Sulfoxide Ligands Research Articles

Thermodynamic Resolution and Enantioselective Synthesis of C2-Symmetric Bis-sulfoxides Based on Chiral Iridium(III) Complexes.

Enantiopure Λ-[Ir(dfppy)2(MeCN)2](PF6) and Δ-[Ir(dfppy)2(MeCN)2](PF6) (where dfppy is (4,6-difluoropheny)pyridine) were demonstrated to preferentially react with (S,S)-1,2-bis(arylsulfinyl)ethane and (R,R)-1,2-bis(arylsulfinyl)ethane, respectively, under thermodynamic equilibrium. Sequential treatment of Λ-[Ir(dfppy)2(MeCN)2](PF6) and Δ-[Ir(dfppy)2(MeCN)2](PF6) with C2-symmetric bis-sulfoxides led to diastereoselective formation of the corresponding diastereomers Λ-[Ir(dfppy)2(R,R)-bis-sulfoxide)](PF6) in 90-92% and Δ-[Ir(dfppy)2(S,S)-bis-sulfoxide)](PF6) in 88-90%, respectively. The uncoordinated (R,S)-bis-sulfoxides were afforded in 45% with >97% de values. Enantiopure (S,S)-bis-sulfoxides and (R,R)-bis-sulfoxides were respectively obtained by the release of sulfoxide ligands from the corresponding complexes in the presence of glycine in yields of 20-21% with 97-99% ee values. The enantioreceptors Λ-[Ir(dfppy)2(MeCN)2](PF6) and Δ-[Ir(dfppy)2(MeCN)2](PF6) can be recycled and reused in the next reaction cycle. Moreover, a protocol for asymmetric oxidation of prochiral bis-sulfide into enantiopure C2 symmetric bis-sulfoxide was also developed in a high enantioselectivity. The absolute configurations at the metal centers and sulfur atoms were determined by X-ray crystallography.

Interaction with Blood Proteins of a Ruthenium(II) Nitrofuryl Semicarbazone Complex: Effect on the Antitumoral Activity.

The steady rise in the cancer burden and grim statistics set a vital need for new therapeutic solutions. Given their high efficiency, metallodrugs are quite appealing in cancer chemotherapy. This work examined the anticancer activity of an anti-trypanosomal ruthenium-based compound bearing the 5-nitrofuryl pharmacophore, [RuII(dmso)2(5-nitro-2-furaldehyde semicarbazone)] (abbreviated as RuNTF; dmso is the dimethyl sulfoxide ligand). The cytotoxicity of RuNTF was evaluated in vitro against ovarian adenocarcinoma, hormone-dependent breast adenocarcinoma, prostate carcinoma (grade IV) and V79 lung fibroblasts human cells. The activity of RuNTF was similar to the benchmark metallodrug cisplatin for the breast line and inactive against the prostate line and lung fibroblasts. Given the known role of serum protein binding in drug bioavailability and the distribution via blood plasma, this study assessed the interaction of RuNTF with human serum albumin (HSA) by circular dichroism (CD) and fluorescence spectroscopy. The fluorescence emission quenching from the HSA-Trp214 residue and the lifetime data upon RuNTF binding evidenced the formation of a 1:1 {RuNTF-albumin} adduct with log Ksv = (4.58 ± 0.01) and log KB = (4.55 ± 0.01). This is supported by CD data with an induced CD broad band observed at ~450 nm even after short incubation times. Importantly, the binding to either HSA or human apo-transferrin is beneficial to the cytotoxicity of the complex towards human cancer cells by enhancing the cytotoxic activity of RuNTF.

Arrangement of a NO ligand and the neighboring sulfur-containing species on a dinuclear ruthenium complex by ligand substitution and linkage isomerism of a dimethyl sulfoxide ligand

The substitution reactions of a NO-ligated dinuclear ruthenium complex with ammonium thiocyanate (NH4SCN), sulfur, and dimethyl sulfoxide (DMSO) gave the corresponding mononitrosyl dinuclear complexes, except for reaction with sulfur, where diastereomers of a S2-bridged tetranuclear complex along with a NO- and S2-bridged dinuclear complex were obtained. According to the scan rate dependent cyclic voltammograms, linkage isomerism of a dmso ligand on the dinuclear complex was revealed, and the linkage isomer was obtained from the chemical oxidation.

Chiral Sulfoxide Ligands in Asymmetric Catalysis.

Since the original idea was explored by James in 1976, the use of chiral sulfoxides as ligands with transition metals in asymmetric catalysis has undergone a long period of development. There have been many studies into their properties, design and application in various kinds of asymmetric transformations. In this article, we document the literatures on chiral sulfoxide ligands in asymmetric catalytic reactions.

Asymmetric, Nearly Barrierless C(sp3)–H Activation Promoted by Easily-AccessibleN-Protected Aminosulfoxides as New Chiral Ligands

Although chiral sulfoxides are important motifs in medicinal chemistry and asymmetric synthesis, design and applications of sulfoxide ligands are still limited, in particular in the context of asym...

Mono(2,2′‐bipyridyl)RuII Complex with Four Dimethyl Sulfoxide Ligands as Precursor for cis‐Bis‐heteroleptic RuII Complex: Syntheses, Structures, and Substitution Reactions

The dication complex trans(O,S)‐[Ru(bpy)(dmso‐O)2(dmso‐S)2](OTf)2 [1·(OTf)2; bpy = 2,2′‐bipyridyl; dmso = dimethyl sulfoxide; OTf– = CF3SO3–] was obtained from the reaction of cis(Cl),cis(S)‐[RuCl2(bpy)(dmso‐S)2] with Ag(OTf) in DMSO. The crystal structure of 1·(OTf)2 revealed two labile dmso‐O ligands and two less‐labile dmso‐S ligands positioned cis to each other. In DMSO, the equatorial dmso‐O in 12+ equilibrates with its linkage isomer dmso‐S to fac(S)‐[Ru(bpy)(dmso‐O)(dmso‐S)3]2+ [1iso2+] ([1iso2+]/[12+] = 3:97 at 298 K and 33:67 at 373 K). The linkage isomerization kinetic parameters, determined by 1H NMR, were ΔH = 22(1) kJ mol–1 and ΔS = 52(2) J mol–1 K–1. The two O‐bonded dmso ligands of 1·(OTf)2 were easily solvolyzed in MeCN to form trans(NMeCN,S)‐[Ru(bpy)(MeCN)2(dmso‐S)2](OTf)2 [2·(OTf)2]. Moreover, the reaction of 1·(OTf)2 with 1,10‐phenanthroline (phen) in acetone afforded cis‐[Ru(bpy)(phen)(dmso‐S)2](OTf)2 [3·(OTf)2] in very good yield (95 %) and excellent purity.

Spectral study of the reactions of dimethyl sulfoxide with the nitrite complexes of Co-porphyrins

It is revealed by FTIR and electron absorption spectroscopy that the reactions of dimethyl sulfoxide with the nitro complexes of Co-porphyrins both in the solid phase and an inert solvent afford six-coordinate complexes with the general formula (DMSO)Со(Por)(NO2) (Por is meso-tetraphenyl- and meso-tetra-p-tolylporphyrinato dianions). These compounds are stable in the solid state, whereas they partially decompose in an inert solvent to form five- and six-coordinate complexes. The ambident nitrite and dimethyl sulfoxide ligands are coordinated to the metal atom through the N and O atoms, respectively, which was confirmed by the application of isotope-containing compounds 15NO2 and DMSO-d6.

Linkage Photoisomerization of an Isolated Ruthenium Sulfoxide Complex: Sequential versus Concerted Rearrangement.

Ruthenium sulfoxide complexes undergo thermally reversible linkage isomerization of sulfoxide ligands from S- to O-bound in response to light. Here, we report photoisomerization action spectra for a ruthenium bis-sulfoxide molecular photoswitch, [Ru(bpy)2(bpSO)]2+, providing the first direct evidence for photoisomerization of a transition metal complex in the gas phase. The linkage isomers are separated and isolated in a tandem drift tube ion mobility spectrometer and exposed to tunable laser radiation provoking photoisomerization. Direct switching of the S,S-isomer to the O,O-isomer following absorption of a single photon is the predominant isomerization pathway in the gas phase, unlike in solution, where stepwise isomerization is observed with each sulfoxide ligand switching in turn. The change in isomerization dynamics is attributed to rapid vibrational quenching that suppresses isomerization in solution. Supporting electronic structure calculations predict the wavelengths and intensities of the peaks in the photoisomerization action spectra of the S,S- and S,O-isomers, indicating that they correspond to metal-to-ligand charge transfer (MLCT) and ligand-centered ππ* transitions.

Photo-induced linkage isomerization in the gas phase probed by tandem ion mobility and laser spectroscopy.

Ruthenium complexes involving sulfoxide ligands can undergo linkage isomerization upon light absorption, accompanied by dramatic changes in their optical properties. These remarkable photochromic properties are sensitive to the nature of the ligand as well as to that of the solvent. We used tandem ion mobility spectrometry coupled to mass spectrometry to gain direct experimental insight into the isomerization pathways connecting the different linkage isomers of an isolated ruthenium complex with two dimethyl-sulfoxide ligands. We find that the isomerization behavior of the solvent-free complex differs from that previously reported in the solution-phase, which is in line with recent theoretical predictions.

Solubility of salts of d-elements in organic and water-organic solvents: V. Inner-sphere chalcogen S–S contacts in the [Ni(DMSO)4(H2O)2]Cl2 solvate

It was proved by the IR spectroscopy that the first coordination sphere of nickel cations in the NiCl2·2DMSO·9H2O, NiCl2·5DMSO·4H2O, and NiCl2·4DMSO·2H2O compounds contains dimethyl sulfoxide and water ligands. According to X-ray structural analysis, in crystals of the NiCl2·4DMSO·2H2O compound, noncovalent contacts between sulfur atoms of neighboring dimethyl sulfoxide molecules are realized in the inner sphere of the complex.

Bis(3,5-dimeth-oxy-2-{[2-(pyridin-2-yl)ethyl-imino-κN]-meth-yl}phenolato-κO)bis-(dimethyl sulfoxide)-manganese(III) perchlorate methanol 0.774-solvate.

The title compound, [Mn(C16H17N2O3)2(C2H6OS)2]ClO4·0.774CH3OH, comprises a central octa-hedrally coordinated MnIII cation, with two bidentate Schiff base ligands occupying the equatorial positions and two dimethyl sulfoxide (DMSO) ligands occupying the axial positions. There are two independant cations in the asymmetric unit, with the MnIII atoms of both cations being positioned on crystallographic centers of inversion. The perchlorate anion is disordered over two equivalent conformations, with occupancies of 0.744 (3) and 0.226 (3). In addition, there is a methanol solvent mol-ecule in the crystal lattice that is too close to the minor component of the perchlorate anion to be present simultaneously and thus it was refined to have the same occupancy as the major component of this anion. There is a Jahn-Teller distortion which results in Mn-ODMSO axial bond lengths of 2.2365 (12) and 2.2368 (12) Å in the two cations. In the crystal, inter-molecular π-π stacking between the non-coordinating pyridine rings of each cation is observed. This π-π stacking, along with extensive O-H⋯O hydrogen bonding and C-H⋯O inter-actions, link the components into a complex three-dimensional array.

Reactions of silicon hydrides catalyzed by rhodium(III) sulfoxide complexes

Dehydrocondensation reactions of silicon hydrides catalyzed by the rhodium(III) complex [RhCl3(Me2SO)3] in the absence of the second substrate were studied. It was found that the complex [RhCl3(Me2SO)3] catalyzed the dehydrocondensation reaction with the formation of compounds containing siloxane bonds. Analysis of NMR spectra has shown that the reaction of [RhCl3(Me2SO)3] with silicon hydride includes sequential desoxygenation of sulfoxide ligands to sulfide ligands with the complex [RhCl3(Me2S)3] formation.

Luminescent Eu3+–dibenzoylmethanate complex with sulfoxide ligand as sensitizer applied to organic light- emitting diodes

In this work the synthesis, characterization and photoluminescent and electroluminescent behavior of the [Eu(DBM)₃(PTSO)₂] complex have been investigated. The emission spectrum of this Eu³⁺–β– diketonate complex show characteristics narrow bands arising from the ⁵D₀→⁷Fȷ (J = 0–4) transitions, which are split according to the selection rule for Cs, Cn or Cnv site symmetries. Triple and doublelayer organic light-emitting diodes (OLEDs) using NPB as hole transporting layer, Alq₃ as electron transporting layer and [Eu(DBM)₃(PTSO)₂] complex as emitting and electron transporting layer were grown and characterized. We found the presence of two concurrent mechanisms for the electroluminescent behavior: (1) the electroluminescence (EL) from the exciton-ligand-Eu³+ ion energy transfer, responsible for the EL narrow bands; and (2) the molecular electrophosphorescence with an initial energy transfer exciton-ligand and posterior intersystem crossing from the excited singlet S₁ to the triplet T state followed by molecular phosphorescence (T→S₀). The electroluminescent behavior of [Eu(DBM)₃(PTSO)₂] complex suggest that this complex is promising to applied at Light Conversion Molecular Devices (LCMDs) such as in OLED devices.

Синтез и строение комплекса родия [trans-Na∙18-crown-6∙(dmso-O)2]+ [trans-RhBr4(dmso-S)2

Шарутин Владимир Викторович – доктор химических наук, профессор, старший научный сотрудник УНИД, Южно-Уральский государственный университет. 454080, г. Челябинск, пр. им. В.И. Ленина, 76. E-mail: vvsharutin@rambler.ru. Шарутина Ольга Константиновна – доктор химических наук, профессор, кафедра теоретической и прикладной химии, Южно-Уральский государственный университет. 454080, г. Челябинск, пр. им. В.И. Ленина, 76. E-mail: sharutinao@mail.ru. Сенчурин Владислав Станиславович – кандидат химических наук, доцент, кафедра теоретической и прикладной химии, Южно-Уральский государственный университет. 454080, г. Челябинск, пр. им. В.И. Ленина, 76. E-mail: senvl@rambler.ru Сонникова Екатерина Сергеевна – студент, химический факультет, Южно-Уральский государственный университет. 454080, г. Челябинск, пр. им. В.И. Ленина, 76. E-mail: katerina_sonnikova@mail.ru V.V. Sharutin, vvsharutin@rambler.ru O.K. Sharutina, sharutinao@mail.ru V.S. Senchurin, senvl@rambler.ru E.S. Sonnikova, katerina_sonnikova@mail.ru South Ural State University, Chelyabinsk, Russian Federation

Synthesis and structure of the rhodium complex [p-Tol4Sb(DMSO-O)] 2 + [trans-RhBr4(DMSO-S)2]–[cis-RhBr4(DMSO-S)2

The complex [p-(Tol)4Sb(DMSO-O)2+[trans-RhBr4(DMSO-S)2]–[cis-RhBr4(DMSO-S)2]– (CIF file CCDC no. 1415243) was synthesized by the reaction of sodium hexabromorhodate with tetra(para-tolyl) stibonium bromide in DMSO and studied by X-ray diffraction. The antimony atoms in two types of crystallographically independent [p-Tol4Sb(DMSO-O)]+ cations have a distorted trigonal-bipyramidal coordination with axially arranged DMSO oxygen atoms (Sb–C, 2.088(9)–2.135(10) A; Sb∙∙∙O, 2.641(10), 2.690(10) A). In the octahedral [trans-RhBr4(DMSO-S)2]– and [cis-RhBr4(DMSO-S)2]– anions, the dimethyl sulfoxide ligands are coordinated to the metal via the sulfur atoms. The Rh–S distances are longer in the trans-isomer (2.333(2), 2.339(2) A) than in the cis-isomer (2.303(3), 2.318(4) A).

ChemInform Abstract: Rhodium‐Catalyzed Asymmetric Arylation of N‐ and O‐Containing Cyclic Aldimines: Facile and Efficient Access to Highly Optically Active 3,4‐Dihydrobenzo[1,4]oxazin‐2‐ones and Dihydroquinoxalinones.

AbstractFor the first time, a highly enantioselective rhodium‐catalyzed arylation of benzoxazinones and quinoxalinones is realized by employing an unsaturated chiral sulfoxide ligand.

Ruthenium(II) DMSO complexes with CˆC* cyclometalated phenylimidazol NHC ligands

We present the synthesis of cyclometalated ruthenium N-heterocyclic carbene (NHC) complexes of the general formula [Ru(CˆC*)(DMSO)3Cl] and their use as starting material for the synthesis of a heteroleptic 2,2′-bipyridine (bpy) complex [Ru(bpy)(CˆC*)(DMSO)Cl]. Starting from the corresponding η6-(p-cymene) complexes [Ru(p-cymene)(CˆC*)Cl], the π-coordinated aryl ligand is substituted by three S-bound dimethyl sulfoxide ligands. In the course of this substitution, the complexes undergo a change in geometry from facial to meridional, which is unambiguously proven by solid state structure determination and DFT calculations. The labile DMSO ligands can be substituted by bidentate ligands as shown for the widely used 2,2′-bipyridine. The resulting air- and moisture-stable heteroleptic complex features two bidentate (CˆC* + bpy) and two monodentate (Cl− + DMSO) ligands.

A novel capped Pd nano-particle GC–MS technique for the identification of terpenoid sulfoxides in petroleum condensates

Capped palladium (Pd) nano-particle column chromatography was first used to separate a novel series of high molecular weight terpenoid sulfoxides (HMTSs) from petroleum condensate oil within the heterocyclic polyaromatic sulfur compound (S-PAH) fraction. The separation technique was based on complex formation between nano-sized heavy charged Pd2+ ions and sulfoxide ligands. HMTSs were identified by interpretation of GC–MS fragmentation patterns. The infrared spectra of the pre-isolated S-PAH fraction confirmed the presence of sulfoxide groups with an absorption band at 1264cm−1. The novel HMTS series included three members with the general formula C20H34OSR (main compound C25H44OS). The mass spectra of these three compounds were characterized by a major fragment ion at m/z 322. We identified a relationship between oil emergence and HTMS structure, indicating a base cross-linked macromolecular structure for the tested petroleum condensates and volatile oils. Atomic emission detection (AED) was unable to detect HMTS in spite of its sulfur atoms, most likely due to the high carbon to sulfur atom ratio producing quenching.

ChemInform Abstract: C—H Coupling Reactions Directed by Sulfoxides: Teaching an Old Functional Group New Tricks

AbstractReview: [62 refs.

C-H Coupling Reactions Directed by Sulfoxides: Teaching an Old Functional Group New Tricks.

Sulfoxides are classical functional groups for directing the stoichiometric metalation and functionalization of C-H bonds. In recent times, sulfoxides have been given a new lease on life owing to the development of modern synthetic methods that have arisen because of their unique reactivity. They have recently been used in catalytic C-H activation proceeding via coordination of an internal sulfoxide to a metal or through the action of an external sulfoxide ligand. Furthermore, sulfoxides are able to capture nucleophiles and electrophiles to give sulfonium salts, which subsequently enable the formation of C-C bonds at the expense of C-H bonds. This Review summarizes a renaissance period in the application of sulfoxides arising from their versatility in directing C-H functionalization.