49548-57-4Relevant articles and documents
A series of hydrido(vinyl)iridium(III) complexes that are thermodynamically more stable than their olefin iridium(I) isomers
Dirnberger, Thomas,Werner, Helmut
, p. 5127 - 5139 (2008/10/09)
The reaction of the in situ generated cyclooctene iridium(I) derivative trans-[IrCl(C8H14)-(PiPr3)2] with methyl vinyl ketone and other Michael systems RCH=C(R′)C(O)R″ (R = H, Me, Ph, OMe; R′ = H, Me, iPr; R″ = H, Me, OMe, NH2, NMe2) resulted in the formation of the octahedral hydrido(vinyl)iridium(III) complexes [IrH(Cl){κ2(C,O)-C(R)= C(R′)C(R″)=O}-(PiPr3)2] (2-13) with the vinyl ligand coordinated in a bidentate fashion. Treatment of trans-[IrCl(C 8H14)(PiPr3)2] with methyl acrylate and either dimethyl fumarate or dimethyl maleate afforded the iridium(I) compounds trans-[IrCl(η2-RCH=CHCO2Me)(PiPr 3)2] (15, 16), which thermally or photochemically rearrange to the thermodynamically more stable iridium(III) isomers [IrH(Cl){κ2(C,O)-C(R)=CHC(OMe)=O}(PiPr3) 2] (17, 18) by intramolecular C-H activation. The reaction of trans-[IrCl(C8H14)(PiPr3)2] with PhCH=CHC(O)Ph gave a 1:1 mixture of the isomeric iridium(III) complexes [IrH(Cl){K2(C,O)-C(Ph)=CHC(Ph)=O}(PiPr3)2] (19) and [IrH(Cl){κ2(C,O)-C6H4C(CH=CHPh)=O} (PiPr3)2] (20), which were separated by column chromatography. From trans-[IrCl(C8H14)(PiPr 3)2] and acrylic acid both [IrH(Cl)- {κ2(C,O)-CH=CHC(OH)=O}(PiPr3)2] (21) and [IrH(Cl){κ2(O,O)-O2CCH=CH2}(PiPr 3)2] (22) were obtained. While the attempted hydrogenation of [IrH(Cl){κ2(C,O)-CH=CHC(Me)=O}-(PiPr3) 2] (2) with Pd/C as the catalyst led to the formation of [IrH 2(Cl)(PiPr3)2] (24) and ethyl methyl ketone, the same starting material reacted with a solution of Cl2 in chloroform to give the dichloro vinyl complex [IrCl2{κ 2(C,O)-CH=C(Cl)C(Me)=O}(PiPr3)2] (27) in virtually quantitative yield. The reaction of both 2 and [IrH(I) {κ2(C,O)-CH=CHC(Me)=O}(PiPr3)2] (29) with CO afforded the carbonyl compounds [IrH(X){η1-(Z)-CH=CHC(O)Me} (CO)(PiPr3)2] (31, 32) by partial opening of the chelate bond. Similarly to the Ir(PiPr3)2 counterparts, a series of (olefin)iridium(I) and hydrido(vinyl)iridium(III) compounds with Ir(PMetBu2)2 as a molecular unit were also prepared. Most remarkably, treatment of trans-[IrCl(η2-CH2= CHC(O)H)(PMetBu2)2] (43) with in situ generated trans-[IrCl(C8H14)(PMetBu2)2] led to a clean cleavage of coordinated acrolein to CO and ethene and afforded a 1:1 mixture of trans-[IrCl(CO)(PMetBu2)2] (44) and trans-[IrCl(C2H4)(PMetBu2)2] (45), respectively.
