A Series of Carbonyl‐, Olefin‐, Alkyne‐, Hydrido‐, and Vinyliridium Complexes Containing Bulky Bifunctional Phosphanes iPr2PCH2X as Ligands

Abstract

AbstractEtheneiridium(I) complexes of the general composition trans‐[IrCl(C2H4)L2] [L = iPr2PCH2CO2Me (2a), iPr2PCH2CO2Et (2b), iPr2P(CH2)3NMe2 (2c)] have been prepared either from [IrClL2] (3) or [IrCl(C2H4)2]2 (7) as starting materials. The corresponding carbonyl derivatives trans‐[IrCl(CO)L2] (6, 10, 11) are obtained along similar routes. Photolysis of trans‐[IrCl(C2H4)L2] (L = 2a, 2b) leads, by intramolecular C–H activation, to the formation of the octahedral hydrido(vinyl)iridium(III) compounds [IrHCl(CHCH2)(k‐L)(k2‐L)] (16, 17), which are highly fluctional in solution. Carbonyl(hydrido)(vinyl) complexes are accessible either from 16 or 17 and CO, or from trans‐[IrCl(C2H4)L2] (L = 2a) and the propargylic alcohol HCCCH(Ph)OH, respectively. Treatment of 3 or the corresponding dihydrido compound [IrH2ClL2] (4) with methyl vinyl ketone or methyl acrylate also yields hydrido(vinyl)iridium(III) complexes [IrHCl(CHCHX)L2] [X = C(=O)Me (18), C(=O)OMe (19)], in which instead of the CO function of the phosphanyl ester the carbonyl group of the vinylic moiety is coordinated to the metal. The reaction of 16 (L = 2a) with terminal alkynes HCCR (R = Ph, CO2Me) affords the structurally related alkynyl(hydrido)iridium(III) compounds [IrHCl(CCR)(k‐L)(k2‐L)] (28, 29), while from 16 and internal alkynes RCCR) the iridium(I) complexes trans‐[IrCl1(RCCR)L2] (30, 31) are obtained, Stepwise treatment of trans‐[IrCl(RCCR)L2] (6: L = 2a) with NaN(SiMe3)2, (ii) H2O, and (iii) HCl leads, in the coordination sphere of the metal center, to a conversion of iPr2PCH2CO2Me to iPr2PCH2CO2H via the isolated phosphanylenolate and phosphanylacetate complexes 32 and 33 as intermediates.