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.     

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.     

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 S^VI 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.     

SuFEx on the Surface: A Flexible Platform for Postpolymerization Modification of Polymer Brushes

Polymer brushes present a unique architecture for tailoring surface functionalities due to their distinctive physicochemical properties. However, the polymerization chemistries used to grow brushes place limitations on the monomers that can be grown directly from the surface. Several forms of click chemistry have previously been used to modify polymer brushes by postpolymerization modification with high efficiency, however, it is usually difficult to include the unprotected moieties in the original monomer. We present the use of a new form of click chemistry known as SuFEx (sulfur(VI) fluoride exchange), which allows a silyl ether to be rapidly and quantitatively clicked to a polymer brush grown by free‐radical polymerization containing native ‐SO₂F groups with rapid pseudo‐first‐order rates as high as 0.04 s^?1. Furthermore, we demonstrate the use of SuFEx to facilely add a variety of other chemical functional groups to brush substrates that have highly useful and orthogonal reactivity, including alkynes, thiols, and dienes.     

Ex situ Generation of Thiazyl Trifluoride (NSF3) as a Gaseous SuFEx Hub**

Sulfur(VI)-fluoride exchange (SuFEx) chemistry, an all-encompassing term for substitution events that replace fluoride at an electrophilic sulfur(VI), enables the rapid and flexible assembly of linkages around a S^VI core. Although a myriad of nucleophiles and applications works very well with the SuFEx concept, the electrophile design has remained largely SO₂-based. Here, we introduce S≡N-based fluorosulfur(VI) reagents to the realm of SuFEx chemistry. Thiazyl trifluoride (NSF₃) gas is shown to serve as an excellent parent compound and SuFEx hub to efficiently synthesize mono- and disubstituted fluorothiazynes in an ex situ generation workflow. Gaseous NSF₃ was evolved from commercial reagents in a nearly quantitative fashion at ambient conditions. Moreover, the mono-substituted thiazynes could be extended further as SuFEx handles and be engaged in the synthesis of unsymmetrically disubstituted thiazynes. These results provide valuable insights into the versatility of these understudied sulfur functionalities paving the way for future applications.     

SuFEx Click: New Materials from SOxF and Silyl Ethers

New forms of click chemistry present new opportunities in materials science. Sulfur(VI) fluoride exchange (SuFEx) is a recently discovered click reaction between molecules containing SO_xF groups and silyl ethers, two functionalities that are orthogonal to all other known click chemistries, that generates sulfate or sulfonate connections upon the addition of certain organobases or fluoride sources. SuFEx also has several important advantages over other click reactions in that it is insensitive to ambient oxygen and water, and its precursor materials, especially SO_xF, are chemically, UV, and thermally inert. This Concept article focuses on the unique reactivity of SuFEx and its relation to building high molecular weight polymers and surface coatings, both of which make it a powerful new tool for materials science.     

Carbofunctional sulfur‐containing organosilicon compounds

This review summarizes literature data and the authors’ own research results from the past 14–15 years relating to practical, valuable organosilicon carbofunctional sulfur‐containing compounds of general formula R_4−n Si(S_x R¹)_n , where R is alkyl, arylalkoxyl, aroxyl or even sylatranyl fragment, R¹ is hydrogen, alkyl, aryl, alkenyl, etc., n = 1–3, x = 1–10, having sulfur functional groups such as thiol, sulfide, di‐ and polysulfide, as well as sulfur heteroatomic groups such as thiocarbamide, dioxothiocarbamide, dithiourethane, thiuramdisulfide, etc. The compounds reviewed have been found to be effective, for example, as ingredients for rubber compositions for non‐flammable, water‐ and wear‐proof tires or as ion‐exchanging and complexing sorbents of heavy and noble metals.     

Gas-phase reactions in plasmas of SF6 with O2: Reactions of F with SOF2 and SO2 and reactions of O with SOF2

The plasma chemistry of SF₆/O₂ mixtures is particularly complicated because of the large number of possible reactions. Over a wide range of conditions, products including SF₄, SOF₄, SOF₂, and SO₂F₂ can be formed but thre is considerable uncertainty about the major reactions which contribute to the formation of these species. In this work reactions of oxygen atoms with SOF₂ and fluorine atoms with SOF₂ and SO₂ have been studied in order to determine the principal sources of SO₂F₂ in these plasmas. Reactions were studied at 295 K in a gas flow reactor sampled by a mass spectrometer. No reaction could be detected between oxygen atoms and SOF₂, which for the conditions employed, means that the upper limit for the reaction rate coefficient is 1×10^–14 cm³ sec^–1. The reaction of fluorine atoms with SOF₂ was studied with the helium bath gas number density ranging from 3.1×10¹⁶ to 2.0×10¹⁷ cm^–3. Within this range the rate coefficient increased with increasing [He] from (4.1 to 10.8)×10^–14 cm³ sec^–1. SO₂ was found to react with fluorine atoms with a rate coefficient which appeared to be independent of the helium bath gas number density over the range given above. The possibility that this reaction occurred entirely on the walls of the reactor is discussed.     

On the reaction of aminobis(diorganylamino)phosphanes with halogenophosphanes—P-hydrogeno(iminophosphoranyl)-halogenophosphanes and P-hydrogeno(iminophosphoranyl)-σ2, λ3-iminophosphanes

Reactions of triaminophosphane (R₂N)₂P–NH₂, (R = ¹Pr) 1a, with aminodihalogenophosphanes ¹Pr₂N–PX₂, 2a–c [X = CL (a), Br (b), I(c)], in the presence of a base yielded the P-hydrogeno-iminophosphoranyl-halogenophosphanes (R₂N)₂PH = N–PX–N(¹Pr)₂ 4a–c [X = Cl (a), Br (b), I(c)]. Analogous reactions between 1a and 1b (b: R = c-hexyl) and chloroiminophosphane (Cl–P = N–Mes^*, (Mes^* = 2,4,6-^tBu₃C₆H₂) 6 , gave the P-hydrogeno(iminophosphoranyl)-σ²,λ³-iminophosphanes, (R₂N)₂PH = N–P = N–Mes^* 8a and 8b. In solution 8a, 8b eliminated amine, yielding σ², λ³-iminophosphanyl-substituted 1,3,2,4-diazadiphosphetidines [(R₂N)PN(P = N–Mes^*)]₂, 10a, 10b , and 11 ( 10a and 10b : cis; 11: trans). The X-ray structure analyses of compounds 4a, 4b, 8a, and 11 are discussed. © 1996 John Wiley & Sons, Inc.     

A Heck–Matsuda Process for the Synthesis of β‐Arylethenesulfonyl Fluorides: Selectively Addressable Bis‐electrophiles for SuFEx Click Chemistry

A Heck–Matsuda process for the synthesis of the otherwise difficult to access compounds, β‐arylethenesulfonyl fluorides, is described. Ethenesulfonyl fluoride (i.e., vinylsulfonyl fluoride, or ESF) undergoes β‐arylation with stable and readily prepared arenediazonium tetrafluoroborates in the presence of the catalyst palladium(II) acetate to afford the E‐isomer sulfonyl analogues of cinnamoyl fluoride in 43–97 % yield. The β‐arylethenesulfonyl fluorides are found to be selectively addressable bis‐electrophiles for sulfur(VI) fluoride exchange (SuFEx) click chemistry, in which either the alkenyl moiety or the sulfonyl fluoride group can be the exclusive site of nucleophilic attack under defined conditions, making these rather simple cores attractive for covalent drug discovery.     

Controlled Redox Chemistry at Cerium within a Tripodal Nitroxide Ligand Framework

Ligand reorganization has been shown to have a profound effect on the outcome of cerium redox chemistry. Through the use of a tethered, tripodal, trianionic nitroxide ligand, [((2‐tBuNOH)C₆H₄CH₂)₃N]^3? (TriNO_x^3?), controlled redox chemistry at cerium was accomplished, and typically reactive complexes of tetravalent cerium were isolated. These included rare cationic complexes [Ce(TriNO_x)thf][BAr^F₄], in which Ar^F=3,5‐(CF₃)₂‐C₆H₃, and [Ce(TriNO_x)py][OTf]. A rare complete Ce–halide series, Ce(TriNO_x)X, in which X=F^?, Cl^?, Br^?, I^?, was also synthesized. The solution chemistry of these complexes was explored through detailed solution‐phase electrochemistry and ¹H NMR experiments and showed a unique shift in the ratio of species with inner‐ and outer‐sphere anions with size of the anionic X^? group. DFT calculations on the series of calculations corroborated the experimental findings.     

Double stereoselective coordination of chiral N,S ligands: Synthesis,coordination chemistry and utilization in Pd‐catalyzed allylic alkylation

A series of chiral pentane‐2,4‐diyl‐based thioether‐amine ligands [ 4 and 5 ; (R,S)‐ and (S,S)‐R¹SCH(CH₃)CH₂CH(CH₃)NHR², respectively, where 4a R¹ = iPr, R² = Ph; 4b R¹ = tBu, R² = Ph; 4c R¹ = 1‐Ad, R² = Ph; 5a R¹ = iPr, R² = Ph; 5b R¹ = tBu, R² = Ph; 5c R¹ = 1‐Ad, R² = Ph; 5d R¹ = iPr, R² = 4‐MeOC₆H₄; 5e R¹ = iPr, R² = 4‐MeC₆H₄; 5f R¹ = iPr, R² = 3,5‐Me₂C₆H₃] with stereogenic S‐ and N‐donor atoms has been prepared starting from cyclic sulfates via optically pure γ‐aminoalcohol or 2,4‐dimethylazetidine intermediates. The synthesis of the novel diastereomerically related ligand sets 4 and 5 was accomplished starting from the same source of chirality. The modular ligand structure and the novel synthetic strategies developed for their synthesis allowed the easy modification of the ligands’ (i) S‐ and (ii) N‐substituents, as well as (iii) the relative stereochemistry within the ligand backbone. Six‐membered [Pd(N,S)Cl₂]‐type chelate complexes of the diastereomerically related ligands 4a and 5a were synthesized and characterized by X‐ray crystallography in the solid phase, by density functional theory calculations and in solution by NMR spectroscopy. The coordination of 5a resulted in the formation of a single chair conformation by the stereospecific locking of both stereolabile (N and S) donor atoms. In contrast, compound 4a forms rapidly equilibrating palladium species due to the fast inversion of the sulfur donor. Ligands with stereochemically fixed donor atoms provided robust and efficient catalytic systems that can be effectively applied in alkylene carbonates as green reaction media. Remarkably, the phosphine‐free catalysts are air‐stable, and at room temperature in the presence of moisture gave excellent ee’s (up to 93%) in asymmetric allylation processes thanks to the double stereoselective coordination.     

Easily available niobium(V) mixed chloro‐alkoxide complexes as catalytic precursors for ethylene polymerization

The dinuclear [NbCl_n(OR)_(5‐n)]₂ (n = 4, R = Et, 1 ; n = 4, R = CH₂Ph, 2 ; n = 3, R = Et, 3 ; n = 2, R = Et, 4 ; n = 2, R = , 5 ), and [Nb(OEt)₅]₂, 6 , and the mononuclear niobium compounds NbCl₄[κ²? OCH₂CH(R′)OR] (R = Me, R′ = H, 7 ; R = Et, R′ = H, 8 ; R = CH₂Cl, R′ = H, 9 ; R = CH₂CH₂OMe, R′ = H, 10 ; R = R′ = Me, 11 ), NbBr₄[κ²? OCH₂CH₂OMe], 12 , and NbCl₃(κ²? OCH₂CH₂OMe)(κ¹? OCH₂CH₂OMe), 13 , were tested in ethylene polymerization. Optimized reaction conditions included the use of D‐MAO as co‐catalyst and chlorobenzene as solvent at 50 °C. Complex 7 , whose X‐Ray structure is described here for the first time, exhibited the highest activity ever reported for a niobium catalyst in alkene polymerization [151 kg_polymer × mol_Nb^?1 × h^?1 × bar^?1]. Compounds 1 , 3‐5 , 8 , 13 showed activities similar to that of 7 . Linear polyethylenes (characterized by FT‐IR, NMR, GPC, and DSC analyses) with a broad polydispersivity were obtained. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

1H-, 13C-UND 31P-NMR-SPEKTROSKOPISCHE UNTERSUCHUNGEN AN BIS-(DIALKOXYTHIOPHOSPHORYL)-UND-(DIALKOXYPHOSPHORYL)-SULFANEN UND-POLYSULFANEN

Abstract

Compounds of the following structure

(R¹O)₂(X)P[sbnd]Y–P(X)(OR²)₂

(X = O, Y = S_n (n = 1–4), R¹ = R² = Me, iPr;

X = S, Y = S_n (n = 1–4), R¹, R² = Me, Et, iPr, iBu;

X = S, Y = S-Se-S, S-Te-S, R¹ = R² = Me

were prepared and their NMR spectra were analysed. Depending on the number of sulfur atoms, bonded between the phosphorus atoms, typical ranges of the P-P coupling constants were found for the different sulfanes investigated: ²J_PP from-10 to-20 Hz, ³J_PP less than 3 Hz, ⁴J_PP from +10 to +13 Hz and ⁵J_PP less than 1 Hz. For the small vicinal coupling constants and the relatively large values of ⁴J_PP different possibilities of their interpretation are given.     

Darstellung und spektroskopische Charakterisierung von Di(halogeno)phthalocyaninato(1–)rhodium(III), [RhX2Pc1−] (X = Cl,Br, I)

Synthesis and Spectroscopical Characterization of Di(halo)phthalocyaninato(1–)rhodium(III), [RhX₂Pc^1?] (X = Cl, Br, I) Bronze-coloured di(halo)phthalocyaninato(1–)-rhodium(III), [RhX₂Pc^1?] (X = Cl, Br) and [RhI₂Pc^1?] · I₂ is prepared by oxidation of (ⁿBu₄N)[RhX₂Pc^2?] with the corresponding halogene. Irrespective of the halo ligands, two irreversible electrode reactions due to the first ringreduction (E_R = ?0,90 V) and ringoxidation (E_O = 0,82 V) are present in the cyclovoltammogram of (ⁿBu₄N)[RhX₂Pc^2?]. The optical spectra show typical absorptions of the Pc^1?-ligand at 14.0 kK and 19.1 kK. Characteristic vibrational bands are at 1 366/1 449 cm^?1 (i. r.) and 569/1 132/1 180/1 600 cm^?1 (resonance Raman (r. r.)). The antisym. (Rh? X)-stretching vibration is observed at 294 cm^?1 (X = Cl), 240 cm^?4 (Br) and 200 cm^?1 (I). Only the sym. (Rh? I)-stretching vibration at 133 cm^?1 is r. r. enhanced together with a strong line at 170 cm^?1, which is assigned to the (I? I)-stretching vibration of the incorporated iodine molecule. Both modes show overtones and combinationbands.     

Enthalpie de dissolution du fluorure et de l′hydrogenofluorure d'ammonium dans les solutions d'acide fluorhydrique

The standard enthalpies of solution of NH₄F and NH₄HF₂ in aqueous solutions of hydrogen fluoride (in the range of concentration 0–30 mol.1^?1) have been measured and from these results the standard enthalpy of formation of NH₄HF_2(c) has been derived as: δH^o_fNH₄HF_2(c) = ?809.9 ± 0.9 kJ.mol^?1     

Gas‐Phase Structure Determination of Dihydroxycarbene,One of the Smallest Stable Singlet Carbenes

Carbenes are reactive molecules of the form R¹? C?? R² that play a role in topics ranging from organic synthesis to gas‐phase oxidation chemistry. We report the first experimental structure determination of dihydroxycarbene (HO? C?? OH), one of the smallest stable singlet carbenes, using a combination of microwave rotational spectroscopy and high‐level coupled‐cluster calculations. The semi‐experimental equilibrium structure derived from five isotopic variants of HO? C?? OH contains two very short CO single bonds (ca. 1.32 Å). Detection of HO? C?? OH in the gas phase firmly establishes that it is stable to isomerization, yet it has been underrepresented in discussions of the CH₂O₂ chemical system and its atmospherically relevant isomers: formic acid and the Criegee intermediate CH₂OO.     

Self-assembly of ionic triorganotin(IV) complexes of tetrafluorophthalic acid with a tetranuclear macrocyclic or polymeric structure: syntheses,characterization and crystal structures

Four triorganotin(IV) complexes constructed from tetrafluorophthalic acid (H₂tfp) with a 1?:?1?:?1 molar ratio of H₂tfp: Et₃N: R₃SnCl gave two of type {[R₃Sn (tfp)].Et₃NH}₄ (R?=?Me 1, R?=?n-Bu 2), and two of type [R₃Sn (tfp).Et₃NH] _n (R?=?PhCH₂ 3, Ph 4). All the complexes are characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR analyses. Complexes 1 and 4 were also confirmed by X-ray crystallography. Complex 1 is tetranuclear with a 28-membered C₁₆O₈Sn₄ macrocyclic ring system with a cavity. The supramolecular structure of 1 has been found to consist of a three-dimensional network built up by intermolecular N–H?···?O, C–H?···?O hydrogen bonds and C–F?···?F weak interactions. Complex 4 is an infinite polymeric structure. The salient feature of the supramolecular structure of 4 is that of a two-dimensional plane, in which intermolecular N–H?···?O and C–H?···?π hydrogen bonds are important.     

Syntheses and reactions of N‐perfluoroalkanesulfonylimino sulfurous dichlorides

Treatment of N,N‐dichloroperfluoroalkanesulfonylamines with sulfur powder at room temperature gave the title products R_fSO₂N=SCl₂ in good yields. They reacted readily with dimethyl sulfoxide, chloral, DMF, benzophenone, and similar compounds to form to corresponding imines R_fSO₂N=YR¹R² (Y: S, C). A reaction mechanism, one involving formation of a four‐membered intermediate, is proposed. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 41–48, 1999     

The Binary Group 4 Azides [PPh4]2[Zr(N3)6] and [PPh4]2[Hf(N3)6]

The binary zirconium and hafnium polyazides [PPh₄]₂[M(N₃)₆] (M=Zr, Hf) were obtained in near quantitative yields from the corresponding metal fluorides MF₄ by fluoride–azide exchange reactions with Me₃SiN₃ in the presence of two equivalents of [PPh₄][N₃]. The novel polyazido compounds were characterized by their vibrational spectra and their X‐ray crystal structures. Both anion structures provide experimental evidence for near‐linear M‐N‐N coordination of metal azides. The species [M(N₃)₄], [M(N₃)₅]^? and [M(N₃)₆]^2? (M=Ti, Zr, Hf) were studied by quantum chemical calculations at the electronic structure density functional theory and MP2 levels.