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  • Chemistry  (25)
  • Nickel complexes  (2)
  • 11
    ISSN: 1434-1948
    Keywords: Ruthenium ; S ligands ; Hydrazine ; Diazene ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the search for ruthenium complexes with sulfur-dominated coordination spheres that bind, activate, or stabilize nitrogenase relevant molecules, complexes containing the new and robust tetradentate ligand ‘tpS4’-H2 were synthesized. Treatment of [RuCl2(PPh3)3] with ‘tpS4’2- gives [Ru(PPh3)2(‘tpS4’)] (1), which contains two labile PPh3 ligands. The reaction of 1 with PEt3 or DMSO led to substitution of both PPh3 ligands, yielding [Ru(PEt3)2(‘tpS4’)] (2) and [Ru(DMSO)2(‘tpS4’)] (3), respectively. When treated with nitrogenous ligands, complex 1 lost only one PPh3 ligand to yield [Ru(L)(PPh3)(‘tpS4’)] complexes where L = py (7), NH3 (8), N2H4 (9), NH2NHMe (10), and CH3CN (12), all of which are labile. The labile acetonitrile complex [Ru(CH3CN)(PPh3)(‘tpS4’)] (12) proved to be particularly suited as a precursor for the syntheses of other [Ru(L)(PPh3)(‘tpS4’)] complexes. The 18 and 19 valence electron NO complexes [Ru(NO)(PPh3)(‘tpS4’)]BF4 (13) and [Ru(NO)(PPh3)(‘tpS4’)] (14), (NEt4)[Ru(N3)(PPh3)(‘tpS4’)] (15), [Ru(I)(PPh3)(‘tpS4’)] (16), and [Ru(N3)(PPh3)(‘tpS4’)] (17) were obtained starting from complex 12. The labile mononuclear hydrazine complex [Ru(N2H4)(PPh3)(‘tpS4’)] (9) gave the dinuclear complex [μ-N2H4{Ru(PPh3)(‘tpS4’)}2] (18) by dissociation of hydrazine. The dinuclear diazene complex [μ-N2H2{Ru(PPh3)(‘tpS4’)}2] (19) was obtained by oxidation of 9 and more readily from [Ru(CH3CN)(PPh3)(‘tpS4’)] (12) and N2H2, which was generated in situ from K2N2(CO2)2 and acetic acid. The molecular structures of 7, 13, 16, 18, and 19 were determined by X-ray structure analyses. The complexes 18 and 19 represent the first complexes containing the hydrazine/diazene couple, which enables us to compare both the bonding features and the formation of N-H···S bridges when hydrazine and diazene bind to transition metal sulfur sites.
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  • 12
    ISSN: 1434-1948
    Keywords: Cleavage reactions ; C-S cleavage ; Ligand synthesis ; Osmium ; Ruthenium ; S ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In search of a tetradentate thioether thiolate ligand that is more stable toward reductive C-S bond cleavage than the parent ligand ′S4′-H2 [′S4′-H2 = 1,2-bis(2-mercaptophenylthio)ethane], the novel tris-phenylene ligand ′tpS4′-H2 (3) [′tpS4′-H2 = 1,2-bis(2-mercaptophenylthio)phenylene] was synthesized via the nitro and amine compounds ′tpS2(NO2)2′ (1) and ′tpS2(NH2)2′ (2). The coordination of ′tpS4′2- to ruthenium centers resulted in the formation of six-coordinate [Ru(L)(PR3)(′tpS4′)] complexes (R = Et, L = PEt34; R = Ph, L = PPh35, CO 6, DMSO 7). The X-ray structure analyses of 4 and 6 revealed that the thiolate donors occupy trans positions; consequently the ′tpS4′2- ligand coordinates in the same way as the ′S4′2- ligand. The stability of the ′tpS4′2- ligand toward reductive C-S cleavage reactions was shown by the synthesis of [Os(PEt3)2(′tpS4′)] (8). In contrast to [Os(PEt3)2(′S4′)], 8 is stable for unlimited periods of time. The X-ray structure analysis of [Ru(Cl)2(PPh3)(′tpS2(NH2)2′)] (9) demonstrates that the potentially tetradentate ligand ′tpS2(NH2)2′ coordinates in 9 through three donors leaving one NH2 donor dangling.
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  • 13
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 59-63 
    ISSN: 1434-1948
    Keywords: Phosphorane imine ; Sulfur ligands ; Nickel ; Palladium ; Platinum ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of the trinuclear [M(′S3′)]3 complexes {M = Ni (4), Pd (5), Pt (6); ′S3′2- = bis(2-mercaptophenyl)sulfide (2-)} with HNPnPr3 yielded the new phosphorane imine complexes [M(NHPnPr3)(′S3′)] {M = Ni (1), Pd (2), Pt (3)}. The complexes 1-3 have been completely characterized and are rare examples of mononuclear phosphorane imine complexes with late transition metals. Spectroscopic and structural results indicate that the HNPnPr3 ligands favor the ylidic structure when binding to [M(′S3′)] fragments. X-ray structure determinations showed that [M(NHPnPr3)(′S3′)] complexes associate through N-H···S(thiolate) bridges to give centrosymmetric dimers.
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  • 14
    ISSN: 1434-1948
    Keywords: Ruthenium ; Sulfur ligands ; Exchange reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a quest for ruthenium complexes having [RuNS4] cores, a non-fluxional configuration, trans-thiolate donors, and exchangeable coligands L, [Ru(L)(‘pyS4’)] complexes have been synthesized [‘pyS4’2- = 2,6-bis(2-mercaptophenylthio)dimethylpyridine(2-)]. Treatment of [RuCl2(PPh3)3] with ‘pyS4’2- gave [Ru(PPh3)(‘pyS4’)] (1). Alkylation of 1 with excess MeI yielded [Ru(PPh3)(‘pyS4’-Me2)]I2 (2). [Ru(DMSO)(‘pyS4’)] (3) was obtained from [RuCl2(DMSO)4] and ‘pyS4’2-. The PPh3 or DMSO coligands in 1, 2, and 3 proved to be very inert to substitution. Only the DMSO could be displaced by CO under drastic conditions yielding [Ru(CO)(‘pyS4’)] (4). Treatment of [RuCl2(CH3CN)4] with ‘pyS4’2- yielded [Ru(‘pyS4’)]2 (5); in the presence of PEt3 or N2H4 mononuclear [Ru(PEt3)(‘pyS4’)] (6) and [Ru(N2H4)(‘pyS4’)] (7) were formed. Template alkylation of NBu4[Ru(NO)(S2C6H4)2] with 2,6-bis(tosyloxymethyl)pyridine gave [Ru(NO)(‘pyS4’)]Tos (8). Complex 8 proved to be the best suited precursor for L exchange reactions. Under reducing conditions, 8 releases its NO ligand and the resulting [Ru(‘pyS4’)] fragments can combine either with each other to give 5, or with PEt3 and N2H4 to yield 6 and 7, respectively. All complexes have been characterized by spectroscopic methods and elemental analysis; 1, 2, 3, and 4 have also been submitted to X-ray structure analysis.
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  • 15
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 2000 (2000), S. 271-279 
    ISSN: 1434-1948
    Keywords: Nickel complexes ; Palladium complexes ; S ligands ; Exchange reactions ; Azide ; Sulfinylimide ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to obtain suitable precursors for nickel and palladium complexes that model the reactivity of the active sites of hydrogenases and CO dehydrogenases, a series of [M(L)(‘S3’)] complexes has been synthesized [M = NiII, PdII; ‘S3’2- = bis(2-mercaptophenyl)sulfide(2-)]. X-ray structure determinations of [Ni(‘S3’)]3 (1) and [Pd(‘S3’)]3 (2) have revealed that the [M(‘S3’)] fragments trimerize to give six-membered [MS]3 rings, which exhibit chair conformations with alternating MII centers and thiolate bridging atoms. Reactions of the parent complex [Ni(‘S3’)]3 (1) with nucleophiles L, such as thiolates SR- (R = tBu, Cy, Me, Ph), phosphanes PR3 (R = Cy, Ph), chloride, or azide, have been found to yield the corresponding anionic or neutral [Ni(L)(‘S3’)] complexes, which were isolated as (NBu4)[Ni(SR)(‘S3’)] [R = tBu (3), Cy (4), Me (5), Ph (6)], [Ni(PR3)(‘S3’)] [R = Cy (7), Ph (8)], (NBu4)[Ni(Cl)(‘S3’)] (9), and (NBu4)[Ni(N3)(‘S3’)] (10). When treated with Me3SiX, the StBu- ligand in (NBu4)[Ni(StBu)(‘S3’)] (3) was exchanged to give (NBu4)[Ni(X)(‘S3’)] [X = Cl- (9), N3- (10), NCS- (11), NSO- (12)]. The palladium complex [Pd(‘S3’)]3 (2) could also be cleaved with StBu-, but the resulting (NBu4)[Pd(StBu)(‘S3’)] (13) proved inert towards exchange reactions with Me3SiX. All the mononuclear complexes have been characterized by standard spectroscopic techniques and by elemental analysis. The molecular structures of 3, 4, 6, 7, 8, 9, and 13 have been determined by X-ray crystallography. The [MS3L] core geometries of all the complexes are non-planar, exhibiting a considerable tetrahedral distortion.
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  • 16
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 1998 (1998), S. 1951-1957 
    ISSN: 1434-1948
    Keywords: Rhodium catalysis ; C-C coupling ; C-H activation ; Alkynes ; Trisubstituted naphthalenes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: RhCl(PPh3)3 in the presence of excess hydrochloric acid and azobenzene in refluxing 1-pentanol catalyzes the cyclodimerization of arylalkynes to 1,2,3-substituted naphthalene derivatives. This enables an easy access to 1,2,3-triphenylnaphthalene (1), 7-methoxy-1,2,3-tris(p-methoxyphenyl)naphthalene (2), 7-methyl-1,2,3-tris(p-methylphenyl)naphthalene (3), and 7-nitro-3-(p-nitrophenyl)-1,2-diphenylnaphthalene (4). A co-cyclodimerization of tolan with 4-octyne affords 3-phenyl-1,2-dipropylnaphthalene (5). The structure of 4 was resolved by single-crystal X-ray structural analysis. The rate of formation of 1 is first-order with respect to tolan and RhCl(PPh3)3 and exhibits activation parameters of ΔH
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  • 17
    ISSN: 0947-6539
    Keywords: dihydrogen activation ; heterolytic cleavage ; hydrido complexes ; rhodium ; S ligands ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: [Rh(H)(L)(“buS4”)] complexes (L = CO (1), PCy3 (2); “buS4”2- = 1,2-bis[(2-mercapto-3,5-di-tert-butylphenylthio)ethane2-]) catalyze the D2/H+ exchange between D2 and EtOH protons in the presence of catalytic amounts of Brønsted acids. A mechanism and complete cycle for the heterolytic D2 cleavage are proposed that are based on characterization of key intermediates and monitoring of key reactions. The key intermediates are the thiol hydride complexes [Rh(H)(L)(“buS4”-H)]BF4, L = CO (3), PCy3 (4), the coordinatively unsaturated complexes [Rh(L)(“buS4”)]BF4, L = CO (5), PCy3 (6), which are the actual catalysts, and the deuterium-labeled derivatives of 1-4. Complexes 3 and 4 form from 1 and 2 by protonation with HBF4, and they release H2 to give 5 and 6. Complex 5 dimerizes in the solid state and was characterized by X-ray structure determination of 5·8CH2Cl2 (triclinic space group P\documentclass{article}\pagestyle{empty}\begin{document}$ \bar 1 $\end{document}, a = 1048.2(4) pm, b = 1430.0(5) pm, c = 1785.7(7) pm, α = 100.49(3)°, β = 102.92(3)°; γ = 103.68(3)°, Z = 1). Complex 6 is mononuclear and adds H2O or THF reversibly to give the highly labile [Rh(L)(PCy3)(“buS4”)]BF4, L = H2O (7), THF (8). CO is irreversibly added to give the stable [Rh(CO)-(PCy3)(“buS4”)]BF4 (9), whose high-frequency ν(CO) (2081 cm-1) indicates a relatively low electron density at the Rh center. Complex 6 also adds to H2 to give 4, which can be deprotonated by solid Na2CO3 or H2O to yield neutral 2. 1H NMR and 2H NMR spectroscopy revealed the scrambling of thiol protons and hydride ligands in 3 and 4 and its deuterium-labeled derivatives. This exchange of thiol protons for hydride ligands is explained by a transient [Rh(η2-H2)] species. Low-temperature 1H/2H NMR spectroscopy showed that protonation of 2 yields four diastereomers of 4 resulting from protonation of the four stereochemically nonequivalent lone pairs at the thiolate donors of 2. The relevance of these findings to H2 activation at transitionmetal sulfur sites in hydrogenases or hydrotreatment catalysts, and differences from the H2 cleavage achieved with other complexes not containing “built-in” Brønsted-basic centers, are discussed.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1998 (1998), S. 1213-1218 
    ISSN: 1434-193X
    Keywords: Cycloadditions ; Diazatetraasteranes ; Crystal structure ; Solid-state chemistry ; Photochemistry ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Upon irradiation, crystalline 4-methoxyphenyl-1,4-dihy-dropyridines 1 undergo nearly quantitative [2+2]cyclo-addition to form, via the ring-open intermediates 2, the centrosymmetric, polyfunctionalized 3,9-diazatetraasteranes 3. The centrosymmetric character of 3 was confirmed by 1H NMR spectral data as well as by X-ray crystal structure analysis. The dimerization reactions prove to be topochemically controlled by the nearest distance between potentially reacting double bonds, as well as by the conformationally determined packing restraints. This latter factor is shown by the X-ray crystal structure analysis of one dimerizing and one photostable derivative of the monomers 1.
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  • 19
    ISSN: 0044-8249
    Keywords: Eisen ; Magnetische Eigenschaften ; Mößbauer ; Spektroskopie ; N-Liganden ; S-Liganden ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 20
    ISSN: 0044-8249
    Keywords: Eisen ; N-Liganden ; S-Liganden ; Mößbauer-Spektroskopie ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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