Syntheses and crystal structures of cyano-bridged cluster-metal layered coordination polymers [Cu(dien)]3[W4Te4(CN)12] · 9H2O and [Ni(en)(NH3)]3[W4Se4(CN)12] · 7.5H2O

Two new tetrahedral tungsten cyanide cluster compounds, [Cu(dien)]₃[W₄Te₄(CN)₁₂] · 9H₂O (1) (dien=diethylenetriamine) and [Ni(en)(NH₃)]₃[W₄Se₄(CN)₁₂] · 7.5H₂O (2) (en=ethylenediamine), were synthesized by treating aqueous solutions of the saltlike cluster compound K₆[W₄Te₄(CN)₁₂] · 5H₂O/K₆[W₄Se₄(CN)₁₂] · 6H₂O with copper(II)/nickel(II) chloride in aqueous ammonia containing dien/en. The cyano-bridged layered coordination polymeric compounds were characterized by single-crystal X-ray diffraction analysis: monoclinic, space group P2₁ for 1; trigonal, space group for 2. Structures of 1 and 2 consist of infinite neutral layers of cluster components {W₄Te₄(CN)₁₂}/{W₄Se₄(CN)₁₂} connected, one another by {Cu(dien)} or {Ni(en)(NH₃)} fragments, respectively.     

Versatility of pyridine-2-methanol as a chelating ligand toward a manganese ion: synthesis and X-ray structural analysis on some manganese-pyridine-2-methanol derivatives

A systematic synthesis and X-ray structural analysis have been made for several manganese derivatives with pyridine-2-methanol as a chelating ligand; neutral Mn(C₅NH₄-2-CH₂OH)₂(C₆F₅CO₂)₂ (1), trans-[Mn(C₅H₄N-2-CH₂-OH)₂{C₆F₄-1,4-(CO₂)₂}]_∞ (2), cis-[Mn(C₅H₄N-2-CH₂-OH)₂{C₆F₄-1,3-(CO₂)₂}]_∞ (3), {Mn(C₅H₄N-2-CH₂-OH)₂(4,4^′-bipyridine)(ClO₄)}_∞ (4), and Mn(C₅H₄N-2-CH₂-OH)₃(ClO₄)₂(4,4-azopiridine) (pyridine-2-methanol) (5) are our results. 1 and 5 are monomers, while 2-4 are polymers. An oxidation state of the manganese ion in 1, 2, 3, and 5 is 2⁺, while that of 4 is suggested to be 3⁺. The magnetic data of 4 down to 2 K are measured. The length of the linker ligand has been suggested to afford a crucial effect on the dimensionality of the product.     

Novel cup-like helical coordination polymers: synthesis, crystal structures and thermal properties

By the design of ligand 1,1^′-(1,5-pentamethylene)bis-1H-benzimidazole (pbbm), we have synthesized polymers {[Co(NO₃)(pbbm)₂]NO₃ · 1/2H₂O}_n (1), {[CdCl(pbbm)₂]Cl · CH₃OH}_n (2) and {[Cu(Ac)₂(pbbm)] · CH₃OH}_n (3), and characterized their structures by single crystal X-ray diffraction as well as thermoanalysis. In polymers 1 and 2, one of the anions coordinates to the central ion, the other is located in the environment. Two pbbm ligands coordinate simultaneously to two metal centers generating one-dimensional cup-like helical chains. To our best knowledge, this cup-like structure has never been observed in the reported polymers. In polymer 3, each Cu atom is five-coordinate by two nitrogen atoms from two pbbm ligands, and three oxygen atoms from one monodentate acetate anion and one chelating acetate anion leading to one-dimensional wave-like linear chain. In addition, the DTA and TG results of the three polymers are in agreement with the crystal structures.     

Synthesis and structural characterization of cadmium(II) complexes with 2-(2-pyridyl)imino-N-(2-thiazolin-2-yl)thiazolidine (PyTT)

We have carried out the synthesis of the cadmium coordination compounds [Cd(NO₃)₂(PyTT)(H₂O)] (1) and [CdCl₂{(μ-Cl)₂CdCl(μ-Cl)(μ-PyTT)Cd}₂]_n (2), together with their structural determination by means of X-ray diffraction. The compounds were also characterized through elemental analysis and infrared spectroscopy. The first complex presents a distorted pentagonal bipyramidal geometry with the axial positions occupied by one oxygen atom from a water molecule and a second one from a nitrate ion which acts as a monodentate ligand, whereas the equatorial plane contains three nitrogen atoms from the organic moiety and two oxygen atoms coming from the other nitrate group, which is bidentate. The structure of the second complex consists of parallel sheets linked by van der Waals forces, each one made up of structural units [CdCl₂{(μ-Cl)₂CdCl(μ-Cl)(μ-PyTT)Cd}₂], which possesses two PyTT ligands, 10 bridging chloro ligands and 5 cadmium(II) centres belonging to three environment types: octahedral CdN₂Cl₄, octahedral CdCl₆, on which a centre of symmetry is located, and tetrahedral CdNCl₃, present in a 2:1:2 ratio.     

Synthesis, characterization and crystal structures of Cu(II) and Pd(II) complexes of the pentadentate mixed donor macrocycle, [17]aneNO2S2

An aza-oxa-thia macrocycle, 5,14-dioxa-2,17-dithia[6](1,2)benzeno[6](2,6)pyridinophane, L1, the related smaller macrocycle 2,14-dithia-11-oxa-[3](1,2)benzeno[6](2,6)pyridinophane, L2, and the complexes with Pd(II) and Cu(II) of the macrocycle, L1, have been synthesized. The crystal structure of L2 and those of the two metal complexes have been determined. In the complexes, the metal ions adopt exclusively square planar geometry in which the pyridine nitrogen, two sulfurs and one chlorine atom are coordinated and there is no appreciable interaction with the oxygen donors. Thus, the `hard-soft acid-base' principle is illustrated by the behaviour of L1. The structures of both complexes are compared with the previously reported mixed aza-thia macrocycle, 2,5,14,17-tetrathia[6](1,2)benzeno[6](2,6)pyridinophane. The crystal structure of the smaller macrocycle, L2, is also discussed and due to the nature of its smaller cavity, attempts to make complexes with it have not been successful.     

Syntheses, structures and properties of three cluster-based coordination polymers: influence of the metal ions on the ligand coordination mode and crystal chirality

Three cluster-based coordination polymers, namely [Zn₃(bpy)₃(hip)₂] · 5H₂O (1), [Co₃(bpy)₃(hip)₂] · 5H₂O (2) and [Cd₃(bpy)₃(hip)₂] (3) (bpy=2,2^′-bipyridine, hip=4-hydroxyl-isophthalate) were synthesized and structurally characterized. X-ray single-crystal structural analyses revealed that both 1 and 2 crystallize in the chiral space group P2₁, while 3 crystallizes in the centric space group Pccn. Compounds 1 and 2 are isomorphous and both have (4,4) topological layered structures constructed from trinuclear metal clusters. Compound 3 also shows layered structure of (4,4) topology constructed from trinulear Cd(II) cores. The layers are stacked in a staggered ?ABAB? fashion in 1 and 2 but in an overlapped ?AAA? fashion in 3. There are two types of coordination modes of hip ligand in 1 and 2 but only one in 3. The structural difference between 1 (or 2) and 3 may be attributed to the difference of metal ion nature such as the ionic radius and coordination preference, resulting in the different orientation fashions of the auxiliary bpy ligands, stacking fashions of the layers, as well as chirality of the crystals. The chiral structures of 1 and 2 were also confirmed by measurements of powder second-harmonic-generation (SHG) measurements, which show that 1 and 2 have SHG intensity of 0.50 and 0.02 relative to that of urea, respectively.     

Synthesis and structural characterisation of the lead-platinum sulfido aggregates [Pt2(μ-S)2(PPh3)4PbX2] (X = Br, I); promotion of rare tetrahedral geometry for lead(II)

The reactions of [Pt₂(μ-S)₂(PPh₃)₄] with excess PbBr₂ or PbI₂ in methanolic suspension result in the formation of the neutral lead(II) halide adducts [Pt₂(μ-S)₂(PPh₃)₄PbX₂] (X = Br, I). The X-ray structure determination of the lead iodide adduct reveals an essentially tetrahedral lead(II) centre, which is a rare coordination geometry for lead(II), which almost invariably is hemidirected, with a stereochemically active lone pair. In contrast, the structure of the PbBr₂ adduct, although suffering from some disorder, shows a more typical, distorted arrangement of ligands; these results are discussed in terms of the tendency for soft, bulky ligands to promote symmetric, holodirected geometries. The ESI mass spectra of the adducts are reported, and yield [M−halide]⁺ ions.     

Versatile nuclearity in copper complexes with ortho functionalized 1,3-bis(aryl)triazenido ligands

The synthesis, characterization and crystal structures of three new copper complexes derived from 1,3-bis(aryl)triazenido ligands bearing either a methoxycarbonyl, methylthio or a hydroxymethyl group in the ortho position of one of the aromatic rings are reported. In addition to the coordination of the triazenido fragment, the Lewis basic groups coordinate to the copper centers to form complexes with different nuclearity: {1-[2-(methoxycarbonyl)phenyl]-3-[4-methylphenyl]}triazene and {1-[2-(methylthio)phenyl]-3-[4-methylphenyl]}triazene form stable dinuclear and tetranuclear Cu(I) complexes, respectively. Reaction of {1-[2-(hydroxymethyl)phenyl]-3-[4-methylphenyl]}triazene with either Cu(I) or Cu(II) results in a novel Cu(II) hexanuclear macrocyclic complex.     

One-dimensional Cu(I) camphor hydrazone polymers: Structure and catalytic properties

Complexes of general formula [{CuX}₂(YNC₁₀H₁₄O)] (X = Cl; Y = NHMe, NH₂ or X = Br; Y = NH₂) were synthesised from camphor hydrazone ligands (YNC₁₀H₁₄O) by reaction with the suitable copper(I) halide. Structural analysis by X-rays performed on a red crystal of [{CuCl}₂(Me₂NNC₁₀H₁₄O)] revealed that the complex is a one-dimensional copper polymer formed by two rather different copper units bridged by chloride. One of the copper units displays a tetrahedral geometry while the other is linear. Although the geometries and neighbourhoods of the two copper units are very different the oxidation state of the metal is the same, i.e. Cu(I) as corroborated by magnetic and electrochemical measurements.The ability of [{CuCl}₂(Me₂NNC₁₀H₁₄O)] to promote the activation of 4-pentyn-1-ol towards cyclization was studied under homogeneous or heterogeneous experimental conditions. The best results were obtained under homogeneous conditions at 40 °C.     

Sonochemical syntheses of strawberry-like nano-structure mixed-ligand lead(II) coordination polymer: Thermal, structural and X-ray powder diffraction studies

Nano-structure of a new Pb(II) two-dimensional coordination polymer, {[Pb(2-pyc)(N₃)(H₂O)]_n (1), 2-Hpyc = 2-pyridinecarboxylic acid} was synthesized by a sonochemical method. The new nano-structure was characterized by scanning electron microscopy, X-ray powder diffraction, IR spectroscopy and elemental analyses. Compound 1 was structurally characterized by single crystal X-ray diffraction and consists of two-dimensional polymeric units. The thermal stability of compound 1 was studied by thermal gravimetric and differential thermal analyses and compared. PbO nano-powder was obtained by calcination of the nano-structure of compound 1 at 400 °C. This study demonstrates the coordination polymers may be suitable precursors for the preparation of nano-scale materials and dependent on their packing they may produce different and interesting morphologies.