well as the mixed-metal compound, which can be used as a single-source precursor for mixed-metal oxide materials.