Umsetzung von Metall- und Metalloidverbindungen mit mehrfunktionellen Molekülen, 31. Mitteilung

The reaction of galliumtrichloride and galliumtribomide resp. with 2,6-dimethyl- and 2,4,6-trimethyl-N-trimethylsilyl-trifluoroacetanilide leads to the trifluoracetanilidodihalogenogallanes1–3. The 2,6,9-trioxa-4,8-diaza-1,5-digalla-bicyclo-[3.3.1]-nonadiene derivatives1 a–3 a are formed probably as by products.N-Trimethylsilyltrifluoroacetamide reacts with galliumtrichloride to yield the trifluoroacetamido-dichlorogallane4.N-Trimethylsilyl-N,N,N-triorganyl-thioureas react with galliumtrichloride under elimination of chlorotrimethylsilane to give the thio-ureido-gallanes5 and6. IfN,N-diorganylureas andN,N-diorganyl-thio-ureas resp. are reacted with galliumtrichloride and methyl-gallium-dichloride resp., the thio-ureido- and ureido-gallanes7–9 are obtained by elimination of hydrogenchloride. The compounds are characterized by analysis and spectral data (NMR:¹H,¹⁹F; MS; IR). The substances are monomeric in the gas phase, obviously due to internal coordination.

30. Mitt.:W. Maringgele undA. Meller, J. Organomet. Chem., im Druck.     

The Synthesis of 4b, 5, 12, 12a-Tetrahydro-5, 12-ethano-13H-indeno[2,3-b]anthracenes, 4b, 5, 10, 10a - tetrahydro-5,10-ethano-11H-indeno[2,3-b]naphtalenes and 1,2,3,4,4a, 9a-Hexahydro-1,4-(peri-naphthaleno)-fluorenes

The synthesis of endo- and exo-13-oxo-4b, 5, 12, 12a-tetrahydro-5, 12-ethanoindeno[2,3-b]anthracene ( 23 ; Schemes 1 and 2), exo- and endo-11-oxo-4b, 5, 10, 10a-tetrahydro-5, 10-ethano-indeno[2,3-b]naphthalene ( 31 ; Scheme 3), 1,2,3,4,4a,9a-hexahydro?1,4-(peri-naphthaleno)-fluoren-9-one (36; Scheme 4), and the corresponding hydrocarbons of the stereoisomeric ketone pairs 23 and 36 , is described.     

Die Trennung des Molybd?ns von Yanadium durch Anionenaustauscher als Thioglykolatkomplex und die photometrische Bestimmung des Vanadiums mit Thioglykols?ure

Zusammenfassung Die Trennung der Thioglykolsäurekomplexe des Molybdäns von dem des Vanadiums verläuft mit einer Molybdänausbeute von 99%. Das Vanadium kann im Durchlauf in bequemer Weise mittels Thioglykolsäure im p_H-Bereich 4,5–8 bei guter Genauigkeit photometriert werden.Herrn Prof. Dr. O. Glemser, Direktor des Anorganisch-Chem.-Instituts, danken wir sehr für das stete Interesse und die Unterstützung, die er uns zuteil werden ließ.Dem Herrn Bundesminster für Atomkernenergie und Wasserwirtschaft sowie der Deutschen Forschungsgemeinschaft danken wir für apparative und finanzielle Hilfe.     

Determination of dissociation constants of 99mTechnetium radiopharmaceuticals by capillary electrophoresis

Capillary electrophoresis was applied to investigate pKa values of 99mTc radiotracers used in nuclear medicine. Therefore, the protonation equilibria of the carboxyl groups of 99mTc-mercaptoacetylglycylglycylglycine (99mTc-MAG3) and 99mTc-ethylenecysteine dimer (99mTc-EC) were studied by pH-dependent determination of electrophoretical velocities. 99mTc-ethylenecysteine dimer diethyl ester (99mTc-ECD) was used as a non-protonable standard. The capillary electrophoresis system was equipped with a radioactivity detector. Measurements were performed using a pressure-driven capillary zone electrophoresis which allowed runs even in the low pH range. For the determination of pKa values, the electrophoretical velocities of the analytes were referred to the electrophoretical velocities of tetraphenyle arsonium chloride as a positively charged marker. Calculation of pKa values was accomplished by non-linear curve fitting of both structure-based equilibria equations and sigmoidal decay functions to the experimental data. 99mTc-MAG3 was shown to have a carboxyl group pKa value of 4.22. The value for the carboxyl groups of 99mTc-EC is 2.90 (determined by structure-based equilibria equations), which represents a common value for both carboxyl groups. By the use of sigmoidal functions, similar values were elucidated. As expected, 99mTc-ECD shows no protonation step.     

Synthesis, structure, and dynamics of six-membered metallacoronands and metallodendrimers of iron and indium

In the reaction of the N-substituted diethanolamines (H(2)L(1-3)) (1-3) with calcium hydride followed by addition of iron(III) or indium(III) chloride, the iron wheels [Fe(6)Cl(6)(L(1))(6)] (4) and [Fe(6)Cl(6)(L(2))(6)] (6) or indium wheels [In(6)Cl(6)(L(1))(6)] (5), [In(6)Cl(6)(L(2))(6)] (8) and [In(6)Cl(6)(L(3))(6)] (9) were formed in excellent yields. Exchange of the chloride ions of 6 by thiocyanate ions afforded [Fe(6)(SCN)(6)(L(2))(6)] (7). Whereas the structures of 4, 5 and 7 were determined unequivocally by single-crystal X-ray analyses, complexes 8 and 9 were characterised by NMR spectroscopy. Contrary to what is normally presumed, the scaffolds of six-membered metallic wheels are not generally rigid, but rather undergo nondissociative topomerisation processes. This was shown by variable temperature (VT) (1)H NMR spectroscopy for the indium wheel [In(6)Cl(6)(L(1))(6)] (5) and is highlighted for the enantiotopomerisation of one indium centre [ 1/6[S(6)-5]<==>[1/6[S(6)-5']]. The self-assembly of metallic wheels, starting from diethanolamine dendrons, is an efficient strategy for the convergent synthesis of metallodendrimers.     

Synthetische Juvenilhormone 3. Mitteilung. p-Substituierte 4-Phenyl-buten(1)-carbonsäurederivate

The syntheses of p-substituted 2-methyl-4-phenylbuten(1)-carboxylic acid derivatives are described, using Blanc's chloromethylation reaction, the Friedel-Crafts alkylation of unsaturated ketones or the Meerwein arylation; the formed intermediates react in subsequent steps to the title compounds.     

Monocyclopentadienylhydride derivatives of ruthenium: stereoselective proton transfer and proton-hydride exchange in an extremely short dihydrogen bond

Diastereomerically pure complexes of formula CpRuCl(PP) and CpRuH(PP) with chiral ferrocenyl diphosphines were prepared and the selectivity of proton-transfer processes over the monohydride compounds with different acids was studied. With 1 equiv of HBF(4) the cis-dihydrogen and trans-dihydride complexes were formed while with 3 equiv of CF(3)CO(2)H the trans-dihydride derivative was the only product. However, the use of 1 equiv of CF(3)CO(2)H led to a dihydrogen bonded complex with an extremely short RuH...HO(2)CF(3) interaction that exhibits proton-hydride exchange. Using the labeled acid CF(3)CO(2)D, a stereoselective transference of the deuteron was demonstrated that implies the previous epimerization of the monohydride and the subsequent attack of the acid in the position previously occupied by the hydride.     

Ab initio study of AmCl(+): f-f spectroscopy and chemical binding

A valence full configuration interaction study with a polarized double-zeta quality basis set has been carried out for the lowest 49 electronic states of AmCl(+). The calculations use a pseudopotential treatment for the core electrons and incorporate a one-electron spin-orbit interaction operator. Electrons in the valence s, p, d, and f subshells were included in the active space. The resulting electronic potential energy curves are largely repulsive. The chemical bonding is ionic in character with negligible participation of 5f electrons. The molecular f-f spectroscopy of AmCl(+) arises essentially from an in situ Am(2+) core with states slightly redshifted by the presence of chloride ion. Am(+)+Cl asymptotes which give rise to the few attractive potential energy curves can be predicted by analysis of the f-f spectroscopy of isolated Am(+) and Am(2+). The attractive curves have substantial binding energies, on the order of 75-80 kcal/mol, and are noticeably lower than recent indirect measurements on the isovalent EuCl(+). An independent empirical correlation supports the predicted reduction in AmCl(+) binding energy. The energies of the repulsive curves are strongly dependent on the selection of the underlying atomic orbitals while the energies of the attractive curves do not display this sensitivity. The calculations were carried out using our recently developed parallel spin-orbit configuration interaction software.     

Carbometallate: Komplexe Anionenverbände [MoC4/26—] in der Kristallstruktur von Pr[MoIIC2]

Carbometalates: Complex Anions equation/tex2gif-stack-4.gif [MoC_4/2^6—] in the Crystal Structure of Pr equation/tex2gif-stack-5.gif [Mo^IIC₂] Criteria for the existence of carbometalates are established and discussed in a broader context. The concept is then applied to the novel compound Pr₂[MoC₂], which is characterized by chemical analyses, X‐ray diffraction and metallography. The crystal structure (tetragonal, P4₂/mnm, Z = 4, a = 581.29(8) pm, c = 1032.53(14) pm) consists of layered polyanions equation/tex2gif-stack-6.gif[MoC_4/2^6—] of distorted vertex and edge sharing MoC₄ tetrahedra. Praseodymium is also in a distorted tetrahedral coordination by carbon. The physical properties show “bad metal” behaviour and localized magnetic 4f‐moments in agreement with the existence of Pr³⁺‐species. A detailed bonding analysis using both the electron localization function ELF and the COHP method justifies the interpretation of the title compound as a carbomolybdate(II).