DFT Study of Cyclopalladation Mechanism of Benzylamines (CROSBI ID 520529)
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Podaci o odgovornosti
Babić, Darko ; Ćurić, Manda ; Smith, David M.
engleski
DFT Study of Cyclopalladation Mechanism of Benzylamines
Cyclopalladation of benzylamine (BA) may be considered as a prototype for a wide variety of orthometalation reactions. There are numerous experimental studies of this reaction with various palladium sources, ligands and solvents [refs]. Different mechanisms have been proposed on the basis of experimental results [refs]. Yet, it was only recently [ref] that the mechanism of this reaction was investigated by quantum-chemical methods. However, as the reacting complex (BA-Pd(OAc)2) employed in that study has a considerably higher energy than other possible species that could exist in solution, a more comprehensive approach is required. Here, we present the results of DFT (B3LYP/6-31G**, SDD) calculations for cyclopalladation reactions starting from several (more stable) reacting species: [BA-Pd-( -OAc)2]2, BA-[Pd-( -OAc)2]2-NCMe, BA-Pd(OAc)2-BA and BA-Pd(OAc)2-NCMe. In all cases considered, the agostic character of the mechanism reported in [ref] was confirmed. However, instead of the six-membered transition state, only four-membered ones were found to be feasible. The barrier heights of the critical step (hydrogen transfer) with reacting species different from the one assumed in [ref] vary between 26.45 and 36.3 kcal/mole, while for BA-Pd(OAc)2 it amounts to 18.3 kcal/mole. Although the energies required for the four-membered transition states are higher, the greater stability of the reacting species makes these mechanisms more realistic than the mechanism involving the reactive BA-Pd(OAc)2. In addition, the possibility that the specific reaction mechanism depends on factors such as the concentration ratio of Pd and ligand, as well as the solvent, should not be neglected.
benzylamines; palladium acetate; cyclopalladation; mechanism; ab initio
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Podaci o prilogu
P377-x.
2006.
objavljeno
Podaci o matičnoj publikaciji
XXII International Conferenceon Organometallic Chemistry : Actas del Congreso
Zaragoza:
Podaci o skupu
XXII International Conferenceon Organometallic Chemistry
poster
23.07.2006-28.07.2006
Zaragoza, Španjolska