Ana Belén Lago

From copper(II) carboxylate to copper(II) 4-pyridylsulfonate coordination polymers as a consequence of the copper(II)-assisted oxidative cleavage of the 4,4′-dipyridyldisulfide ligand

Five coordination polymers 1 {[Cu4(HCO2)6(OH)2(4dpds)2]·2CH2Cl2}n, 2 {[Cu4(CH3CO2)6(OH)2(4dpds)2]}n, 3 {[Cu(4dpds)2(H2O)2](4pySO3)2·2H2O}n, 4 {[Cu(4pySO3)2(4dpds)2]·2H2O}n and 5 {[Cu(4pySO3)2(dmso)2]·2H2O}n (where 4dpds = 4,4′-dipyridyldisulfide, 4pySO3 = 4-pyridylsulfonate) have been obtained during a study into the reactivity of basic copper(II) salts (formate and acetate) with 4,4′-dipyridyldisulfide (4dpds). The coordination polymers 1 and 2 consist of a repeated rhomboid structure in which analogous Cu4(RCO2)6(OH)2 cores are joined by two 4,4′-dipyridyldisulfide bridging ligands to generate two different chain topologies: planar ribbon in 1 and ruffled ribbon in 2. 4-Pyridylsulfonate ions appear as ligands or counterions in the coordination polymers 3, 4 and 5 due to oxidative cleavage of the 4,4′-dipyridyldisulfide under mild conditions. The coordination polymer 3 has been isolated repeatedly in several direct reactions of the copper(II) carboxylates with 4,4′-dipyridyldisulfide. However, the coordination polymers 4 and 5 have been obtained from 1 and 2, respectively, by recrystallization from DMF and DMSO. In compound 4, as in 3, the 4,4′-dipyridyldisulfide has only been partially oxidized to 4-pyridylsulfonate and a proportion of these units remain in the structure as disulfide. However, in 5 the oxidation is complete. The structural analysis of these coordination polymers reveals that, in all cases, weak interactions such as classical and non-classical hydrogen bonds, as well as CH⋯π, S⋯π and S⋯O interactions, join the polymeric chains to generate three-dimensional networks.

Control over the preparation of two pH-dependent Cu(II) supramolecular isomers based on 1,3,5-benzenetricarboxylic acid and the bis(4-pyridylthio)methane ligand

The possibility of controlling the formation of copper(II) coordination polymers based on the rigid carboxylate ligand 1,3,5-benzenetricarboxylic acid (H3btc) and an N,N-divergent spacer with conformational flexibility, bis(4-pyridylthio)methane (SCS), was investigated. The new coordination polymers 1∞[Cu(H2btc)2(SCS)] (1) and 2∞[Cu(Hbtc)(SCS)2]·H2O (2) have been prepared and characterized. Compounds 1 and 2 were obtained as a mixture and optimization of the synthetic conditions allowed the isolation of pure phases in high yield. Topological analysis showed the interpenetration of three networks with a vcm-type topology in 2. The thermal stability and the structural dynamics of these systems have also been investigated.

Homo‐ and Heteronuclear Compounds with a Symmetrical Bis‐hydrazone Ligand: Synthesis, Structural Studies, and Luminescent Properties

Nine new coordination compounds have been synthesized by the reaction of salts of bivalent metal ions (a=Zn(II) , b=Cu(II) , c=Ni(II) , d=Co(II) ) with the bis(benzoylhydrazone) derivative of 4,6-diacetylresorcinol (H4 L). Three kinds of complexes have been obtained: homodinuclear compounds [M2 (H2 L)2 ]⋅nH2 O (1 a, 1 b, 1 c, and 1 d), homotetranuclear compounds [M4 (L)2 ]⋅n(solv) (2 a and 2 c), and heterotetranuclear compounds [Zn2 M2 (L)2 ]⋅n(solv) (2 ab, 2 ac, and 2 ad). The structures of the free ligand H4 L⋅2 DMSO and its complexes [Zn2 (H2 L)2 (DMSO)2 ] (1 a*), [Zn4 (L)2 (DMSO)6 ] (2 a*), and [Zn0.45 Cu3.55 (L)2 (DMSO)6 ]⋅2 DMSO (2 ab*) were elucidated by single-crystal X-ray diffraction. The ligand shows luminescence properties and its fluorimetric behavior towards M(II) metals (M=Zn, Cu, Ni and Co) has been studied. Furthermore, the solid-state luminescence properties of the ligand and compounds have been determined at room temperature. (1) H NMR spectroscopic monitoring of the reaction of H4 L with Zn(II) showed the deprotonation sequence of the OH/NH groups upon metal coordination. Heteronuclear reactions have also been monitored by using ESI-MS and spectrofluorimetric techniques.

Metallosupramolecular compounds based on Cu(II)/oxalate/twisted NSSN ligands showing a new in situ S–C bond cleavage

Four new complexes, [Cu2(C2O4)2(SCS)]·3H2O (1), [Cu2(C2O4)3(SCSH)2]·H2O (2), [Cu(C2O4)(SS)2]·3H2O (3) and [Cu(C2O4)(SS)]·6H2O (4) [where SCS = bis(4-pyridylthio)methane and SS = 4,4′-dipyridyldisulfide], have been synthesized by the reaction of the SS and SCS ligands with the corresponding copper(II) oxalate salt. The different synthetic conditions allowed control of the preparation of a 3D open metal–organic framework in 1, a dinuclear zwitterionic molecular compound in 2 and one- and two-dimensional (1D and 2D) coordination polymers in 3 and 4, respectively. Compound 4 was also obtained by in situ transformation of the dithioether ligand (SCS) to the disulfide ligand (SS) under hydrothermal conditions at 150 °C. The topology of the structures has been studied and 1 is a new 3D MOF with a binodal 4-connected node in a scarcely known network topology. Different numbers and topologies of water molecules are hosted in the crystal lattices of the compounds. The integrity of the frameworks after dehydration has been validated and discussed. The magnetic properties of compounds 1, 2 and 4 have also been investigated. Strong antiferromagnetic behaviour was found in 1 and weak antiferromagnetic coupling was observed in 2 and 4. The magneto-structural correlations that govern these interactions are discussed in detail.

Mononuclear discrete complexes and coordination polymers based on metal(II) chelidonate complexes with aromatic N,N-chelating ligands†

The versatile coordination chemistry of the anion chelidonate (chelidonic acid, H2chel, 4-oxo-4H-pyran-2,6-dicarboxylic acid) allowed for the synthesis of different mixed-ligand complexes with the N,N′-chelating ligands 2,2′-bipyridine and 1,10-phenanthroline. We describe here the synthesis and structural characterization of a series of compounds that illustrate the structural diversity of which 4-oxo-4H-pyran-2,6-dicarboxylate ligands are capable: the 2D coordination polymer [Cu(chel)(bipy)] (1), the 1D coordination polymer [Zn(chel)(bipy)(OH2)]·1/2H2O (2), the discrete neutral mononuclear compounds [Zn(chel)(phen)(OH2)2] (3) and [M(chel)(phen)(OH2)3]·nH2O, M = Zn and n = 1 (4), M = Ni and n = 2 (5), and the discrete mononuclear cationic complex [Zn(OH2)2(phen)2]chel·3.3H2O (6). The effects of the weak interactions on the crystal packing were also analyzed. The thermal behaviour of the hydrated compounds was investigated. The study of the magnetic properties of 1 revealed weak antiferromagnetic coupling between the copper(II) centres.

Metal coordination and in situ S–C bond cleavage of the bis(2-pyridylthio)methane ligand

The compound [2bpytmH](2)[I(3)](2)[I(2)], which contains protonated 2bpytm, and four neutral monomeric complexes [CoCl(2)(2bpytm)]·H(2)O (1), [CoBr(2)(2bpytm)] (2), [CoI(2)(2bpytm)]·1/2H(2)O (3) and [NiBr(2)(2bpytm)]·H(2)O (4) have been obtained during a study into the reactivity of the bis(2-pyridylthio)methane (2bpytm) ligand towards cobalt(II) and nickel(II) halides. Furthermore, a cyclic dimer [CuBr(2)(2bpytm)](2) (5) and a 1D polymer [CuBr(2)(2bpytm)](n)·CH(3)CN (6) have been obtained from copper(II)/(I) bromide salts. An unprecedented S-CH(2)-S activation and cleavage in 2bpytm has been observed on using copper(II) salts with organic and voluminous inorganic anions. The cleavage of 2bpytm enabled the isolation of copper(II) complexes containing the in situ generated ligands 2-pyridinethiolate, 2-pyridinesulfenate or 2-pyridinesulfonate.

Stabilization of Discrete (H2O)14 Water Clusters in the Supramolecular Crystal Host of [Ni(phen)3](HB)2 · 7H2O (HB−=benzilate)

A discrete tetradecameric water cluster has been observed in the lattice of [Ni(phen)3](HB)2 · 7H2O, HB=benzilate (diphenylglycolate). The cluster, which is based on one cyclic tetramer and two acyclic pentamers, is entrapped in the hydrogen‐bonded layer constructed by the benzilate anions and the water molecules. This layer is located between two hydrophobic layers generated by association of [Ni(phen)3]+ cations through π‐π interactions.

Molecular metallocycles, acyclic metallodimers and 2D coordination polymers containing the twisted ligand bis(pyrimidin-2-ylthio)methane.

The versatile coordination chemistry of bis(pyrimidin-2-ylthio)methane (bptm) allows the synthesis of a series of different metal complexes with diverse structures. We describe here the synthesis and structural characterization of three kinds of compounds: four cyclic dimers, [Co(2)Cl(4)(bptm)(2)] (1), [Zn(2)I(4)(bptm)(2)] (2), [Cd(2)I(4)(bptm)(2)] (3), [Cu(2)(NO(3))(4)(bptm)(2)] (4); two acyclic dimers, [Cu(2)Br(4)(bptm)(3)] (5), [Cu(2)(AcO)(4)(bptm)(2)] (6); and two 2D coordination polymers, [CuBr(bptm)] (7) and [CuI(bptm)] (8). Different structural models are obtained on making small changes in the building units under different synthetic conditions. The effects of the weak interactions in the crystal packing were also analyzed.

Chiral and achiral 1D copper(II) coordination polymers based on glycolato and chelating aromatic diamine ligands

Achiral glycolic acid and chelating aromatic diamine ligands were employed at room temperature to prepare five 1D copper(II) coordination polymers which were structurally characterized. The polymers ∞1{[Cu(HG)(dipyam)](HG)} (1) (dipyam = 2,2′-dipyridylamine) and ∞1[Cu(HG)(ClO4)(NN)] (NN = 2,2′-bipyridine (2), NN = 1,10-phenanthroline (3)) adopt homochiral helical structures in the crystal state and undergo spontaneous chiral resolution in the solid state. On the other hand, the polymers containing bidepronated glycolato ligand G, ∞1{[Cu(G)(dipyam)]·H2O} (1a), obtained from a solution of 1 in MeOH/iPrOH and ∞1{[Cu2(μ-G)(ClO4)(H2O)(dipyam)2](ClO4)(H2O)2} (4b) are achirals. Crystals of 4b have been obtained together with crystals of the molecular complex [Cu(HG)(H2O)(dipyam)](ClO4) (4a). Analysis by Hirshfeld surface generation and two-dimensional fingerprinting was carried out to study the nature of the interactions and their contributions towards the crystal packing.

A Hexameric Cationic Copper(II) Metallacrown as a Pertechnetate and Perrhenate Scavenger

Materials based on the cationic copper(II) hexanuclear 18-membered metallacrown [18-MCCuII-N(2ph)-6](6+) (2phH=2-piconyl hydrazide) and tetrafluoroborate, perchlorate, nitrate, sulfate, and perrhenate anions were prepared by an easy method in aqueous medium. Single-crystal X-ray characterization of six members of this new family of complexes showed that the anions are attached to the metallacrown by direct coordination to a copper cation or by hydrogen-bonding interaction with the center of the hexamer. The stable cationic nature of the complexes and their ability to bind different anions allows them to adsorb and immobilize environmentally relevant anions such as MO4(-) (M=Tc, Re). The MO4(-) trapping capacities suggest that these materials would be useful in the treatment of oxoanionic contaminants in water.