Ab initio calculations of small hydrides including electron correlation

Five different structures of CH₅ ⁺ and one structure of CH₅ ^– are calculated using a gaussian basis both in the SCF approximation and with the inclusion of electron correlation in the independent electron pair approximation (IEPA). While on SCF level the C _sstructure of CH₅ ⁺ has to lowest energy, the energy difference between the C _sand C _2vstructures becomes negligible if correlation is included. In contrast to this the approach of a proton to CH₄ at large and intermediate distances is most favorable towards a corner of the CH₄ tetrahedron which means a structure. The decomposition of CH₅ ⁺ into CH₃ ⁺ and H₂ requires 20kcal/mol on SCF level and 40 kcal/mol if correlation is included.     

The Absolute Configuration of 1-Methylindane

It is shown unequivocally by chemical correlations (cf. Schemes 1--3) and Raman optical activity spectra (cf. Fig. 1 and 2) that the (R)-configuration has to be attributed to (+)-1-methylindane ((+)- 1 ). This is in contradiction to an earlier assignment of the (R)-configuration to (?)- 1 [2] which was based on the (R)-configuration of (+)-indane-1-carboxylic acid ( 3 ) [11].     

MO-LCAO-Calculations on polymethines. V. PPP-type calculations and configuration analyses of simple prototype dyes in terms of molecular subsystems

In order to elucidate certain controversies in interpreting the π-electronic structure of some simple quinone and indigo dyes the Pariser–Parr–Pople SC _β,γ-wave-functions have been subjected to configuration analyses. Whereas 2,5-diamino-quinone (1) can be excellently represented by coupling of two trimethine-merocyanine chains, the analogous consideration is less appropriate with bispyrrolindigo (2). In this case the results of the configuration analyses indicate clearly the limited applicability of the Longuet/Higgins–Murrell–method.     

Sorptionseffekte an Eisen(III)-hydroxid-F?llungen

Zusammenfassung Um Material zur Deutung des Mechanismus der Sorption von Sr²⁺-Ionen an Eisen(III)-hydroxid zu gewinnen, werden Meßreihen mitgeteilt, in denen die pH-Abhängigkeit der Sorption sowie deren Beeinflussung bei Fällung mit verschiedenen Basen (NaOH, Ammoniak, Trimethylamin, Benzylamin) untersucht wird. Aus den charakteristischen Unterschieden der Sorptionskurven muß gefolgert werden, daß die Art der Base für die Sorption eine wichtige Rolle spielt.

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Summary The sorption of Sr²⁺ ions on iron(III) hydroxide was studied as a function of the pH, of the precipitating reagent (NaOH, ammonium hydroxide, benzylamine, trimethylamine), of the temperature and of the total concentration.The curves of the relative sorption vs. pH are found to show characteristic differences which have to be explained in a detailed theory of the mechanism.

     

Darstellung und Eigenschaften von Chromtricarbonyl-Komplexen strukturisomerer Borazin-Derivate

The new hexaalkylborazine chromium tricarbonyls (n-Pr)₃B₃N₃Me₃Cr(CO)₃ (V), Me₃B₃N₃(n-Pr)₃Cr(CO)₃ (VI), (i-Pr)₃B₃N₃Me₃Cr(CO)₃ (VII) and Me₃B₃N₃(i-Pr)₃Cr(CO)₃ (VIII) have been prepared from fac-Cr(CO)₃(MeCN)₃ and the corresponding borazine in dioxane or without solvent. They are much more labile than the isomeric complex Et₃B₃N₃Et₃Cr(CO)₃ (IV) which can be readily obtained from Et₃B₃N₃Me₃Cr(CO)₃ and Et₃B₃N₃Et₃ by ring ligand exchange. The NMR., IR., UV. and Mass spectroscopic data of the complexes IV–VIII will be briefly discussed. The preparation of the borazine derivatives (n-Pr)₃B₃N₃Me₃ (IX) and Me₃B₃N₃(n-Pr)₃ (X) is also reported.     

Basische Metalle. LXIV. Lewis-basische Bis(trimethylphosphan)cobalt-Komplexe mit Indenyl und Trifluormethylcyclopentadienyl als Liganden

Basic Metals. LXIV. Lewis-basic Bis(trimethylphosphine)cobalt Complexes with Indenyl and Trifluormethylcyclopentadienyl as Ligands The half-sandwich type compounds C₉H₇Co(PMe₃)₂ ( 1 ) and (C₅H₄CF₃)Co(PMe₃)₂ ( 6 ) are prepared from CoCl(PMe₃)₃ and C₉H₇Li or TlC₅H₄CF₃, respectively. They behave like metal bases and react with HBF₄, CH₃I (or CF₃SO₃CH₃), I₂, and CH₃COCl by oxidative addition to give the cationic complexes [C₉H₇CoX(PMe₃)₂]⁺ and [(C₅H₄CF₃)CoX(PMe₃)₂]⁺ (X ? H, CH₃, I, COCH₃) which are isolated as the PF₆ salts ( 2–5 and 7–10 ). The ¹HNMR and the IR spectra of the compounds 1–10 are discussed, also in comparison to those of the corresponding cyclopentadienylcobalt complexes.     

Die gasförmigen Komplexe NiAl2Cl8 und NiAl3Cl11

Gaseous Complexes NiAl₂Cl₈ and NiAl₃Cl₁₁ Spectral photometric measurements of equilibria which are established by reaction of solid NiCl₂ with gaseous Al₂Cl₆ have been made. Results see ?Inhaltsübersicht”?.     

Borazin—metallkomplexe : VI. Über ligandenaustauschreaktionen an borazin—metallkomplexen: synthese von B-trimethylborazin-tricarbonylchrom

Me₃B₃N₃H₃Cr(CO)₃ has been obtained by ring-ligand exchange starting from Et₃B₃N₃Me₃Cr(CO)₃ and Me₃B₃N₃H₃. The new compound has been characterised by means of their IR, NMR, UV and mass spectroscopic data.     

Open- and closed-shell states in few-particle quantum mechanics. II. Classification of atomic states

The system developed in the first paper of this series for the classification of states as open- or closed-shed type is applied to atomic states. These may be classified in the isoelectronic limit (Z → ∞) from knowledge of the true wave function in this limit. One-matrix occupation numbers are tabulated for a number of states of the first-row atoms in the limit Z → ∞ and the states classified. A classification for finite Z is possible in the framework of the Z-dependent perturbation theory by use of a thoerem for the stability of a closed-shed with respect to small perturbations. Such a stability does not hold in general for open-shel states.     

Totalsynthese von (+)-D-Homoöstron-3-methyläther

Total Synthesis of (+)-D-Homoestrone 3-methyl ether A novel total synthesis of (+)-D-homoestrone 3-methyl ether ( 21 ) is described starting from (S)-8a-methyl-3,4,8,8a-tetrahydro-2H, 7H-naphthalene-1,6-dione ( 1 ) as a chiral synthon for the rings C and D. The key step involves alkylation of the derived 3 with m-methoxyphenacyl bromide ( 4 ) as an AB-building block to give the dioxo-secosteroid 5 . Hydrogenation of 5 affords the trans-decalone 11 . As by-products the epimeric cis-decalones 12 and 13 were characterized. Cyclization of 11 leads under kinetic control predominantly to the Δ⁹⁽¹¹⁾-tetraene 14 . Catalytic hydrogenation of 14 and subsequent modification in ring D give the title compound 21 . It was found that 14 and also the derived Δ⁸-isomer 15a add hydrogen from the α-face of the molecule to an extent of about 80%. The 8α-D-homoestrone derivatives 20a and 23 as well as the 9β-isomers 19a and 22 were characterized.