Preparation of hydrido(vinyl)iridium(III) complexes from functionalized olefins by C—H activation

Abstract

The four-coordinate iridium(I) precursor trans-[IrCl(N2)(PPh3)2] (1) reacts with functionalized olefins RCH=C(R′)C(O)R′′ by displacement of the dinitrogen ligand and oxidative addition of the C—H bond to the metal center to give six-coordinate hydrido(vinyl)iridium(III) complexes [IrH(Cl){κ2(C,O)-C(R)=C(R′)C(R′′)=O}(PPh3)2] (2–12) in good to excellent yields. The reaction of [IrH(Cl){κ2(C,O)-CH=CHC(Me)=O}(PPh3)2] (2) with AgClO4 affords the cationic compound [IrH{κ2(C,O)-CH=CHC(Me)=O}(PPh3)2]ClO4 (15), which in solution equilibrates with the uncharged isomers [IrH(OClO3){κ2(C,O)-CH=CHC(Me)=O}(PPh3)2] (15a and 15b). In contrast, five-coordinate [IrH{κ2(C,O)-CH=CHC(Et)=O}(PPh3)2]ClO4 (16), prepared from 3 and AgClO4, is stable and undergoes addition reactions with CO, PPh3, C2H4, CH3C≡CH, MeCN, and PhCN to give the six-coordinate complexes [IrH(L){κ2(C,O)-CH=CHC(Et)=O}(PPh3)2]ClO4 (17–22). The neutral hydrido(thiolato) compound [IrH(SPh){κ2(C,O)-CH=CHC(Et)=O}(PPh3)2] (23) was obtained on treatment of 21 with NaSPh. Key words: iridium, C—H activation, hydrido complexes, vinyl complexes, phosphine complexes.