SOF4 Research Articles

Streamlining Thionyl Tetrafluoride (SOF4) and Pentafluorooxosulfate [OSF5]- Anions Syntheses.

A one pot room temperature synthesis of thionyl tetrafluoride (SOF4) from elemental fluorine (F2) and thionyl fluoride (SOF2) is reported. The selective decagram scale process (100 mmol) allows a quantitative preparation of SOF4 with high purity. The solid-state structure has also been elucidated and compared with the reported gas-phase one. The use of this reagent for the formation of the emerging pentafluorooxosulfate [cat][OSF5] anions led to the preparation of multiple ion-pairs (cat = Ag, NEt3Me, PPN, PPh4) in different organic solvents. The SuFEx reservoir ability of this anion was studied and by tuning the solvent system, the reactivity of pure thionyl tetrafluoride was observed using Ag[OSF5] in THF and acetone.

Perfluorooxosulfate Salts as SOF4‐Gas‐Free Precursors to Multidimensional SuFEx Electrophiles

AbstractSulfur(VI) Fluoride Exchange (SuFEx) chemistry stands as a well‐established method for swiftly constructing complex molecules in a modular fashion. An especially promising segment of this toolbox is reserved for multidimensional SuFEx hubs: three or more substituents pluggable into a singular SVI centre to make ‘beyond‐linear’ clicked constructions. Sulfurimidoyl difluorides (RNSOF2) stand out as the prime example of this, however their preparation from the scarcely available thionyl tetrafluoride (SOF4) limits this chemistry to only a few laboratories with access to this gas. In this work, we identify silver pentafluorooxosulfate (AgOSF5) as a viable SuFEx hub with reactivity equal to SOF4. The AgF2‐mediated oxidation of SOCl2 gives rise to the hexacoordinate AgOSF5 adduct, which in contact with primary amines produces the sulfurimidoyl fluorides in high yields. In addition, we have found this workflow to be fully extendable to the trifluoromethyl homologue, AgOSF4CF3, and we propose the use of AgOSF4X salts as a general route to azasulfur SuFEx electrophiles from commercial starting materials.

Perfluorooxosulfate Salts as SOF4-Gas-Free Precursors to Multidimensional SuFEx Electrophiles.

Sulfur(VI) Fluoride Exchange (SuFEx) chemistry stands as a well-established method for swiftly constructing complex molecules in a modular fashion. An especially promising segment of this toolbox is reserved for multidimensional SuFEx hubs: three or more substituents pluggable into a singular SVI centre to make 'beyond-linear' clicked constructions. Sulfurimidoyl difluorides (RNSOF2) stand out as the prime example of this, however their preparation from the scarcely available thionyl tetrafluoride (SOF4) limits this chemistry to only a few laboratories with access to this gas. In this work, we identify silver pentafluorooxosulfate (AgOSF5) as a viable SuFEx hub with reactivity equal to SOF4. The AgF2-mediated oxidation of SOCl2 gives rise to the hexacoordinate AgOSF5 adduct, which in contact with primary amines produces the sulfurimidoyl fluorides in high yields. In addition, we have found this workflow to be fully extendable to the trifluoromethyl homologue, AgOSF4CF3, and we propose the use of AgOSF4X salts as a general route to azasulfur SuFEx electrophiles from commercial starting materials.

Enantioselective sulfur(VI) fluoride exchange reaction of iminosulfur oxydifluorides.

Linkage chemistry and functional molecules derived from the stereogenic sulfur(VI) centre have important applications in organic synthesis, bioconjugation, drug discovery, agrochemicals and polymeric materials. However, existing approaches for the preparation of optically active S(VI)-centred compounds heavily rely on synthetic chiral S(IV) pools, and the reported linkers of S(VI) lack stereocontrol. A modular assembly method, involving sequential ligand exchange at the S(VI) centre with precise control of enantioselectivity, is appealing but remains elusive. Here we report an asymmetric three-dimensional sulfur(VI) fluoride exchange (3D-SuFEx) reaction based on thionyl tetrafluoride gas (SOF4). A key step involves the chiral ligand-induced enantioselective defluorinative substitution of iminosulfur oxydifluorides using organolithium reagents. The resulting optically active sulfonimidoyl fluorides allow for further stereospecific fluoride-exchange by various nucleophiles, thereby establishing a modular platform for the asymmetric SuFEx ligation and the divergent synthesis of optically active S(VI) functional molecules.

Phosphorus fluoride exchange: Multidimensional catalytic click chemistry from phosphorus connective hubs

Phosphorus Fluoride Exchange (PFEx) represents a cutting-edge advancement in catalytic click-reaction technology. Drawing inspiration from Nature's phosphate connectors, PFEx facilitates the reliable coupling of P(V)-F loaded hubs with aryl alcohols, alkyl alcohols, and amines to produce stable, multidimensional P(V)-O and P(V)-N linked products. The rate of P-F exchange is significantly enhanced by Lewis amine base catalysis, such as 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). PFEx substrates containing multiple P-F bonds are capable of selective, serial exchange reactions via judicious catalyst selection. In fewer than four synthetic steps, controlled projections can be deliberately incorporated along three of the four tetrahedral axes departing from the P(V) central hub, thus taking full advantage of the potential for generating three-dimensional diversity. Furthermore, late-stage functionalization of drugs and drug fragments can be achieved with the polyvalent PFEx hub, hexafluorocyclotriphosphazene (HFP), as has been demonstrated in prior research.

SuFExable polymers with helical structures derived from thionyl tetrafluoride.

Sulfur(VI) fluoride exchange (SuFEx) is a category of click chemistry that enables covalent linking of modular units through sulfur(VI) connective hubs. The efficiency of SuFEx and the stability of the resulting bonds have led to polymer chemistry applications. Now, we report the SuFEx click chemistry synthesis of several structurally diverse SOF4-derived copolymers based on the polymerization of bis(iminosulfur oxydifluorides) and bis(aryl silyl ethers). This polymer class presents two key characteristics. First, the [-N=S(=O)F-O-] polymer backbone linkages are themselves SuFExable and undergo precise SuFEx-based post-modification with phenols or amines to yield branched functional polymers. Second, studies of individual polymer chains of several of these new materials indicate helical polymer structures. The robust nature of SuFEx click chemistry offers the potential for post-polymerization modification, enabling the synthesis of materials with control over composition and conformation.

Theoretical Study of the Role of a Catalytic Water Molecule in the Hydrolysis of Thionyl Tetrafluoride (SOF4).

Sulfuryl fluoride (SO2F2) plays an important role in the operation of gas-insulated switchgear (GIS) equipment where it is widely used as the characteristic gas for discharge diagnostics. However, the formation mechanism of SO2F2 is currently unclear, and as a consequence, we have employed a range of ab initio methods to investigate the hydrolysis reaction of SOF4 that is known to afford SO2F2 in the gas phase. These results suggest that two H2O molecules are incorporated into a low energy transition state to afford an H-bond network that facilitates proton transfer during the hydrolysis of SOF4.

Solution-Phase DNA-Compatible Pictet-Spengler Reaction Aided by Machine Learning Building Block Filtering.

SummaryThe application of machine learning toward DNA encoded library (DEL) technology is lacking despite obvious synergy between these two advancing technologies. Herein, a machine learning algorithm has been developed that predicts the conversion rate for the DNA-compatible reaction of a building block with a model DNA-conjugate. We exemplify the value of this technique with a challenging reaction, the Pictet-Spengler, where acidic conditions are normally required to achieve the desired cyclization between tryptophan and aldehydes to provide tryptolines. This is the first demonstration of using a machine learning algorithm to cull potential building blocks prior to their purchase and testing for DNA-encoded library synthesis. Importantly, this allows for a challenging reaction, with an otherwise very low building block pass rate in the test reaction, to still be used in DEL synthesis. Furthermore, because our protocol is solution phase it is directly applicable to standard plate-based DEL synthesis.

Biocompatible SuFEx Click Chemistry: Thionyl Tetrafluoride (SOF4 )-Derived Connective Hubs for Bioconjugation to DNA and Proteins.

We report here the development of a suite of biocompatible SuFEx transformations from the SOF4 -derived iminosulfur oxydifluoride hub in aqueous buffer conditions. These biocompatible SuFEx reactions of iminosulfur oxydifluorides (R-N=SOF2 ) with primary amines give sulfamides (8 examples, up to 98 %), while the reaction with secondary amines furnish sulfuramidimidoyl fluoride products (8 examples, up to 97 %). Likewise, under mild buffered conditions, phenols react with the iminosulfur oxydifluorides (Ar-N=SOF2 ) to produce sulfurofluoridoimidates (13 examples, up to 99 %), which can themselves be further modified by nucleophiles. These transformations open the potential for asymmetric and trisubstituted linkages projecting from the sulfur(VI) center, including versatile S-N and S-O connectivity (9 examples, up to 94 %). Finally, the SuFEx bioconjugation of iminosulfur oxydifluorides to amine-tagged single-stranded DNA and to BSA protein demonstrate the potential of SOF4 -derived SuFEx click chemistry in biological applications.

SuFEx Chemistry of Thionyl Tetrafluoride (SOF4 ) with Organolithium Nucleophiles: Synthesis of Sulfonimidoyl Fluorides, Sulfoximines, Sulfonimidamides, and Sulfonimidates.

Thionyl tetrafluoride (SOF4 ) is a valuable connective gas for sulfur fluoride exchange (SuFEx) click chemistry that enables multidimensional linkages to be created via sulfur-oxygen and sulfur-nitrogen bonds. Herein, we expand the available SuFEx chemistry of SOF4 to include organolithium nucleophiles, and demonstrate, for the first time, the controlled projection of sulfur-carbon links at the sulfur center of SOF4 -derived iminosulfur oxydifluorides (R1 -N=SOF2 ). This method provides rapid and modular access to sulfonimidoyl fluorides (R1 -N=SOFR2 ), another array of versatile SuFEx connectors with readily tunable reactivity of the S-F handle. Divergent connections derived from these valuable sulfonimidoyl fluoride units are also demonstrated, including the synthesis of sulfoximines, sulfonimidamides, and sulfonimidates.

Click chemistry reaches a new dimension

In 2014, K. Barry Sharpless and coworkers at Scripps Research Institute California developed sulfur fluoride exchange (SuFEx), a simple and rapid click chemistry reaction that uses sulfuryl fluoride (SO2F2) to make carbon-sulfate links. They used the technique to synthesize disulfates, polysulfate polymers, and other linear products. Suhua Li, Sharpless, and coworkers have now devised a variation that kicks SuFEx click chemistry into another dimension. Using thionyl tetrafluoride (SOF4) instead of SO2F2 as a SuFEx reagent enables them to make up to three tetrahedrally oriented connections to each sulfur hub molecule instead of two linear linkages (Angew. Chem. Int. Ed. 2017, DOI: 10.1002/anie.201611048). Thionyl tetrafluoride reacts initially with a primary amino group, forming a tetrahedral iminosulfur product with two fluoride “handles.” One fluoride or both can then react with aryl alcohols or alkyl amines to create products that are doubly or triply substituted along the sulfur hub’s tetrahedral axes. Potential applications

Multidimensional SuFEx Click Chemistry: Sequential Sulfur(VI) Fluoride Exchange Connections of Diverse Modules Launched From An SOF4 Hub.

Sulfur(VI) fluoride exchange (SuFEx) is a new family of click chemistry based transformations that enable the synthesis of covalently linked modules via SVI hubs. Here we report thionyl tetrafluoride (SOF4 ) as the first multidimensional SuFEx connector. SOF4 sits between the commercially mass-produced gases SF6 and SO2 F2 , and like them, is readily synthesized on scale. Under SuFEx catalysis conditions, SOF4 reliably seeks out primary amino groups [R-NH2 ] and becomes permanently anchored via a tetrahedral iminosulfur(VI) link: R-N=(O=)S(F)2 . The pendant, prochiral difluoride groups R-N=(O=)SF2 , in turn, offer two further SuFExable handles, which can be sequentially exchanged to create 3-dimensional covalent departure vectors from the tetrahedral sulfur(VI) hub.

Multidimensional SuFEx Click Chemistry: Sequential Sulfur(VI) Fluoride Exchange Connections of Diverse Modules Launched From An SOF4 Hub

AbstractSulfur(VI) fluoride exchange (SuFEx) is a new family of click chemistry based transformations that enable the synthesis of covalently linked modules via SVI hubs. Here we report thionyl tetrafluoride (SOF4) as the first multidimensional SuFEx connector. SOF4 sits between the commercially mass‐produced gases SF6 and SO2F2, and like them, is readily synthesized on scale. Under SuFEx catalysis conditions, SOF4 reliably seeks out primary amino groups [R‐NH2] and becomes permanently anchored via a tetrahedral iminosulfur(VI) link: R−N=(O=)S(F)2. The pendant, prochiral difluoride groups R−N=(O=)SF2, in turn, offer two further SuFExable handles, which can be sequentially exchanged to create 3‐dimensional covalent departure vectors from the tetrahedral sulfur(VI) hub.

Kinetics of the manganese(III)-oxalate reaction in acidic sulphate media

The kinetics of the reaction of manganese(III) with oxalic acid (OA) has been studied in H2SO4 solutions. Under the experimental conditions of 6 × 10−3 < [OA]0 < 0.4 mol dm−3 and [H2SO4]0 ⩾ 0.2 mol dm−3 the observed pseudo-first order rate constant kobs follows the expression $$k_{obs} = k_1 + k_2 K_2 \left[ {C_2 O_4^{2 - } } \right]/\left\{ {1 + K_2 \left[ {C_2 O_4^{2 - } } \right]} \right\}$$ where k1, k2 and K2 have been estimated by a non-linear least-squares method. The kinetics of this component reaction of the BZ type oscillation system with oxalic acid was influenced by the addition of HSO f4 p− , SO f4 p2+ and ClO f4 p− ions. Oxalate complexes of manganese(III) decompose by a net process that can be generalized as 2MnIII + C2O f4 p2− → 2MnII + 2CO2.

Gas-phase hydrolysis of SOF2 and SOF4

The rates for gas-phase hydrolysis of SOF2 (thionylfluoride) and SOF4 (thionyl tetrafluoride) have been measured at a temperature of 298 K. The second order rate constant for SOF2 hydrolysis in SF6 buffer gas was found to have the value (1.2±0.3)×10−23 cm3/s which agrees with previous estimates of Sauers et al., but is three orders of magnitude lower than the value obtained by Rüegsegger et al. at 340 K. The rate constant for SOF4 hydrolysis has not previously been measured and its value in both SF6 and N2 buffer gases was found here to be (1.0±0.3)×10−21 cm3/s.

Quadratic force fields for phosphorus pentafluoride and thionyl tetrafluoride

Quadratic force fields for phosphorus pentafluoride and thionyl tetrafluoride

Thionyl tetrafluoride. Reanalysis of the molecular structure and resolution of the multiple model problem

Thionyl tetrafluoride. Reanalysis of the molecular structure and resolution of the multiple model problem

ChemInform Abstract: GEOMETRIC AND ELECTRONIC STRUCTURES OF METHYLENESULFUR TETRAFLUORIDE, CH2:SF4, THIONYL TETRAFLUORIDE, O:SF4, AND SULFUR TETRAFLUORIDE, SF4: AN AB INITIO STUDY

Chemischer InformationsdienstVolume 11, Issue 1 Physical Organic Chemistry ChemInform Abstract: GEOMETRIC AND ELECTRONIC STRUCTURES OF METHYLENESULFUR TETRAFLUORIDE, CH2:SF4, THIONYL TETRAFLUORIDE, O:SF4, AND SULFUR TETRAFLUORIDE, SF4: AN AB INITIO STUDY H. OBERHAMMER, H. OBERHAMMERSearch for more papers by this authorJ. E. BOGGS, J. E. BOGGSSearch for more papers by this author H. OBERHAMMER, H. OBERHAMMERSearch for more papers by this authorJ. E. BOGGS, J. E. BOGGSSearch for more papers by this author First published: January 8, 1980 https://doi.org/10.1002/chin.198001072AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume11, Issue1January 8, 1980 RelatedInformation

Geometric and electronic structures of methylene sulfurtetrafluoride, CH 2SF 4, thionyl tetrafluoride, OSF 4, and sulfurtetrafluoride, SF 4: an ab initio study

Fully optimized geometric structures for SF 4, OSF 4, and CH 2SF 4 have been calculated by the ab initio gradient method. Test calculations for SF 4 have indicated that the inclusion of d functions for sulfur is necessary for a quantitative description of its molecular structure. The experimental geometries of SF 4 and CH 2SF 4 are reproduced very well by the calculations. On the basis of the calculations for OSF 4, a choice between the four possible molecular models derived from electron diffraction experiments is possible. For CH 2SF 4, only the conformer with the hydrogen atoms of the methylene group in the axial plane is stable, while the conformer with the hydrogen atoms in the equatorial plane does not correspond to an energy minimum and is about 77 kcal mol −1 above the stable configuration. Variations in the geometry, especially in the bond angles, of the SF 4 groups in these three compounds can be rationalized on the basis of the electronic structures.

Aryloxy-derivatives of thionyl tetrafluoride

Thionyl tetrafluoride reacts with arylsilyl ethers to give substituted derivatives ArO·S(:O)F3(Ar = Ph; o-, m-, p-MeC6H4; m-, p-ClC6H4; o-, m-, p-FC6H4), (ArO)2S(:O)F2(Ar = Ph, p-MeC6H4, p-ClC6H4, p-NO2·C6H4), (ArO)3S(:O)F (Ar = Ph, p-MeC6H4, p-ClC6H4, C6F5), (m-MeC6H4O)4SO, and (o-C6H4O2)2SO. Spectroscopic data and modes of thermal and hydrolytic decomposition were studied for most derivatives. The thionyl trifluorides and difluorides appear to have structures based on a trigonal bipyramidal co-ordination about sulphur.