Reaction of an (Alkyl)(alkenyl)(alkynyl)iridium(III) Complex with HCl:  Intramolecular C−C Bond Formation from Alkyl, Alkenyl, and Alkynyl Groups Coordinated to “Ir(CO)(PPh₃)₂”. H/D Exchange between CH₃ and DCl

Reaction of the (alkyl)(alkenyl)(alkynyl)iridium(III) complex [Ir(CH 3 )(CH CHNEt 3 )(C⋮C( p -C 6 H 4 CH 3 ))(CO)(PPh 3 ) 2 ]ClO 4 ( 3 ) with aqueous HCl initiates an intramolecular coupling reaction between −CH 3 and −C⋮C( p -C 6 H 4 CH 3 ) groups to give [Ir(C(CH 3 ) CH( p -C 6 H 4 CH 3 )(CH CHNEt 3 )(Cl)(CO)(PPh 3 ) 2 ]ClO 4 ( 5 ), which further reacts with aqueous HCl to produce [Ir(CH CHNEt 3 )(Cl) 2 (CO)(PPh 3 ) 2 ]ClO 4 ( 6 ) and cis -CH 3 CH CH( p -C 6 H 4 CH 3 ) ( 7 ). Complex 5 yields the C−C coupling product [( p -C 6 H 4 CH 3 )HC C(CH 3 )CH CHNEt 3 ]ClO 4 ( 8 ) when it is refluxed in CHCl 3 . The (alkyl)bis(alkynyl)iridium(III) compound Ir(CH 3 )(C⋮C( p -C 6 H 4 CH 3 )) 2 (CO)(PPh 3 ) 2 ( 4 ) reacts with aqueous HCl to give H 2 C C CH( p -C 6 H 4 CH 3 ) ( 9 ). Complex 3 reacts with excess DCl to give the d 5 isotopomer CD 3 CD CD( p -C 6 H 4 CH 3 ) ( 7 - d 5 ), while the reaction of 4 with DCl gives the d 1 isotopomer H 2 C C CD( p -C 6 H 4 CH 3 ) ( 9 - d 1 ). Plausible reaction pathways are discussed for the formation of 7 and 9 and for the H/D exchange to give the isotopomer 7 - d 5 .