Phosphine Research Articles

Synthesis of Mixed Arylalkyl Tertiary Phosphines via the Grignard Approach.

Trialkyl and triaryl phosphines are important classes of ligands in the field of catalysis and materials research. The wide usability of these low-valent phosphines has led to the design and development of new synthesis routes for a variety of phosphines. In the present work, we report the synthesis and characterization of some mixed arylalkyl tertiary phosphines via the Grignard approach. A new asymmetric phosphine is characterized extensively by multi-spectroscopic techniques. IR and UV–Vis spectra of some selected compounds are also compared and discussed. Density functional theory (DFT)-calculated results support the formation of the new compounds.

Substituent effects of tertiary phosphines on the structures and electrochemical performances of azadithiolato‐bridged diiron model complexes of [FeFe]‐hydrogenases

In this work, a new series of azadithiolato‐bridged diiron complexes [Fe2(μ‐adtNOH)(CO)5{P(C6H4R)3}] (adtNOH = (SCH2)2N(C6H4CH2CH2OH‐p) and R = Cl‐p, 1; Me‐m, 2; OMe‐p, 3 supported by tertiary phosphines, which may be considered as the active site models of [FeFe]‐hydrogenases, has been prepared in 73–81% yields by the Me3NO‐assisted decarbonylating reactions of all‐CO precursor [Fe2(μ‐adtNOH)(CO)6] (A) with several tertiary phosphines [(P(C6H4R)3] in MeCN at room temperature. All the new complexes 1–3 are fully characterized by elemental analysis, spectroscopic techniques (Fourier transform‐infrared spectroscopy [FT‐IR] and nuclear magnetic resonance [NMR]), and especially for 1 and 3 by X‐ray crystallography. The IR and 31P{1H} NMR spectroscopic analyses have shown that the electron density of diiron center in 1–3 may be adjusted by the introduction of the different substituents (R) of the P(C6H4R)3 ligands into the [2Fe2S] cluster. The X‐ray crystallographic investigation has displayed that the typical Fe‐Fe, Fe‐P, and Fe‐C distances of 1–3 are significantly influenced by the electronic effects of the P(C6H4R)3 phosphines coordinated apically to one Fe atom, whereas their Papical‐Fe‐Fe and Capical‐Fe‐Fe angles are mainly controlled by the steric interaction between the phosphine ligands and the dithiolate bridges. Further, the electrochemical performances of 1–3 are studied and compared in the absence or presence of acetic acid (HOAc) as proton source by using cyclic voltammetry, suggesting that they are active for the electrocatalytic proton reduction to hydrogen (H2).

Catalyst‐Free Visible Light Mediated Synthesis of Unsymmetrical Tertiary Arylphosphines

AbstractArylation of tertiary aryl and alkyl phosphines bearing 2‐cyanoethyl group with aryl(mesityl)iodonium triflates under blue light irradiation followed by retro‐Michael reaction of the in situ generated quaternary phosphonium salts initiated by DBU represent a novel efficient and general method for the preparation of distinctly substituted tertiary arylphosphines. An operationally simple, one‐pot protocol features mild, transition‐metal‐free conditions, high selectivity, broad functional group compatibility, as well as scalability and would be applied to substrates with different electronic and steric nature.magnified image

New poly(ether-phosphoramide)s sulfides based on green resources as sensitive films for the specific impedimetric detection of nickel ions

For the development of selective and sensitive chemical sensors, we have developed a new family of poly(ether-phosphoramide) polymers. These polymers were obtained with satisfactory yields by nucleophilic aromatic polycondensation using isosorbide as green resources, and bisphenol A with two novel difluoro phosphinothioic amide monomers. Unprecedented, the thiophosphorylated aminoheterocycles monomers, functionalized with two heterocyclic amine, N-methylpiperazine and morpholine were successfully obtained by nucleophilic substitution reaction of P(S)–Cl compound. The resulting polymers were characterized by different analytical techniques (NMR, MALDI–ToF MS, GPC, DSC, and ATG). The resulting partially green polymers, having tertiary phosphine sulfide with P–N side chain functionalities along the main chain of polymers are the sensitive film at the surface of a gold electrode for the impedimetric detection of Cd, Ni, Pb and Hg. The bio-based poly(ether-phosphoramide) functionalized with N-methylpiperazine modified sensor showed better analytical performance than petrochemical based polymers for the detection of Ni2+. A detection limit of 50 pM was obtained which is very low compared to the previously published electrochemical sensors for nickel detection.

Exploring the Reactivity of B-Connected Carboranylphosphines in Frustrated Lewis Pair Chemistry: A New Frame for a Classic System.

The primary phosphines MesPH2 and tBuPH2 react with 9‐iodo‐m‐carborane yielding B9‐connected secondary carboranylphosphines 1,7‐H2C2B10H9‐9‐PHR (R=2,4,6‐Me3C6H2 (Mes; 1 a), tBu (1 b)). Addition of tris(pentafluorophenyl)borane (BCF) to 1 a, b resulted in the zwitterionic compounds 1,7‐H2C2B10H9‐9‐PHR(p‐C6F4)BF(C6F5)2 (2 a, b) through nucleophilic para substitution of a C6F5 ring followed by fluoride transfer to boron. Further reaction with Me2SiHCl prompted a H−F exchange yielding the zwitterionic compounds 1,7‐H2C2B10H9‐9‐PHR(p‐C6F4)BH(C6F5)2 (3 a, b). The reaction of 2 a, b with one equivalent of R'MgBr (R’=Me, Ph) gave the extremely water‐sensitive frustrated Lewis pairs 1,7‐H2C2B10H9‐9‐PR(p‐C6F4)B(C6F5)2 (4 a, b). Hydrolysis of the B−C6F4 bond in 4 a, b gave the first tertiary B‐carboranyl phosphines with three distinct substituents, 1,7‐H2C2B10H9‐9‐PR(p‐C6F4H) (5 a, b). Deprotonation of the zwitterionic compounds 2 a, b and 3 a, b formed anionic phosphines [1,7‐H2C2B10H9‐9‐PR(p‐C6F4)BX(C6F5)2]−[DMSOH]+ (R=Mes, X=F (6 a), R=tBu, X=F (6 b); R=Mes, X=H (7 a), R=tBu, X=H (7 b)). Reaction of 2 a, b with an excess of Grignard reagents resulted in the addition of R’ at the boron atom yielding the anions [1,7‐H2C2B10H9‐9‐PR(p‐C6F4)BR’(C6F5)2]− (R=Mes, R’=Me (8 a), R=tBu, R’=Me (8 b); R=Mes, R’=Ph (9 a), R=tBu, R’=Ph (9 b)) with [MgBr(Et2O) n ]+ as counterion. The ability of the zwitterionic compounds 3 a, b to hydrogenate imines as well as the Brønsted acidity of 3 a were investigated.

Cooperative Tertiary Phosphine/Palladium Catalyzed Nucleophilic Allylation between Morita‐Baylis‐Hillman Carbonates and Alkenes

AbstractIn this work, we report an unusual nucleophilic allylation reaction between isatin‐derived Morita–Baylis–Hillman carbonates and simple alkenes synergistically catalyzed by tertiary phosphines and palladium complexes, through chemoselective assemblies of in situ formed onium salts and η1‐allylpalladium species, respectively. A range of 3,3‐disubstituted oxindoles were easily constructed in moderate to good yields with exclusive linear regioselectivity. Moreover, a number of control and deuterium experiments have been conducted to elucidate the catalytic mechanism.

9-Phosphatriptycene Derivatives: From Their Weak Basicity to Their Application in Frustrated Lewis Pair Chemistry.

The accurate prediction of the basicity of tertiary phosphines in acetonitrile and water is reported by the linear correlation between computed ΔpKa's obtained by density functional theory (DFT) and experimental values extracted from the literature. This method is applied to the prediction of pKa values of 9-phosphatriptycene derivatives and showed that they are weaker Brønsted bases than their triphenylphosphine analogues. This lower reactivity is attributed to their high pyramidalization that increases their lone pair 3s character, stabilizing its energy level. Their potential application in frustrated Lewis pair chemistry is then considered by investigating the hydrogenation of 1,1-diphenylethylene by the tris(pentafluorophenyl)borane/1-chloro-9-phosphatriptycene frustrated Lewis pair.

Synthesis and structural characterization of some 1:1 adducts of silver(I) salts with (hindered) PR3 bases (R = phenyl, o-tolyl, cyclohexyl)

Syntheses, spectroscopy and single crystal X-ray structural characterizations are recorded for a number of adducts AgX: PR3 (1:1)n obtained from the reaction of silver(I) salts with sterically hindered tertiary phosphine bases, extending previous studies. With tris(o-tolyl)phosphine, P(o-tolyl)3, binuclear adducts AgX: P(o-tolyl)3 (1:1)2 are defined, in arrays with eight-membered central rings [(o-to1yl)3PAg(μ-tfa)2AgP(o-tolyl)3] (1) (tfa = trifluoroacetate, O.CO.CF3) where two independent atoms of the anion bridge to the two silver atoms, and four-membered central rings where one atom bridges (Cl, NCO, acetate (= 'ac', O.CO.CH3)) (complexes 2–4); the perchlorate (5) is intermediate, one perchlorate bridging via one oxygen and the other by two. The nitrate is mononuclear, [(o-tolyl)3PAgO2NO], (6) with chelating nitrate. The bromide takes a tetranuclear 'cubane' form (7). With the cyanide, an interesting 2:1 AgCN: (o-tolyl)3P adduct (8) is defined as a two-dimensional polymer. The archetypical cubane series with triphenylphosphine is extended with a new bromide structure, MeCN solvated [(Ph3P)AgBr]4.0.22MeCN (9), to encompass also the cyanate [(Ph3P)Ag(NCO)]4 (10), isomorphous with the previously defined Cu/As/I chloroform solvate. The 'cubane' form is defined also for a further iodide polymorph AgI: Pcy3 (1:1)4 (11).

Visible-Light-Promoted Unsymmetrical Phosphine Synthesis from Benzylamines.

Herein, by applying visible-light photoredox catalysis, we have achieved the catalytic deaminative alkylation of diphenylphosphine and phenyl phosphine with benzylamine-derived Katritzky salts at room temperature. The use of Eosin Y as photoredox catalyst and visible light can largely promote the reaction. A series of unsymmetrical tertiary phosphines were successfully synthesized, including phosphines with three different substituents that are otherwise difficult to obtain.

Copper(I)‐Catalyzed Asymmetric Synthesis of P‐Chiral Aminophosphinites

AbstractHerein, a copper(I)‐catalyzed reaction of diarylphosphines and O‐benzoyl hydroxylamines is developed. In the cases of symmetrical diarylphosphines, a series of aminophosphinites is prepared in high yields. In the cases of unsymmetrical diarylphosphines, an array of P‐chiral aminophosphinites is synthesized in high yields with high enantioselectivity by using a copper(I)‐(R,RP)‐Ph‐FOXAP complex as a chiral catalyst. Based on several control experiments and 31P NMR studies, a two‐electron redox mechanism involving the dynamic kinetic asymmetric transformation of unsymmetrical diarylphosphines is proposed for the copper(I)‐catalyzed asymmetric reaction. Finally, one representative P‐chiral phosphoric amide generated through the oxidation with H2O2 is transformed to a chiral diarylphosphinate in high yield with retained enantioselectivity, which allows further transformations towards various P‐chiral tertiary phosphines.

Copper(I)-Catalyzed Asymmetric Synthesis of P-Chiral Aminophosphinites.

Herein, a copper(I)-catalyzed reaction of diarylphosphines and O-benzoyl hydroxylamines is developed. In the cases of symmetrical diarylphosphines, a series of aminophosphinites is prepared in high yields. In the cases of unsymmetrical diarylphosphines, an array of P-chiral aminophosphinites is synthesized in high yields with high enantioselectivity by using a copper(I)-(R,RP )-Ph-FOXAP complex as a chiral catalyst. Based on several control experiments and 31 P NMR studies, a two-electron redox mechanism involving the dynamic kinetic asymmetric transformation of unsymmetrical diarylphosphines is proposed for the copper(I)-catalyzed asymmetric reaction. Finally, one representative P-chiral phosphoric amide generated through the oxidation with H2 O2 is transformed to a chiral diarylphosphinate in high yield with retained enantioselectivity, which allows further transformations towards various P-chiral tertiary phosphines.

Ni-Catalyzed Enantioselective Benzylation of Secondary Phosphine Oxide.

A nickel-catalyzed benzylic substitution of secondary phosphine oxide was described, affording the dialkylated P-stereogenic tertiary phosphine oxides with high to excellent enantioselectivities. The reaction was performed under mild conditions with commercially available benzyl chlorides and bench stable secondary phosphine oxides, exhibiting broad functional group tolerance. It represented a practical example for the preparation of P-stereogenic phosphine compounds.

The stereoselective conversion of epimerized alkoxyl phosphine-borane to P,C, axial-stereogenic tertiary phosphine via cleavage of P-O bond.

The P-O bond of epimerized alkoxyl phosphine-borane was cleaved by naphthalene-lithium, to form two diastereomers of P-anions in a ratio of 86 : 14, which was then converted to secondary phosphine-borane via acidification, and to tertiary phosphines with alkyl halides with enhanced 96 : 4 dr. The isolated tertiary phosphine containing hydroxyl (in >99 : 1 dr) was converted to multi-stereogenic tertiary phosphines via O-alkylation with alkylene dihalides.

Electrochemical oxidative N-H/P-H cross-coupling with H2 evolution towards the synthesis of tertiary phosphines.

Tertiary phosphines(iii) find widespread use in many aspects of synthetic organic chemistry. Herein, we developed a facile and novel electrochemical oxidative N–H/P–H cross-coupling method, leading to a series of expected tertiary phosphines(iii) under mild conditions with excellent yields. It is worth noting that this electrochemical protocol features very good reaction selectivity, where only a 1 : 1 ratio of amine and phosphine was required in the reaction. Moreover, this electrochemical protocol proved to be practical and scalable. Mechanistic insights suggested that the P radical was involved in this reaction.

Theoretical studies on structure-directing interactions of diphenyl N-(2-pyrazinyl carbonyl) phosphoramidate

Herein, we report the strength of structure-directing interactions in the crystal packing of diphenyl N-(2-pyrazinyl carbonyl) phosphoramidate (1) through computing their binding energies by DFT. Further, the non-covalent interaction (NCI) analysis, molecular Hirshfeld surfaces, and the corresponding two-dimensional fingerprint plots are obtained to gain a deep understanding of the importance of these interactions in the stability of a crystal structure. Despite the important role of the phosphorus—chalcogenid bond in optimizing tertiary phosphine chalcogenides, their computational studies have been lagging far behind. The nature and electronic structure of this bond in (N2C4H3)C(O)NHP(E)(OC6H5)2 (E = O (1), S (2), and Se (3)) are evaluated by QTAIM, MEP, and HOMO—LUMO energy gaps.

Sulfonium cations as versatile strongly π-acidic ligands.

More than a century old, sulfonium cations are still intriguing species in the landscape of organic chemistry. On one hand they have found broad applications in organic synthesis and materials science, but on the other hand, while isoelectronic to the ubiquitous tertiary phosphine ligands, their own coordination chemistry has been neglected for the last three decades. Here we report the synthesis and full characterization of the first Rh(i) and Pt(ii) complexes of sulfonium. Moreover, for the first time, coordination of an aromatic sulfonium has been established. A thorough computational analysis of the exceptionally short S–Rh bonds obtained attests to the strongly π-accepting nature of sulfonium cations and places them among the best π-acceptor ligands available today. Our calculations also show that embedding within a pincer framework enhances their π-acidity even further. Therefore, in addition to the stability and modularity that these frameworks offer, our pincer complexes might open the way for sulfonium cations to become powerful tools in π-acid catalysis.

Synthesis of Tertiary Phosphine Chalcogenides and Their Derivatives with Azine and Azole Groups from Red Phosphorus and Functionalized Pyridines, Imidazoles, Pyrazoles and Their Antimicrobial and Cytostatic Activity

Synthesis of Tertiary Phosphine Chalcogenides and Their Derivatives with Azine and Azole Groups from Red Phosphorus and Functionalized Pyridines, Imidazoles, Pyrazoles and Their Antimicrobial and Cytostatic Activity

Regulation of Silver Precursor Reactivity via Tertiary Phosphine to Synthesize Near-Infrared Ag2Te with Photoluminescence Quantum Yield of up to 14.7%

Regulation of Silver Precursor Reactivity via Tertiary Phosphine to Synthesize Near-Infrared Ag₂Te with Photoluminescence Quantum Yield of up to 14.7%

Antibacterial, spectroscopic and X-ray crystallography of newly prepared heterocyclic thiourea dianion platinum(II) complexes with tertiary phosphine ligands

Treatment of one molar equivalent of [PtCl2(diphos)] (diphos = dppe, dppp, dppb or dppf) or [PtCl2(PPh3)2] with one molar equivalent of (H2CPPT) in the presence of Et3N afforded the new heterocyclic thiourea dianion complexes [Pt(κ2-CPPT)(diphos)] and [Pt(κ2-CPPT)(PPh3)2] (1–5). The synthesized complexes were characterized by FT-IR, 1H NMR and 31P-{1H} NMR spectroscopy. Moreover, X-ray single crystal structure determination for complexes [Pt(κ2-CPPT)(dppe)] (1) and [Pt(κ2-CPPT)(dppb)] (3) showed a four membered ring structure with the Pt(II) ion being central and adopting a slightly distorted square planar geometry. Furthermore, the X-ray structures showed that the sulfur atom is trans to the phosphine ligand with the shortest Pt-P bond, compared to the nitrogen atom that is trans to the other Pt-P bond. Interestingly, the obtained complexes, apart from previously synthesized ones, showed one isomer formation only. This behavior is probably due to the inductive effect for both of the heteroatoms and the chlorine atom on the pyridyl group. Generally, the prepared complexes showed similar behavior to their analogous non-substituted thiourea dianion complexes, with no observable effect of the heteroatom on the overall structure. Furthermore, antibacterial activities were tested against three pathogenic bacterial species; among the four tested complexes, complexes 4 and 2 showed high activity values.

Orthopalladated tetralone oxime compounds bearing tertiary phosphines: Synthesis, structure, biological and in silico studies

The halido-α-bridge cleavage reactions between [Pd(C2,N-tetrox)(μ-Cl)]2 precursor (tetrox = E-α-tetralone oxime) with phosphines, in 1:2 molar ratio, have afforded mononuclear cyclopalladated compounds of the type [PdCl(C2,N-tetrox)(L)] {L = triphenylphosphine (1); tris(4-methylphenyl)phosphine (2); tris(4-fluorophenyl)phosphine (3) and tris(4-methoxyphenyl)phosphine (4)}. The compounds have been characterized by elemental analyses, infrared (FT-IR) and 1H, 13C{1H} and 31P{1H}-NMR spectroscopies. The molecular structure of 3 has been determined by single crystal X-ray diffraction (SC-XRD) and the Hirshfeld Surface calculation (HS) has been performed. The antiproliferative activity of compounds 1–4 has been evaluated against breast (MCF-7) and lung (A549) human cancer cells, and human lung fibroblast (MRC-5). All cyclopalladated compounds have been more active than cisplatin against MCF-7 cells, with IC50 values ranging from 19 to 26 µM. Binding experiments involving compound 3 with ct-DNA and human serum albumin (HSA) have been carried out using spectroscopic techniques. The interaction between compound 3 and HSA has been studied by means of molecular docking.