Iridium Oxidation States in Catalytic Hydrogenation Intermediates
نویسندگان
چکیده
Os conhecidos hidretos de irídio(III) [IrH2(NCMe)3(PiPr3)]BF4, [IrH(h-C3H5)(NCMe)2(PiPr3)] BF4, [IrH(E-CH=CHPh)(NCMe)3(PiPr3)]BF4 e [IrH{C(Ph)=CH2}(NCMe)3(PiPr3)]BF4, derivados do precursor catalítico tipo Crabtree [Ir(cod)(NCMe)(PiPr3)]BF4, foram investigados em reações com substratos tipicamente envolvidos na catálise homogênea de hidrogenação. Novos complexos como as espécies tris-etileno irídio(I) [Ir(NCMe)(h-C2H4)3(PiPr3)]BF4, os produtos de inserção de difenilacetileno [IrH{Z-C(Ph)=CHPh}(NCMe)3(PiPr3)]BF4 e [Ir(h-C3H5){Z-C(Ph)=CHPh} (NCMe)2(PiPr3)]BF4, e os derivados de [Ir(kO-acac)(h-C3H5){Z-C(Ph)=CHPh}(PiPr3)] e [Ir{kC-C6H4-2-E-(CH=CPh)}(NCMe)3(PiPr3)]BF4, foram caracterizados. O conjunto de observações experimentais sugere que espécies irídio(I), embora acessíveis, são improváveis como intermediários de hidrogenação. Baseados em experimentos de deuteração, uma nova tautomerização do hidreto de alquenil a carbeno foi proposta.
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