Electrostatic <i>vs.</i> inductive effects in phosphine ligand donor properties and reactivity

Kelty, Margaret L; McNeece, Andrew J.; Kurutz, Josh W.; Filatov, Alexander S.; Anderson, John S.

doi:10.1039/d1sc04277g

Cited by 13 publications

(17 citation statements)

References 141 publications

(287 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The fluxional nature of the ethyl linkage may support a varied distance between 9BBN and the iron core, and so it appears that none of these configurations makes a measurable contribution to E p,c . We note however that it is known that redox-inactive Lewis acid SCS groups can have significant effects on reaction outcomes, as in homogeneous CO hydrogenation, , and in C–F bond activation chemistry, and we hope that future studies on the reactivity of 2 – might uncover effects that are not related to the E p,c of 2 – .…”

Section: Resultsmentioning

confidence: 93%

Using Substituted [Fe₄N(CO)₁₂]⁻ as a Platform To Probe the Effect of Cation and Lewis Acid Location on Redox Potential

2022

View full text Add to dashboard Cite

The impact of cationic and Lewis acidic functional groups installed in the primary or secondary coordination sphere (PCS or SCS) of an (electro)catalyst is known to vary depending on the precise positioning of those groups. However, it is difficult to systematically probe the effect of that position. In this report, we probe the effect of the functional group position and identity on the observed reduction potentials (E p,c ) using substituted iron clusters, [Fe 4 N(CO) 11 R] n , where R = NO + , PPh 2 -CH 2 CH 2 -9BBN, ( Me PTA + ) 2 , ( Me PTA + ) 4 , and H + and n = 0, −1, +1, or +3 (9-BBN is 9-borabicyclo(3.3.1)nonane; Me PTA + is 1-methyl-1-azonia-3,5-diaza-7-phosphaadamantane). The cationic NO + and H + ligands cause anodic shifts of 700 and 320 mV, respectively, in E p,c relative to unsubstituted [Fe 4 N(CO) 12 ] − . Infrared absorption band data, ν CO , suggests that some of the 700 mV shift by NO + results from electronic changes to the cluster core. This contrasts with the effects of cationic Me PTA + and H + which cause primarily electrostatic effects on E p,c . Lewis acidic 9-BBN in the SCS had almost no effect on E p,c .

show abstract

Section: Resultsmentioning

confidence: 93%

Using Substituted [Fe₄N(CO)₁₂]⁻ as a Platform To Probe the Effect of Cation and Lewis Acid Location on Redox Potential

2022

View full text Add to dashboard Cite

show abstract

“…16 Top: major resonance contributors to the ground state of a novel phosphine selenide architecture bearing an appended -BF 3 À unit. 94 Bottom: the computational use of a point charge near a neutral varient (-Et) of the phosphine was needed to mimic experimental observables for the properties of the phosphine selenide.…”

Section: Intermolecular Electrostatic Interactions In Homogeneous Sys...mentioning

confidence: 99%

“…The inductive and electrostatic properties of this unique, anionic phosphine were studied through its use as a ligand on nickel/rhenium and through the formation of a phosphine selenide. 94 This latter species was studied in detail, and analysis of its 1 J PSe NMR coupling constants in a variety of solvents revealed a dramatic dependence on the solvent dielectric constant. Since the R 3 P]Se interaction exhibits signicant ylidic character in the form of R 3 P + -Se À , the impact of the solvent dielectric on 1 J PSe suggested that local ESFs emanating from the borate group impact the ground state of the molecule.…”

Section: Molecular Electrostatic Effects In Small Molecule Activation...mentioning

confidence: 99%

Oriented internal electrostatic fields: an emerging design element in coordination chemistry and catalysis

2022

View full text Add to dashboard Cite

show abstract

“…A more suitable system involves the oxidation of a phosphine to its phosphine selenide and analyzing the 1 JPSe spin-spin coupling constants via 31 P-NMR. [54][55][56]182,183] The methodology shows good correlation to the TEP and basicity of the phosphine and shows high selectivity towards phosphorus oxidation. However, to ensure its validity bulky moieties at the phosphorus and hydrogen bonds towards the selenium should be avoided.…”

Section: Phosphine Selenides and 1 Jpse Coupling Constantsmentioning

confidence: 99%

“…However, using a solvent with smaller dielectrics should decrease the medium's ability to shield the charge, which should result in an increase of the 1 JPSe spin-spin coupling constant for cationic charges (electrostatic effect). [183] This effect should not be present for neutral phosphines or reversed for anionic phosphines. The increase of 1 JPSe can be seen in the case of Na + , Mg 2+ , Zn 2+ and Ru 2+ .…”

Section: Scheme 85: Strategies Towards Phosphine Selenidesmentioning

confidence: 99%

Tuning the donor properties of bipyridyl-substituted phosphines by metal ion encapsulation & Photocatalytic synthesis of 6H-benzo[c]chromenes from S-aryl sulfonium salts

Karreman¹

View full text Add to dashboard Cite

Lewis acid catalysis vs. Brønsted acid catalysisWith the corresponding costs for ligands and noble metals, the question arises why one cannot simply use proton catalysis instead (Brønsted acid catalysis). A proton is after all isolobal to the LAu + and Hg 2+ fragments. An evident difference is the contrasting hardness according to the Pearson concept. [6] Protons are hard Lewis acids, while mentioned metal fragments are soft Lewis acids. This difference leads to the fact that protons often need harsh reaction conditions and are less selective. The softer metal fragments, however, have higher affinity to soft substrates and therefore require less harsh conditions and react in higher selectivity. Besides this evident difference, the use of metal fragments also allows the possibility of stabilizing carbene-like intermediates and to unlock their reactivity. In the case of gold(I), this topic is highly controversial, and resonances of gold carbenes or gold-stabilized carbocations are discussed (→"carbenoid" [6] or "carbene" [11] , Scheme 2). [11,12] Scheme 2: Gold carbene [11] Scheme 14:Chalk-Harrod mechanism [36] The latter mechanism is composed of oxidative addition (I) followed by ligand association (II), insertion (III) and reductive elimination (IV). As a side reaction, mainly β-hydride elimination is present. Because of its ability to activate inert bonds, platinum(II) is also used in the activation of methane, which represents a classic example of CꟷH activation (Shilov system). [37] Methanol and chloromethane can Scheme 20: Oxidation of phosphines to phosphine selenides [55] Since the J-coupling constant contains information about the electronic environment, bonding situation and hybridization of 31 P (I = ½) and 77 Se (I = ½) via the Fermi contact interaction, it is also strongly influenced by the polarization of the PꟷSe bond. If electron pushing substituents are chosen on the phosphorus, the coupling constant 1 JPSe decreases, while electron withdrawing substituents result in high coupling constants. In other words, the coupling constant decreases as the basicity of the corresponding unoxidized phosphine increases (Scheme 21).

show abstract

Electrostatic vs. inductive effects in phosphine ligand donor properties and reactivity

Abstract: Enhanced rates and selectivity in enzymes are enabled in part by precisely tuned electric fields within active sites. Analogously, the use of charged groups to leverage electrostatics in molecular systems...

Cited by 13 publications

References 141 publications

Using Substituted [Fe₄N(CO)₁₂]⁻ as a Platform To Probe the Effect of Cation and Lewis Acid Location on Redox Potential

Using Substituted [Fe₄N(CO)₁₂]⁻ as a Platform To Probe the Effect of Cation and Lewis Acid Location on Redox Potential

Oriented internal electrostatic fields: an emerging design element in coordination chemistry and catalysis

Tuning the donor properties of bipyridyl-substituted phosphines by metal ion encapsulation & Photocatalytic synthesis of 6H-benzo[c]chromenes from S-aryl sulfonium salts

Contact Info

Product

Resources

About

Electrostatic vs. inductive effects in phosphine ligand donor properties and reactivity

Abstract: Enhanced rates and selectivity in enzymes are enabled in part by precisely tuned electric fields within active sites. Analogously, the use of charged groups to leverage electrostatics in molecular systems...

Cited by 13 publications

References 141 publications

Using Substituted [Fe4N(CO)12]− as a Platform To Probe the Effect of Cation and Lewis Acid Location on Redox Potential

Using Substituted [Fe4N(CO)12]− as a Platform To Probe the Effect of Cation and Lewis Acid Location on Redox Potential

Oriented internal electrostatic fields: an emerging design element in coordination chemistry and catalysis

Tuning the donor properties of bipyridyl-substituted phosphines by metal ion encapsulation & Photocatalytic synthesis of 6H-benzo[c]chromenes from S-aryl sulfonium salts

Contact Info

Product

Resources

About

Using Substituted [Fe₄N(CO)₁₂]⁻ as a Platform To Probe the Effect of Cation and Lewis Acid Location on Redox Potential

Using Substituted [Fe₄N(CO)₁₂]⁻ as a Platform To Probe the Effect of Cation and Lewis Acid Location on Redox Potential