[EN]: The known iridium(III) hydrides [IrH2(NCMe)3(PiPr3)]BF4, [IrH(η3-C3H5)(NCMe)2(PiPr3)] BF4, [IrH(E-CH=CHPh)(NCMe)3(PiPr3)]BF4 and [IrH{C(Ph)=CH2}(NCMe)3(PiPr3)]BF4, derived from the Crabtree-type catalyst precursor [Ir(cod)(NCMe)(PiPr3)]BF4, have been investigated in reactions with substrates typically involved in homogeneous catalytic hydrogenations. New complexes such as the iridium(I) tris-ethylene species [Ir(NCMe)(η2-C2H4)3(PiPr3)]BF4, the products of diphenylacetylene insertion [IrH{Z-C(Ph)=CHPh}(NCMe)3(PiPr3)]BF4 and [Ir(η3-C3H5){Z-C(Ph)=CHPh}(NCMe)2(PiPr3)]BF4, and the derivatives of the latter [Ir(κ2O-acac) (η3-C3H5){Z-C(Ph)=CHPh}(PiPr3)] and [Ir{κ2C-C6H4-2-E-(CH=CPh)}(NCMe)3(PiPr3)]BF4, have been characterized. The set of experimental observations suggests that iridium(I) species, though accessible, are unlikely hydrogenation intermediates. On the basis of deuteration experiments, a new hydride-alkenyl to carbene tautomerization is proposed.

[PT]: Os conhecidos hidretos de irídio(III) [IrH2(NCMe)3(PiPr3)]BF4, [IrH(h3-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)(h2-C2H4)3(PiPr3)]BF4, os produtos de inserção de difenilacetileno [IrH{Z-C(Ph)=CHPh}(NCMe)3(PiPr3)]BF4 e [Ir(η3-C3H5){Z-C(Ph)=CHPh}(NCMe)2(PiPr3)]BF4, e os derivados de [Ir(k2O-acac)(η3-C3H5){Z-C(Ph)=CHPh}(PiPr3)] e [Ir{k2C-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.

This research was supported by the Spanish MINECO (Grants CTQ2009-080023) and CTQ2012-31774).

Peer Reviewed