597-50-2Relevant academic research and scientific papers
Lewis Acidic Boranes, Lewis Bases, and Equilibrium Constants: A Reliable Scaffold for a Quantitative Lewis Acidity/Basicity Scale
Mayer, Robert J.,Hampel, Nathalie,Ofial, Armin R.
supporting information, p. 4070 - 4080 (2021/01/29)
A quantitative Lewis acidity/basicity scale toward boron-centered Lewis acids has been developed based on a set of 90 experimental equilibrium constants for the reactions of triarylboranes with various O-, N-, S-, and P-centered Lewis bases in dichloromethane at 20 °C. Analysis with the linear free energy relationship log KB=LAB+LBB allows equilibrium constants, KB, to be calculated for any type of borane/Lewis base combination through the sum of two descriptors, one for Lewis acidity (LAB) and one for Lewis basicity (LBB). The resulting Lewis acidity/basicity scale is independent of fixed reference acids/bases and valid for various types of trivalent boron-centered Lewis acids. It is demonstrated that the newly developed Lewis acidity/basicity scale is easily extendable through linear relationships with quantum-chemically calculated or common physical–organic descriptors and known thermodynamic data (ΔH (Formula presented.)). Furthermore, this experimental platform can be utilized for the rational development of borane-catalyzed reactions.
Rotation-Triggered Transmetalation on a Heterobimetallic Cu/Al N-Phosphine-Oxide-Substituted Imidazolylidene Complex
Asada, Takahiro,Hoshimoto, Yoichi,Ogoshi, Sensuke
supporting information, p. 9772 - 9784 (2020/07/10)
A novel strategy for the preparation of heterobimetallic N-heterocyclic carbene (NHC) complexes is demonstrated using N-phosphine-oxide-substituted imidazolylidenes (PoxIms). In these heterobimetallic Cu/Al complexes, the Cu and Al centers can be either completely separated or brought near each other via the rotation of the N-phosphinoyl group in the PoxIm ligands. Triggered by this rotation, transmetalation to exchange the Cu-OtBu and Al-C6F5 bonds occurs on in situ-generated Cu/Al PoxIm complexes, and the Cu-C6F5 and Al-OtBu bonds are formed in excellent yield. On the basis of the results of mechanistic studies, including the isolation/in situ observation of key complexes and theoretical calculations, a plausible reaction mechanism for an intramolecular transmetalation is proposed to proceed via an activation complex that includes the simultaneous coordination of the phosphinoyl oxygen atom to the Cu as well as the Al centers. Furthermore, the formation of carbon-carbon bonds between Al(C6F5)3 and allyl bromide mediated/catalyzed by Cu/Al PoxIm complexes is demonstrated. Upon the consecutive transfer of three C6F5 groups from a single molecule of Al(C6F5)3, allyl pentafluorobenzene derivatives were obtained. The present results demonstrate the role of phosphine oxide in the activation of organoaluminum reagents for the transmetalation between Cu(I) complexes bearing NHCs as well as the benefit of constructing an intramolecular system based on a heterobimetallic complex to achieve efficient transmetalation by programming the encounter of two organometallic fragments.
Reactivity of auranofin with selenols and thiols - Implications for the anticancer activity of gold(I) compounds
Di Sarra, Francesca,Fresch, Barbara,Bini, Riccardo,Saielli, Giacomo,Bagno, Alessandro
, p. 2718 - 2727 (2013/07/11)
The enzyme thioredoxin reductase (TrxR) is attracting much interest as a potential target for cancer therapy. The presence of a selenium atom in the catalytic site makes it sensitive to inhibition by electrophilic molecules, including the AuI complex auranofin [2,3,4,6-tetra-O-acetyl-1-thio- β-D-glucopyranosato-S-(triethylphosphane)gold]. The reactions between auranofin and models of thiol and selenol nucleophiles present in TrxR (PhSH and PhSeH) have been investigated in chloroform and methanol by means of 1H, 31P, and 77Se NMR spectroscopy. In chloroform, auranofin undergoes ligand substitution of the tetraacetylthioglucose moiety by a PhS or PhSe group. The reaction is reversible in both cases, but it is characterized by widely different equilibrium constants (ca. 1 for S and at least 103 for Se). In polar solvents, such as methanol, the reaction is more complex, and the phosphane moiety also undergoes ligand exchange. Some features have been clarified through the investigation of Et3PAuCl. The elementary processes involved have been characterized by DFT calculations. Copyright
Seleno-auranofin (Et3PAuSe-tagl): Synthesis, spectroscopic (EXAFS, 197Au Moessbauer, 31P, 1H, 13C, and 77Se NMR, ESI-MS) characterization, biological activity, and rapid serum albumin-induced triethylphosphine oxide generation
Hill, David T.,Isab, Anvarhusein A.,Griswold, Don E.,Dimartino, Michael J.,Matz, Elizabeth D.,Figueroa, Angel L.,Wawro, Joyce E.,Debrosse, Charles,Reiff, William M.,Elder, Richard C.,Jones, Benjamin,Webb, James W.,Shaw, C. Frank
scheme or table, p. 7663 - 7675 (2010/11/19)
Seleno-auranofin (SeAF), an analogue of auranofin (AF), the orally active antiarthritic gold drug in clinical use, was synthesized and has been characterized by an array of physical techniques and biological assays. The Moessbauer and extended X-ray absorption fine structure (EXAFS) parameters of the solid compound demonstrate a linear P-Au-Se coordination environment at a gold(I) center, analogous to the structure of auranofin. The 31P, 13C, and 1H NMR spectra of SeAF in chloroform solution closely resemble those of auranofin. The 77Se spectrum consists of a singlet at 481 ppm, consistent with a metal-bound selenolate ligand. The absence of 2JPSe coupling in the 31P and 77Se spectra may arise from dynamic processes occurring in solution or because the 2JPSe coupling constants are smaller than the observed bandwidths. Electrospray ionization mass spectrometry (ESI-MS) spectra of SeAF in 50:50 methanol-water exhibited strong signals for [(Et 3P)2Au]+, [(Et3PAu) 2-μ-Se-tagl]+, and [Au(Se-tagl)2] -, which arise from ligand scrambling reactions. Three assays of the anti-inflammatory activity of SeAF allowed comparison to AF. SeAF exhibited comparable activity in the topically administered murine arachadonic acid-induced and phorbol ester-induced anti-inflammatory assays but was inactive in the orally administered carragenan-induced assay in rats. However, in vivo serum gold levels were comparable in the rat, suggesting that differences between the in vivo metabolism of the two compounds, leading to differences in transport to the inflamed site, may account for the differential activity in the carrageenan-induced assay. Reactions of serum albumin, the principal transport protein of gold in the serum, demonstrated formation of AlbSAuPEt3 at cysteine 34 and provided evidence for facile reduction of disulfide bonds at cysteine 34 and very rapid formation of Et3P=O, a known metabolite of auranofin.
Reactions of elemental phosphorus and phosphines with electrophiles in superbasic systems: XII. Synthesis of unsymmetrical tertiary phosphine oxides from red phosphorus and organyl halides
Gusarova,Shaikhudinova,Ivanova,Reutskaya,Albanov,Trofimov
, p. 718 - 720 (2007/10/03)
Alkyldibenzyl- and benzyldialkylphosphine oxides were prepared in one stage by direct phosphorylation of a mixture of alkyl bromides and benzyl chloride with red phosphorus under the conditions of phase-transfer catalysis (concentrated aqueous KOH solution-dioxane-benzyltriethylammonium chloride).
Solvolysis of phosphonium compounds containing a thiophenoxy group linked to phosphorus
Aksnes, Gunnar
, p. 43 - 50 (2007/10/03)
A kinetic study of the solvolysis of six alkylphenyl thiophenoxyphosphonium chlorides in 50% water/ methanol is reported. The rates of solvolysis, where thiophenol and phosphine oxides are formed, are little influenced by the substituents linked to phosphorus. The present findings are in sharp contrast to the 104 higher rate of the alkaline decomposition of tetraphenyl as compared to trialkylphenyl phosphonium salts, where phenyl is the leaving group. Further, the rate of solvolysis of the cyclic phenyl thiophenoxyphospholanium salt, is nearly identical to the rate of the corresponding dialkylphenyl thiophenoxyphosphonium compound. Calculation of the activation parameters of the solvolysis of thiophenoxyphosphonium compounds shows that the underlying reaction forces, expressed as activation energies and entropies, are strongly influenced by the substituents. The results suggest that the thiophenoxy group is expelled from the pentacovalent, trigonal bipyramidal reaction intermediate, before pseudorotation of the substituents linked to phosphorus takes place.
Stepwise metal-assisted conversion of η2-CSe2 to η1-Se2CPEt3, η2-Se2CO, and η2-Se2. Crystal structures of the complexes [(triphos)Rh(Se2CO)]BPh4·0.5CH2Cl 2·0.5C4H9OH ...
Bianchini, Claudio,Masi, Dante,Mealli, Carlo,Meli, Andrea,Sabat, Michal,Vizza, Francesco
, p. 3716 - 3721 (2008/10/08)
Full title: Stepwise metal-assisted conversion of η2-CSe2 to η1-Se2CPEt3, η2-Se2CO, and η2-Se2. Crystal structures of the complexes [(triphos)Rh(Se2CO)]BPh4·0.5CH2Cl 2·0.5C4H9OH and [(triphos)Rh(μ-Se2)2Rh(triphos)](BPh4) 2·2DMF [triphos = MeC(CH2PPh2)3]. The reaction of (triphos)RhCl(η2-CSe2) (1) in CH2Cl2 with PEt3 gives the phosphoniodiselenoformate complex (triphos)RhCl(Se2CPEt3) (2). Compound 2 reacts at room temperature in CH2Cl2 solution with dioxygen to yield OPEt3 and (triphos)-RhCl(Se2CO) (3). The chloride ligand can be removed from 3 in CH2Cl2 by NaBPh4 in 1-butanol to give the 16-electron complex [(triphos)Rh(Se2CO)]BPh4·0.5CH2Cl 2·0.5C4H9OH (4), which photochemically or thermally undergoes the chelotropic elimination of CO to form the bis(μ-diselenium) complex [(triphos)Rh(μ-Se2)2Rh(triphos)](BPh4) 2·2DMF (5b). The crystal structures of 4 and 5b have been determined by X-ray crystallography. 4 crystallizes in the triclinic system, space group P1, with a = 18.853 (6) A?, b = 16.744 (5) A?, c = 11.021 (3) A?, α = 69.45 (2)°, β = 81.23 (2)°, γ = 77.35 (2)°, and Z = 2. The structure was refined to an R factor of 0.071 (Rw, = 0.072) for 4093 unique reflections. The structure consists of monomeric complex cations [triphos)Rh(Se2CO)]+, BPh4- anions, and some amount of CH2Cl2 and 1-butanol molecules of crystallization. The metal atom is five-coordinated by the three phosphorus atoms of triphos and by the two selenium atoms of the diselenocarbonate ligand in a distorted-square-pyramidal environment. 5b crystallizes, in the triclinic system, space group P1, with a = 16.950 (5) A?, b = 13.710 (4) A?, c = 13.379 (4) A?, α = 90.19 (1)°, β = 98.53 (2)°, γ = 104.03(2)°, and Z = 1. The structure was refined to a final R factor of 0.053 (Rw = 0.057) for 5458 unique reflections. The structure consists of binuclear [(triphos)Rh(μ-Se2)2Rh(triphos)]2+ cations, BPh4- anions, and DMF molecules of crystallization. The system consists of two (triphos)Rh(η2-Se2) fragments related by a crystallographic inversion center. Each rhodium atom is coordinated by the three phosphorus atoms of triphos, an η2-diselenium molecule, and one selenium atom from the other (triphos)Rh(η2-Se2) moiety.
Hexanuclear iron-sulfur basket clusters: Topological isomers of prismanes. Synthesis, structure, and reactions
Snyder, Barry S.,Holm
, p. 2339 - 2347 (2008/10/08)
The new set of cluster molecules Fe6S6(PEt3)4X2 (X = Cl- (1), Br-, I-) has been prepared by the reaction of Fe(PEt3)2X2 (2) with (i) (Me3Si)2S or Li2S in THF, (ii) the cubane clusters [Fe4S4X4]2- in acetonitrile, and (iii) the prismane clusters [Fe6S6X6]3- in acetonitrile. Also prepared by similar means were Fe6S6(PMe3)4Cl2, Fe6Se6(PEt3)4Cl2, and Fe6S6(P-n-Bu3)4Cl2 (3). The compounds were obtained as black crystalline solids, usually in purified yields of 50-65%. Precursor complex 2 (X = Br-) was isolated as pale yellow crystals with monoclinic space group Pn, a = 7.316 (1) ?, b = 12.316 (2) ?, c = 11.356 (2) ?, β = 97.15 (2)°, and Z = 2. The expected (distorted) tetrahedral structure was confirmed, with a notably open Br-Fe-Br angle (121.9 (1)°) presumably set by steric interactions. This angle is one of the largest in the tetrahedral series M(PR3)2X2, all of which thus far have X-M-X angles ≥105°; no previous structural data have been reported for type 2 complexes. Compound 3 crystallizes in tetragonal space group I41 with a = 33.78 (1) ?, c = 12.362 (7) ?, and Z = 8. It contains a [Fe6(μ2-S)(μ3-S)4(μ 4-S)]2+ core, formally including 2 Fe(III) + 4 Fe(II), and is built by the fusion of six nonplanar Fe2S2 rhombs to form an open basket with a bridging group Fe-(μ2-S)-Fe of bond angle 75.5° as the handle . The core has idealized C2v symmetry with the 2-fold axis containing the μ2-S and μ4-S atoms. Each Fe atom is four-coordinate; the two FeS3Cl sites have trigonally distorted tetrahedral geometry whereas the four FeS3P sites resemble very distorted trigonal pyramids with the Fe atoms only ca. 0.11 ? above the S3 planes and expanded S-Fe-S angles, one at each site (mean 127.5°), which form edges of the basket and handle in the form of two chairlike Fe3S3 rings or open faces . A simple conceptual relationship among 6-Fe core structures is presented as a scheme wherein different cores are transformed by formal addition (or subtraction) of Fe and S atoms. Arguments based on electrochemical properties are provided to show that basket and prismane ([Fe6(μ3-S)6]) cores do not interconvert even in the same oxidation level and are therefore topological isomers. The typical cluster 1 exhibits a versatile reaction chemistry that includes unique transformations that result in core conversions. In addition to being formed from [Fe6S6Cl6]3- (4) in a reductive-substitution reaction and from [Fe4S4Cl4]2- (5) in a process of core enlargement and reductive substitution, it is also spontaneously generated in solution from Fe7S6(PEt3)4Cl3. Further, in the presence of sulfur and chloride, the phosphines of 1 are removed in the form of Et3PS in high yield. In acetone solution in the presence of (Me4N)Cl, (Me4N)2[5] was isolated, whereas the use of (PPN)Cl resulted in isolation of the (PPN)+ salts of 4 and [Fe2S2(S5)2]2-, the latter in low yield. (PPN)3[4] could be identified securely only by X-ray crystallography. This compound crystallizes in monoclinic space group C2/c with a = 28.929 (8) ?, b = 15.296 (5) ?, c = 28.898 (6) ?, β = 122.39 (2)°, and Z = 4. The anion has a slightly distorted hexagonal prismatic structure with dimensions comparable to those found previously for another salt. In these conversions 85% of the Fe content of 1 is accounted for in the products. The basket and prismane Fe6S6 cores are the only open or closed polyhedral cores of this stoichiometry. The open faces of the prismane can be capped by certain metal fragments. These faces of the basket core have the same potential, but their less regular shape and longer S?S separations (3.93-4.10 ?) presumably will require core structural adjustment in the event of formation of a stable capped product.
Isolable Chlorotriorganylphosphoniumchlorides as Intermediates of the Oxirane (Thiirane)-Halogenation with Dichlorophosphoranes
Appel, Rolf,Glaesel, Volker Ingo
, p. 447 - 450 (2007/10/02)
Isolable chlorotriorganylphosphoniumchlorides (+)Cl(-) are synthesized by reaction of oxiranes (2-5) (oxetane (6), thiiranes 18a-c)) with dichlorophosphoranes (1a-f).Structure and stability are discussed.Thermal Arbusov-rearrangement yields vicinal di- resp. trihalo-alkanes and phosphanoxides.The structures are confirmed by 31P and 13C NMR data. - Keywords: Halogenation, Oxiranes, Thiiranes, Dichlorophosphoranes, Chlorophosphonium Salts
