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  • 1
    ISSN: 0009-2940
    Schlagwort(e): Rhenium complexes ; Silylene complexes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reactions of (η5-C5H5)Re(NO)(PPh3)(SiMe2H) (1) and CHCl3, CBr4, and CHI3 give halosilyl complexes (η5-C5H5)Re(NO)-(PPh3)(SiMe2X) [X = Cl (2), Br (3), I (4); 66-84%]. Addition of Me3SiOTf to 2 gives triflate (η5-C5H5)Re(NO)(PPh3)(SiMe2OTf) (5; 97%), which in turn reacts with (Me2N)3S⊕ [SiMe3F2]⊖ to give (η5-C5H5)Re(NO)(PPh3)(SiMe2F) (6; 77%). Reaction of 5 and pyridine gives the base-stabilized silylene complex [(η5-C5H5)Re(NO)(PPh3){SiMe2(NC5H5)}]⊕ TfO⊖ (7; 84%). CH2Cl2 solutions of (η5-C5H5)Re(NO)(PPh3)(CH3) (8) or 2 and Lewis acids are studied by IR and NMR. As assayed by IR, 8/ECl3 solutions (E = B, Al) show ReNO-ECl3 (major) and Re-ECl3 (minor) adducts. Solutions of 2/BCl3 show analogous adducts (-78°C), and in the presence of excess BCl3 (η5-C5H5)Re-(NO-BCl3)(PPh3)(SiMe2Cl) (11) crystallizes. Solutions of 2/AlCl3 show uncomplexed 2 and Re-AlCl3 (major) and ReNO-AlCl3 (minor) adducts. In contrast to 2-7 and 2/BCl3, 1H- and 13C-NMR spectra of 2/AlCl3 suggest an equilibrium with the base-free silylene complex [(η5-C5H5)Re(NO)(PPh3)-( = SiMe2)]⊕ X⊖.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 176-178 
    ISSN: 0749-1581
    Schlagwort(e): INADEQUATE ; 2D NMR ; Carbon-carbon scalar coupling ; Polarization transfer ; Quaternary carbons ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The two-dimensional INEPT-INADEQUATE experiment gives correlation peaks for unprotonated carbons which show only half of the total available signal, because the enhanced 13C signal generated by polarization transfer is shared equally between protonated and unprotonated coupling partners by the double quantum filtration step. If precautions are taken to attenuate unwanted signals from protonated carbons, then the double quantum filtration step may be dispensed with, leaving a hydrogen-carbon-carbon relay sequence. This gives unidirectional coherence transfer, ensuring that the maximum possible signal is concentrated in a single cross-peak identifying the correlation between protonated and unprotonated carbons. By extending the basic HCC relay sequence to include an evolution period an enhanced 13C-13C COSY 2D spectrum may be produced, with the further advantage over the 2D INADEQUATE experiment that the range of 13C-13C coupling constants detectable is limited only by the available resolution.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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