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  • 1
    Electronic Resource
    Electronic Resource
    The quadruply bondedbis-carboxylatescis-Re2(μ-O2CCH3)2X4L2 (X = halide;L = neutral donor) as synthons in dirhenium chemistry (1994)
    Springer
    Journal of cluster science 5 (1994), S. 173-184 
    Details
    ISSN: 1572-8862
    Keywords: Rhenium ; dimetal comptexes ; phosphine ligands ; carboxylatebridged complexes ; redox chemistry ; preparation ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reactions of the quadruply bonded dirhenium(III) carboxylatescis-Re2(μ-O2CR)2X4L2 (X=CI or Br; L=a monodentate donor) with monodentate, bidentate, and tridentate phosphine donors result in several types of redox behavior, usually involving partial or complete reductive decarboxylation of the dirhenium unit. Examples of dirhenium(VI, II), dirhenium(IV, II), dirhenium(III, II), and dirhenium(II, II) complexes, in which Re-Re bond orders of 4, 3.5, 3, l, or zero are encountered, have been isolated and repre-sentative examples structurally characterized. The course of these reactions is dependent upon the nature of the phosphine. The scope of this remarkably rich chemistry is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01165498
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  • 2
    Electronic Resource
    Electronic Resource
    The oxidative addition of hydrogen sulfide to the electron-rich triple bond: The isolation and characterization of compounds that contain the Re2(μ-H)(μ-SH) cluster unit (1991)
    Springer
    Journal of cluster science 2 (1991), S. 259-270 
    Details
    ISSN: 1572-8862
    Keywords: Rhenium ; clusters ; hydrido-bridged ; hydrosulfido-bridged ; preparation ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reactions of Re2X4(μ-dppm)2 (X=Cl or Br; dppm=Ph2PCH2PPh2) with H2S in THF afford the dirhenium (III) complexes Re2(μ-H)(μ-SH)X4(μ-dppm)2, the first examples of the oxidative addition of an S-H unit across an electron-rich metal-metal triple bond. The bromide complex Re2(μ-H)(μ-SH)Br4(μ-dppm)2 (C2H5)2O crystallizes in the space group P21/n witha=16.631(2) Å,b=15.967(3) Å,c=19.904(2) Å, β=92.698(7)°,V=5279(2) Å3, andZ=4. The structure which was refined toR=0.053 (R w=0.070) for 4903 data withI〉3.0σ(I), shows the presence of an edge-shared bioctahedral geometry with a very short Re-Re distance of 2.4566(7) Å. While the hydrogen atoms of the μ-H and μ-SH ligands were not located in the X-ray structure determination, their presence is confirmed by IR and1H NMR spectroscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702956
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  • 3
    Electronic Resource
    Electronic Resource
    The oxidative addition of diphenylphosphine and monophenylphosphine to the electron-rich rhenium-rhenium triple bond. The isolation and characterization of compounds that contain the four-center Re(μ-X)(μ-PR2)Re cluster (X=halide) (1992)
    Springer
    Journal of cluster science 3 (1992), S. 83-102 
    Details
    ISSN: 1572-8862
    Keywords: Rhenium ; dimetal clusters ; hydrido-complexes ; phosphidobridged ; preparation ; structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Diphenylphosphine oxidatively adds to the Re≡Re bonds of Re2 X 4(μ-dppm)2 (X=Cl or Br; dppm=Ph2PCH2PPh2) and Re2Cl4(μ-dpam)2 (dpam=Ph2AsCH2AsPh2) to afford the dirhenium(III) complexes Re2(μ-X)(μ-PPh2)HX 3(μ-LL)2. The dppm complexes have also been prepared from the reactions of Re2(μ-O2CCH3)X 4(μ-dppm)2 with Ph2PH, and a similar strategy has been used to prepare Re2(μ-Cl)(μ-PPh2)HCl3(μ-dmpm)2 (dmpm=Me2PCH2PMe2) from Re2(μ-O2CCH3)Cl4(dmpm)2. Phenylphosphine likewise reacts with Re2 X 4(μ-dppm)2 to give Re2(μ-X)(μ-PHPh)HX 3(μ-dppm)2. An X-ray crystal structure determination on Re2(μ-Cl)(μ-PPh2)HCl3(μ-dppm)2 confirms its edge-shared bioctahedral structure. This complex crystallizes in the space group $$R\bar 3$$ (No. 148) witha=21.699(3) Å, α=84.50(4)°,V=10084(5) Å3, andZ=6. The structure was refined toR=0.049 (R w 0.069) for 5770 data withI〉3.0σ(I). The Re-Re distance is 2.5918(7) Å. Oxidation of the bromide complex Re2(μ-Br)(μ-PPh2)HBr3(μ-dppm)2 with NOPF6 produces the unusual dirhenium(III, II) cation [Re2(μ-H)(μ-Br)[P(O)Ph2]Br2(NO)(μ-dppm)2]+ which has been structurally characterized as its perrhenate salt, [Re2(μ-H)(μ-Br)[P(O)Ph2]Br2(NO)(μ-dppm)2]ReO4 · 2CH2Cl2. This complex crystallizes in the space group $$P\bar 1$$ (No. 2) witha=14.187(7) Å,b=16.419(5) Å,c=16.729(5) Å, α=98.76(2)°, β=110.11(3)°, γ=104.66(3)°,V=3414(6) Å3,Z=2. The structure was refined toR=0.040 (R w =0.051) for 5736 data withI〉3.0σ(I). The presence of a phosphorus-bound [P(O)Ph2]− ligand, a linear nitrosyl and a bridging hydrido ligand has been confirmed. The Re-Re distance is 2.6273(8) Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00814613
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  • 4
    Electronic Resource
    Electronic Resource
    Ambident reactivity of aryloxide ions towards 1,3,5-trinitrobenzene, low-temperature characterization of the elusive Oxygen-bonded σ-complexes by 1H and 13C NMR spectroscopy (1993)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 71-82 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The ambident reactivity of phenoxide ion towards 1,3,5-trinitrobenzene (TNB) was re-examined by means of a novel reaction system(CD3CN-glyme-d10) which allows the investigation of species formed at low temperatures (-40°C), contrasting with previous studies in dimethyl sulfoxide (DMSO) at ambient temperature. The new method coupled with 400 MHz NMR spectroscopy has allowed the definitive observation of both O- and C-bonded phenoxide σ-complex adducts for the first time, confirming the formation of the former through kinetic control and of the latter through thermodynamic control. The corresponding O-bonded σ-adduct in the TNB-mesitoxide system (whereC-bonded σ-adduct formation is not possible but where there is competing nitro group displacement) has also been characterized by 1H and 13C NBR. Another O-bonded aryloxide adduct characterized is that from the reaction of TNB with3,5-di-tert-butylphenoxide; in this system there is also competing NO2 displacement. Stereoelectronic factors in the O-bonded σ-adducts and aryl ethers are discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610060202
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  • 5
    Electronic Resource
    Electronic Resource
    Kinetics of solvolysis of 1-acetyl-4-(1-ethoxycarbonyl-1-cyano) methylene-1,4-dihydroquinoline in undried DMSO-d6· formation of Acetic Anhydride as an intermediate (1992)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 24 (1992), S. 447-454 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The kinetics of solvolysis of the title compound (QAc) in undried DMSO-d6 to give 4-(1-ethoxycarbonyl-1-cyano)methylquinoline (QH) and HOAc at ambient temperature were investigated by 1H nmr spectrometry. With a limited excess of water the solvolysis follows a three-step process of \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm QAc} + {\rm H}_2 {\rm O}\mathop \to \limits^{k_1} {\rm QH} + {\rm HOAc}, $\end{document} , and \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm Ac}_{\rm 2} {\rm O} + {\rm H}_2 {\rm O}\mathop \to \limits^{k_3} {\rm 2\,HOAc}, $\end{document} where k2 〉 k1 and k3 〈 k1. Addition of pyridine-d5 to the reaction mixture markedly catalyzes the overall solvolysis, while addition of CF3CO2D to the reaction mixture simplifies the kinetics to pseudo first-order in [QAc] with k = 4.3 × 10-3 min-1.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550240505
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetics of a second order reaction involving two intermediate second order reactions (1992)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 24 (1992), S. 455-466 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied the kinetics of a reaction in which starting materials A and B react to form the products C and D directly, as well as by way of two additional intermediate reactions. In the first intermediate reaction, A and C react to form D and E, and in the second intermediate reaction, B and E react to form 2C. There are three conservation laws, which effectively reduce the number of variables to two, resulting in nonlinear coupled first order differential equations for [A](t) and [B](t). These equations are readily solved by standard numerical procedures, for various values of the relative reaction rates and starting concentrations. Our results are used to fit experimental data for the case in which A and B are 1-acetyl-4-(1-ethoxycarbonyl-1-cyano)methylene-1,4-dihydroquinoline and water, for which the first and third reverse reactions can be neglected.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550240506
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