Solvent‐Mediated Generation of Cobalt‐Cluster‐Stabilised Propargyl Cations and Radicals: Allyl Migration versus Peroxide Formation Journal Articles uri icon

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abstract

  • AbstractThe protonation of [Co2(CO)6{9‐[(allyldimethylsilyl)ethynyl]‐9H‐fluoren‐9‐ol}] (4), with HBF4 in CH2Cl2 led to migration of the allyl group from silicon to the cobalt‐stabilised cationic site to furnish [Co2(CO)6{9‐allyl‐9‐[(dimethylfluorosilyl)ethynyl]‐9H‐fluorene}] (17). However, under the same conditions, [Co2(CO)6{9‐[(benzyldimethylsilyl)ethynyl]‐9H‐fluoren‐9‐ol}] (5) underwent desilylation and rearrangement of the resulting terminal alkyne–dicobalt complex to give [Co3(CO)9(9H‐fluorenylmethylcarbynyl)] (24); moreover, dimerisation of the (benzyldimethylsilyl)ethynyl‐9H‐fluorenyl moiety led to the propargyl–allene 26. In contrast, protonation of 5 in THF yielded [{Co2(CO)6{[(benzyldimethylsilyl)ethynyl‐9H‐fluorenyl])}2peroxide] (27) through a radical coupling process. Analogously, protonation of [Co2(CO)6{9‐[(vinyldimethylsilyl)ethynyl]‐9H‐fluoren‐9‐ol}] (6) yields the corresponding peroxide 28. X‐ray crystallographic data are reported for, among others, complexes 17, 24, 26, 27 and 28.

publication date

  • November 10, 2008