An official website of the United States government
Abstract Adducts between OsO4and Lewis bases exert a role in important oxidation processes such as epoxidation and dihydroxylation. It has been shown that the attractive interaction driving the formation of these adducts is a σ‐hole bond involving the metal as the electrophilic species; the term Osme Bond (OmB) was proposed for designating it. Here some new adducts between OsO4and various bases have been characterized through single crystal x‐ray diffraction (XRD) and computational studies (density functional theory, DFT), confirming the existence of a robust correlation between σ‐hole interaction energy and deformation of the tetrahedral geometry of OsO4. Also, some adducts formed by RuO4with nucleophiles were investigated computationally.
more »
« less
Examining the reactivity of tris(ortho-carboranyl)borane with Lewis bases and application in frustrated Lewis pair Si–H bond cleavage
Reactions of tris(ortho-carboranyl)borane with Lewis bases reveals only small bases bind. The tremendous bulk and Lewis acidity is leveraged in frustrated Lewis pair Si–H cleavage with a wider range of Lewis bases and greater efficacy than B(C6F5)3.
more »
« less
- Award ID(s):
- 1753025
- PAR ID:
- 10523397
- Publisher / Repository:
- Royal Society of Chemistry
- Date Published:
- Journal Name:
- Dalton Transactions
- Volume:
- 52
- Issue:
- 28
- ISSN:
- 1477-9226
- Page Range / eLocation ID:
- 9639 to 9645
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Organoantimony Lewis acids have been coveted for their ability to bind hard anions like fluoride in competing media. Herein, we describe the synthesis of a phenyl dithienostibole (1) in which the antimony(III) center is embedded within a planar dibenzodithiophene chromophore. Compound1reacts witho‐chloranil to form the corresponding catecholatostiborane (2); it also reacts withtert‐butyl peroxide in the presence of perfluoropinacol to form the corresponding pinacolatostiborane (3). Compound2was investigated as a platform for anion binding. UV–vis titrations in CH2Cl2afforded an association constant greater than 107 M−1pointing to the high fluoridophilicity of this new system. Density functional theory calculations highlight the role played by theσ*(Sb‐Cphenyl) orbital in imparting Lewis acidity to the antimony center of2.more » « less
-
Abstract While SbCl3is typically inert toward oxidation byortho‐quinones, we useo‐chloranil to show that the outcome of such reactions may be altered by the presence of a donor such as triphenylphosphine oxide, which readily traps the SbCl3(catCl) synthon (catCl = tetrachlorocatecholate) in the form of the corresponding adduct Ph3PO→SbCl3(catCl). The same reaction in the presence of a chloride salt affords the corresponding antimonate anion [Cl4Sb(catCl)]−. Computational studies indicate that the putative SbCl3(catCl) synthon has a higher chloride ion affinity than SbCl5, suggesting significant Lewis acidity. This property is further demonstrated by the use of the SbCl3/o‐chloranil system for both THF polymerization and a Friedel–Crafts‐type alkylation of benzene using 1‐fluorooctane. Finally, the reaction ofE‐stilbene witho‐chloranil in the presence of SbCl3affords the corresponding benzodioxene, suggesting that SbCl3may also operate as a redox‐active catalyst.more » « less
-
Abstract Olefin oligomerization by γ‐Al2O3has recently been reported, and it was suggested that Lewis acid sites are catalytic. The goal of this study is to determine the number of active sites per gram of alumina to confirm that Lewis acid sites are indeed catalytic. Addition of an inorganic Sr oxide base resulted in a linear decrease in the propylene oligomerization conversion at loadings up to 0.3 wt %; while, there is a >95 % loss in conversion above 1 wt % Sr. Additionally, there was a linear decrease in the intensity of the Lewis acid peaks of absorbed pyridine in the IR spectra with an increase in Sr loading, which correlates with the loss in propylene conversion, suggesting that Lewis acid sites are catalytic. Characterization of the Sr structure by XAS and STEM indicates that single Sr2+ions are bound to the γ‐Al2O3surface and poison one catalytic site per Sr ion. The maximum loading needed to poison all catalytic sites, assuming uniform surface coverage, was ∼0.4 wt % Sr, giving an acid site density of ∼0.2 sites per nm2of γ‐Al2O3, or approximately 3 % of the alumina surface.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1039/d3dt01557b
