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(CH3)(CH=C HNEt3)(C equivalent to C(p-C6H4CH3))(CO)(PPh3)(2)]ClO4 (3) with aqueous HCl initiates an intramolecular coupling reaction between -CH3 and -C equivale nt to C(p-C6H4CH3) groups to give [Ir(C(CH3)=CH(p-C6H4CH3)(CH-CHNEt3)(Cl)(C O)(PPh3)(2)]ClO4 (5), which further reacts with aqueous HCl to produce [Ir( CH=CHNEt3)(Cl)(2)(CO)(PPh3)(2)]ClO4 (6) and cis-CH3CH=CH(p-C6H4CH3) (7).Com plex 5 yields the C-C coupling product [(p-C6H4CH3)HC=C(CH3)CH=CHNEt3]ClO4 (8) when it is refluxed in CHCl3. The (alkyl)bis(alkynyl)iridium(III) compo und Ir(CH3)(C equivalent to C(p-C6H4CH3))(2)- (CO)(PPh3)(2) (4) reacts with aqueous HCl to give H2C=C=CH(p-C6H4CH3) (9). Complex 3 reacts with excess DCl to give the d(5) isotopomer CD3CD=CD(p-C6H4CH3) (7-d(5)), while the rea ction of 4 with DCl gives the d(1) isotopomer H2C=C=CD(p-C6H4CH3) (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).