Cleavage of both C(sp3)−C(sp2) bonds of alkylidenecyclopropanes: Formation of ethylene−osmium−vinylidene vomplexes

2 páginas, 1 figura, 2 esquemas.The complex [OsTp(κ1-OCMe)2(PiPr3)]BF4 [Tp = hydridotris(pyrazolyl)borate] promotes the cleavage of both C(sp3)−C(sp2) bonds of benzylidenecyclopropane and 3-phenylpropylidenecyclopropane to yield the complexes [OsTp(═C═CHR)(η2-CH2═CH2)(PiPr3)]BF4 (R = Ph, CH2CH2Ph). The process is proposed to take place via metallacyclopropene intermediates stabilized by an ethylene chelation assistant. The driving force for the fragmentation is the high stability of the resulting ethylene−Os−vinylidene species.Financial support was provided by the Spanish MICINN [Projects CTQ2008-00810, SAF2007-61015, and Consolider Ingenio 2010 (CSD2007-00006)], Diputacio´n General de Arago´n (E35), and Xunta de Galicia (GRC2006/132). L.S. and L.V. thank MICINN and Xunta de Galicia for their grants.Peer reviewe