- Mechanism of catalytic chalcogen atom replacement of phosphine chalcogenides and separation of the intermediate phosphine
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The reaction mechanism of the chalcogen atom replacement of phosphine chalcogenides has been revealed to be dissociative from a kinetic investigation for the reaction of phosphine selenide with sulfur. The dissociation is enthalpically promoted by the catalysis of Pd0. For a bidentate phosphine chalcogenide, the intermediate phosphine was separated as the Pd II complex by the catalysis and oxidative addition of Pd0 complex. The novel catalytic replacement and dissociation of chalcogen atom are applicable to regeneration of phosphines from their oxides via the phosphine sulfides. Copyright
- Aizawa, Sen-Ichi,Majumder, Arpi,Maeda, Daisuke,Kitamura, Akina
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- Phosphorus-Chalcogen Ring Expansion and Metal Coordination
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The reactivity of 4-membered (RPCh)2 rings (Ch = S, Se) that contain phosphorus in the +3 oxidation state is reported. These compounds undergo ring expansion to (RPCh)3 with the addition of a Lewis base. The 6-membered rings were found to be more stable than the 4-membered precursors, and the mechanism of their formation was investigated experimentally and by density functional theory calculations. The computational work identified two plausible mechanisms involving a phosphinidene chalcogenide intermediate, either as a free species or stabilized by a suitable base. Both the 4- and 6-membered rings were found to react with coinage metals, giving the same products: (RPCh)3 rings bound to the metal center from the phosphorus atom in tripodal fashion.
- Graham, Cameron M. E.,Valjus, Juuso,Pritchard, Taylor E.,Boyle, Paul D.,Tuononen, Heikki M.,Ragogna, Paul J.
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- Reaction of 1,2,3-selenadiazoles with phosphines
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Nucleophilic attack of tributyl- and triphenylphosphines on 4-phenyl- and 5-ethoxycarbonyl-4-methyl-1,2,3-selenadiazoles leads to the quantitative formation of selenophosphoranes and substituted acetylenes. The molecular structure of 4-phenyl-1,2,3-selenadiazole was confirmed by X-ray crystallography.
- Arsenyan,Oberte,Rubina,Belyakov,Lukevics
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- Oxo-sulfido- and oxo-selenido-molybdenum(vi) complexes possessing a dithiolene ligand related to the active sites of hydroxylases of molybdoenzymes: Low temperature preparation and characterisation
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Oxo-sulfido- and oxo-selenido-molybdenum(vi) complexes with an ene-1,2-dithiolate ligand are generated as models of the active sites of molybdenum hydroxylases. The sulfide and selenide groups are highly reactive toward triphenylphosphine in the order of Se > S.
- Sugimoto, Hideki,Tatemoto, Susumu,Toyota, Kazuo,Ashikari, Kenji,Kubo, Minoru,Ogura, Takashi,Itoh, Shinobu
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- Novel formation of 1,2,4-triselenolanes by the reaction of tert-butylarylmethylenetriphenylphosphoranes with elemental selenium
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Reaction of tert-butylarylmethylenetriphenylphosphoranes with elemental selenium afforded the corresponding 1,2,4-triselenolanes (1), 1,3-diselenetanes (4), and triphenylphosphine selenide. Triselenolanes 1 were formed from selenation of 4, which may suggest a stepwise selenation of selenoketones.
- Okuma, Kentaro,Kubota, Tomoaki
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- Ruthenium chalcogenonitrosyl and bridged nitrido complexes containing chelating sulfur and oxygen ligands
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Ruthenium thio- and seleno-nitrosyl complexes containing chelating sulfur and oxygen ligands have been synthesised and their de-chalcogenation reactions have been studied. The reaction of mer-[Ru(N)Cl3(AsPh3)2] with elemental sulfur and selenium in tetrahydrofuran at reflux afforded the chalcogenonitrosyl complexes mer-[Ru(NX)Cl3(AsPh3)2] [X = S (1), Se (2)]. Treatment of 1 with KN(R2PS)2 afforded trans-[Ru(NS)Cl{N(R2PS)2}2] [R = Ph (3), Pri (4), But (5)]. Alternatively, the thionitrosyl complex 5 was obtained from [Bun4N][Ru(N)Cl4] and KN(But2PS)2, presumably via sulfur atom transfer from [N(But2PS)2]- to the nitride. Reactions of 1 and 2 with NaLOEt (LOEt- = [Co(η5-C5H5){P(O)(LOEt)2}3]-) gave [Ru(NX)LOEtCl2] (X = S (8), Se (9)). Treatment of [Bun4N][Ru(N)Cl4] with KN(R2PS)2 produced RuIV-RuIV μ-nitrido complexes [Ru2(μ-N){N(R2PS)2}4Cl] [R = Ph (6), Pri (7)]. Reactions of 3 and 9 with PPh3 afforded 6 and [Ru(NPPh3)LOEtCl2], respectively. The desulfurisation of 5 with [Ni(cod)2] (cod = 1,5-cyclooctadiene) gave the mixed valance RuIII-RuIV μ-nitrido complex [Ru2(μ-N){N(But2PS)2}4] (10) that was oxidised by [Cp2Fe](PF6) to give the RuIV-RuIV complex [Ru2(μ-N){N(But2PS)2}4](PF6) ([10]PF6). The crystal structures of 1, 2, 3, 7, 9 and 10 have been determined.
- Ng, Ho-Yuen,Cheung, Wai-Man,Kwan Huang, Enrique,Wong, Kang-Long,Sung, Herman H.-Y.,Williams, Ian D.,Leung, Wa-Hung
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- Heteroleptic Samarium(III) Chalcogenide Complexes: Opportunities for Giant Exchange Coupling in Bridging σ- And π-Radical Lanthanide Dichalcogenides
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The introduction of (N2)3-? radicals into multinuclear lanthanide molecular magnets raised hysteresis temperatures by stimulating strong exchange coupling between spin centers. Radical ligands with larger donor atoms could promote more efficient magnetic coupling between lanthanides to provide superior magnetic properties. Here, we show that heavy chalcogens (S, Se, Te) are primed to fulfill these criteria. The moderately reducing Sm(II) complex, [Sm(N??)2], where N?? is the bulky bis(triisopropylsilyl)amide ligand, can be oxidized (i) by diphenyldichalcogenides E2Ph2 (E = S, Se, Te) to form the mononuclear series [Sm(N??)2(EPh)] (E = S, 1-S; Se, 1-Se, Te, 1-Te); (ii) S8 or Se8 to give dinuclear [{Sm(N??)2}2(μ-η2:η2-E2)] (E = S, 2-S2; Se, 2-Se2); or (iii) with Te=PEt3 to yield [{Sm(N??)2}(μ-Te)] (3). These complexes have been characterized by single crystal X-ray diffraction, multinuclear NMR, FTIR, and electronic spectroscopy; the steric bulk of N?? dictates the formation of mononuclear complexes with chalcogenate ligands and dinuclear species with the chalcogenides. The Lα1 fluorescence-detected X-ray absorption spectra at the Sm L3-edge yielded resolved pre-edge and white-line peaks for 1-S and 2-E2, which served to calibrate our computational protocol in the successful reproduction of the spectral features. This method was employed to elucidate the ground state electronic structures for proposed oxidized and reduced variants of 2-E2. Reactivity is ligand-based, forming species with bridging superchalcogenide (E2)-? and subchalcogenide (E2)3-? radical ligands. The extraordinarily large exchange couplings provided by these dichalcogenide radicals reveal their suitability as potential successors to the benchmark (N2)3-? complexes in molecular magnets.
- Dimucci, Ida M.,Giansiracusa, Marcus J.,Goodwin, Conrad A. P.,Kragskow, Jon G. C.,Lancaster, Kyle M.,Mills, David P.,Réant, Benjamin L. L.,Sproules, Stephen,Vettese, Gianni F.
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supporting information
(2020/06/08)
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- Synthesis of Phosphine Chalcogenides Under Solvent-Free Conditions Using a Rotary Ball Mill
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The mechanochemical technique of ball milling has been applied to the solventless and eco-friendly synthesis of chalcogenides (sulfide and selenide) of a variety of tertiary and aminophosphines. In most of the cases, the products are obtained in almost quantitative yields with high purity by applying a simple workup procedure without using chromatographic techniques or any other purification methods. The scope of this methodology was explored by using a range of phosphines (mono, di and tetra) to synthesize partial as well as mixed chalcogenides. The use of almost equimolar amounts of starting materials and the absence of any byproducts significantly simplifies the product isolation compared with the standard solution state reactions, thus providing a highly atom economic (100 %) method with an ideal E-factor (E = 0). The solid-state reactions were monitored by 31P{1H} NMR spectroscopy. The structures of some of the products are also confirmed by single-crystal X-ray analyses. Although most of the reactions were carried out on ca. 100-mg scale, the scaling up of the reaction did not affect the course of the reaction.
- Kumar, Rajnish,Kumar, Saurabh,Pandey, Madhusudan K.,Kashid, Vitthalrao S.,Radhakrishna, Latchupatula,Balakrishna, Maravanji S.
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p. 1028 - 1037
(2018/02/26)
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- Assessing the Activity of Lewis Bases Organocatalysts in Halonium-Induced Carbocyclization Reactions
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Lewis bases were evaluated as catalysts for halocarbocyclization reactions of alkynylstyrenes and a cinnamylaniline derivative. Phosphines and phosphorus chalcogenides exhibited high activity for the conversion of alkynylstyrenes in the presence of N -halosuccinimides with up to a 30-fold increase of the initial reaction rate with respect to the background reaction. Phosphorus sulfides and selenides showed the best catalytic activity for the iodocarbocyclization of a cinnamylaniline derivative in the presence of diiodohydantoin. An asymmetric variant of the iodocarbocyclization reaction of an alkynylstyrene using a chiral phosphorus selenide resulted in a modest enantioselectivity.
- Grandclaudon, Charlotte,Ruamps, Mirko,Duboc, Rapha?l,Michelet, Véronique,Toullec, Patrick Y.
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supporting information
p. 1181 - 1186
(2018/04/16)
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- Palladium-Catalyzed Cross-Coupling of Silyl Electrophiles with Alkylzinc Halides: A Silyl-Negishi Reaction
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We report the first example of a silyl-Negishi reaction between secondary zinc organometallics and silicon electrophiles. This palladium-catalyzed process provides direct access to alkyl silanes. The delicate balance of steric and electronic parameters of the employed DrewPhos ligand is paramount to suppressing isomerization and promoting efficient and selective cross-coupling.
- Cinderella, Andrew P.,Vulovic, Bojan,Watson, Donald A.
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supporting information
p. 7741 - 7744
(2017/06/21)
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- Effect of positive-charges in diphosphino-imidazolium salts on the structures of Ir-complexes and catalysis for hydroformylation
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The effect of positive charges in the diphosphino-imidazolium salts of L2 was investigated in terms of coordinating character, structures of corresponding Ir-complexes and catalysis for hydroformylation. It was found that the involved positive charges exhibited strong electron-withdrawing effect on the neighbored phosphine fragment, rendering L2 more π-acceptor ability than the corresponding neutral counterpart of L1. Consequently, the changed coordinating ability of L1 and L2 led to the variety in the structures and components for the Ir-complexes (Ir-L1a, Ir-L1b, Ir-L2a, and Ir-L2b). The complexation of L2 with Ir(acac)(CO)2 led to a novel five-coordinate Ir(II)-complex of Ir-L2a chelated by a PCC (phosphine-carboanion-carbene) pincer in tripodal mode, whereas the complexation of L1 with Ir(acac)(CO)2 led to a four-coordinate square-planar Ir(I)-complex of Ir-L1a chelated by a PCP (phosphine-carboanion-phosphine) pincer. In addition, the different catalytic performances of these Ir-complexes ligated by L1 and L2 for hydroformylation of olefins were investigated.
- Zhang, Heng,Li, Yong-Qi,Wang, Peng,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
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p. 337 - 343
(2015/12/01)
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- Synthetic strategies of gold(I)-selenolates from ortho-substituted diaryl diselenides via selenol and selenenyl sulfide intermediates
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In the present study we describe the synthetic strategies to gold(I)-selenolate complexes by the reaction of ortho-substituted diaryl diselenides and electrophilic anti-arthritic gold(I)-compounds in the presence of thiol such as PhSH. Diselenides react with thiol to generate a mixture of selenol and selenenyl sulfide. While selenols react with electrophilic Au(I) compounds to form gold(I)-selenolate complexes, the selenenyl sulfides do not react and therefore, a prior conversion of selenenyl sulfide to selenol is necessary for an effective formation of gold(I)-selenolate from diselenide. However, this process is associated with the ligand exchange reaction in selenenyl sulfide in the presence of PhSH that hampers the regeneration of selenol. The structural aspects as well as the mode of reactivities of selenenyl sulfides and the products (gold(I)-selenolates) were analyzed using experimental as well as computational methods. These studies indicated that the presence of ortho-coordinating donor groups and oxidation state of Se-center play crucial roles towards their reactivities. Density functional theory calculations were undertaken to determine the natural charges on heteroatoms and to find the site for nucleophilic attack related to ligand exchange reactions.
- Bhabak, Krishna P.,Bhowmick, Debasish
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p. 337 - 345
(2016/07/06)
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- Co-catalysis of a bi-functional ligand containing phosphine and Lewis acidic phosphonium for hydroformylation-acetalization of olefins
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A novel ionic bi-functional ligand of L2 containing a phosphine and a Lewis acidic phosphonium with I- as the counter-anion was prepared and fully characterized. The molecular structure indicated that the bi-functionalities in L2 were well retained without the incompatibility problem for quenching of the acidity of the phosphonium cation by the Lewis basic phosphine fragment or the anionic I- when the incorporated phosphine fragment and the Lewis acidic phosphonium were strictly located in the confined cis-positions. The co-catalysis over L2-Rh(acac)(CO)2 in the ways of synergetic catalysis and sequential catalysis was successfully fulfilled for one-pot hydroformylation-acetalization, which proved not to be the result of the simple mixture of the mono-phosphine (L4) and the phosphonium salt (L4′). In L2, the phosphonium not only acted as a Lewis acid organocatalyst to drive the sequential acetalization of aldehydes, but also contributed to the synergetic catalysis for the preceding hydroformylation through stabilizing the Rh-acyl intermediate with the phosphine cooperatively. The L2-Rh(acac)(CO)2 system is also generally applied to hydroformylation-acetalization of a wide range of olefins in different alcohols. Advantageously, as an ionic phosphonium-based ligand, L2 could be recycled for 7 runs with Rh(acac)(CO)2 together in RTIL of [Bmim]BF4 without obvious activity loss or metal leaching.
- Li, Yong-Qi,Wang, Peng,Liu, Huan,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
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p. 1798 - 1806
(2016/04/01)
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- Ionic palladium complex as an efficient and recyclable catalyst for the carbonylative Sonogashira reaction
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The neutral palladium(II) complex bis-[1-(5'-diphenylphosphinothiazol-2'-yl)-imidazolyl] dichloropalladium(II) (1A) ligated by thiazolylimidazolyl-based phosphine (L1) in which thiazolylimidazolyl acted as an S- and N-donor provider with weak coordinating nature, and the ionic complex bis-[1-(5'-diphenylphosphinothiazol-2'-yl)-3-methylimidazolium] dichloropalladium(II) trifluoromethanesulfonate (2A) ligated by thiazolylimidazolium-based phosphine (L2) after quaternization of L1 using methyl trifluoromethanesulphonate were synthesized. It was found that the introduced positive charges and strong electron-withdrawing effect in 2A not only led to changes in the configuration and structural stability of the complex, but also lowered its catalytic performance in carbonylative Sonogashira reactions. These effects reveal the important role of the N-donor in 1A. In addition, as an ionic palladium complex, 2A combined with the room-temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate could be recycled eight times as the catalyst in carbonylative Sonogashira reactions without detectable metal leaching.
- Yang, Da,Wang, Dongliang,Liu, Huan,Zhao, Xiaoli,Lu, Yong,Lai, Shijun,Liu, Ye
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p. 405 - 411
(2016/03/16)
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- In Situ FTIR and NMR Spectroscopic Investigations on Ruthenium-Based Catalysts for Alkene Hydroformylation
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Homogeneous ruthenium complexes modified by imidazole-substituted monophosphines as catalysts for various highly efficient hydroformylation reactions were characterized by in situ IR spectroscopy under reaction conditions and NMR spectroscopy. A proper protocol for the preformation reaction from [Ru3(CO)12] is decisive to prevent the formation of inactive ligand-modified polynuclear complexes. During catalysis, ligand-modified mononuclear ruthenium(0) carbonyls were detected as resting states. Changes in the ligand structure have a crucial impact on the coordination behavior of the ligand and consequently on the catalytic performance. The substitution of CO by a nitrogen atom of the imidazolyl moiety in the ligand is not a general feature, but it takes place when structural prerequisites of the ligand are fulfilled.
- Kubis, Christoph,Profir, Irina,Fleischer, Ivana,Baumann, Wolfgang,Selent, Detlef,Fischer, Christine,Spannenberg, Anke,Ludwig, Ralf,Hess, Dieter,Franke, Robert,B?rner, Armin
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p. 2746 - 2757
(2016/02/27)
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- An examination of the effects of borate group proximity on phosphine donor power in anionic (phosphino)tetraphenylborate ligands
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The ligand electron-donating abilities are compared among a series of monodentate, anionic (phosphino)tetraphenylborate phosphines [Ph4P][Ph2P-R-C6H4BPh3] (R = -C6H4-, -CH2-, -CH2CH2- or none), and their neutral counterparts Ph2PR (R = biphenyl, -CH2Ph, -CH2CH2Ph or Ph). Among the anionic ligands, the position of the tetraphenylborate group relative to the diphenylphosphino donor moiety was systematically varied in an effort to examine how its proximity impacts donor power. The donor power was determined by measuring the 31P-77Se coupling constant for the corresponding selenide of each phosphine ligand via 31P NMR spectroscopy. The anionic ligands yield lower 31P-77Se coupling constants than those measured for their respective neutral counterparts. Moreover, the 31P-77Se coupling constants among the anionic ligands increase when the tetraphenylborate group is positioned further from the phosphorus centre.
- Tassone, Joseph P.,Mawhinney, Robert C.,Spivak, Gregory J.
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supporting information
p. 153 - 156
(2015/02/19)
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- Photoinduced Synthesis of P-Perfluoroalkylated Phosphines from Triarylphosphines and Their Application in the Copper-Free Cross-Coupling of Acid Chlorides and Terminal Alkynes
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A practical synthesis yielding P-perfluoroalkylated phosphines from triarylphosphines and perfluoroalkyl iodides has been developed. The photoinduced reaction involves the substitution of aryl groups on the phosphorus atom with perfluoroalkyl groups to successfully afford P-perfluoroalkylated phosphines. In addition, the P-perfluoroalkylated phosphines were found to promote the Cu-free cross-coupling reaction of acid chlorides with terminal alkynes.
- Kawaguchi, Shin-Ichi,Minamida, Yoshiaki,Okuda, Takumi,Sato, Yuki,Saeki, Tomokazu,Yoshimura, Aya,Nomoto, Akihiro,Ogawa, Akiya
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p. 2509 - 2519
(2015/08/18)
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- Promotion effect of water on hydroformylation of styrene and its derivatives with presence of amphiphilic zwitterionic phosphines
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Two kinds of novel zwitterionic phosphines of L1 and L2 have been synthesized in which the sulfonate groups (-SO3-) are incorporated to render them amphiphilic. Both of them are strong π-acceptor ligands in which the positive-charged imidazoliums with intensive electron-withdrawing effect are vicinal to the coordinating phosphorous atoms. The amino-group of piperidyl is additionally incorporated in L2 to make it behave as a hybrid ligand with potential hemilability. The comparison of the ligands of L1 and L2 in Rh-catalyzed hydroformylation of styrene (and its derivatives) and the effect of water on their behaviors were discussed. Without the involvement of water, the catalytic system of Rh(acac)(CO)2-L2 exhibited lower activity than that of Rh(acac)(CO)2-L1 under the same conditions. However, the dramatic promotion effect of water as a suspension was observed especially for Rh(acac)(CO)2-L2 system with TOF spurred up from 195 to 470 h-1. The corresponding in situ high pressure FT-IR spectral information showed that the presence of water in Rh(acac)(CO)2-L2 system greatly facilitated the formation and stability of the active Rh-H species (νRh-H, 2047 cm-1), which was in charge of the efficient hydroformylation of styrene and its derivatives.
- Chen, Sheng-Jie,Li, Yong-Qi,Wang, Peng,Lu, Yong,Zhao, Xiao-Li,Liu, Ye
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p. 212 - 220
(2015/07/28)
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- Novel C1-symmetric dibenzophosphole ligands: Application in hydroformylation reactions
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A new family of non-symmetrical disubstituted dibenzophospholes possessing different steric and electronic effects have been synthesized and characterized. Their preliminary evaluation in rhodium-catalyzed hydroformylation reactions is presented.
- Oukhrib, Abdelhouad,Bonnafoux, Laurence,Panossian, Armen,Waifang, Sandrine,Nguyen, Duc Hanh,Urrutigoity, Martine,Colobert, Fran?oise,Gouygou, Maryse,Leroux, Frédéric R.
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p. 1431 - 1436
(2014/02/14)
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- Unexpected one-electron oxidation of a secondary phosphite selenide Cp(CO)2FeP(Se)(OiPr)2 by GaCl3 and InCl 3 - Rare examples of Di- and triselenide formation
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The reactions of the neutral phosphonoselenoate [Cp(CO)2FeP(Se) (OiPr)2] (1) with Lewis acids (GaCl3, InCl3) produce dicationic complexes [{Cp(CO)2FeP(OiPr)2} 2Sen][GaCl4]2, [n = 2 (2), 3 (3)] and [{Cp(CO)2FeP(OiPr)2}2Sen] [InCl4]2 [n = 2 (4), 3 (5)] in good yields; the complexes comprise an Se3 (or Se2) chain that bridges two FpP(OiPr)2 groups [Fp = Cp(CO)2Fe]. These compounds are the one-electron oxidation products of secondary phosphite selenide 1 by group 13 (Ga, In) trichlorides. On the other hand, the reaction of GaCl3 with (iPrO)2PSe2- (dsep) yields only the Lewis adduct tris(O,O-diisopropyldiselenophosphate)gallium (6). The 31P NMR spectrum of 6 at 183 K reveals that the gallium(III) center is surrounded by one chelating and two pendant dsep ligands, which is in line with the obtained X-ray structure. In addition, the two-electron oxidation of 1 leads to phosphite [Cp(CO)2FeP(O)(OiPr)2] formation. Copyright
- Kuimov, Vladimir A.,Liao, Ping-Kuei,Chiou, Ling-Song,You, Hong-Chih,Fang, Ching-Shiang,Liu
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p. 2083 - 2092
(2013/06/26)
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- Reaction of ruthenium phenyl acetylide with iron-chalcogen clusters and iron pentacarbonyl
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Photolysis of a THF solution containing ruthenium acetylide [(η5-C5H5)Ru(PPh3) 2(η1-CCPh)] with [Fe3(CO) 9(μ3-Se)2] cluster affords an adduct [{μ-SeC(CpRu(PPh3)(CO))C(Ph)Se}(CO)6Fe2] (1), while under similar reaction condition with [Fe3(CO) 9(μ3-Te)2] cluster a Ru-inserted product [(η5-C5H5)(PPh3) (η1-CCPh)RuFe2(μ3-Te) 2(CO)6] (2) was obtained. Under thermal condition [(η5-C5H5)Ru(PPh3) 2(η1-CCPh)] react with Fe(CO)5 to give an acetylide stabilised Fe2Ru mixed metal cluster [(η5- C5H5)RuFe2(CO)7(η2: η2:η1-CCPh)], (3).
- Mathur, Pradeep,Raghuvanshi, Abhinav,Ji, Radhe Shyam,Mobin, Shaikh M.
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- Gold phosphole complexes as efficient catalysts for alkyne activation
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Gold(I) complexes bearing monophosphole ligands were synthesized, and their electronic and steric properties were compared to those of their triphenylphosphine-based counterparts. Cationic phosphole-based gold(I) complexes are active and selective in enyne cycloisomerization and in olefin cyclopropanation, with a good correlation between the ligand σ-donor ability and the catalytic activity. For the most efficient ligand, 1-phenyl-2,3,4,5-tetramethylphosphole (TMP), a highly active, selective, and stable cationic [Au(TMP)(CH3CN)]SbF6 complex was isolated.
- Fourmy, Kevin,Mallet-Ladeira, Sonia,Dechy-Cabaret, Odile,Gouygou, Maryse
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supporting information
p. 1571 - 1574
(2013/05/08)
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- Mechanistic study of the synthesis of CdSe nanocrystals: Release of selenium
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We outline a reaction pathway for the cleavage of the P=Se bond in trialkylphosphine selenide during the synthesis of CdSe nanocrystals. The reaction between cadmium carboxylate and trimethylphosphine selenide in the presence of an alcohol produces alkoxytrimethylphosphonium (2). Control experiments and density functional theory calculations suggested that the cleavage of the P=Se bond is initiated by nucleophilic attack of carboxylate on a Cd2+-activated phosphine selenide to produce an acyloxytrialkylphosphonium intermediate (1), which is converted to 2 in the presence of an alcohol.
- Garcia-Rodriguez, Raul,Liu, Haitao
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supporting information; experimental part
p. 1400 - 1403
(2012/03/12)
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- Mysteries of TOPSe revealed: Insights into quantum dot nucleation
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We have investigated the reaction mechanism responsible for QD nucleation using optical absorption and nuclear magnetic resonance spectroscopies. For typical II-VI and IV-VI quantum dot (QD) syntheses, pure tertiary phosphine selenide sources (e.g., trioctylphosphine selenide (TOPSe)) were surprisingly found to be unreactive with metal carboxylates and incapable of yielding QDs. Rather, small quantities of secondary phosphines, which are impurities in tertiary phosphines, are entirely responsible for the nucleation of QDs; their low concentrations account for poor synthetic conversion yields. QD yields increase to nearly quantitative levels when replacing TOPSe with a stoiciometric amount of a secondary phosphine chalcogenide such as diphenylphosphine selenide. Based on our observations, we have proposed potential monomer identities, reaction pathways, and transition states and believe this mechanism to be universal to all II-VI and IV-VI QDs synthesized using phosphine based methods.
- Evans, Christopher M.,Evans, Meagan E.,Krauss, Todd D.
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supporting information; experimental part
p. 10973 - 10975
(2010/09/17)
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- Rapid phosphorus(III) ligand evaluation utilising potassium selenocyanate
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Oxidative addition of SeCN- to tertiary phosphine ligands has been investigated in methanol at 298 K by use of UV-Vis stopped-flow and conventional spectrophotometry. In most cases kobsvs. [SeCN -] plots were linear with zero intercepts corresponding to a rate expression of kobs = k1[SeCN-]. Reactions rates are dependent on the electron density of the phosphorus centre with k 1 varying by five orders of magnitude from 1.34 ± 0.02 × 10-3 to 51 ± 3 mol-1 dm3 s-1 for P(2-OMe-C6H4)3 to PCy3 respectively. Activation parameters range from 27 ± 1 to 49.0 ± 1.3 kJ mol-1 for ΔH? and -112 ± 9 to -140 ± 3 J K-1 mol-1 for ΔS ? supporting a SN2 mechanism in which the initial nucleophilic attack of P on Se is rate determining. Reaction rates are promoted by more polar solvents supporting the mechanistic assignment. Reasonable linear correlations were observed between log k1vs. pKa, 1JP-Se and χd values of the phosphines. The reaction rates are remarkably sensitive to the steric bulk of the substituents, and substitution of phenyl rings in the 2 position resulted in a decrease in the reaction rate. The crystal structures of SePPh2Cy and SePPhCy2 have been determined displaying Se-P bond distances of 2.111(2) and 2.1260(8) respectively. The Royal Society of Chemistry 2008.
- Muller, Alfred,Otto, Stefanus,Roodt, Andreas
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p. 650 - 657
(2008/09/17)
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- REACTIONS OF ISOTOPICALLY ENRICHED ELEMENTS
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Reactions of isotopically enriched samples of elements selected from phosphorus, sulfur, selenium and/or tellurium involving the addition of atoms of the isotope to organic or inorganic molecules comprising use of an ionic liquid as a reaction medium.
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- REACTIONS OF GROUP 16 ELEMENTS
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Reactions of Group 16 elements involving the addition of atoms such as sulfur, selenium or tellurium to organic or inorganic molecules comprising use of an ionic liquid as a reaction medium.
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Page/Page column 16
(2008/06/13)
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- Mechanism of the sulfurisation of phosphines and phosphites using 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride)
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Contrary to a previous report, the sulfurisation of phosphorus(iii) derivatives by 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride) does not yield carbon disulfide and cyanamide as the additional reaction products. The reaction of xanthane hydride with triphenyl phosphine or trimethyl phosphite yields triphenyl phosphine sulfide or trimethyl thiophosphate, respectively, and thiocarbamoyl isothiocyanate which has been trapped with nucleophiles. The reaction pathway involves initial nucleophilic attack of the phosphorus at sulfur next to the thiocarbonyl group of xanthane hydride followed by decomposition of the phosphonium intermediate formed to products. The Hammett ρ-values for the sulfurisation of substituted triphenyl phosphines and triphenyl phosphites in acetonitrile are ～ -1.0. The entropies of activation are very negative (-114 ± 15 J mol-1 K-1) with little dependence on solvent which is consistent with a bimolecular association step leading to the transition state. The negative values of ΔS ≠ and ρ values indicate that the rate limiting step of the sulfurisation reaction is formation of the phosphonium ion intermediate which has an early transition state with little covalent bond formation. The site of nucleophilic attack has been also confirmed using computational calculations. The Royal Society of Chemistry 2007.
- Hanusek, Jiri,Russell, Mark A.,Laws, Andrew P.,Jansa, Petr,Atherton, John H.,Fettes, Kevin,Page, Michael I.
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p. 478 - 484
(2008/03/27)
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- Palladium-catalyzed activation of E-E and C-E bonds in diaryl dichalcogenides (E = S, Se) under microwave irradiation conditions
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The first example of palladium-catalyzed stereoselective addition of diphenyl disulfide and diphenyl diselenide to the triple bond of terminal alkynes under microwave irradiation conditions is described. It was found that both the element-element (E-E) and carbon-element bonds can be activated in the catalytic system studied. The products of both reactions were isolated in quantitative yields. According to quantum-chemical calculations, the reaction mechanism involves the oxidative addition of the E-E bond to Pd0. Depending on the microwave power and reaction conditions, the next stage is either the reaction with alkyne or the carbon-element bond activation. The product of the oxidative addition of Ph2Se2 to Pd 0, namely, dinuclear complex [Pd2(SePh) 4(PPh3 2], was detected by 31P{ 1H}NMR spectroscopy directly in the Ph2Se 2/PPh3 melt formed under microwave irradiation conditions.
- Ananikov,Orlov,Beletskaya
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p. 576 - 587
(2007/10/03)
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- Electron-donating ability of triarylphosphines and related compounds studied by 31P NMR spectroscopy
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The influence of aryl, heterocyclic, amide, alkyl, alkoxyl, thioalkoxyl, and ferrocenyl substituents at the phosphorus atom on its electron-donating ability was studied by the measurement of direct 31P-77Se spin-spin coupling constants for the corresponding selenides. Series of diphenylorganylphosphines and their selenides were studied.
- Chevykalova,Manzhukova,Artemova,Luzikov,Nifant'ev,Nifant'ev
-
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- Coordination of cyclo-octasulfur and cyclo-heptaselenium to dinuclear rhenium(I) systems
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By substitution reactions of the coordinated THF ligands of Re2(μ-X)2(CO)6(THF)2 by elemental chalcogens (S8 and red selenium), the complexes Re2(μ-X)2(CO)6(S8) (X = Br, 1; 1, 2), and Re2(μ-X)2(CO)6(Se7), (X = I, 3; Br, 4) have been prepared. Binuclear compound 3 was crystallographically established to be a coordination compound of cyclo-heptaselenium, two adjacent selenium atoms of the Se7 ligand [Se-Se distance, 2.558(3) A] being bonded to rhenium(I), at an average Re-Se distance of 2.586(3) A, and the nonbonding ReRe distance being 4.077(3) A. Spectroscopic evidence of the existence of these chalcogen complexes in solution is reported. The Re2(μ-X)2(CO)6(S8) complexes undergo S8 displacement by THF, while the coordinated Se7 moiety is less readily displaced from 3.
- Bacchi, Alessia,Baratta, Walter,Calderazzo, Fausto,Marchetti, Fabio,Pelizzi, Giancarlo
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p. 3894 - 3900
(2008/10/08)
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- Chalcogen atom transfer reactions. Kinetics of terminal bonded sulfur atom transfer between main group metal centers
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The first comprehensive investigation of S atom transfer between two different metal centers is presented using the reaction of the terminal chalcogen atom bearing complex [CyNC((t)Bu)NCy]2SnS with [CyNC((t)Bu)NCy]2Ge(II); this multielectron redox reaction between Ge(II) and Sn(IV) proceeds via a second-order process with an inner sphere mechanism involving a μ-S intermediate as the proposed pathway; results of S and Se atom transfer between [CyNC((t)Bu)NCy]2Ge and PPh3 are also presented.
- Foley, Stephen R.,Richeson, Darrin S.
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p. 1391 - 1392
(2007/10/03)
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- Syntheses, structures, and reactions of the first rotational isomers of stable selenobenzaldehydes, 2,4,6-tris[bis(trimethylsilyl)methyl]selenobenzaldehydes, and their η1-tungsten complexes
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Deselenation of a cyclic polyselenide mixture, Tbt(s)CHSe(n) 5, resulted in the formation of Tbt(s)CHSe 3a, which gave its head-to-tail dimer 12 upon concentration of the reaction solution although it was stable in a dilute solution. Thermolysis of 12 gave an equilibrium mixture of 12, 3a, and its rotational isomer Tbt(a)CHSe 3b, and 3b was isolated as a solid stable even in air. Reaction of 3a and 3b with W(CO)5. THF gave the corresponding η1-selenoaldehyde tungsten complexes 4a and 4b, respectively. Some reactions of 4a were carried out to give products accompanied by decomplexation.
- Takeda, Nobuhiro,Tokitoh, Norihiro,Okazaki, Renji
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p. 12167 - 12182
(2007/10/03)
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- Isolation, Structure and Reaction of Selenobenzophenones. X-Ray Molecular Structure of 4,4'-Dimethoxyselenobenzophenone and of 4,4-Diphenyl-2,3-diselenabicyclooct-7-ene
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4,4'-Dimethoxy- 1a and 4,4'-dimethyl-selenobenzophenone 1b could be isolated in moderate yields by the reaction of the corresponding ylides 3 with elemental selenium in benzene at 80 deg C.Their spectral data are described.Attempted isolation of unsubstituted selenobenzophenone afforded only its dimer 5.Compound 1a crystallizes in space group P21/n with unit-cell parameters a = 7.191(3), b = 7.505(4=, c = 24.856(4) Angstroem, β = 90.32(1) deg, Z = 4, R = 0.055.The oxidation and thiation of 4,4'-dimethoxyselenobenzophenone 1a afforded the corresponding benzophenone and thiobenzophenone in good yields.The reaction of compound 1 with cyclopentadiene afforded the corresponding cycloadducts 7 (3,3-diaryl-2-selenabicyclohept-5-enes), whereas bicyclic diselenides 8 (4,4-diaryl-2,3-diselenabicyclooct-7-enes were obtained by using an excess of selenium and a higher temperature.Oxidation of compound 8c gave the corresponding diol 12, aldehyde 13, and diphenylfulvene 11.The reaction of compound 1a with benzenediazonium carboxylate afforded 2,2-bis-(4-methoxyphenyl)-4H-3,1-benzooxaselenin-4-one 17.
- Okuma, Kentaro,Kojima, Kazuki,Kaneko, Isao,Tsujimoto, Yoshikazu,Ohta, Hiroshi,Yokomori, Yoshinobu
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p. 2151 - 2160
(2007/10/02)
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- Dihydroselenapyrans by Cycloaddition of Diaryl Selenoketones
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The phosphorus ylides Ph3P=CAr1Ar2 5 1=Ph, Ar2=4-CH3C6H4 (c); Ar1=Ar2=Ph (d); 4-ClC6H4 (e); 4-FC6H4 (f); 3-CF3C6H4 (g); Ar1=Ph, Ar2=4-ClC4H4 (h)> were allowed to react with elemental selenium at ca. 75 deg C in toluene in the presence of an excess of 2,3-dimethylbutadiene.The diaryl selenoketones 1 thus generated in situ by means of the "Staudinger chalcogenation" reaction were trapped by the added conjugated diene to give the 2,2-diaryl-3,6-dihydro-4,5-dimethyl-2H-selenapyrans 7 in high yield.Similarly, the ylides 5c-f and 5h were treated with selenium, and the resulting diaryl selenoketones 1 added to 1,3-butadiene to give the corresponding 2,2-diaryl-3,6-dihydro-2H-selenapyrans 8.Selenobenzophenone, synthesized analogously, was employed in a cycloaddition reaction with 2,3-dimethoxybutadiene to yield 3,6-dihydro-4,5-dimethoxy-2,2-diphenyl-2H-selenapyran (9), which was characterized by an X-ray crystal structure analysis.Compound 9 crystallizes in the space group P21/n.In the crystal the dihydro-2H-selenapyran adopts a distorted half-chair conformation. - Key Words: Selenoketones / Selenapyrans, dihydro / Staudinger chalcogenation / Phosphorus ylides / Cycloadddition
- Hock, Regina,Hillenbrand, Stefanie,Erker, Gerhard,Krueger, Carl,Werner, Stefan
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p. 1895 - 1904
(2007/10/02)
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- A new, stereoselective interconversion of phosphinothio-phosphinoseleno compounds, reduction of phosphinoseleno derivatives and retro pishchimuka rearrangement based on methylthio- and methylselenophosphonium salts chemistry
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The interconversion of thiono- into seleno compounds was found to proceed with retention of the configuration at phosphorus and the mechanistic course of this process has been proposed. The isomerization reaction of phosphinothiolates into thiono-isomers via the phosphonium salts has been developed and considered as the "retro Pishchimuka" rearrangement.
- Omelanczuk, Jan
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p. 8887 - 8898
(2007/10/02)
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- The Reaction of Electron-deficient Selenoaldehydes with Thiols
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Electron-poor selenoaldehydes, generated in-situ in refluxing toluene, reacted with thiols in the presence of triethylamine to give selenenyl sulfides, RSeSR'.The formation of a selenodisulfide, RSSeSR, was also evidenced.
- Duchenet, Virginie,Vallee, Yannick
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p. 4925 - 4926
(2007/10/02)
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- Preparation of 1,4-Dienes from 2-(2-Hydroxyalkylseleno)benzothiazoles by the Reaction Involving Se -> O Azaaromatic Ring Rearrangement
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The reactions of 2-(2-oxoalkylseleno)benzothiazoles with allylic Grignard reagents in the presence of BF3*OEt2 gave the corresponding 2-benzothiazoles which, on treatment with Ph3P and NaH, afforded 1,4-dienes in good to excellent yields.
- Shibata, Koichi,Mitsunobu, Oyo
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p. 3163 - 3173
(2007/10/02)
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- Preparation of 1,4-Dienes from 2-(2-Hydroxyalkylseleno)benzothiazoles by the Reaction involving Se->O Aza-aromatic Ring Rearragement
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The reaction of 2-(acylmethylseleno)benzothiazoles with allylic Grignard reagents in the presence of BF3*OEt2 gave the corresponding 2-(2-hydroxyalkylseleno)benzothiazoles which, on treatment with NaH and Ph3P, afforded 1,4-dienes in good to excellent yields.
- Shibata, Koichi,Shiono, Hirofumi,Mitsunobu, Oyo
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p. 661 - 664
(2007/10/02)
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- Regioselective synthesis of bicyclic diselenides by the reaction of phosphonium ylides with elemental selenium
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Selenabicyclo[2.2.1]heptenes reacted with elemental selenium to produce unusual bicyclic diselenides in 30-40% yield. The reaction of phosphonium ylides with excess of elemental selenium also afforded bicyclic diselenides in good yields. The reactions might proceed via biradical intermediates.
- Okuma, Kentaro,Kaneko, Isao,Ohta, Hiroshi,Yokomori, Yoshinobu
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p. 2107 - 2110
(2007/10/02)
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- ATOM TRANSFER AND EXCHANGE REACTIONS INVOLVING OXYGEN, SULFUR AND SELENIUM
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A systematic comparison has been made of the reaction conditions required to bring about the thermal transfer or exchange of Group 16 terminal elements between Group 15 molecular centers.Where reaction conditions were suitable, kinetic analyses have been performed, with the observed second-order behavior supporting the presumed bimolecular character of these reactions.
- Baechler, Raymond D.,Stack, Mary,Stevenson, Karen,Vanvalkenburgh, Virginia
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- STERIC AND ELECTRONIC DESTABILIZATION OF THE P-Se BOND IN TRIARYLPHOSPHINE SELENIDE SYSTEMS
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Electronic and steric effects in SeP(Ar)3 compounds are discussed with the assistance of 1J(77Se-31P) correlations with d(P-Se) values and the pKa of the arylphosphines.
- Malito, John,Alyea, Almer C.
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- STEREOSELECTIVE SYNTHESIS OF TRANS OLEFINS BY THE REACTION OF WITTIG REAGENTS WITH SELENIUM. FORMATION OF SELENOCARBONYL COMPOUNDS.
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Wittig reagents were successfully changed to symmetrical olefins when treated with elemental selenium.The reaction proceeds through a selenocarbonyl intermediate, which existence was confirmed by Diels-Alder reaction.
- Okuma, Kentaro,Sakata, Jun-ichi,Tachibana, Yuji,Honda, Takumi,Ohta, Hiroshi
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p. 6649 - 6652
(2007/10/02)
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- OXIDATIVE DESULPHURISATION AND DESELENATION AT PENTACOVALENT PHOSPHOROUS BY PHOTOGENERATED PEROXIDIC SPECIES
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The peroxidic species generated by photooxidation of dialkylsulphides and diazocompounds are able to effect oxidative desulphurisation and deselenation at pentacovalent phosphorus.
- Bhardwaj, Raj K.,Davidson, R. Stephen
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p. 4473 - 4480
(2007/10/02)
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- SELONES AS INTERMEDIATES IN THE PREPARATION OF EXTREMELY STERICALLY HINDERED MOLECULES
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The preparation and reactions of selones, selenium analogues of ketones, are described with particular emphasis on their utility in the preparation of extremely sterically hindered molecules.Mechanistic questions related to these reactions are discussed and evidence for "active selenium" is presented.Selenophilic additions of organometallic compounds to selones are also reported.
- Guziec, Frank S.,Sanfilippo, Lynn James,Murphy, Christopher J.,Moustakis, Christine A.,Cullen, Edward R.
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p. 4843 - 4852
(2007/10/02)
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- STEREOSPECIFIC INTERCONVERSION OF THIO- AND SELENOPHOSPHORYL COMPOUNDS
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The conversion of chiral methyl-n-propylphenylphosphine sulphide into the corresponding selenide and the reverse reaction are easily accomplished by treatment of the corresponding methylthio- and methylselenophosphonium salts with sodium hydrogen selenide and sodium hydrogen sulphide, respectively.Both reactions occur with retention of configuration at phosphorus and high stereospecificity.
- Omelanczuk, Jan,Mikolajczyk, Marian
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p. 321 - 326
(2007/10/02)
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- Oxygen, Sulphur, and Selenium Abstraction from WCl4Y (Y = O, S, or Se) by Triphenylphosphine. Crystal and Molecular Structure of Tetrachlorobis(triphenylphosphine)tungsten(IV)
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Excess of triphenylphosphine has been allowed to react with the series of compounds WCl4Y (Y = O, S, or Se).The products from each reaction have been analysed and subjected to spectroscopic studies which have shown that in each reaction abstraction of the chalcogen atom took place thus reducing tungsten(VI) to tungsten(IV) and yielding WCl4*2PPh3 and P(Y)Ph3.With Y = O a second product, WCl4O*P(O)Ph3*PPh3, was also isolated.The complex WCl4*2PPh3 crystallises in the monoclinic space group P21/n, with a = 9.605(8), b = 21.320(13), c = 9.313(8) Angstroem, β = 117.5(1) deg, and Z = 2.The WCl4*2PPh3 molecules are centrosymmetric with two equivalent W-Cl distances and a long W-P distance .
- Drew, Michael G. B.,Page, Elizabeth M.,Rice, David A.
-
-
- The Chemistry of Heteroarylphosphorus Compounds. Part 15. Phosphorus-31 Nuclear Magnetic Resonance Studies of the Donor Properties of Heteroarylphosphines towards Selenium and Platinum(II)
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The donor properties of a series of heteroarylphosphines (bearing 2- and 3-furyl, 2- and 3-thienyl, and 1-methylpyrrol-2-yl groups directly bound to phosphorus) towards selenium and platinum(II) acceptors have been investigated by 31P n.m.r. studies of the one-bond coupling constants 1J(77Se-31P) and 1J(195Pt-31P).It is shown that the respective coupling constants increase as the heteroaryl groups become more electron withdrawing, indicating an increased s character for the phosphorus lone pair.The implications of this for the relative donor properties of the heteroarylphosphines and PPh3 are considered.
- Allen, David W.,Taylor, Brian F.
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