| Abstract
| - When high-pressure NMR techniques are employed, the following two facts are revealed.(1) The cis/trans isomerization from (SP-4-4)-[Pt(CH3)(CO)(L1)][BAr4] (8a; L1 = (R,S)-BINAPHOS; Ar = 3,5-(CF3)2C6H3) to the more stable SP-4-3 isomer (8b) is faster than COinsertion into either 8a or 8b, the CO insertion being reversible. (2) For the PdII−L1-catalyzedcopolymerization of propene and CO, there exist at least two major resting states, mostprobably acylpalladium, (SP-4-3)-[Pd(COR)(L2)(L1)][BAr4] (3; L2 = CH3CN, CO), and alkylpalladium, [Pd{CH2CH(CH3)C(O)R}(L1)][BAr4] (5a).
- Reactions of MII−L (M = Pt, Pd; L = (R,S)-BINAPHOS) have been studied using high-pressure NMR techniques in relation to the PdII−L-catalyzed alternating copolymerization of propene with CO. The isomerization of 8a to 8b is proven to be a faster process than CO insertion to give 9. For the PdII−L-catalyzed copolymerization, two major species, acyl−Pd complex 3 and alkyl−Pd complex 5a, are suggested as resting states.
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