Sulfur Diimide Research Articles

Experimental Charge Density Study of Hypersilyl Sulfur Diimide

AbstractIn here three newly synthesized silyl substituted sulfur diimides S(NSi(SiMe3)3)2 (2), S(NSi(NMe2)3)2 (3) and S(NSiHiPr2)2 (4) are presented. 2 is characterised by experimental charge density investigations and compared to the di‐tert‐butyl sulfur diimide S(NtBu)2 (1). While the silylation seems not to have much impact on the sulfur‐nitrogen bonding the increase of negative charge at the nitrogen atoms is obvious. Hence, the silylated molecules should be better donors in metal chelation, provided the change from the genuine E/Z conformation to E/E is facilitated. Indeed, their calculated free energy gaps between initial and transition states, related to the rotation of the silyl substituted derivatives 2–4, interestingly found via different rearrangements, turned out to be only a third of that of 1, despite of changing the substituents linked to the Si atoms. This is due to the longer and more polar N−Si bonds compared to the N−C bonds.

Functionalization of Tetraphosphido Ligands by Heterocumulenes.

Although numerous polyphosphido complexes have been accessed through the transition-metal-mediated activation and functionalization of white phosphorus (P4), the selective functionalization of the resulting polyphosphorus ligands in these compounds remains underdeveloped. In this study, we explore the reactions between cyclotetraphosphido cobalt complexes and heterocumulenes, leading to functionalized P4 ligands. Specifically, the reaction of carbon disulfide (CS2) with [K(18c-6)][(Ar*BIAN)Co(η4-P4)] ([K(18c-6)]1, 18c-6 = [18]crown-6) affords the adduct [K(18c-6)][(Ar*BIAN)Co(η3:η1-P4CS2)] ([K(18c-6)]3), in which CS2 is attached to a single phosphorus atom (Ar* = 2,6-dibenzhydryl-4-isopropylphenyl, BIAN = 1,2-bis(arylimino)acenaphthene diimine). In contrast, the insertion of bis(trimethylsilyl)sulfur diimide S(NSiMe3)2 into a P-P bond of [K(18c-6)]1 yields [K(18c-6)][(Ar*BIAN)Co(η3:η1-P4SN2(SiMe3)2)] (K(18c-6)]4). This salt further reacts with Me3SiCl to form [(Ar*BIAN)Co(η3:η1-P4SN2(SiMe3)3] (5), featuring a rare azatetraphosphole ligand. Moreover, treatment of the previously reported complex [(Ar*BIAN)Co(η3:η1-P4C(O)tBu)] (2) with isothiocyanates results in P-C bond insertion, yielding [(Ar*BIAN)Co(η3:η1-P4C(S)N(R)C(O)tBu)] (6a,b; R = Cy, Ph).

N,N'-Diaryl-Sulfurdiimides are Strongly Redox Tuned.

The synthesis and extensive characterization of nine aryl sulfur diimides (SDIs, Ar-NSN-Ar) are presented with a robust computational and experimental investigation of the fundamental properties of these important members of the thiazyl family of compounds, with particular attention paid to their highly tunable electrochemical behaviour. This is the first work to undertake a systematic comparison of the electrochemical profiles of a coherent series of SDIs to demonstrate and quantify the response of their reduction potentials to substituent electron-donating and -withdrawing properties. This effect is found to be not only exceptionally strong, but also correlates very closely with computed orbital energies. Electron paramagnetic resonance spectroscopy is used to determine the nature, localization, and qualitative lifetimes of the radical anions of SDIs. This work also addresses significant misconceptions about physical properties of SDIs. Experimental data and modern computational methods are employed to provide a resolute answer to the long-standing contention of the solution-state conformations of SDIs, and to correct historical mistakes in the assignment of infrared spectroscopic data. High-quality crystal structures of all SDIs in this work showcase the utility of the recently introduced structural refinement software NoSpherA2, enabling full anisotropic refinement of H-atoms with accurate C-H bond lengths.

Cycloadditions of Donor–Acceptor Cyclopropanes and ‐butanes using S=N‐Containing Reagents: Access to Cyclic Sulfinamides, Sulfonamides, and Sulfinamidines

AbstractWe present (3+2)‐ and (4+2)‐cycloadditions of donor–acceptor (D–A) cyclopropanes and cyclobutanes with N‐sulfinylamines and a sulfur diimide, along with a one‐pot, two‐step strategy for the formal insertion of HNSO2 into D–A cyclopropanes. These are rare examples of cycloadditions with D–A cyclopropanes and cyclobutanes whereby the 2π component consists of two different heteroatoms, thus leading to five‐ and six‐membered rings containing adjacent heteroatoms.

Cycloadditions of Donor-Acceptor Cyclopropanes and -butanes using S=N-Containing Reagents: Access to Cyclic Sulfinamides, Sulfonamides, and Sulfinamidines.

We present (3+2)‐ and (4+2)‐cycloadditions of donor–acceptor (D–A) cyclopropanes and cyclobutanes with N‐sulfinylamines and a sulfur diimide, along with a one‐pot, two‐step strategy for the formal insertion of HNSO2 into D–A cyclopropanes. These are rare examples of cycloadditions with D–A cyclopropanes and cyclobutanes whereby the 2π component consists of two different heteroatoms, thus leading to five‐ and six‐membered rings containing adjacent heteroatoms.

The reactions of N-trimethylsilyl substituted ethers of α- and β-amino acids with sulfur tetrafluoride and morpholinosulfur trifluoride

ABSTRACT The reactions of N-trimethylsilyl derivatives of α- and β-amino acid esters with sulfur tetrafluoride lead to the formation of the corresponding difluorides of imidosulfurous acids F2S=N-X (X = α or β-amino acid residue). The reaction products of difluorides with N-trimethylsilylmorpholine are ketimines or aldimines of new types, containing an imine fragment =N-S-NR2 at the α- or β-carbon atom of the amino acid. The reactions of difluorides F2S=N-X with N-trimethylsilyl esters of α- and β-amino acids lead to the formation previously unknown derivatives of sulfur diimides with amino acid residues at the nitrogen atoms of the group -N=S=N-.

Oxidative Coupling with S–N Bond Formation

Oxidative strategies are a powerful tool in organic synthesis for the formation of heteroatom–heteroatom, carbon–heteroatom, and carbon–carbon bonds. Among these processes the reactions of oxidative S–N bond formation deserve considerable interest as convenient, effective, and environmentally friendly alternatives to existing methods for the synthesis of a great variety of organic compounds widely used in organic and medicinal chemistry. These transformations take place through the interaction of S‐ and N‐reagents and an oxidant, by radical or ionic mechanisms. Sulfinic acids and their salts, thiols, sulfonyl hydrazides, and thiosulfonates are generally used as S‐reagents; aliphatic and aromatic amines are usually applied as N‐reagents. The role of the oxidant mostly lies in the oxidation of the S‐reagent, after which the formed active species reacts with the N‐reagent to result in the S–N coupling product. There are two versions of oxidative S–N coupling processes: the intermolecular variant opens simple pathways to sulfen‐, sulfin‐, and sulfonamides, sulfenyl‐ and sulfoximines, sulfanes, and sulfur diimides, whereas the intramolecular one leads to the formation of various heterocycles. Of the major problems associated with successful performance of oxidative S–N coupling reactions, the first relates to the search for coupling partners that will work together to form a new bond under oxidative conditions. The second is the choice of a suitable oxidative system that will not overoxidize starting compounds. That is why mild oxidants, such as hypervalent iodine compounds and copper salts and complexes, are generally applied in these processes. This is the first exhaustive review relating to achievements in oxidative transformations involving S–N bond formation. It summarizes 134 references, mainly from 2000 to 2018, and is divided into chapters according to the classes of compounds synthesized.

Reactions of [(dpp-Bian)Ln(dme)2] (Ln = Eu, Yb) with some oxidants

Europium and ytterbium complexes [(dpp-Bian)Ln(dme)2] (Ln=Eu (1), Yb(2), dme=1,2-dimethoxyethane) with redox-active dianionic 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene ligand (dpp-Bian) have been tested in the reactions with nitrous oxide and sulfur. The reactions performed in 1:1M ratio afford quantitatively neutral dpp-Bian, while the use of a half equivalent of oxidants leads to the europium complex with two radical-anionic dpp-Bian ligands [(dpp-Bian)2Eu(dme)] (3) and the known ytterbium ionic compound [(dpp-Bian)2Yb]−[(dpp-Bian)Yb(dme)2]+ (4). The same products have been produced by the treatment of 1 and 2 with dpp-Bian. The oxidation of 1 and 2 with either sulfur dioxide or sulfur diimide (Me3SiN=)2S proceeds with the total release of the neutral dpp-Bian. DFT calculations performed for 1 and 2 show pure ligand nature of the frontier molecular orbitals in both cases.

Copper‐Catalyzed Aminothiolation of 1,3‐Dienes via a Dihydrothiazine Intermediate

AbstractHeteroatom‐containing organic molecules are of particular interest to medicinal chemists and materials scientists. A strategy to reach these architectures via direct difunctionalization of abundant 1,3‐dienes is especially attractive. Herein, we describe the development of a regio‐ and diastereoselective 1,4‐aminothiolation of 1,3‐dienes with a sulfur diimide reagent, a copper catalyst, and alkyl Grignard reagents. This unique protocol provides remote nitrogen and sulfur functionalities with high levels of stereocontrol. The reaction proceeds via a tandem hetero‐Diels–Alder cycloaddition of N,N′‐bis(benzenesulfonyl)sulfur diimide with 1,3‐diene followed by copper‐catalyzed Grignard substitution. Mechanistic studies support a copper catalyzed formation of an unprecedented [10‐S‐4] sulfurane that reductively eliminates to afford a 3,6‐dihydrothiazine, which is selectively converted to 1,4‐aminothiols.

Frontispiece: The First Lanthanide Complexes with a Redox‐Active Sulfur Diimide Ligand: Synthesis and Characterization of [LnCp*2(RN=)2S], Ln=Sm, Eu, Yb; R=SiMe3

Frontispiece: The First Lanthanide Complexes with a Redox‐Active Sulfur Diimide Ligand: Synthesis and Characterization of [LnCp*₂(RN=)₂S], Ln=Sm, Eu, Yb; R=SiMe₃

The First Lanthanide Complexes with a Redox-Active Sulfur Diimide Ligand: Synthesis and Characterization of [LnCp*2 (RN=)2 S], Ln=Sm, Eu, Yb; R=SiMe3.

The first lanthanide complexes with a redox-active sulfur diimide ligand, [LnCp*2 (Me3 SiN=)2 S] (Ln=Sm, Eu, Yb; Cp*=η5 -C5 Me5 ), are reported. The complexes were synthesized by using [LnCp*2 (THF)2 ] and (Me3 SiN=)2 S and have been thoroughly characterized by single-crystal X-ray diffraction, EPR spectroscopy, UV/Vis/NIR electronic absorption spectroscopy and SQUID magnetometry. The results, as interpreted by CASSCF/SOC-RASSI calculations providing a non-perturbative treatment of spin-orbit coupling, indicate that these paramagnetic complexes are best described as Ln3+ and [(Me3 SiN=)2 S]-. adducts. As such, these complexes contain the first isolated and structurally characterized acyclic [(RN=)2 S]-. radical anions.

The structure of the first stable monosubstituted sulfur diimide.

The title compound, 4-(4-methylphenyl)-1,3-diaza-2,4-dithiabuta-1,2-diene, C7H8N2S2, was the first example of a stable monosubstituted sulfur diimide to be documented [Jones (1988). PhD thesis, Imperial College, University of London, England]. Although a partial description of this structure was published previously, the full details are presented here. This allows a detailed comparison against the only other example of this system published to date, highlighting differences in bonding, conformation and packing.

Se-N chemistry: Revisiting an old molecule in the design of novel compounds

Chalcogenide chemistry is rich and diverse: The large variety of molecular sulfur and selenium compounds can be ascribed to their multiple stable oxidation states and large radius enabling high coordination. Sulfur-nitrogen chemistry is thoroughly explored and well-understood; polyimido sulfur species S(NR)n with charge m- (n = 2, 3, 4; m = 0, 2) are analogues of SOn molecules (with charge: m-) in which oxygen has been replaced by isovalent NR imido groups [1]. These compounds have been studied in depth and have been demonstrated to be versatile ligand systems which form multifaceted potentially catalytic metal complexes and compounds with lithium organics [2]. Selenium-nitrogen chemistry is comparatively less developed than sulfur-nitrogen chemistry despite of significant contributions to the field [3]. This may be ascribed to the rich redox chemistry of selenium in addition to its ability to polymerize, unfortunately none of these properties are easily controlled. A crucial parameter in the development of sulfur-nitrogen chemistry is attributed to the access to sulfur diimides S(NR)2 and sulfur triimides S(NR)3. Therefore, our starting point in exploring new directions of selenium-nitrogen chemistry was to revisit Se(NtBu)2 (tBu = tertbutyl), which has been used as ligand for metal complexes, but also discussed in large detail with respect to structural geometry and stability. Herein, we are presenting a study of selenium-nitrogen chemistry based on Se(NtBu)2.

Synthesis and Oligomerization of Cyclodiphosph(V)azene Adducts

AbstractThe reaction of R1R2PCl (R1 = Me, Ph; R2 = Ph, oTol) with N,N′‐bis(trimethylsilyl)sulfur diimide in the presence of GaCl3 yields Lewis acid/base adducts of the corresponding cyclodiphosph(V)azenes: [MePhPN]2·(GaCl3)2, [Me(dmp)PN]2·(GaCl3)2 (dmp = 2,6‐dimethylphenyl), and [Ph(oTol)PN]2·(GaCl3)2. The same synthetic protocol was applied for the model compound Ph2AsCl. All isolated products were characterized spectroscopically and by single‐crystal X‐ray diffraction studies. Their ability to form oligomers/polymers induced by abstraction of the Lewis acid was investigated with the model compounds [MePhPN]2·(GaCl3)2 and [Ph2PN]2·(GaCl3)2.

ChemInform Abstract: Rapid and Effective Synthesis of Diarylsulfur Diimides from Substituted Anilines and Sulfur Monochloride.

AbstractThe proposed intermediate (III) can be isolated at lower temperature and independently converted to sulfur diimides under similar conditions.

ChemInform Abstract: Polyimido Sulfur Anions and Ylides

AbstractReview: 127 refs.

Polyimido sulfur anions and ylides

Isovalent electronic replacement of the oxygen atoms in the classic SO(n)(m-) molecules and ions by NR imido groups yields the polyimido sulfur species S(NR)(n)(m-), n = 2, 3, 4 and m = 0, 2. The crucial cornerstone to the richness of SN chemistry is the access to sulfur diimides S(NR)(2) and triimides S(NR)(3). While the syntheses of the first are well established the preparations of the second were hazardous and of poor yields. A new facile, safe and elaborated route to give quantitative yields is presented. It involves the synthesis of triimido sulfites S(NR)(3)(2-), which are versatile ligands in their own right. With a trigonal pyramidal shape, containing three basal negatively charged nitrogen atoms, they are rare examples of dianionic tripodal ligands. Various (mixed) metal complexes are presented. Lithium coordination at the N-S-N bisections converts the dianion into the inverse tripod ligand Li(3)(NR)(3)S(+), capable of anion solvation. Among others, this motif stabilizes unprecedented monomeric methyllithium and lithium enolate. In the reaction of sulfur diimides S(NR)(2) and triimides S(NR)(3) with organometallics the diimidosulfinates RS(NR)(2)(-) and triimidosulfonates RS(NR)(3)(-) are synthesised. Both display a rich coordination chemistry to various metals, which is discussed in the review. Furthermore, the S-organo substituent can be modified in various ways. It can be a linker between two SN moieties or can be shaped to a R(2)N- or R(2)P-donating side arm of any form or length to give hemilabile scorpionates. Their ample application in metal coordination and anion solvation is presented. These monoanions can be converted to the related ylides by deprotonation of the S-alkyl group. The diimidosulfur(IV) ylides (R(2)C)S(NR)(2)(2-) and triimidosulfur(VI) ylides (R(2)C)S(NR)(3)(2-) contain the CR(2) methylene group, isoelectronic to the NR imido group. Their coordination behaviour and reactivity are discussed. In addition to the rich SN chemistry the S-N and S-C bonding is elucidated by means of theoretical and experimental charge density investigations and topological analyses on the basis of multipole refinement. As the most important result hypervalency at sulfur and S=N(C) double bonding are ruled out as superfluous concepts.

Stitching together SNx units in the coordination sphere of zirconium: assembly of a tris(imido)sulfite and a hydrazidobis(imido)sulfite

Reaction of a zirconium imido and a hydrazinediido complex with bis(trimethylsilyl)sulfur diimide yielded the corresponding formal [2+2] cycloaddition products, the trisimidosulfito complex and the hydrazidobis(imido)sulfito complex containing an unprecedented SN(2)(N-N) unit.

Novel Multidentate Sulfur-Nitrogen Ligands with Enhanced Complexation Properties

Di(tert-butyl)sulfur diimide and bis(trimethylsilyl)sulfur diimide were reacted with different metalated amines to form versatile novel multidentate ligand systems with side-arm donation. Their complexation properties in terms of ligand design, denticity and the cation size are discussed. We report herein the synthesis and structure elucidation of [(tBuN)(2)S{LiMe(2)N(C(6)H(4))S(NtBu)(2)}(2)] (1), [(Li{Me(2)N(C(6)H(4))S(NSiMe(3))(2)})(2)] (2), [(Li(thf){Me(2)N(C(6)H(4))S(NSiMe(3))(2)})(2)] (3), [(Li{2-PicS(NSiMe(3))(2)})(2)] (4), [(Li{Me(2)N(CH(2))(2)N(Me)S(NSiMe(3))(2)})(2)] (5), [(Na{Me(2)N(CH(2))(2)N(Me)S(NSiMe(3))(2)})(2)] (6) and [(K{Me(2)N(C(6)H(4))S(NSiMe(3))(2)})(2)] (7).

Access to new Janus head ligands: linking sulfur diimides and phosphanes for hemilabile tripodal scorpionates

Reactions of lithium dialkyl/phenyl phosphanylmethylides, RR'PCH(X)Li (R, R' = Me, Et, Ph and R = Me, R' = Ph; X = H or Me), with sulfur diimides S(NR'')2 (R'' = (t)Bu or SiMe3) in an equimolar ratio yielded Janus head complexes with the structural motif [Li{RR'PCH(X)S(NR'')2}]2 (R'' = (t)Bu, SiMe3). The basic core of these dimeric complexes is composed of a (LiN)(2) four-membered ring containing two four-coordinated lithium atoms. A lithium complex of the new Janus head ligand with another structural motif [TMEDA·Li{Ph(2)PCH(2)S(NSiMe3)2}] (6) could be isolated from the reaction of [Ph2PCH2Li·TMEDA] with S(NSiMe3)2. Two monomeric complexes [Mg{Me2PCH2S(NR'')2}2] (7, 8) were synthesised by a straightforward reaction of [Li{Me2PCH2S(NR'')2}2] with MgCl2 in pentane. The magnesium atom is chelated by one phosphorus atom and two nitrogen atoms of each unit of the hemilabile ligand in a tripodal manner, leading to octahedral geometry around the magnesium cation. A complete analysis of [Ph2PCH2(SNSiMe3)(HNSiMe3)] (9) is also described in which one nitrogen atom of the imido moiety is protonated.