Ab initio calculations on P?C bond cleavage in phosphoranyl radicals: implications for the biodegradation of organophosphonate derivatives

Lim, Myong H.; Cramer, Christopher J.

doi:10.1002/(sici)1099-1395(199802)11:2<149::aid-poc983>3.0.co;2-2

Cited by 9 publications

(5 citation statements)

References 65 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…While there is more general agreement between the MP2 and the B3LYP results, significant discrepancies arise in several instances, most of which are discussed further below. We consider the MP2 level to be more reliable, given the known tendency of DFT to “over-delocalize” charge , and spin, , which can be an issue in some of the systems described below. Single-point calculations at the CCSD or CCSD(T) levels of theory for select instances bear this analysis out, and we therefore largely confine the discussion below to MP2 results.…”

Section: Resultsmentioning

confidence: 99%

Quantum Chemical Characterization of Cycloaddition Reactions between the Hydroxyallyl Cation and Dienes of Varying Nucleophilicity

Cramer

Barrows

1998

J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

Hydroxyallyl cation prefers to undergo cycloaddition reactions with dienes in a stepwise fashion. Analysis of positive charge distribution in the intermediate formed after initial C−C bond formation provides a simple unifying method for rationalizing changes in reactivity as a function of diene nucleophilicity. Predicted product distributions are consistent with results from experimental studies. Interestingly, for the initial intermediate generated from 1,3-butadiene, [3 + 2] cycloaddition reactions are favored, but closure to form a C−O bond as the second step results in an intermediate that can undergo a low-energy Claisen rearrangement to form a seven-membered-ring product identical to that expected from compact [4 + 3] cycloaddition.

show abstract

Section: Resultsmentioning

confidence: 99%

Quantum Chemical Characterization of Cycloaddition Reactions between the Hydroxyallyl Cation and Dienes of Varying Nucleophilicity

Cramer

Barrows

1998

J. Org. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…It was also found that, in some instances, an additional “ligand π” structure (IV), in which the unpaired electron was carried by one of the ligands (usually a phenyl group), is possible. More recently, ab initio molecular orbital studies have confirmed these electronic structure assignments and provided an insight into the mechanisms for ligand permutation , The apicophilicity of a variety of ligands has been found to depend mainly on their group electronegativities, though other factors (such as the potential for hyperconjugative interactions between the ligands 11 ) are also important.…”

Section: Introductionmentioning

confidence: 94%

Effects of Substituents on the Stability of Phosphoranyl Radicals

Hodgson

Coote

2005

J. Phys. Chem. A

View full text Add to dashboard Cite

The effect of substituents on the geometries, apicophilicities, radical stabilization energies, and bond dissociation energies of (*)P(CH(3))(3)X (X = CH(3), SCH(3), OCH(3), OH, CN, CF(3), Ph) were studied via high-level ab initio molecular orbital calculations. Two alternative definitions for the radical stabilization energy (RSE) were considered: the standard RSE, in which radical stability is measured relative to H-P(CH(3))(3)X, and a new definition, the alpha-RSE, which measures stability relative to P(CH(3))(2)X. We show that these alternative definitions yield almost diametrically opposed trends; we argue that alpha-RSE provides a reasonable qualitative measure of relative radical stability, while the standard RSE qualitatively reflects the relative strength of the P-H bonds in the corresponding H-P(CH(3))(3)X phosphines. The (*)P(CH(3))(3)X radicals assume a trigonal-bipyramidal structure, with the X-group occupying an axial position, and the unpaired electron distributed between a 3p(sigma)-type orbital (that occupies the position of the "fifth ligand"), and the sigma orbitals of the axial bonds. Consistent with this picture, the radical is stabilized by resonance (along the axial bonds) with configurations such as X(-) P(*+)(CH(3))(3) and X(*) P(CH(3))(3). As a result, substituents that are strong sigma-acceptors (such as F, OH, or OCH(3)) or have weak P-X bonds (such as SCH(3)) stabilize these configurations, resulting in the largest apicophilicities and alpha-RSEs. Unsaturated pi-acceptor substituents (such as phenyl or CN) are weakly stabilizing and interact with the 3p(sigma)-type orbital via a through-space effect. As part of this work, we challenge the notion that phosphorus-centered radicals are more stable than carbon-centered radicals.

show abstract

“…Despite the fact that aminophosphonates are rather stable compounds, their P−C bond cleavage was observed in basic, neutral, and acidic media. These cleavage reactions are also catalyzed by enzymes in living organisms. , The P−C bond breaking generally leads phosphorus to form derivatives of phosphonic (H 3 PO 3 ) or phosphoric acid (H 3 PO 4 ) in the final products. The factors which control the formation of the products in such cleavage reactions include the structural characteristics of the reactants, path of the reaction followed (mechanism), and the physical conditions applied.…”

Section: Introductionmentioning

confidence: 99%

“…The factors which control the formation of the products in such cleavage reactions include the structural characteristics of the reactants, path of the reaction followed (mechanism), and the physical conditions applied. Both homolytic 12 and heterolytic mechanisms 9 were postulated for such a cleavage, but the mechanism is still not well-understood. 8 This uncertainty of understanding the mechanism of P-C bond cleavage of R-aminophosphonates warrants detailed theoretical studies on such reactions as not much effort has been made in this direction.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Studies on the Mechanism of C−P Bond Cleavage of a Model α-Aminophosphonate in Acidic Condition

et al. 2007

View full text Add to dashboard Cite

Various reaction paths of the P-C bond cleavage of alpha-aminophosphonates in acidic media, resulting in the derivatives of phosphonic acid, has been investigated using density functional level of theories in the gas phase as well as in aqueous medium. Dimethyl (alpha-anilinobenzyl)phosphonate has been used as the model molecule and our investigation confirms a three steps process including protonation, P-C bond cleavage, and the transformation of the products from the final transition state (imine cation and H-phosphonate) through hydrolysis. The most favorable reaction path starts from the amino group protonation, followed by a proton transfer through N-H...O(P) hydrogen bond, and the P-C bond cleavage from the resulting protonated structure. Explicit inclusion of water molecules indicated that two waters are needed for the P-C bond cleavage, and the calculated mechanistic paths in this hydrated model are similar to those of the aqueous solvation model.

show abstract

Ab initio calculations on P?C bond cleavage in phosphoranyl radicals: implications for the biodegradation of organophosphonate derivatives

Cited by 9 publications

References 65 publications

Quantum Chemical Characterization of Cycloaddition Reactions between the Hydroxyallyl Cation and Dienes of Varying Nucleophilicity

Quantum Chemical Characterization of Cycloaddition Reactions between the Hydroxyallyl Cation and Dienes of Varying Nucleophilicity

Effects of Substituents on the Stability of Phosphoranyl Radicals

Theoretical Studies on the Mechanism of C−P Bond Cleavage of a Model α-Aminophosphonate in Acidic Condition

Contact Info

Product

Resources

About