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  • Organic Chemistry  (18)
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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 64 (1981), S. 2175-2182 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The photophysical and electron transfer properties of the lowest excited state of nine ruthenium (polypyridine) complexes have been characterized. The complexes studied are Ru (bpy)3-n (LL)2+n, where n varies from 0 to 3, and LL is 4, 4′-di-t-butyl-2,2′-bipyridine (DTB-bpy), 3, 3′-dimethyl-2, 2′-bipyridine (DM-bpy), or a 2, 2′-diquinolyl derivative (DMCH). The results obtained show that the Ru (bpy)2(DMCH)2+ complex is expected to be a more efficient mediator than Ru (bpy)2+3 in the water-splitting reaction by solar energy.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 2
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 2,6-Diphenylpyridine forms, as twofold-deprotonated, terdentate ligand, complexes with Pt(II) and Pd(II), having two adjacent five-membered metallocycles. As mono-deprotonated, bidentate ligand, it forms cis-bis-complexes having a chirality axis. Pt(II) complexes undergo thermal and photochemical oxidative addition reactions, yielding stable Pt(IV) compounds. Pd(II) complexes yield substitued 2,6-diphenylpyridine in photochemical reactions.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1855-1857 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Cyclometallated complexes of the type cis-bis(2-phenylpyridine)platinum(II) (C22H16N2Pt) and cis-bis(2-(2′-thienyl)pyridine)platinum(II) (C18H12N2S2Pt) undergo thermal or photochemical oxidative addition (TOA or POA) reactions with a number of substrates. TOA (with CH3I, CH3CH2I etc.) yield mixtures of several isomers which rearrange slowly (within ca. one week at room temperature) to one of the possible cis-isomers. CH2Cl2, CHCl3, or (E)—ClCH=CHCl, e.g., do not react thermally. POA yield directly complexes of Pt(IV) with the halide and a σ-bonded C-atom in cis-position. The configuration, as assigned by extensive use of 1H-NMR data, can be characterized for the two chelating ligands C … N and C′ … N′ by C,C′-cis; N,N′-cis and C(chelate), Cl-trans.
    Materialart: Digitale Medien
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  • 4
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The absorption spectra, luminescence spectra, and luminescence lifetimes of the isomeric [M(bph)(bpy)] and [M(phpy)2] complexes M = Pt(II) or Pd(II), bph2- = 1,1′-biphenyl-2,2′-diyl dianion, phpy- = 2-phenylpyridine-2′-yl anion, and bpy = 2,2′-bipyridine have been investigated and compared with those of [M(bpy)2]2+ complexes and of the free protonated ligands H2bph, Hbpy+, and Hphpy. In the absorption spectra, the region below 320 mm is dominated by ligand-centered (LC) transitions, whereas metal-to-ligand charge transfer (MLCT) transitions are responsible for the bands present in the near UV/VIS region. The MLCT bands move to higher energies on replacing Pt with Pd and in going from [M(bph)(bpy)] to the [M(phpy)2] isomer. For the mixed-ligand complexes, evidence for both M → bph2- (at higher energies) and M → bpy bands is found. The structured luminescence observed at 77 K shows lifetimes of 4.0 and 1.1 μs for [Pt(phpy)2] and [Pt(bph)(bpy)], respectively, and 480 and 250 μs for the analogous Pd complexes. On the basis of the energy and lifetime data, the luminescence of the Pt(II) complexes is assigned to the lowest triplet MLCT excited state, whereas for the Pd complexes the luminescent state is thought to result from a mixture of MLCT and LC triplet levels.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 1108-1115 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of tri-heteroleptic complex of Ru(II) with diimine ligands is describe. Ten compounds [Ru(R2bpy) (biq) (L)][PF6]2 (R = H, CH3); L = 2,2′-bipyridine (bpy), 4,4′-dimethyl-2,2′-bipyridine (Me2bpy), 2,2′-bipyrimidine (bpm), 2,2′-biisoquinoline (biiq), 1,10-phenanthroline (phen), dipyrido[3,2-c:2′,3′-e]pyridazine (taphen), 2,2′-biquinoline (biq), 6,7-dihydrodipyrido[2,3-b:3,2-j][1,10]-phenanthroline (dinapy), 2-(2[pyridyl)quinoline (pq), 1-(2-pyrimidyl)pyrazole] (pzpm), 2,2′-biimidazole (H2biim) are characterized by elemental analysis, electronic and 1H-NMR spectroscopy. The relative photosustitution rates of biq in MeCN are given at three temperatures.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 6
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The polarized optical absorption and emission (spectra, decay times) of single crystals of [Pd(thpy)2] and [Pt(thpy)2] (thpy ≡ C(3′)-deprotonated form of 2-(2-thienyl)pyridine) at temperatures 1.9 K ≤ T ≤ 80 K are reported. The emission of [Pt(thpy)2] can be influenced strongly by applied magnetic fields (0 ≤ H ≤ 6 T). Depending on the central ions Pd and Pt, the lowest excited electronic states of the single complexes are ligand-centered (LC) states and metal-to-ligand charge transfer (MLCT) states, respectively. This difference leads to distinctly dissimilar properties of the emission of both compounds. The experimental data show that the emission of single crystals of [Pd(thpy)2] and [Pt(thpy)2] at T ≤ 30 K originates from several types of traps (defect states of symmetry 3B2-stabilized below the exciton band) with LC and MLCT character, respectively. In the Pt compound, the 3B2 is split by spin-orbit coupling into three states. The states B1′ and A2′, which determine the emission properties, are separated by Δv ∼ 13 cm-1. Both states can mix under the influence of an applied magnetic field yielding an increase of the emission intensity by a factor of ∼ 1.5 at H = 6 T.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 72 (1989), S. 377-382 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: A synthetic route leading to bis-heteroleptic cyclometalated complexes is described. The complexes [2-(2′-thienyl)pyridinato-N, C-3′]{2-[3′-(trimethylsilyl)2′-thienyl]pyridinato-N, C3′}platinum(II) ([Pt(thpy) (TMS-thpy)]; I) and (l-phenylpyrazolato-N2, C2′)[2-(2′-thienyl)pyridinato-N, C3′]platinum ([Pt(Phpz)(thpy)]; II) are characterized by UV/VIS, NMR, and mass spectroscopy. Thermal and photochemical oxidative addition reactions yield two out of the 10 possible pairs of enantiomers of octahedral Pt(IV) compounds.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 79 (1996), S. 2176-2179 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 5,5′-Bi-5H-cyclopenta[2,1-b;3,4-b′]dipyridinylidene(1) was synthesized in three steps from 9,10-phenanthroline and characterized by UV/VIS and NMR spectroscopy, mass spectrometry, and cyclic voltammetry. Its ability to act as a bridging ligand is demonstrated by the synthesis of the complexes [Ru(bpy)2(1)](PF6)2 (6) and [{Ru(bpy)2}2(1)](PF6)4 (7) (bpy = 2,2′-bipyridine).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1085-1087 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of a mononuclear Rh(III) complex, as a representative example of a series of related species, containing two cyclometallating ligands ppy (2-phenylpyridine) and one diimine bpy (2,2′-bipyridine) from a binuclear Cl-bridged compound is described. The absorption spectrum shows a maximum at 364 nm (ε = 7000), with a very weak shoulder (ε = 10) at 454 nm. This band is tentatively assigned to a metal-to-ligand charge-transfer transition. A reversible, one-electron reduction appears in the cyclic voltammogram at E1/2 = -1.41 V (vs. NHE) and a irreversible oxydation at Ep = + 1.1 V. A detailed NMR analysis including 13C-NMR, NOE, SFORD as well as deuteration of the bpy ligand indicates the formation of only one isomer, having a C2 axis, bisecting the bpy ligand, with the two carbon ligands in cis-position. 103Rh, 13C and 103Rh,H couplings are observed.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 71 (1988), S. 134-139 
    ISSN: 0018-019X
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The absorption and emission spectra, emission lifetimes, luminescence quantum yields, and electrochemical behavior of the complexes Pd(Phpy)2, Pd(Thpy)2, and Pd(bhq)2 (Phpy-, Thpy-, and bhq-, and bhq- are the deprotonated forms of 2-phenylpyridine, 2-(2-thienyl)pyridine, and benzo[h] quinoline, respectively) have been studied, and the results obtained have been compared with those available for Pt(II) and Pt(IV) complexes containing the same ligands. The intense ligand-centered absorption bands below 340 nm are strongly perturbed by matalation, and the absorption features in the 340-450-nm region are likely to include contributions from formally metal-to-ligand charge-transfer transitions. The structured luminescence spectra observed at 77 K (lifetimes are 0.48, 0.28 and 2.6 ms for Pd(Phpy)2, Pd(Thpy)2, and Pd(bhq)2, respectively) have been assigned to transitions having mainly ligand-centered character, with an increasing metal-to-ligand charge-transfer contribution in going from Pd(bhq)2 to Pd(Phpy)2 and to Pd(Thpy)2. The complexes Pd(phpy)2 and Pd(thpy)2 show two reversible one-electron reduction waves, whereas reduction of Pd(bhq)2 is irreversible, as is the oxidation of the three complexes.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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