Comparison of the Bonding of Benzene and C60 to a Metal Cluster: Ru3(CO)9(μ3-η2,η 2,η2-C6H6) and Ru3(CO)9(μ3-η2,η2,η2-C60)

The electron distributions and bonding in Ru₃(CO)₉( ³- ², ², ²-C₆H₆) and Ru₃(CO)₉( ³- ², ², ²-C₆₀) are examined via electronic structure calculations in order to compare the nature of ligation of benzene and buckminsterfullerene to the common Ru₃(CO)₉ inorganic cluster. A fragment orbital approach, which is aided by the relatively high symmetry that these molecules possess, reveals important features of the electronic structures of these two systems. Reported crystal structures show that both benzene and C₆₀ are geometrically distorted when bound to the metal cluster fragment, and our ab initio calculations indicate that the energies of these distortions are similar. The experimental Ru–C_fullerene bond lengths are shorter than the corresponding Ru–C_benzene distances and the Ru–Ru bond lengths are longer in the fullerene-bound cluster than for the benzene-ligated cluster. Also, the carbonyl stretching frequencies are slightly higher for Ru₃(CO)₉( ³- ², ², ²-C₆₀) than for Ru₃(CO)₉( ³- ², ², ²-C₆H₆). As a whole, these observations suggest that electron density is being pulled away from the metal centers and CO ligands to form stronger Ru–C_fullerene than Ru–C_benzene bonds. Fenske-Hall molecular orbital calculations show that an important interaction is donation of electron density in the metal–metal bonds to empty orbitals of C₆₀ and C₆H₆. Bonds to the metal cluster that result from this interaction are the second highest occupied orbitals of both systems. A larger amount of density is donated to C₆₀ than to C₆H₆, thus accounting for the longer metal–metal bonds in the fullerene-bound cluster. The principal metal–arene bonding modes are the same in both systems, but the more band-like electronic structure of the fullerene (i.e., the greater number density of donor and acceptor orbitals in a given energy region) as compared to C₆H₆ permits a greater degree of electron flow and stronger bonding between the Ru₃(CO)₉ and C₆₀ fragments. Of significance to the reduction chemistry of M₃(CO)₉( ³- ², ², ²-C₆₀) molecules, the HOMO is largely localized on the metal–carbonyl fragment and the LUMO is largely localized on the C₆₀ portion of the molecule. The localized C₆₀ character of the LUMO is consistent with the similarity of the first two reductions of this class of molecules to the first two reductions of free C₆₀. The set of orbitals above the LUMO shows partial delocalization (in an antibonding sense) to the metal fragment, thus accounting for the relative ease of the third reduction of this class of molecules compared to the third reduction of free C₆₀.     

α,β-Butenolides

,-Dibromo--('-carbethoxyacetony)-^,-butenolide (I) reacts with amines in diethyl ether solution to give -bromo-amino--('-carbethoxyacetony)-^,-butenolides. Compounds n are converted to -bromo-amino--('-carbethoxyacetony)-^,-butenolides on reaction with amines. The corresponding arylhydrazones (VI and VII) are obtained by the reaction of I and II with p-nitro- and 2,4-dinitrophenylhydrazines. Compound I reacts with phenylhydrazine to give furopyridazine VIII.See [1] for communication IV.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–871, July, 1972.     

Comparison Between a Generalized Electronic Diabatic Approach and the Born–Oppenheimer Separation Scheme in Inertial Frames

We discuss a generalized electronic diabatic (GED) approach to diagonalize the exact Hamiltonian of an n-electron system which embeds an external background of positive charges. This Hamiltonian, denoted by _e(q,), is defined in an inertial frame, and it contains a quantum part (the electrons with coordinates q) and a classical part (the external charges in a three-dimensional configuration ). We derive a GED basis set { _k (q)} using an operator _e(q,⁰) for a single configuration ⁰, and then show that these are also eigenfunctions for any other _e(q,); only the ordering of eigenvalues may depend on (i.e., k=k()). The GED functions can also be used to represent the eigenstates of a fully quantum-mechanical system of electrons and nuclei. We discuss briefly the differences between the present procedure and the standard Born–Oppenheimer (BO) technique in the clamped-nuclei approximation. As illustration, we show how chemical changes emerge as transitions among diabatic states mediated by an electromagnetic field.     

Effect of vanadium content on the character of acidic sites on V2O5/Al2O3 catalysts

By IR spectroscopy and TPD the effect of vanadium content on the relative proportion of strongly acidic sites of V₂O₅/Al₂O₃ catalyst was studied.

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- - V₂O₅/Al₂O₃.

     

Synthesis of furan analogs of 1, 3, 5-triphenylpyrazoline derivatives

Furan analogs of chalcones are condensed with phenylhydrazine to give a number of ²-pyrazolines hitherto not described in the literature. It is shown that in , -unsaturated ketones, a nitro-group in the nucleus and remote from the carbonyl group makes cyclization to the corresponding ²-pyrazolines more difficult than does one adjacent to the carbonyl.     

The kinetics of base hydrolysis of [Co(trien)(amine)Cl]2+ complexes (amine=imidazole,pyridine,n-butylamine and 2,2-dimethoxyethylamine)

Summary The complexescis--[Co(trien)(ImH)Cl]²⁺ (ImH=imidazole, trien=1,8-diamino-3,6-diazaoctane),cis--[Co(trien)(Buⁿ-NH₂)Cl^–]²⁺,cis--[Co(trien)(NH₂CH₂-CH(OMe)₂)Cl^–]²⁺ andcis-₂-[Co(trien)(py)Cl]²⁺ (py=pyridine) have been characterised and their kinetics of base hydrolysis studied. Thecis--isomers which have afac-fac arrangement of the trien ligand have values of k _OH ²⁵ in the 73 to 253 dm³ mol^–1 s^–1 range at I=0.1 mol dm^–3. Extremely rapid base hydrolysis is observed withcis-₂-[Co(trien)(py)Cl]²⁺ where k _OH ²⁵ is 6.65×10⁶ mol³ mol^–1 s^–1 at I=0.1 mol dm^–3. This complex has amer-fac arrangement of the trien ligand with flatsec-NH donor leading to rapid base hydrolysis due to good -overlap between the conjugate base and cobalt(III). The pyridine ligand causes aca. 30 fold rate increase compared with the hydrolysis ofcis-₂-[Co(trien)(NH₃)Cl]²⁺.     

Study on the thermokinetic properties of bacterial growth

The power-time curves of bacterial growth at different temperatures were determined by using the 2277 Thermal Activity Monitor (Sweden). From these curves, the growth rate constant () and activation energy (E _a) were calculated. According to the transition state theory of reaction dynamics, the activation entropy (S), activation Gibbs free energy (G) and equilibrium constant (K ) of the activation state could be calculated. These results permitted thermodynamic analysis of the bacterial growth metabolism.Supported by the Natural Science Foundation of Shandong Province.     

The multi-centre integrals of derivative,spherical GTOs

The multi-centre integrals of the orbital system ⁿ Y _lm () exp (–r ²) are evaluated using the Talmi transformation of nuclear shell theory. The integrals are simpler than those of the systems r ²ⁿ Y lm(r) exp (–r ²), x ^l y ^m z ⁿ exp (–r ²), (/x) ^l (/y) ^m (/z) ⁿ exp (–r ²) and the spherical oscillator functions. The integral types investigated are: overlap, electric dipole transition (momentum operator), kinetic energy, three-centre nuclear attraction, four-centre electronic repulsion, three-centre spin-orbit coupling, and magnetic dipole transition (three-centre integrals of the angular momentum operator).     

Stereochemie von Metallocenen, 40. Mitt.

Starting from optically active methylferrocene-- and--carboxylic acids (1 a and1 b) of known absolute configuration and enantiomeric purity about 15 chiral ferrocenes (of each isomeric series— and ) were obtained by suitable ligand transformations. Thereby (almost) all possible chiral combinations of the ligands CH₃, COOH (COO^–), COOCH₃, CN and NH₂ (NH₃ ⁺) were accessible which are necessary for a potential test of approximations of chirality functions for compounds with basic symmetry C_5v. The chiroptical properties of these disubstituted ferrocenes are recorded.Preliminary tests using a shortened Ansatz revealed large discrepancies between calculated () and found [M]_D-values. Possible reasons for this failure are discussed.

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61. Mitt. über Ferrocenderivate

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39. Mitt.:A. Meyer, H. Neudeck undK. Schlögl, Chem. Ber.110, 1403 (1977).

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60. Mitt.:V. Rapi, K. Schlögl undB. Steinitz, J. Organometal. Chem.94, 87 (1975).     

Polydentate coordination of the thallium atom in complexes with chiral amidinylcyclopentadienyl ligands

The chiral thallium amidinium cyclopentadiene-N-ylide complexes [C₅(CO₂Me)₄{ArNC(Ar")NAr}]Tl were synthesized and structurally characterized by X-ray diffraction analysis and NMR spectroscopy. In these complexes, an unusual mode of coordination of the thallium atom was found, viz., the thallium atom is coordinated by both the side-chain nitrogen atom (N—Tl, 2.833(6) ) and the system of the cyclopentadienyl ring (Tl—Cp, 2.887(4) ⁵-bonding).     

Hydrophosphorylation of 1,3-Diphenyl-2-propen-1-one and 4-Phenyl-3-buten-2-one in the Coordinational Sphere of Carbonyl Complexes of Group VIB Metals

Synthetic procedures for preparing ²- and ⁴-complexes of chalcone and benzalacetone with hexacarbonyl mononuclear complexes of Group VIB metals were developed and conditions for selective ²- and ⁴-coordination of the heterodiene ligand were established. Hydrophosphorylation of the obtained complexes proceeds in the coordination sphere of the metal by the Abramov reaction scheme and yields the corresponding ²-coordinated -hydroxyphosphonates. As follows from quantum-chemical calculations, -coordination with metals makes the heterodienes no longer planar, which explains their regioselective phosphorylation by the more electrophilic carbonyl group.     

The Exciton Model and the Circular Dichroism of Polypeptides

Summary. Exciton coupling of the 190nm ^* transition is an important factor in the CD spectrum of peptides and proteins. The CD spectrum of the -helix is dominated by the exciton effect. The spectrum is sensitive to the direction of the ^* transition dipole moment, especially for short helices. Exciton theory is much less successful in accounting for the CD spectrum of the poly(proline)II (PPII) conformation, an important conformer in collagen and in unordered peptides. Mixing of the ^* transition with high-energy transitions in the peptide backbone and in side chains must be considered to explain the strong negative CD band near 200nm of PPII.     

Determination of unperturbed dimensions of polymers in binary solvent mixtures from viscosity measurements

Intrinsic viscosity measurements were carried out on poly(vinyl pyrrolidone) and poly(vinyl alcohol) in various solvents and solvent mixtures. The values of, [] andk, the latter two being the fundamental terms in the equationC/ _sp =1/kC, were utilized for the determination of the unperturbed dimensions in solution. The values of (¯r _o ² /M _w )^1/2 were calculated.     

Determination of cadmium, lead, and thallium in materials of the environmental specimen bank using mass spectrometric isotope dilution analysis (MS-IDA)

Summary An analytical procedure for the simultaneous determination of cadmium, lead, and thallium in the mg/kg- and g/kg-range in biological materials and sewage sludge by mass spectrometric isotope dilution analysis (MS-IDA) is described.Cadmium, lead, and thallium were separated by electrolytical deposition after low temperature ashing (LTA) of the samples in oxygen plasma and dissolution of the ashes in HNO₃ or HNO₃/HF. Measurement of the isotopic ratio was carried out with a thermal ionization mass spectrometer using the silica gel technique. Cadmium contents ranging from 1.03 to 4.60 mg/kg with relative standard deviations from 0.3 to 1.3%, lead contents ranging from 75 g/kg to 25 mg/kg with relative standard deviations from 0.6 to 3.5%, and thallium contents ranging from 2.9 to 247.7 g/kg with relative standard deviations from 0.1 to 1.7% were determined in the materials of the environmental specimen bank analyzed.

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Bestimmung von Cadmium, Blei und Thallium in Materialien der Umweltprobenbank mit der massenspektrometrischen Isotopenverdünnungsanalyse

Zusammenfassung Ein Analysenverfahren zur simultanen Bestimmung von Cadmium, Blei und Thallium im mg/kg- und g/kg-Bereich in biologischen Materialien und Klärschlamm mit der massenspektrometrischen Isotopenverdünnungsanalyse (MS-IDA) wird beschrieben.Nach Niedertemperaturveraschung (LTA) der Proben im Sauerstoffplasma und Lösen der Aschen in HNO₃ oder HNO₃/HF-Gemisch werden Cadmium, Blei und Thallium durch elektrolytische Abscheidung abgetrennt. Die Isotopenverhältnismessung erfolgt mit der Silicageltechnik in einem Thermionen-Massenspektrometer. In den analysierten Probenbankmaterialien werden Cadmiumgehalte im Bereich von 1,03 bis 4,60 mg/kg mit relativen Standardabweichungen von 0,3 bis 1,3%, Bleigehalte im Bereich von 75 g/kg bis 25 mg/kg mit relativen Standardabweichungen von 0,6 bis 3,5 % und Thalliumgehalte im Bereich von 2,9 bis 247,7 g/kg mit relativen Standardabweichungen von 0,1 bis 1,7% bestimmt.

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Dedicated to Prof. Dr. W. Fresenius on the occasion of his 70th birthday     

Quantum chemical calculations on the catalytic dehydration of 2-propanol

The charge on atoms and the bond strengths in CH₃CHOHCH₃, CH₃ CH₃, CH₃CHOHCH ₂ ^– , CH₃ CH ₂ ^– and CH₃ CH₃...O(H)CH(CH₃)₂ have been calculated by the CNDO/2 method. The results are in agreement with published experimental observations on catalytic dehydration. A modified mechanism of anti-elimination on solid catalysts is proposed.

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CH₃CHOHCH₃, CH₃ CH₃, CH₃CHOHCH ₂ ^– , CH₃ CH ₂ ^– CH₃ CH₃...O(H)CH(CH₃)₂, CNDO/2. . .

     

Kinetics of Gold Electrodeposition from Cyanide Electrolytes at a Monitored Surface Coverage by Thallium Atoms

A procedure for measuring kinetic parameters of gold electrodeposition in the presence of catalytically active thallium(I) ions while monitoring the coverage of the gold surface by thallium adatoms, , is described. The procedure accounts for the duration of contact between a freshly renewed surface of gold and a thallium-containing solution and assumes that the incorporation rate of thallium adatoms is proportional to and the current density of gold electrodeposition. At = const, kinetic dependences correspond to the Tafel equation. Values of and i ₀ increase with . At = 0.3, 0.6 and i ₀ 3 × 10^–4 A cm^–2, which conforms to values calculated from anodic curves obtained in similar conditions.     

Thermal and infrared spectrum analyses of natural and synthetic andersonites

The thermal decompositions of natural and synthetic andersonites were studied. Two partly overlapping dehydration steps and three partly overlapping decarbonation steps were observed. The second dehydration and the first decarbonation steps also partly overlap. During decarbonation, the gradual formation of sodium diuranate and monoclinic and hexagonal phases in the Na₂U₂O₇-CaUO_4–x system was proved. The results were correlated with measured infrared spectra using site and factor group analysis and X-ray structure analysis. The chemical formula inferred for natural andersonite, Na₂Ca[UO₂(CO₃)₃] 5.6H₂O, agrees with that proposed for its synthetic analogue.

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Zusammenfassung Die thermische Zersetzung von natürlichem und synthetischem Andersonit wurde untersucht. Sie umfasst zwei teilweise überlappende Entwässerungs- und drei teilweise überlappende Decarboxylierungsstufen. Der zweite Entwässerungs- und der erste Decarboxylierungsschritt überlagern einander ebenfalls teilweise. Während der Decarboxylierung wird die allmähliche Bildung von Natriumdiuranat und monoklinen und hexagonalen Phasen des Systems Na₂U₂C₇-CaUO_4–x nachgewiesen. Die Ergebnisse wurden mit den gemessenen IR-Spektren unter Benutzung der site- und Faktor-Gruppenanalyse sowie Röntgenbeugungsuntersuchungen korreliert. Die für natürlichen Andersonit abgeleitete Formel Na₂Ca[UO₂(CO₃)₃].5,6H₂O stimmt mit der für synthetischen Andersonit vorgeschlagenen überein.

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. . . , Na₂U₂O₇-CaUO_4–x. . Na₂Ca[UO₂(CO₃)₃] 5,6₂, ** , .

     

Improvement of some pharmaceutical properties of nocloprost by β- and γ-Cyclodextrin Complexation

Inclusion complexation of nocloprost, a potent antiulcer prostaglandin derivative, with -, -, and -cyclodextrins (CyDs) in aqueous solutions has been studied by the solubility method and¹³C-NMR spectroscopy. The steric requirement of host-guest interaction was reflected in the magnitude of the stability constants and the thermodynamic parameters of the inclusion complexes. Solid complexes of nocloprost with - and -CyDs in a molar ratio of 1 : 2 were obtained on the basis of aBs-type phase solubility diagram. The X-ray diffraction data suggested that nocloprost is included in the cylindrical channel formed by coaxial alignment of -CyD molecules to give a channel type structure. Release and thermal behavior of the solid complexes was examined and compared with nocloprost itself. The results indicated that the -CyD complex may have great utility among the three CyDs, being a rapid dissolving form of nocloprost with improved thermal stability.     

Internal Mobility, Phase Transition, and Ionic Conductivity in Thallium(I) Heptafluorodiantimonate(III)

The internal mobility of fluorine ions and the electrophysical properties of TlSb₂F₇ were studied by the ¹⁹F NMR method and impedance spectroscopy. Modes of ionic motions in the fluoride subsystem were determined in the temperature range 213–430 K. A structural phase transition is found to occur at 400 K, resulting in the TlSb₂F₇ modification characterized by high ionic (superionic) conductivity in the temperature range of 400–430 K 2.5·10^-3 S/cm at 430 K).     

Theory of chirality functions,generalized for molecules with chiral ligands

The theory of chirality functions described in a previous publication is generalized to allow for chiral ligands. In the earlier theory, all symmetry operations of the molecular frame could be thought of as permutations of the ligands among the sites; in the present work, improper rotations not only permute the ligands, but convert them into mirror images. The group that generates all isomers from a given ordered molecule belonging to a frame with n sites is now the hyperoctahedral group of order 2ⁿ n! consisting of all possible combinations of permutations and site reflections. The representation theory of these groups is described, and applied to the problem of constructing qualitatively complete chirality functions, and of deciding which ligand partitions, and which isomer mixtures, are chiral. It is found useful to classify chiral representations of the covering group as ligand specific and class specific. The ligand specific representations describe chiral properties which are common to all frames and arise purely from the chirality of the ligands, while the class specific representations describe the chiral properties of the frame. A number of examples are explicitly worked out.