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Two organic salts of 1,4-butanebisphosphonic acid, bis(ethylenediammonium) butanebisphosphonate hydrate ( 1 ) and bis(hexamethylenediammonium) butanebisphosphonate hydrate ( 2 ), have been structurally characterized using single-crystal x-ray diffraction analyses. Compound 1 exhibits a H-bonded pillared bilayered structure, in which etheylenediammonium cation acts as a spacer between the anions resulting in the formation of two types of cavities. The larger cavity is filled by four water molecules though having hydrophobic character. Thus, the material behaves as a nanoporous organic solid. Compound 2 shows a multidimensional hydrogen bonding networks: one-dimensional arrays parallel to the b axis and two-dimensional sheets parallel to the ab plane. The N--H···O--P hydrogen bonds, forming H-bonded supramolecular networks, are regarded to be strong and directional hydrogen bonds. [ABSTRACT FROM AUTHOR]

A series of complexes of the type trans-[Co((BA)[sub 2] en)(amine)[sub 2] ]ClO[sub 4] — where (BA)[sub 2] en is the bis(benzoylacetone)ethylenediimine dianion and the amines are morpholine (mrpln) 1, aniline (aniln) 2, benzylamine (bzlan) 3, piperidine (pprdn) 4, p-toluidine (p-toldn) 5, and pyrrolidine (prldn) 6 — has been synthesized and characterized by elemental analysis, UV–vis, [sup 1] H NMR, and [sup 13] C NMR spectroscopy. The crystal and molecular structure of trans-[Co((BA)[sub 2] en)(mrpln)[sub 2] ]ClO[sub 4] (1) has been determined by X-ray crystallography. The electrochemical reduction of these complexes at a glassy-carbon electrode, in the potential range of 0.5 to –2.0 V (vs. Ag/AgCl), in acetonitrile solution, indicates that the first reduction potential of Co(III/II) is irreversible, which is accompanied by the dissociation of the axial amine–cobalt bonds. This potential is dependent on the pK[sub a] of the axial amines. The second reduction potential of Co(II/I) shows reversible behavior and is also independent of the axial amine pK[sub a] . These results indicate the loss of the axial amines in the first redox process and the involvement of a four-coordinate species in the second redox step.Key words: Schiff base, cobalt(III), axial amine, electrochemical properties, crystal structure.On a synthétisé une série de complexes du type trans-[Co(BA)[sub 2] en)(amine)[sub 2] ]ClO[sub 4] dans lesquels (BA)[sub 2] en = dianion bis(benzoylacétone)éthylènediimine et amine = morpholine (mrpln) 1; aniline (aniln) 2; benzylamine (bzlan) 3; pipéridine (pprdn) 4; p-toluidine (p-toldn) 5 et pyrrolidine (prldn) 6 et on les a caractérisés par analyse élémentaire et spectroscopies UV–vis et RMN du [sup 1] H et du [sup 13] C. On a étudié les structures cristallines et moléculaires du trans-[Co(BA)[sub 2] en)(mrpln)[sub 2] ]ClO[sub 4] (1) par diffraction des rayons X. La réduction électrochimique de ces complexes au niveau d'une électrode de carbone vitreux, à un potentiel allant de 0,5 à –2,0 V (vs. Ag/AgCl), en solution dans l'acétonitrile, indique que le premier potentiel de réduction de Co(III/II) est irréversible et qu'il est accompagné d'une dissociation des liaisons amine–cobalt axiales. Ce potentiel varie avec le pK[sub a] des amines axiales. Le deuxième potentiel de réduction de Co(II/I) met en évidence un comportement réversible et il est aussi indépendant du pK[sub a] de l'amine axiale. Ces résultats indiquent que la perte des amines axiales se produit dans le premier processus redox et que les quatre espèces coordinées sont impliquées dans la deuxième étape. Mots clés : base de Schiff, cobalt(III), amine axiale, propriétés électrochimiques, structure cristalline. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The potential use of organic phosphorus acids for the architecture of supramolecular hydrogen-bonded assemblies has been demonstrated by the structural determination of phenylphosphonic acid (1), anilinium phenylphosphonate (2), p-phenylazoanilinium phenylphosphonate (3), ethylenediammonium phenylphosphonate hydrate (4) and hexamethylenediammonium phenylphosphonate hydrate (5). Compounds 1, 2, 4 and 5 exhibit layered structures with two-dimensional networks of hydrogen bonds from which the organic tails point out. Compound 3 crystallizes as two concomitant polymorphs showing supramolecular isomerism: a monoclinic phase (3a) with a layered structure and a triclinic phase (3b) in which hydrogen bonds form columns. In these assemblies, there are supramolecular motifs such as chains and rings of hydrogen-bonded moieties. Water molecules are involved in the formation of hydrogen-bonding networks for compounds 4 and 5. For compound 5, hexamethylenediammonium ions link the adjacent sheets, forming a pillared-layered structure. It has been shown that the phosphonate groups can act as both donor and acceptor of hydrogen bonds. Analysis of the hydrogen bonds of the types (P–)O–H⋯O(–P) and N–H⋯O(–P) reveals that they can be regarded as medium to strong hydrogen bonds. [Copyright &y& Elsevier]

Two organic salts of methylphosphonic acid with aniline (1) and ethylenediamine (2) has been synthesized and structurally characterized using single-crystal X-ray diffraction analysis. Compound 1 exhibits a H-bonded layered structure, in which anilinium cations and methylphosphonate anions are arranged alternately at both side of H-bonded sheets. In compound 2, methylphosphonic acid is deprotonated to form a dianion while ethylenediamine is protonated to form a dication. They are linked together via N–H⋯O–P hydrogen bonds forming a three-dimensional H-bonded network. Analysis of hydrogen bonds using graph-set theory was performed to assign supramolecular motifs. A comparison of the geometry of methylphosphonate anions with that for phosphite anions in closely related compounds, reveals the stereochemical equivalence of the (P–)H atom and (P–)CH3 group. We have also found strong structural correlations between inorganic and organic salts of methylphosphonic and phosphorus acids. [Copyright &y& Elsevier]

Strontium phenylphosphonate, Sr(PhPO3H)2, was synthesized by the reaction of strontium carbonate and phenylphosphonic acid. The compound was structurally characterized by Rietveld refinement on X-ray powder diffraction data. It consists of a layered structure with inorganic framework of SrO8 polyhedra from which phenyl groups are pointing out. The compound is isomorphous with the already known calcium and barium phenylphosphonates. Infrared spectroscopy analysis shows the presence of (P&z.sbnd;)O&z.sbnd;H…O hydrogen bonds in the solid material. The thermal behavior of the compound in the range 30–650 °C, studied by thermogravimetry (TG), differential thermal analysis (DTA) and X-ray powder thermodiffractometry, revealed that strontium phenylphosphonate is stable up to 330 °C. The compound undergoes consequent thermal decomposition and phase transitions above 330 °C temperatures until it converts to crystalline Sr(PO3)2 above 570 °C. [ABSTRACT FROM AUTHOR]

Abstract: Two symmetrical and asymmetrical Zn(II) complexes of a pentadentate (N5) macrocyclic Schiff-base ligands, were prepared via templated [1+1] cyclocondensation of 2,6-diacetylpyridine with two different amines containing piperazine moiety. The complexes have been characterized by a variety of methods including, IR, FAB mass spectrometry, elemental analysis and conductivity measurements. The crystal structure of the asymmetric complex, [ZnL1Br]ClO4 was determined by X-ray diffraction. It is shown that in the solid state the complex adopts a distorted pentagonal–pyramidal geometry, with the macrocycle in the pentagonal plane and the bromide ion in the axial position. [Copyright &y& Elsevier]