The formation of metallacyclopentadienyl derivatives was studied under controlled conditions, and the kinetics and mechanism of reactions between pyridylthioether olefin Pd(0) substrates and substituted alkynes of the type ZC equivalent to CZ (Z = COOMe, COOEt, COOt-Bu) leading to the corresponding palladacyclopentadienyl species were systematically investigated. In the case of less hindered ancillary ligands the attack of the alkyne forming a reactive monoalkyne intermediate was found to be the rate-determining step. In this respect the rates of reaction were discussed in terms of the substituent-induced basicity of sulfur and nitrogen of the ancillary ligands. The associative nature of the attack was unequivocally established, and the formation of a transition state bearing a monodentate ancillary ligand was proposed. In the case of more hindered ancillary ligands a partially stabilized monoalkyne intermediate is formed irrespective of the olefin in the starting complex, and this species strongly influences the reaction progress. Formation of hexamethylmellitate under mild conditions is also observed.

Attack of substituted alkynes on olefin palladium(0) derivatives of pyridylthioethers. The first kinetic study on the mechanism of formation of palladacyclopentadiene complexes

DOLMELLA, ALESSANDRO
2005

Abstract

The formation of metallacyclopentadienyl derivatives was studied under controlled conditions, and the kinetics and mechanism of reactions between pyridylthioether olefin Pd(0) substrates and substituted alkynes of the type ZC equivalent to CZ (Z = COOMe, COOEt, COOt-Bu) leading to the corresponding palladacyclopentadienyl species were systematically investigated. In the case of less hindered ancillary ligands the attack of the alkyne forming a reactive monoalkyne intermediate was found to be the rate-determining step. In this respect the rates of reaction were discussed in terms of the substituent-induced basicity of sulfur and nitrogen of the ancillary ligands. The associative nature of the attack was unequivocally established, and the formation of a transition state bearing a monodentate ancillary ligand was proposed. In the case of more hindered ancillary ligands a partially stabilized monoalkyne intermediate is formed irrespective of the olefin in the starting complex, and this species strongly influences the reaction progress. Formation of hexamethylmellitate under mild conditions is also observed.
2005
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/1476786
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 44
  • ???jsp.display-item.citation.isi??? 41
social impact