reaction mechanisms

Reaction mechanisms of iron(iii) catalyzed carbonyl–olefin metatheses in 2,5- and 3,5-hexadienals: significant substituent and aromaticity effects

Olefin metathesis is a fundamental organic reaction of great importance that led to the 2005 Nobel Prize in Chemistry. As a variation of olefin–olefin metathesis, carbonyl–olefin metathesis (COM) is less developed, but still significant progress has been made recently. However, how the aromaticity affects the reaction mechanisms remains unclear. Here we perform density functional theory calculations on iron(III) catalyzed COM in 2,5- and 3,5-hexadienals.

Probing the Origin of Challenge of Realizing Metallaphosphabenzenes: Unfavorable 1,2-Migration in Metallapyridines Becomes Feasible in Metallaphosphabenzenes

Metallabenzenes have attracted considerable interest of both theoretical and experimental chemists. However, metallaphosphabenzene has never been synthesized. Thus, understanding the origin of the challenge of synthesizing metallaphosphabenzene is particularly urgent for experimentalists. Now density functional theory (DFT) calculations have been carried out to examine this issue.

Why Does Activation of the Weaker C═S Bond in CS2 by P/N-Based Frustrated Lewis Pairs Require More Energy Than That of the C═O Bond in CO2? A DFT Study

The sequestration of carbon disulfide (CS2), a common pollutant in environmental systems, is of great importance due to its physical harm to human beings. Compared with CO2 capture, that of CS2 is much less developed. The use of P/N-based frustrated Lewis pairs (FLPs) has been proven, both experimentally and theoretically, to be an alternative strategy to efficiently sequestrate CO2. Therefore, we pose the question of whether the analogue CS2 could also be sequestrated by the same FLPs, given that the C═S bond in CS2 is weaker than the C═O bond in CO2.

Mechanistic Insight into the Copper-Catalyzed Phosphorylation of Terminal Alkynes: A Combined Theoretical and Experimental Study

The reaction mechanism of copper-catalyzed phosphorylation of terminal alkynes under different conditions has been investigated experimentally and theoretically. The important role of dioxygen has been elucidated, including the formation of η1-superoxocopper(II), η2-superoxocopper(III), μ-η2:η2-peroxodicopper(II), and bis(μ-oxo)dicopper(III) complexes.

Mechanism, Reactivity, and Selectivity in Rh(III)-Catalyzed Phosphoryl-Directed Oxidative C–H Activation/Cyclization: A DFT Study

Density functional theory calculations (DFT) have been performed on Rh(III)-catalyzed phosphoryl-directed oxidative C–H activation/cyclization to investigate the detailed mechanism, including four basic steps: C–H activation, alkyne insertion, reductive elimination, and catalyst recycling, each of which consists of different steps. Interestingly, the Rh(III)–AgOAc catalyst system was found to be more favorable in the C–H activation step in comparison with the Rh(III)–Ag2CO3 system, whereas the Rh(I)–Ag2CO3 catalyst system was more efficient for catalyst recycling.

Concerted or Stepwise Mechanism? New Insight into the Water-Mediated Neutral Hydrolysis of Carbonyl Sulfide

The water-mediated neutral hydrolysis mechanism of carbonyl sulfide (OCS) has been re-examined using the hybrid supramolecule/continuum models with n = 2–8 explicit water cluster at the level of MP2(fc)(CPCM)/6-311++G(d,p)//MP2(fc)(CPCM) /6-31+G(d). Present calculations indicate that the potential energy surface in water solution is different from the one in the gas-phase, and only stepwise mechanism is observed in aqueous solution, i.e., monothiocarbonic acid (H2CO2S) is formed via monothiocarbonate (OCSOH–, MTC) and its counterion, protonated water cluster, (H2O)nH3O+.

Unconventional Facile Way to Metallanaphthalenes from Metal Indenyl Complexes Predicted by DFT Calculations: Origin of Their Different Thermodynamics and Tuning Their Kinetics by Substituents

Metallaaromatics have attracted considerable interest from both experimentalists and theoreticians over the past three decades. However, most studies in this field have focused on metallabenzene, in which a CH group is replaced by a transition metal fragment. In comparison with monocyclic metallabenzenes, bicyclic metallanaphthalenes are rather limited. Thus, it is urgent to explore more synthetic approaches to this less developed system. One of the difficulties in the synthesis of metallanaphthalenes could be due to its low thermodynamic stability relative to the metal indenyl complexes.

Computations Offer an Unconventional Route to Metallaphosphabenzene from a Half-Phosphametallocene

Metallaaromatics have attracted continuing interest of both theoretical and experimental chemists since the first metallabenzene was predicted by Hoffmann and isolated by Roper. In sharp contrast to metallabenzenes, metallaphosphabenzene (MPB) is much less developed and has not been synthesized so far. Thus, developing synthetic approaches is urgent. Here we present thorough density functional theory (DFT) calculations on the thermodynamics and kinetics of the rearrangement between MPBs and the corresponding η5-phosphacyclopentadiene (η5-PCp) complexes.

Double Role of the Hydroxy Group of phosphoryl in Palladium(II)-catalyzed ortho-Olefination: A Combined Experimental and Theoretical Investigation

Density functional theory (DFT) calculations have been carried out on Pd-catalyzed phosphoryl-directed ortho-olefination to probe the origin of the significant reactivity difference between methyl hydrogen benzylphosphonates and dialkyl benzylphosphonates. The overall catalytic cycle is found to include four basic steps: C−H bond activation, transmetalation, reductive elimination and recycling of catalyst, each of which is constituted from different steps.

Mechanistic Insight into the CO2 Capture by Amidophosphoranes: Interplay of the Ring Strain and the trans Influence Determines the Reactivity of the Frustrated Lewis Pairs

CO2 capture has attracted increasing attention owing to its contribution to global warming and climate change as a greenhouse gas. As an alternative strategy to transition-metal-based chemistry and catalysis, frustrated Lewis pairs have been developed to sequester CO2 efficiently under mild conditions. However, the mechanism of CO2 sequestration with amidophosphoranes remains unclear. Herein, we present a thorough density functional theory study on a series of amidophosphoranes.