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  • 1
    ISSN: 0947-6539
    Keywords: alkyne complexes ; carbon-carbon coupling ; pentaenes ; rhodium complexes ; vinylidene complexes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of [Rh(η3-C3H5)-(PiPr3)2] (1) with HC≡C—CH(Ph)OH yields the alkynyl(vinylidene) complex trans-[Rh{C≡C—CH(Ph)OH}{=C=CH-CH(Ph)OH}(PiPr3)2] (2), while from 1 and HC≡C—CPh2OH the alkynyl-(enyne)metal derivative trans-[Rh(C≡C—CPh2OH){n2-(E)-Ph2(OH)C—C≡C—CH=CH-CPh2OH} (PiPr3)2] (3) is obtained. On treatment with 1-alkyn-3-ols HC≡C—CR2OH (R = Me, Ph, iPr), the highly reactive π-benzyl compound [Rh(n3-CH2Ph)(PiPr3)2] (4) yields the five-coordinate complexes [RhH(C≡C—CR2OH)2(PiPr3)2] (5-7) of which those with R = Me and Ph can be converted to the alkynyl(vinylidene)metal isomers trans-[Rh(C≡C—CR2OH)(=C=CH-CR2OH)-(PiPr3)2] (8, 9). Compounds 8 and 9 react with L′ = CO and isocyanides by migration of the alkynyl ligand to the vinylidene unit to give the enynylrhodium(I) complexes trans-[Rh{n1-(Z)-C(C≡C—CR2—OH)=CH-CR2OH}(L′)(PiPr3)2] (10, 11: L′ = CO; 12-15: L′ = CNR′). Cleavage of the Rh-C s̰-bond of 10 with CF3-CO2H affords trans-[Rh(n1-O2CCF3)-(CO)(PiPr3)2] (16) and the enyne (E)-Me2(OH)C—C≡C—CH=CH-CMe2OH (17). Compounds 5-7 react with L′ = CO and isocyanides to give the octahedral 1:1 adducts [RhH(C≡C—CR2OH)2(L′)(P-iPr3)2] (18-20 and 24-27), of which the CO derivatives 18-20 readily eliminate HC≡C—CR2OH to yield trans-[Rh-(C≡C—CR2OH)(CO)(PiPr3)2] (21-23). On treatment of 6 or 9 (R = Ph) with Al2O3 in the presence of chloride ions, besides trans-[RhCl(=C=C=CPh2)(P-iPr3)2] (28) the hexapentaenerhodium(I) complex trans-[RhCl(n2-Ph2C=C=C=C=C=CPh2)(PiPr3)2] (29) is formed. The kinetically preferred isomer trans-[RhCl(n2-Ph2C=C=C=C=C=CPh2)(P-iPr3)2] (33) has been prepared from [RhCl(PiPr3)2]2 and Ph2C=C=C=C=C=CPh2; it rearranges smoothly at room temperature to the thermodynamically more stable isomer 29. The molecular structures of 7 and 29 have been determined.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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