Electron-Withdrawing Effects on Metal−Olefin Bond Strengths in Ni(PH₃)₂(CO)(C₂X_nH_4-n), X = F, Cl; n = 0−4:  A DFT Study

Abstract

Density functional theory (DFT) studies have been performed in the title complexes to determine the effect of electron-withdrawing halogens around the CdC bond on the metal-olefin bond dissociation energy. Calculations indicate that the nickel-olefin bond dissociation energy would be nearly independent of the number of electron-withdrawing elements around the double bond. The results are explained in terms of electronic, steric, and reorganizational effects that derive from the olefin-metal interaction and are compared to computational and experimental results for related complexes, which show similar metal-olefin bond strength behavior. It has been found that reorganizational effects in both the olefin and Ni(PH 3 ) 2 (CO) play a determining role in the overall bond dissociation energy trend.

Factors Controlling the Selective Hydroformylation of Internal Alkenes to Linear Aldehydes. 1. The Isomerization Step

“…Concerning the TDIs; the relative energies for the butene and octene complexes show a small advantage for the octene complex. According to the Dewar−Chatt−Duncanson model and other studies, one could have expected that the back-donation in the octene case would be slightly more favorable than for butene, and since back-donation is more important in this kind of TDI complexes, this would have stabilized the corresponding octene complex . However, looking at the overall TOF results, one can see that the stabilization of the TDTSs is more pronounced and has a stronger effect on the full catalytic cycle than the stabilization of the TDI.…”

A DFT study of the interaction between olefins and Cu2+ on silica and MCM-41 model surfaces

“…10 Clearly, the metal-olefin interaction is not only determined by the extent of orbital interactions, but other factors as well. Further studies [11][12][13][14] show that although the attractive orbital interaction between the metal and the olefin increases as the olefin becomes more electron withdrawing, this bond-favoring trend is counterbalanced by the Pauli (steric) repulsion energy, which also increases as the number of electron-withdrawing substituents increases. Besides, metal-olefin bond strengths are influenced to a great extent by the deformation of the olefin in addition to the well known influence of electronic and steric effects.…”

“…Besides, metal-olefin bond strengths are influenced to a great extent by the deformation of the olefin in addition to the well known influence of electronic and steric effects. [11][12][13][14] Deformation of the olefin involves: elongation of the CvC bond and bending of substituents out from the CvC plane. The stronger the metal-olefin interaction, the larger the deformation of the olefin.…”

“…Most of the reported quantum mechanical calculations for the metalolefin interaction were carried out by density functional theory (DFT), which has emerged during the past few decades as a powerful methodology for the simulation of chemical systems because of its good accuracy and reasonable computational cost. [11][12][13][14][15] In comparison with ab initio calculations, the DFT method includes electron correlation via functions and is more biased toward π-electron delocalization. 16 Therefore, DFT can perform quite satisfactorily on conjugated molecules of moderate size, such as polyenes and carotenoids.…”

Metal−Olefin Interactions in M(CO)5(cycloolefin) (M = Cr, Mo, W; Cycloolefin = Cyclopropene to Cyclooctene): Strain Relief and Metal−Olefin Bond Strength

“…Steric interactions may decrease the bond strength, because repulsive orbital interactions force the olefin and metal complex to avoid each other, thereby decreasing the overlap of those orbitals contributing to bonding. It has also been established that rehybridization of the olefin is responsible for a decrease in the metal−olefin bond strength. − This is due to the elongation of the C−C bond and pyramidalization (i.e. bending of the substituents around the CC bond out of the plane containing the bond) of the olefin, resulting in an energetic cost at the expense of the energy gained through bonding interactions.…”