Inorganic coordination polymers. XII. Chromium(III) tris(phosphinates)

Cohesive films of a series of chromium(III) tris(phosphinates)[Cr(OPRR′O)(OPR″-R?O)(OPR^*R^**O)]_y in which the side groups on the phosphorus are alkyl, phenyl, and/or hydrogen groups have been prepared by reaction casting or by hot pressing. The preparative reaction appears to involve conversion of an aquahydroxo or hydroxo chromium(III) bis(phosphinate) to an intermediate hydroxo bis(phosphinate) containing coordinated phosphinic acid followed by an intrachain reaction leading to the tris(phosphinate). Tensile strengths of the chromium(III) tris(phosphinates) range from 100 to 5600 psi, elongations from less than 1 to 100%. Thermogravimetric data indicate that major decomposition occurs at temperatures from 200 to 435°C in air and from 410 to 510°C in nitrogen. Infrared spectra and physical properties are interpreted to support a structure for the chromium(III) tris(phosphinates) which is based on linear, triple-bridged chains. The presence of octyl or other long alkyl side groups on the phosphorus improves the physical properties, presumably by internal plasticization, but leads to decreased thermal stability.     

Inorganic coordination polymers. VIII. Cobalt(II) and zinc(II) phosphinate polymers and copolymers

The preparation, properties, x-ray powder patterns, and TGA curves are given for cobalt(II) dimethyl-, methylphenyl- and diphenylphosphinate. The polymeric character of cobalt(II) methylphenylphosphinate is demonstrated by its colligative properties and melt indexes. These cobalt(II) phosphinates along with hybrid copolymers of zinc(II) or cobalt(II) were prepared by the reaction of the metal acetate with the appropriate phosphinic acid or mixture of phosphinic acids. A consideration of the hybrid copolymers leads to the conclusion that both the zinc(II) and cobalt(II) dimethyl- and diphenylphosphinates are likewise polymeric. Thermal stability is discussed in terms of the structures suggested, and it is shown that crystallinity is related to polymer symmetry.     

Inorganic coordination polymers. XVI. Zinc(II) phosphinate polymers containing polyphenylene and poly(phenylene oxide) side groups

The synthesis and characterization of a series of new phosphinic acids and the zinc polymers prepared from them are reported. These compositions are characterized by the presence of short polyphenylene and poly(phenylene oxide) chains as side groups. Some of the zinc derivatives were found to be tractable polymers with good thermal stability.     

Metal coordination polymers. III. Molecular weights of beryllium phosphinate polymers in chloroform

Vapor-phase osmometric molecular weight measurements on beryllium di-n-butyl-phosphinate are in general agreement with the results obtained in chloroform by Ripamonti and co-workers. The degree of polymer association in anhydrous chloroform is approximately twice that obtained in reagent-grade chloroform, and the values obtained in both types of chloroform are higher than those obtained by Ripamonti. Membrane osmometric molecular weight measurements on beryllium 4-biphenyl (phenyl)-phosphinate in chloroform indicate a reversible degradation exists between a number-average molecular weight of 170 000 and 30 000, with the value dependent upon the polymer concentration. Treatment of chloroform solutions of this polymer with ammonia prevents reassembly of the polymer from 30 000 to higher values. To explain this and other solution properties of this polymer, a structure is proposed which involves endgroup hydrogen bonding of phosphinate-bonded aggregates containing approximately 50 monomer units (M _n = 30 000). Under certain conditions, the hydrogen-bonded aggregates may contain up to 300 monomer units, but in polar solvents such as water or chloroform they are rapidly degraded.     

Inorganic coordination polymers. XI. A new family of chromium(III) bis(phosphinate) polymers, [Cr(OH)(OPRR′O)2]x

Heating hydroxyaquochromium(III) bis(phosphinates) at temperatures up to 200°C under vacuum yields the corresponding anhydrous polymers [Cr(OH)(OPRR'O)₂]_x. The infrared and visible spectra and solution properties lead to the following conclusions. When R and R′ are phenyl groups, the hydroxyl groups appear to bridge between adjacent chromium atoms in the chain together with the phosphinate ligands to yield a linear, triple-bridged polymer. When at least one substituent on the phosphorus is an alkyl group, some of the hydroxyl groups crosslink between chains to yield less soluble polymers. Comparison of the properties of these new polymers with the parent polymers suggests that the latter should be formulated [Cr(H₂O)_n(OH)(OPRR′O)₂]_x·pH₂O and that they contain more than one kind of monomer unit. The parent polymers can be readily prepared by a new method which involves reaction of a soluble chromium(III) salt with alkali metal phosphinates or of chromium(III) hydroxide with phosphinic acids in a water–tetrahydrofuran mixture.     

Metal coordination polymers. I. Synthesis and thermogravimetric analysis of beryllium phosphinate polymers

The preparation, properties, infrared, DTA, and TGA data are given for beryllium dimethyl-, tetramethylene-, di-n-butyl-, di-n-pentyl-, di-n-heptyl-, methylphenyl-, diphenyl-, and bispentafluorophenylphosphinates. Synthesis of dimeric beryllium acetylacetonyl phenyl-[o-methylcarboranyl (B₁₀)] phosphinate is reported. The beryllium phosphinates were prepared by the reaction of beryllium acetylacetonate with the appropriate phosphinic acid.     

Metal coordination polymers. II. Molecular weight studies of beryllium phosphinate polymers in toluene

The number-average molecular weights of beryllium 4-biphenyl(phenyl)phosphinate, di-n-pentylphosphinate, di-n-heptylphosphinate, and trifluoromethyl(phenyl)phosphinate are degraded by the presence of water in toluene. It is proposed that easily hydrolyzable P? O? P bonds contribute, in part, to the bonding of these polymers.     

One-dimensional coordination polymers incorporating silver(I) perfluorocarboxylate cuboctahedral clusters and the bis(methylthio)methane ligand

Two topologically comparable complexes, [Ag6(CF3CO2)3(L1-Me)3(SCH3)3]infinity (1) and [Ag6(CF3CF2CO2)3(L1-Me)2(SCH3)3(H2O)]infinity (2), were prepared and characterized by single-crystal diffractometry. The structures consist of Ag12S6 clusters linked by bis(methylthio)methane ligands, L1-Me, thus forming 1D coordination polymers. The 12 Ag atoms of the cluster are situated at the corners of a distorted cuboctahedron. The sulfur atoms of the six mu4-SCH3 entities occupy a position approximately 0.8 A above the center of each of the square faces of the polyhedron. The cleavage of the C-S bond of some of the ligands occurs during the syntheses, producing the -SCH3 anions. The coordination of the silver atoms varies from 5 to 7. The Ag...Ag contacts range from 2.9250(5) to 3.3615(6) A and from 2.961(1) to 3.380(1) A for 1 and 2, respectively. A polymeric ribbon is obtained when four ligands link a given cluster to two others. The chains of 1, held only by van der Waals forces, pack in a hexagonal manner. The two water molecules in 2 (Ag-OH2 = 2.385(7) A) are coordinated to silver atoms of the cluster. They are also strongly hydrogen bonded to the oxygen atoms of two pentafluoropropionate groups, one within the cluster (O...O = 2.741(1) A), the other in an adjacent chain (O...O = 2.818(1) A). The chains, thus H bonded to one another, generate a 2D coordination network.     

Inorganic coordination polymers. VII. Zinc(II) dimethyl-, methylphenyl-, and diphenylphosphinates

Zinc dimethyl-, methylphenyl-, and diphenylphosphinate have been prepared by the reaction of Zn(C₂H₃O₂)₂·2H₂O with the appropriate acid or salt and found to exist in amorphous and crystalline forms. Zinc methylphenylphosphinate, the most tractable, exhibits many of the physical attributes of polymeric materials, both in solution and bulk form, supporting our earlier suggestion that these compounds are double-bridged coordination polymers. Thermogravimetric analysis indicates initial decomposition temperatures of 440, 425, and 490°C., respectively, for the three polymers, but long-term studies show initiation of decomposition at somewhat lower temperatures.     

Variation in coordination modes of aromatic N-oxides in lanthanum(III) coordination polymers

Two new coordination polymers of lanthanum(III) benzoate having pyridine N-oxide and 4,4′-bipyridyl-N,N′-dioxide as ancillary ligands are synthesized and characterized. Different binding modes of the N-oxide are demonstrated; pyridine N-oxide binds as a bridging ligand, whereas 4,4′-bipyridyl-N,N′-dioxide is monodentate.     

Linear rheology of water-soluble reversible neodymium(III) coordination polymers

The rheology of reversible coordination polymer networks in aqueous solution is studied. The polymers are formed by neodymium(III) ions and bifunctional ligands, consisting of two pyridine-2,6-dicarboxylate groups connected at the 4-positions by an ethylene oxide spacer. Neodymium(III) ions can bind three of these terdendate ligand groups. At high concentrations, the polymer networks yield viscoelastic materials, which can be described with the Maxwell model. The scaling of the elastic modulus, relaxation time, and zero-shear viscosity with concentration are in good agreement with the predictions of Cates' model that describes the dynamics of linear equilibrium polymers. This indicates that the networks have only few cross-links and can be described as linear equilibrium polymers. The gels are also thermo-reversible. At high temperatures, fast relaxation was found, resulting in liquidlike behavior. Upon cooling, the viscoelastic properties returned immediately. From the temperature dependence of the relaxation time, an activation energy of 49 kJ/mol was determined for the breaking and reptation of the polymers.     

Lanthanide(III)-cobalt(II) heterometallic coordination polymers with radical adsorption properties

Two new coordination polymers {[Ln(2)(PDA)(6)Co(3)(H(2)O)(6)] x xH(2)O}(n) [Ln = Nd, x = 7 (1); Ln = Gd, x = 3.25 (2); H(2)PDA = pyridine-2,6-dicarboxylic acid] have been prepared under hydrothermal conditions with Ln(NO(3))(3) x 6H(2)O, CoO, and H(2)PDA in a molar ratio of 2:3:6. X-ray crystallographic analyses reveal that they crystallize in the hexagonal group P6/mcc and exhibit a nanotubular 3D framework. The adsorption experiment shows that 1 and 2 can adsorb radicals, which is proven by electron paramagnetic resonance spectra with the characteristic bands of the radicals at g = 2.006 and 2.005, respectively.     

Chromium(III) and Chromium(IV) Tetraphenylporphine Complexes

Stable chromium complex (AcO)CrTPP was synthesized through the reaction of meso-tetraphenylporphine with chromium(III) acetate in boiling phenol. Coordination properties of chromium porphyrin in reaction with imidazole and pyridine in o-xylene were studied by electronic absorption spectroscopy and computer modeling. A single-electron oxidation of chromium(III) complex was found to be affected by peroxide compounds. The stability of an extra complex depends on the basic properties of the extra ligand and oxidation number of the central metal atom. The complex stability correlates with the calculated energy of formation of the metal–extra ligand bond. The geometrical structure and energy parameters of hexacoordinated chromium porphyrins were calculated using the quantum-chemical method. The effect of the cis and trans position of ligands in the composition of a macrocyclic compound was established to be significant only in the extra complexes (AcO)CrTPP.     

Synthesis,characterization and applications of coordination polymers of Ln(III)

The resin was synthesized by condensation of 2‐hydroxy‐4‐ethoxybenzophenone with 1,4‐butane diol in presence of polyphosphoric acid as a catalyst at 155 °C for 10 h. The synthesized resin was used to get polychelates of 4f‐block elements. The resin and its polychelates were characterized on the basis of elemental analyses, electronic spectra, magnetic susceptibilities, FTIR, NMR and thermogravimetric analyses. Morphological study of resin and polychelates were carried out by scanning electron microscope. The number average molecular weight (M?_n) was determined using a vapor pressure osmometry method. The catalytic activity of selected polychelates was examined for organic synthesis. It is observed from the study that polychelates give excellent results. They were found to be efficient and effective catalysts and antimicrobial agents. Copyright © 2008 John Wiley & Sons, Ltd.     

Interconvertable modular framework and layered lanthanide(III)-etidronic acid coordination polymers

Isostructural modular microporous Na2[Y(hedp)(H2O)0.67] and Na4[Ln2(hedp)2(H2O)2].nH2O (Ln = La, Ce, Nd, Eu, Gd, Tb, Er) framework-type, and layered orthorhombic [Eu(H2hedp)(H2O)2].H2O and Na0.9[Nd0.9Ge0.10(Hhedp)(H2O)2], monoclinic [Ln(H2hedp)(H2O)].3H2O (Ln = Y, Tb), and triclinic [Yb(H2hedp)].H2O coordination polymers based on etidronic acid (H5hedp) have been prepared by hydrothermal synthesis and characterized structurally by (among others) single-crystal and powder X-ray diffraction and solid-state NMR. The structure of the framework materials comprises eight-membered ring channels filled with Na+ and both free and lanthanide-coordinated water molecules, which are removed reversibly by calcination at 300 degrees C (structural integrity is preserved up to ca. 475 degrees C), denoting a clear zeolite-type behavior. Interesting photoluminescence properties, sensitive to the hydration degree, are reported for Na4[Eu2(hedp)2(H2O)2].H2O and its fully dehydrated form. The 3D framework and layered materials are, to a certain extent, interconvertable during the hydrothermal synthesis stage via the addition of HCl or NaCl: of the 3D framework Na4[Tb2(hedp)2(H2O)2].nH2O, affords layered [Tb(H2hedp) (H2O)].3H2O, whereas layered [Tb(H2hedp)(H2O)2].H2O reacts with sodium chloride yielding a material similar to Na4[Tb2(hedp)2(H2O)2].nH2O. In layered [Y(H2hedp)(H2O)].3H2O, noncoordinated water molecules are engaged in cooperative water-to-water hydrogen-bonding interactions, leading to the formation of a (H2O)13 cluster, which is the basis of an unprecedented two-dimensional water network present in the interlayer space.     

Synthesis,structures and photoluminescence of two Er(III) coordination polymers

Two new erbium compounds, [Er₂(BDC)₃(DMF)₂] (1) and [Er₂(CQC)₃(DMF)₃(H₂O)]?·?DMF?·?H₂O (2), where BDC stands for 1,4-benzenedicarboxylate, CQC for 2-(4-carboxyquinolin-2-yl)quinoline-4-carboxylate, and DMF for N,N-dimethylformamide, have been synthesized through pre-heating and cooling-down crystallization. In 1 the Er(III) is seven-coordinate with oxygen atoms from six BDC and one DMF, forming a three-dimensional open-framework structure. Compound 2 possesses a 2D structure based on dinuclear Er(III) building units. The photoluminescence of 1 has also been investigated.     

Structures and luminescent properties of Sm(III) and Dy(III) coordination polymers with 2,4,6-pyridinetricarboxylic acid

Two rare earth coordination compounds with 2,4,6-pyridinetricarboxylic acid (H₃pta) have been synthesized by the hydrothermal method; the formula is {[RE(pta)(H₂O)₃]?·?H₂O} _n [RE?=?Sm (1) and Dy (2)]. Complexes 1 and 2 are crystallized in the monoclinic crystal system with P2₁/c space group. X-ray structure analyses show the two complexes have the same structure. Each pta^3? connects three rare earth ions. Both the Sm(III) and Dy(III) complexes exhibit characteristic luminescence in the visible region upon excitation with UV-rays.     

Chiral heterocyclic ligands. XIV. Control of directionality in silver coordination polymers through ligand design

Four C(2)-symmetric homochiral ligands derived from (+)-camphor are shown to produce linear chain and ladder silver coordination polymers wherein the directionality and polarisation can be controlled by subtle differences in ligand design.     

Spectrophotometric Determination of Trace Chromium(VI) in Mass Chromium(III)

There is little conclusive evidence of the toxic effects of Cr(III) so far, but Cr(VI) has carcinogenic activity, so the analysis of the chromine ions is very important in environmental research and the quality control of industry products. Usually Cr(III) and Cr(VI) interfere with each other in the species analysis, the measurement of Cr(VI) of numerous previous papers is related to the Cr(VI) samples, which contain a little Cr(III). When the amount of trivalent chromine exceeds ten …