The structure and thermal behaviour of sodium and potassium multinuclear compounds with hexamethylenetetramine

Sodium and potassium thiocyanate complex compounds of formulae [Na(hmta)(H₂O)₄]₂²⁺·2SCN⁻ (1) and [K₂(hmta)(SCN)₂] _n (2) have been synthesized and characterised by IR spectroscopy, thermogravimetry coupled with differential thermal analysis, elemental analysis and X-ray crystallography. Each sodium and potassium cation is six co-ordinated, the sodium by one monofunctional hmta molecule, three terminal water molecules and two bridging water molecules, and the potassium by two bridging tetrafunctional hmta molecules and four bridging tetrafunctional thiocyanate ions. The coordination polyhedra of the central atoms can be described as distorted tetragonal bipyramids. The complex cations and anions of (1) are interconnected by multiple intramolecular O(water)—H···N(hmta/NCS) and O(water)—H···S hydrogen bonds to the three dimensional net. In each complex cation the intramolecular O–H···O hydrogen bonds link two terminal water molecules bonded to two metal cations. The compound (2) forms the three dimensional hybrid network in which the classical two-dimensional coordination polymers are linked by inorganic SCN⁻ spacers to the third-dimension. Thermal analyses show that the compounds decompose gradually in three (for 1) and two (for 2) steps with formation of Na₂SO₄ and K₂S as the final products, respectively, for 1 and 2.     

Attempts of synthesis of Hg(SCN)4-based coordination polymers in conjunction with [Cu(L–L)2] building blocks

Five novel heterobimetallic compounds [Cu(bpzm)₂Hg(SCN)₄]_n (1), [Cu(bdmpzm)₂(μ-SCN)Hg(SCN)₃] (2), [Cu(pybzim)₂(μ-SCN)Hg(SCN)₃]·H₂O (3), [Cu(bipy)₂(μ-SCN)Hg(SCN)₃][Cu(bipy)₂(μ-SCN)₂Hg(SCN)₂] (4) and [Cu(bipy)(NCS)]₂[Hg(SCN)₄] (5) have been synthesized and structurally characterized (bpzm-bis(pyrazol-1-yl)methane, bdmpzm-bis(3,5-dimethylpyrazol-1-yl)methane, pybzim-2-(2-pyridyl)benzimidazole, phen-1,10-phenantroline and bipy-2,2′-bipyridine). The compounds 2, 3, 4 and 5 are molecular complexes, whereas 1 is an alternating 1-D zigzag chain of [Cu(bpzm)₂]²⁺ and Hg(SCN)₄]²⁻ moieties in which the metal atoms are bridged via thiocyanate ions. The polymer 1 has been studied by magnetic measurement.     

Coordination behaviour of 2,2′-bipyridine towards the dichloroacetates of zinc and cadmium

The coordiantion compounds [Zn(C₁₀H₈N₂)(Cl₂HCCOO)(H₂O)₃]⁻·[Zn(C₁₀H₈N₂)(Cl₂HCCOO)₃]⁺ and [Cd(C₁₀H₈N₂)₂(Cl₂CHCOO)₂] were synthesised and characterised by elemental and thermal analysis, IR and UV–VIS spectroscopy, and X-ray crystallography. The complexes are air stable and well-soluble in water. The zinc atoms are five and six coordinated and the cadmium atom is six coordinated. The coordination polyhedra of central atoms can be described as trapezoidal pyramid and octahedron in zinc compound and as rectangular bipyramid strongly distorted towards skew trapezoidal bipyramid in cadmium compound. In both compounds all dichloroacetate groups are monodentate. The bond valences considerations show that all 2,2′-bipyridine molecules are bonded almost 2 times stronger than carboxylate groups. In the structure of zinc compound exist O–H···O hydrogen bonds and in both structures can be found weak C–H···O hydrogen bonds. Additionally, both compounds are pile-stacked by π···π interactions. The IR spectra show typical vibrations for chelating 2,2′-bipyridine molecules and terminal monodentate carboxylate groups. The thermal decomposition studies show zinc compound decomposes in 4 steps and cadmium compound decomposes in 5 steps with formation of oxides as a final products. The ligands decompose gradually, first dichloroacetates and next 2,2′-bipyridine.     

Tricarbonyl rhenium complexes of bis(pyrazol-1-yl)methane and bis(3,5-dimethylpyrazol-1-yl)methane – Synthesis,spectroscopic characterization,X-ray structure and DFT calculations

Two novel tricarbonyl rhenium complexes based on the bidentate heterocyclic N–N ligands [bis(pyrazol-1-yl)methane(bpzm) and bis(3,5-dimethylpyrazol-1-yl)methane(bdmpzm)] have been synthesized by heating at reflux [Re(CO)₅Cl] with the appropriate N–N ligand in toluene. The compounds have been characterized by IR and UV–Vis spectroscopy and X-ray analysis. Density functional theory (DFT) and time-dependent (TD) DFT calculations have been carried out for the [Re(CO)₃(bdmpzm)Cl] complex.     

A structural and theoretical study of the intermolecular interactions in 8‐hydroxyquinolinium‐7‐carboxylate monohydrate

In the title compound, C₁₀H₇NO₃·H₂O, the zwitterionic organic molecules and the water molecules are connected by N—H...O and O—H...O hydrogen bonds to form ribbons, and π–π stacking interactions expand these ribbons into a three‐dimensional net. The energies of these hydrogen bonds adopt values typical for mildly weak interactions (3.33–7.75 kcal mol⁻¹; 1 kcal mol⁻¹ = 4.184 kJ mol⁻¹). The total π–π stacking interactions between aromatic molecules can be classified as mildly strong (energies of 15.3 and 33.9 kcal mol⁻¹), and they are made up of multiple constituent π–π interactions between six‐membered rings. The short intermolecular C—H...O contact between two zwitterionic molecules is nonbonding in character.     

Novel oxorhenium complexes with 2-(2′-hydoxy-5′-methylphenyl)benzotriazolato ligand. X-ray studies,spectroscopic characterization and DFT calculations

The [ReOCl₂(hmpbta)(AsPh₃)] · MeCN, [ReOBr₂(hmpbta)(AsPh₃)] · MeCN, [ReOCl₂(hmpbta)(PPh₃)] · MeCN, [ReOBr₂(hmpbta)(PPh₃)] · MeCN, and [ReBr₂(hmpbta)(PPh₃)] · MeCN complexes have been prepared in the reactions of [ReOX₃(EPh₃)₂] (X = Cl, Br; E = P, As) with 2-(2’-hydoxy-5′-methylphenyl)benzotriazole in molar ratio 1:1. All the compounds were structurally and spectroscopically characterized. The electronic structure of [ReOCl₂(hmpbta)(AsPh₃)] has been calculated with the density functional theory (DFT) method. The TDDFT/PCM calculations have been employed to produce a hundred of singlet excited-states starting from the ground-state geometry optimized in the gas phase, and the UV–Vis spectrum of [ReOCl₂(hmpbta)(AsPh₃)] has been discussed on this basis. The paper reports also X-ray structure and DFT calculations for the disubstituted [ReOCl(hmpbta)₂] chelate.     

Solid‐state conformation of the 1,3,2‐oxazaphospholane ring in 2‐dialkylamino‐3,4‐dimethyl‐5‐phenyl‐1,3,2‐oxazaphospholane sulfides

Dialkylamino‐3,4‐dimethyl‐5‐phenyl‐1,3,2‐oxazaphospholane sulfides (where the alkyl is an isopropyl, ethyl or methyl group) was obtained by sulfurization of the respective phospholanes. The structures of these compounds were determined by X‐ray crystal structure analysis. Five‐membered rings exist in the envelope conformation in the crystalline state. The planar part of the 1,3,2‐oxazaphospholane rings undergoes twisting with the enlargement of a substituent. The environment of the P atom has the geometry of a distorted tetrahedron. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:146–150, 2001     

Synthesis,spectroscopic characterization,crystal and molecular structure of [ReOX2(bopyH)(PPh3)] complexes: DFT calculations for [ReOCl2(bopyH)(PPh3)]

The reactions of [ReOX₃(PPh₃)₂] (X = Cl, Br) with benzoylpyridine (bopy) have been examined and novel [ReOX₂(bopyH)(PPh₃)] oxocompounds have been obtained. The complexes were structurally and spectroscopically characterised. In the both structures two-electron reduced form of benzoylpyridine is coordinated to the central ion. The electronic structure of [ReOCl₂(bopyH)(PPh₃)] has been calculated with the density functional theory (DFT) method, and additional information about binding has been obtained by NBO analysis. The UV–Vis spectrum of the [ReOCl₂(bopyH)(PPh₃)] has been discussed on the basis of TDDFT calculations.     

Novel oxorhenium complexes with 2-(2′-hydroxyphenyl)-2-benzothiazolinato ligand: X-ray studies,spectroscopic characterization and DFT calculations

The [ReOX₂(hbt)(EPh₃)] (X = Cl, Br; E = As, P) chelates have been prepared in the reactions of [ReOX₃(EPh₃)₂] complexes (X = Cl, Br; E = P, As) with 2-(2′-hydroxyphenyl)-2-benzothiazole (hbtH) in acetone. From the reactions of [ReOX₃(PPh₃)₂] with hbtH two kind of crystals [ReOX₂(hbt)(PPh₃)] · MeCN and [ReOX₂(hbt)(PPh₃)] with different arrangement of halide ions (cis and trans) were isolated, whereas the [ReOX₃(AsPh₃)₂] oxocompounds react with hbtH to give only cis-halide isomers. The complexes were structurally and spectroscopically characterised. The electronic structures of both [ReOBr₂(hbt)(PPh₃)] isomers have been calculated with the density functional theory (DFT) method. The TDDFT/PCM calculations have been employed to produce a hundred of singlet excited-states starting from the ground-state geometry optimized in the gas phase of cis- and trans-halide isomers of [ReOBr₂(hbt)(PPh₃)] and the UV–Vis spectra of these complexes have been discussed on this basis.