Cs. Chin et al., OXIDATIVE ADDITION OF PHENYLACETYLENE TO [IR(CO)(RCN)(PPH(3))(2)]CLO4- PREPARATION, KINETICS, AND MECHANISM, Inorganic chemistry, 32(26), 1993, pp. 5901-5904
Reactions of PhC=CH (la) and p-CH3C6H4C=CH (1b) with [Ir(RCN)(CO)(PPh(
3))(2)]ClO4, 2 (R = Ph (a), CH3 (b), CH=CHPh (c)), give [Ir(H)(-C=CR')
(RCN)(CO)(PPh(3))(2)]ClO4, 3 (R' = Ph, R = Ph (a), CH3 (b), CH=CHPh (c
); R' = P-CH3C6H4, R = Ph (d)), where the hydride is cis both to two P
Ph(3) groups and trans to RCN. The oxidative addition of 1a to 2a,b is
first order both in 1a and 2a,b and depressed by the presence of RCN
added. The suggested reaction pathway involves the initial replacement
of RCN of 2a,b by 1a to give [Ir(PhC=CH).(CO)(PPh(3))(2)]ClO4, which
undergoes an intramolecular oxidative cleavage of the coordinated 1a t
o give [Ir(H)(-C=CPh)(CO) (PPh(3))(2)]ClO4, to which RCN is added back
to give the stable complexes 3a,b. Kinetic data obtained for alkyne h
ydrogen deuterated phenylacetylene, PhC=CD (1a-d), support the suggest
ed mechanism.