The solubility parameters of metal acetylacetonates

Solubility parameters for Be(acac)₂ and Th(acac)₄ calculated from viscosity measurements on dilute solutions in benzene at 25.0°C have been compared with data for tris-acetylacetonates of Al, Cr, Mn, Fe and Co. In non-polar solvents the value does not vary much with the nature of the metal (average δ₂ = 9.4 ± 0.4) nor do the molar volumes, which can be calculated from V_m = 90.5n ± 5%.     

Fractional sublimation of various metal acetylacetonates

A simple fractional sublimator is described which possesses a continuous temperature gradient along its length. Samples are placed in the high temperature end of the tube and volatilized at 1-mm pressure. The gases are moved through the tube with air as a carrier. The metal chelates recrystallize on the walls of the tube in discrete and reproducible temperature zones. Characteristic recrystallization zones are reported for 21 metal acetylacetonates. The chelates can be grouped according to zone temperatures into 6 fairly distinct groups over the range 15 to 200°, which makes many separations possible. Separations of mixtures of Mg, Al and Be ; Ni, Fe and Be ; and, Cu and Fe were studied quantitatively. The separations achieved compared favorably with those reported by gas chromatography. The method offers real promise for the purification of a number of metals but appears especially good as a method for beryllium and certain platinum group metals.     

Diamagnetic muon yields of metal acetylacetonates

Diamagnetic muon yields /P_D/ in various metal acetylacetonates were measured at room temperature by the muon spin rotation technique. We have found a clear difference in P_D between complexes of typical elements and those of transition elements. We suggest that partially filled inner orbitals play some important role in determining the diamagnetic yield in these complexes.     

Gas chromatographie behaviour of some metal acetylacetonates

Summary The gas Chromatographie behaviour of metal Cr(III), Al(III) and Co(III) chelates on columns containing OV-17 and OV-25 methyl phenyl silicone oil as the liquid stationary phase at different temperatures and different flow ratios was investigated. The optimum separation conditions for investigated acetylacetonates mixture have been evaluated. The temperature of 200–250° C range and 60–90 cm³/min flow ratio were found to be the best.

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Uber das Verhalten einiger Metallkomplexe mit Acetylaceton (AA) bei der Gaschromatographie

Zusammenfassung Das gaschromatographische Verhalten der Komplexe Cr(AA)₃, Al(AA)₃ und Co(AA)₃ auf Säulen, die OV-17 und OV-25, Methyl-Phenyl-Siliconöl, als stationäre Phase enthalten, wurde bei verschiedenen Temperaturen und verschiedenen Trägergasflüssen untersucht. Die optimalen Trennungsbedingungen für Gemische der genannten Komplexe wurden bestimmt. Temperaturen zwischen 200° und 250° und ein Trägergasfluß von 60 bis 90 cm³/ min erwiesen sich als günstig.

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These studies were carried out within Project MR-I-14.     

Capillary gas chromatography of some metal acetylacetonates

Summary The retention and resolution of simple mixture of Al(III), Cr(III), Co(III), and Fe(III) acetylacetonates were investigated on capillary columns coated with methyl and methyl phenyl silicones (OV-1 or OV-17) used as the stationary phase, at different column temperatures and carrier gas flow rates. Successful elution and good resolution were obtained only for the Al(III) and Cr(III) complexes, both under isothermal and programmed-temperature conditions; better resolution was observed on the column coated with OV 17.     

3-R-Thio- and 3-R-Oxy-substituted metal acetylacetonates

New S- and O-substituted metal acetylacetonates were prepared from phenylthio-, butylthio-, benzenesulfonato-, and 3-acetoxyacetylacetone and appropriate metal salts. The spectral characteristics of the compounds were obtained. The effect of the α-substituent on the stability of the chelates under the conditions of chromatographic separation on silica gel was revealed. The reactivity of the acetate group bonded to the chelate ring is decreased, which does not allow preparation of new substituted complexes by common transformations of esters.     

Correlation of the ionization potentials of pseudo-aromatic metal complexes with hammett's substituent constants—II: Chromium acetylacetonates

The first ionization potentials, E_I, of substituted chromium(III) acetylacetonates are found to be a linear function of the sum of Hammett's σ_m and σ_p constants for substituents in various positions of the pseudo-aromatic rings, relative to the Cr atom. The equation for the regression is E_I = 7·40 + 0·380Σσ ± 0·02 eV, where 7·40 eV is the interpolated value for the tris-Cr chelate of malonaldehyde, and the slope of the correlation line is 0·380. From the value of the slope and other considerations, it is deduced that the ejected electron is an unpaired d_xyCr electron in at_2gMO.     

Molecular orbital calculations on transition metal complexes

INDO SCF MO calculations are reported for the complexes (C₅H₅)M(C₇H₇) (M = Ti, V and Cr), and for the corresponding V and Cr cations. The results correctly predict¹ A ₁ ground states for the V⁺ and the neutral Ti and Cr species, and for the neutral V and Cr⁺ complexes confirm the² A ₁ ground levels. The formally metald-levels followed theH ^core sequencee ₂<a ₁<e ₁, and the most important interactions were those between the metale ₂ level and the ligand C₇H₇ -orbitals, and between the metale ₁ level and the ligand C₅H₅ -orbitals. Calculations also satisfactorily reproduced other experimental quantities, and the results indicate that thee ₂ ligand interaction becomes more important, and thee ₁ ligand interaction less important, with increasing size of the ligand ring.     

Diffusion coefficients of metal acetylacetonates in supercritical carbon dioxide

Binary diffusion coefficients, D₁₂, of the metal acetylacetonates, palladium(II) acetylacetonate and cobalt(III) acetylacetonate, were measured from 308.2 to 343.2 K over the pressure range from 9 to 40 MPa at infinite dilution in supercritical carbon dioxide using the chromatographic impulse response method. The effects of pressure, temperature, density, and viscosity on D₁₂ values were examined. It was observed that the D₁₂ values of palladium(II) acetylacetonate and cobalt(III) acetylacetonate were larger than those of lipids with similar molecular weights, such as arachidonic acid and monoolein, respectively. Furthermore, the measured D₁₂ data of each metal acetylacetonate were well correlated by the hydrodynamic equation D₁₂/T as a function of carbon dioxide viscosity.     

Molecular orbital studies of some transition metal complexes

A set of molecular orbital calculations based on a particular semi-empirical method, has been undertaken on a homologue series of bis(-2-methylallyl)transition metal (Ni, Co, Fe, Cr) complexes (abbreviated as ML₂). Arguments are found for predicting the stability of the NiL₂ system, which is the only one that could be synthetized.

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Zusammenfassung Eine Reihe von semiempirischen MO-Rechnungen wurde für die homologe Reihe von bis(-2-methylallyl) Metallkomplexen (Ni, Co, Fe, Cr) durchgeführt. Gründe für die Stabilität der Ni-Verbindung, die als einzige synthetisiert wurde, werden angeführt.

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Résumé Un ensemble de calculs par une méthode semi-empirique particulière d'orbitales moléculaires a été effectué sur une série homologue de complexes bis (-2-méthylallyl)-métal de transition (Ni, Co, Fe, Cr): ML₂.Certains arguments sont trouvés en faveur de la stabilité du système NiL₂, le seul à avoir été synthétisé.

     

Molecular complexes of 4-NH2-benzophenone with bismuth(III) halides and with iodine

The following solid complexes of 4-NH₂-benzophenone (L) with bismuth (III) chloride, bromide and iodide and with iodine were prepared: BiCl₃·L (yellow), BiCl₃·2L (red), 3BiBr₃·2L (orange), BiBr₃·2L (red). 2BiI₃·3L (red), I·L (yellow), I·2L (orange), I·3L (red). The iodine complexes are obtained from ethanolic solutions of BiI₃ and the ligand, by precipitation with water or ligroin, the iodide ion being oxydized to iodine by the oxygen dissolved in the solvents. From an oxygen free ligroin-ethanolic solution only 2 BiI₃·3L is obtained. The i.r. spectra of the solids show that in the yellow or orange BiX₃ complexes the NH₂ group is involved into the coordination while in the red BiX₃ complexes and in the orange and red iodine complexes the v(NH) bands of the ligand remain unaltered. The carbonylic oxygen is not involved in the coordination. In DCM solution the red BiX₃ complexes and all the iodine complexes show a C.T. band at 440-420 nm, the energy of which gives a linear plot versus the electron affinity of the three halogens. The electronic spectra of the solids show a C.T. band in the region 470–500 nm.     

Heterophase synthesis and standard enthalpies of formation of metal acetylacetonates

Vaporization of Mn(acac)₃ has been studied by mass spectrometry on a quadrupole mass spectrometer with direct insertion probe, which was not previously used for these purposes. The enthalpy of sublimation of Mn(acac)₃ was calculated to be 130.5 ± 4.0 kJ/mol. Heterophase interactions in the [M-Mn(acac)₃] system were studied directly during the mass spectral experiment (in situ method). The reaction products were judged from the mass spectra of the gas phase. The enthalpies of formation in the gas phase Δ _f H _gas ^T of Pb, In, and Ga acetylacetonates were estimated to be −654, −1057, and −1035 kJ/mol, respectively.     

Features of intermolecular interactions in the crystals of metal acetylacetonates

For 12 acetylacetonates of the composition M(acac) _n (n = 2, 3, or 4) and M(acac)(C₂H₄)₂ (M is a metal) the total area (⁰ S) of the faces of Voronoi-Dirichlet polyhedra (VDP) corresponding to all intermolecular contacts of one molecule in the crystal structure and the total volume of pyramids (⁰ V), whose bases are formed of such faces and the vertices are occupied by the nuclei of atoms participating in intermolecular contacts, are determined. The key features of non-bonded interactions are considered. The existence of a linear dependence of the sublimation enthalpy of acetylacetonates on the ⁰ S or ⁰ V parameters of their molecular VDP is revealed. It is shown that the sublimation enthalpy of Ga(acac)₃ requires the refinement and theoretically should be 124 kJ/mol.     

The crosslinking reaction of acrylic PSA using chelate metal acetylacetonates

In this work, metal chelate zirconium acetylacetonate (ZrACA) was added into acrylic polymers with self-adhesive properties. These acrylic polymers, known as acrylic pressure-sensitive adhesives (PSA), were crosslinked with ZrACA to obtain acrylic self-adhesives with which to study the crosslinking reaction between carboxylic groups of the polymer chain and metal chelate crosslinking agent.