Density Functional Study of Possible Intermediates in the Mechanism of Olefin Cyclopropanation Catalyzed by Metal Carboxylates

Abstract

The structures of several complexes arising from the interaction between methylene and palladium and rhodium diformates were optimized through density functional calculations. For palladium, mono‐, di‐, and trimeric complexes were considered. The results obtained show that in all cases the most stable structures correspond to complexes in which methylene has inserted in one of the M–O bonds, while metal–carbene complexes are energy minima only for monomeric palladium diformate and for rhodium diformate. Trimeric palladium formate is thermodynamically stable upon fragmentation. However, when it reacts with methylene, fragmentation becomes favorable. The role of the resulting monomeric complex in the olefin cyclopropanation mechanism catalyzed by palladium dicarboxylates is discussed.

Mechanism of Olefin Cyclopropanation by Diazomethane Catalyzed by Palladium Dicarboxylates. A Density Functional Study

“…Let us now consider the reaction between 1a and ethylene, which leads to the formation of 4a . If we compare the energies involved in this process with those corresponding to the formation of 1b (Table ), we can observe that the reaction of 1a with diazomethane is both thermodynamically and kinetically more favorable than the coordination of ethylene, thus confirming our previous assumption that cyclopropanation does not involve olefin coordination as the first step …”

Cyclopropanation of Cyclohexenone by Diazomethane Catalyzed by Palladium Diacetate: Evidence for the Formation of Palladium(0) Nanoparticles

“…Computational Details. All calculations are based on the density functional theory using the BPW91 functional, , which is the functional used in previous studies. , Geometries have been fully optimized using the LANL2DZ basis set supplemented with d polarization functions for C, N, and O. This basis set uses effective core potentials for Pd 51 and the D95 basis set for the remaining atoms .…”

Versatile Reactivity of Metalloid‐Substituted π‐Allylpalladium Species

“…This result also suggested that the reaction could involve a catalytic species distinct from the palladium-complexed vinylcarbenes. In addition to the typical reactivities of other transition-metal carbenes, [29] this cyclopropanation only proceeded with the strained cycloalkenes. For example, cyclopropanation did not occur with styrene, indene, 2,3-dimethyl-1,3-butadiene, ethyl vinyl ether, and allyltrimethylsilane.…”