The intramolecular allenylidene RuCl2(PR3)(2)(C=C=CPh2) to indenylidene RuCl2(PR3)(2)(Ind) rearrangement that occurs during the synthesis of Ru-based precatalysts for olefin metathesis is presented. In the absence of acid, the ring closure via C-H activation was shown to be unfavored for energy barriers up to 70 kcal/mol. Thus, it turned out to be HCl (or other acid) that plays a crucial role during formation of the indenylidene, as the upper energy barrier decreases to a reasonable 35 kcal/mol. Moreover, we proved computationally that depending on the nature of the phosphine the intramolecular rearrangement is either facilitated (PPh3) or slightly hampered (PCy3), which is in line with experimental results.
Mechanism of the Ru-Allenylidene to Ru-Indenylidene Rearrangement in Ruthenium Precatalysts for Olefin Metathesis
Cavallo, Luigi;
2015
Abstract
The intramolecular allenylidene RuCl2(PR3)(2)(C=C=CPh2) to indenylidene RuCl2(PR3)(2)(Ind) rearrangement that occurs during the synthesis of Ru-based precatalysts for olefin metathesis is presented. In the absence of acid, the ring closure via C-H activation was shown to be unfavored for energy barriers up to 70 kcal/mol. Thus, it turned out to be HCl (or other acid) that plays a crucial role during formation of the indenylidene, as the upper energy barrier decreases to a reasonable 35 kcal/mol. Moreover, we proved computationally that depending on the nature of the phosphine the intramolecular rearrangement is either facilitated (PPh3) or slightly hampered (PCy3), which is in line with experimental results.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
