A Series of Carbonyl‐, Olefin‐, Alkyne‐, Hydrido‐, and Vinyliridium Complexes Containing Bulky Bifunctional Phosphanes iPr 2 PCH 2 X as Ligands

Etheneiridium( I ) complexes of the general composition trans ‐[IrCl(C 2 H 4 )L 2 ] [L = i Pr 2 PCH 2 CO 2 Me ( 2a ), iPr 2 PCH 2 CO 2 Et ( 2b ), i Pr 2 P(CH 2 ) 3 NMe 2 ( 2c )] have been prepared either from [IrClL 2 ] ( 3 ) or [IrCl(C 2 H 4 ) 2 ] 2 ( 7 ) as starting materials. The corresponding carbonyl derivatives trans ‐[IrCl(CO)L 2 ] ( 6, 10, 11 ) are obtained along similar routes. Photolysis of trans ‐[IrCl(C 2 H 4 )L 2 ] (L = 2a, 2b ) leads, by intramolecular C–H activation, to the formation of the octahedral hydrido(vinyl)iridium(III) compounds [IrHCl(CHCH 2 )(k‐L)(k 2 ‐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(C 2 H 4 )L 2 ] (L = 2a ) and the propargylic alcohol HCCCH(Ph)OH, respectively. Treatment of 3 or the corresponding dihydrido compound [IrH 2 ClL 2 ] ( 4 ) with methyl vinyl ketone or methyl acrylate also yields hydrido(vinyl)iridium(III) complexes [IrHCl(CHCHX)L 2 ] [X = C(=O)Me ( 18 ), C(=O)OMe ( 19 )], in which instead of the CO 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 HCCR (R = Ph, CO 2 Me) affords the structurally related alkynyl(hydrido)iridium(III) compounds [IrHCl(CCR)(k‐L)(k 2 ‐L)] ( 28, 29 ), while from 16 and internal alkynes RCCR) the iridium(I) complexes trans ‐[IrCl1(RCCR)L 2 ] ( 30, 31 ) are obtained, Stepwise treatment of trans ‐[IrCl(RCCR)L 2 ] ( 6 : L = 2a ) with NaN(SiMe 3 ) 2 , (ii) H 2 O, and (iii) HCl leads, in the coordination sphere of the metal center, to a conversion of i Pr 2 PCH 2 CO 2 Me to i Pr 2 PCH 2 CO 2 H via the isolated phosphanylenolate and phosphanylacetate complexes 32 and 33 as intermediates.