Phosphine Research Articles

Amine‐containing tertiary phosphine‐substituted diiron ethanedithioate (edt) complexes Fe2(μ‐edt)(CO)6‐nLn (n= 1, 2): Synthesis, protonation, and electrochemical properties

As diiron subsite models of [FeFe]‐hydrogenases for catalytic proton reduction to hydrogen (H2), a new series of the phosphine‐substituted diiron ethanedithiolate complexes Fe2(μ‐edt)(CO)6‐nLn (n = 1, 2) were prepared from the variable substitutions of all‐CO precursor Fe2(μ‐edt)(CO)6 (A) and tertiary phosphines (L1‐L4) under different reaction conditions. While the Me3NO‐assisted substitutions of A and one equiv. ligands L1‐L4 [L = Ph2P(CH2NHBut), Ph2P(CH2CH2NH2), Ph2P(NHBut), and Ph2P(C6H4Me‐p)] produced the monosubstituted complexes Fe2(μ‐edt)(CO)5L (1–4) in good yields, the refluxing xylene solution of A and two equiv. ligand L1 prepared complex Fe2(μ‐edt)(CO)5{κ1‐Ph2P(CH2NHBut)} (1) in low yield. Meanwhile, the UV‐irradiated toluene solution of A and two equiv. ligand L3 resulted in the rare formation of the disubstituted complex Fe2(μ‐edt)(CO)4{κ1, κ1‐(Ph2PNHBut)2} (5) in low yield, whereas the Me3NO‐assisted substitution of A and two equiv. ligand L4 afforded the disubstituted complex Fe2(μ‐edt)(CO)4{κ1, κ1‐(Ph2PC6H4Me‐p)2} (6) in good yield. All the model complexes 1–6 have been characterized by elemental analysis, FT‐IR, NMR spectroscopy, and particularly for 1, 3, 5 by X‐ray crystallography. Further, the protonations of complexes 1–4 are studied and compared with excess acetic acid (HOAc) and trifluoroacetic acid (TFA) by using FT‐IR and NMR techniques. Additionally, the electrochemical and electrocatalytic properties of model complexes 1–6 are investigated and compared by cyclic voltammetry (CV), suggesting that they are electrocatalytically active for proton reduction to H2 in the presence of HOAc.

Correlated ab initio calculations of one-bond 31 P77 Se and 31 P125 Te spin-spin coupling constants in a series of PSe and PTe systems accounting for relativistic effects (part 2).

Synthetic chalcogen-phosphorus chemistry permanently makes new challenges to computational Nuclear Magnetic Resonance (NMR) spectroscopy, which has proven to be a powerful tool of structural analysis of chalcogen-phosphorus compounds. This paper reports on the calculations of one-bond 31 P77 Se and 31 P125 Te NMR spin-spin coupling constants (SSCCs) in the series of phosphine selenides and tellurides. The applicability of the combined computational approach to the one-bond 31 P77 Se and 31 P125 Te SSCCs, incorporating the composite nonrelativistic scheme, built of high-accuracy correlated SOPPA (CC2) and Coupled Cluster Single and Double (CCSD) methods and the Density Functional Theory (DFT) relativistic corrections (four-component level), was examined against the experiment and another scheme based on the four-component relativistic DFT method. A special J-oriented basis set (acv3z-J) for selenium and tellurium atoms, developed previously by the authors, was used throughout the NMR calculations in this work at the first time. The proposed computational methodologies (combined and 'pure') provided a reasonable accuracy for 31 P77 Se and 31 P125 Te SSCCs against experimental data, characterizing by the mean absolute percentage errors of about 4% and 1%, and 12% and 8% for selenium and tellurium species, respectively. The present study reports typical relativistic corrections to 77 Se31 P and 125 Te31 P SSCCs, calculated within the four-component DFT formalism for a broad series of tertiary phosphine selenides and tellurides with different substituents at phosphorus.

Synthesis of Aryldiphenylphosphine Oxides by Quaternization of Tertiary Diphenylphosphines with Aryl Bromides Followed by the Wittig Reaction.

A two-step method for the synthesis of aryldiphenylphosphine oxides from tertiary diphenylphosphines and aryl bromides is developed. The first step is the quaternization of methyldiphenylphosphine or benzyldiphenylphosphine with aryl bromides. This quaternization can be nickel-catalyzed (metal-free in some cases), and tolerate of a variety of functional groups, furnishing quaternary phosphonium salts in 48–90% yields. The second step is Wittig reactions of these quaternary phosphonium salts with furan-2-carbaldehyde or p-chlorobenzaldehyde to provide aryldiphenylphosphine oxides in 27–90% yields. The use of the Wittig reaction for the synthesis of tertiary phosphine oxides is in contrast to its traditional use for the synthesis of olefins, leaving tertiary phosphine oxide as a byproduct. This quaternization–Wittig method can be applied to synthesize aryldiphenylphosphine oxides that are difficult to access by the alkaline hydrolysis of aryltriphenylphosphonium salts, especially those bearing an electron-deficient aryl group. The ligand-coupling mechanism for the alkaline hydrolysis of (p-acylphenyl)triphenylphosphonim salts is also discussed.

Secondary Phosphine Oxides: Bifunctional Ligands in Catalysis

AbstractMetal complexes of secondary phosphine oxides (SPOs) were introduced as homogeneous catalysts in the 1980s for hydroformylation and hydrogenation with platinum as the metal. As neutral species, the ligand properties resemble those of the corresponding tertiary phosphines as was shown in the coordination chemistry developed in the 1970s, but the participation of the OH in bonding and reaction mechanisms provides them with a peculiar additional function. While this was already proposed and recognized in the first publications, it took a while before this found wider appreciation. Meanwhile, SPOs have become popular ligands for homogeneous catalysts, and more recently also for catalysis based on metal nanoparticles. Here we review the relatively small number of publications that pay attention to SPOs as bifunctional ligands.

Metallized Phosphane-Ene Polymer Networks as Precursors for Ceramics with Excellent Shape Retention.

Our research group has reported the synthesis of phosphane-ene photopolymer networks, where the networks are composed of cross-linked tertiary alkyl phosphines. Taking advantage of the rich coordination chemistry of alkyl phosphines and the material's susceptibility to solution chemistry, we were able to generate Co, Al, and Ge macromolecular adducts. The metallized polymer networks can be pyrolyzed to make metal-doped carbon, commodity materials in the areas of battery, and fuel cell research. The polymer precursors can also be shaped by spin coating and lithography, before being metallized and pyrolyzed to give patterned ceramics, which display excellent shape retention of the original patterns.

Taming the Reactivity of Phosphiranium Salts: Site-Selective C-Centered Ring Opening for Direct Synthesis of Phosphinoethylamines.

Advances in the field of phosphorus chemistry are documented, by revealing the synthetic utility of previously underutilized quaternary phosphiranium salts (QPrS) as three-chain-atom electrophilic building blocks. Notably, control of their challenging C-centered electrophilicity is disclosed with an expedient synthesis of tertiary β-anilino phosphines as a proof-of-concept.

Effective Control of the Electron‐donating Ability of Phosphines by using Phosphazenyl and Phosphoniumylidyl Substituents

Phosphoniumylidyl and phosphazenyl groups are effective substituents to increase the electron‐donating ability of tertiary phosphines. However, the influence of structural variations among those substituents on the electronic properties of the phosphines is little explored. Herein, we show that protonation of the ylidic carbon atom of phosphoniumylidyl phosphines increases the Tolman electronic parameter (TEP) by ΔTEP = 16.0–18.8 cm–1. Furthermore, phosphazenyl phosphines were synthesized with isopropyl groups (NP{iPr}3) and tetramethylguanidino groups (NP{tmg}3) at the phosphonium center. Determination of their TEP values reveals a remarkable low substituent parameter of χ = –18.5 cm–1 for the NP(tmg)3 group. In addition, we prepared the corresponding gold(I) complexes and determined their solid‐state structures using single‐crystal X‐ray diffraction studies to analyze the steric profile of the new phosphine ligands.

Aluminum Phosphide Poisoning and Blast in Gastric Tube a Rare Phenomenon- A Case Report

Suicide by poisoning is the second most common cause of death by suicide (27.9%) as per The National Crime Records Bureau (NCRB) India in 2015.Aluminum phosphide (ALP) is the leading agricultural poison used to commit suicide as where its availability is not properly regulated. Aluminum phosphide (ALP) is a highly toxic solid fumigant pesticide, rodenticide and insecticide. It is commonly used as outdoor and indoor pesticide in developing countries like India, Pakistan, Srilanka and Iran because it is a cheap, effective, free from toxic residue and do not alter the viability of seeds. Aluminium Phosphide (ALP) is a highly toxic fumigant which is used commonly as an indoor pesticide in agriculture based industry for storage of grains. ALP on ingestion reacts with a gastric water and release phosphine gas, which is highly flammable, and very toxic in nature. Over the last few decades ALP has emerged as an agent of choice being used as suicidal poisoning in a country where it is readily available. The high mortality rate is due to severe mitochondrial dysfunction leading to disruption of cellular respiration, causing tissue hypoxia and organ dysfunction. Despite long research no specific antidote could be developed and the treatment remained supportive. Spontaneous ignition of phosphine (PH3) is a rare but very peculiar phenomenon reported in the case of aluminium phosphide poisoning. Here we share our experience in a case of phosphine (PH3) poisoning, which presented with spontaneous ignition and blast during treatment which caught the attention of local and national media in India,

Unusual Racemization of Tertiary P-Chiral Ferrocenyl Phosphines.

Tertiary phosphines are generally known to withstand inversion under moderate conditions. In this work, a remarkable racemization process of three P‐chiral ferrocenyl phosphines is reported. Subjected to conventional column chromatography as highly enantioenriched compounds, they greatly experienced racemization when collected at the column outlet within minutes. Initially, attention was drawn to this unusual inversion behavior after observing that the superb enantiomeric excess of these ligands (>95 % ee in all cases) was almost lost in their corresponding ruthenium(II) complexes. Successively excluding possible racemization causes, these P‐chiral ferrocenyl phosphines were found to undergo a significant, acid‐catalyzed racemization process at room temperature within a few minutes. This process is mainly observed during standard column chromatography by using conventional silica or alumina, but can also be triggered deliberately by addition of certain acids. Therefore, the stereochemical preservation of P‐chiral phosphines during their purification may per se not always be guaranteed, since column chromatography is the most frequently used technique for purifying such types of compounds.

Tertiary Phosphine and Arsine Complexes of Phosphorus Pentafluoride: Synthesis, Properties, and Electronic Structures.

The reaction of PMe3 or PPh3 with PF5 in anhydrous CH2Cl2 or hexane forms the white, moisture-sensitive complexes [PF5(PR3)] (R = Me, Ph). Similar reactions involving the diphosphines o-C6H4(PR2)2 afford the complexes [PF4{o-C6H4(PR2)2}][PF6]. The X-ray structures of [PF5(PR3)] and [PF4{o-C6H4(PMe2)2}][PF6] show pseudo-octahedral fluorophosphorus centers. Multinuclear NMR spectra (1H, 19F{1H}, 31P{1H}) show that in solution in CH2Cl2/CD2Cl2 the structures determined crystallographically are the only species present for [PF5(PMe3)] and [PF4{o-C6H4(PMe2)2}][PF6] but that [PF5(PPh3)] and [PF4{o-C6H4(PPh2)2}][PF6] exhibit reversible dissociation of the phosphine at ambient temperatures, although exchange slows at low temperatures. The complex 19F{1H} and 31P{1H} NMR spectra have been analyzed, including those of the cation [PF4{o-C6H4(PMe2)2}]+, which is a second-order AA'XX'B2M spin system. The unstable [PF5(AsMe3)], which decomposes in a few hours at ambient temperatures, has also been isolated and spectroscopically characterized; neither AsPh3 nor SbEt3 forms similar complexes. The electronic structures of the PF5 complexes have been explored by DFT calculations. The DFT optimized geometries for [PF5(PMe3)], [PF5(PPh3)], and [PF4{o-C6H4(PMe2)2}]+ are in good agreement with their respective crystal structure geometries. DFT calculations on the PF5-L complexes reveal the P-L bond strength falls with L in the order PMe3 > PPh3 > AsMe3, consistent with the experimentally observed stabilities, and in the PF5-L complexes, electron transfer from L to PF5 on forming these complexes also follows the order PMe3 > PPh3 ≈ AsMe3.

Carbon-Phosphorus Coupling from C^N Cyclometalated AuIII Complexes.

With the aim of exploiting new organometallic species for cross‐coupling reactions, we report here on the AuIII‐mediated Caryl−P bond formation occurring upon reaction of C^N cyclometalated AuIII complexes with phosphines. The [Au(C^N)Cl2] complex 1 featuring the bidentate 2‐benzoylpyridine (CCON) scaffold was found to react with PTA (1,3,5‐triaza‐7‐phosphaadamantane) under mild conditions, including in water, to afford the corresponding phosphonium 5 through C−P reductive elimination. A mechanism is proposed for the title reaction based on in situ 31P{1H} NMR and HR‐ESI‐MS analyses combined with DFT calculations. The C−P coupling has been generalized to other C^N cyclometalated AuIII complexes and other tertiary phosphines. Overall, this work provides new insights into the reactivity of cyclometalated AuIII compounds and establishes initial structure–activity relationships to develop AuIII‐mediated C−P cross‐coupling reactions.

Late-Stage Modification of Tertiary Phosphines via Ruthenium(II)-Catalyzed C-H Alkylation.

Ru(II)-catalyzed direct alkylation of tertiary phosphines via hydroarylation of activated olefins promoted by mono-N-protected amino acid (MPAA) was achieved. This protocol provides a straightforward access to a large library of Buchwald-type bulky alkylated monophosphines from commercially available biaryl phosphine. Moreover, two ruthenacycle intermediates of tertiary phosphines via C-H bond cleavage were isolated to illustrate the mechanism of P(III)-directed C-H activation.

C–P vs C–H Bond Cleavage of Triphenylphosphine at Platinum(0): Mechanism of Formation, Reactivity, Redox Chemistry, and NMR Chemical Shift Calculations of a μ-Phosphanido Diplatinum(II) Platform

Transition-metal phosphanides M–PR2 are key intermediates in catalytic C–P bond functionalization. M–PR2 formation from tertiary phosphines through P–C bond cleavage widens the scope beyond P–H fun...

Tertiary phosphines in reactions with substituted cinnamic acids

A new effective method for the synthesis of quaternary phosphonium salts has been elaborated. Quaternary phosphonium salts have been obtained on the basis of reactions of tertiary phosphines of different structure with substituted cinnamic acids. The structure and composition of the synthesized compounds have been proved by IR, NMR 1H, 31P and 13C spectroscopy, elemental analysis.

Asymmetric Electrophilic Reactions in Phosphorus Chemistry

This review is devoted to the theoretic and synthetic aspects of asymmetric electrophilic substitution reactions at the stereogenic phosphorus center. The stereochemistry and mechanisms of electrophilic reactions are discussed—the substitution, addition and addition-elimination of many important reactions. The reactions of bimolecular electrophilic substitution SE2(P) proceed stereospecifically with the retention of absolute configuration at the phosphorus center, in contrast to the reactions of bimolecular nucleophilic substitution SN2(P), proceeding with inversion of absolute configuration. This conclusion was made based on stereochemical analysis of a wide range of trivalent phosphorus reactions with typical electrophiles and investigation of examples of a sizeable number of diverse compounds. The combination of stereospecific electrophilic reactions and stereoselective nucleophilic reactions is useful and promising for the further development of organophosphorus chemistry. The study of phosphoryl group transfer reactions is important for biological and molecular chemistry, as well as in studying mechanisms of chemical processes involving organophosphorus compounds. New versions of asymmetric electrophilic reactions applicable for the synthesis of enantiopure P-chiral secondary and tertiary phosphines are discussed.

Synthesis, structural and toxicological investigations of quarternary phosphonium salts containing the P-bonded bioisosteric CH2F moiety

Tertiary alkyl, aryl or amino phosphines PR3 (R = Me, nBu, C2H4CN, NEt2) and the bis[(2-diphenylphosphino)phenyl]ether (POP) were allowed to react with fluoroiodomethane to produce fluoromethyl phosphonium salts in yields between 60–99%.

Synthesis, characterization, kinetic investigation and biological evaluation of Re(i) di- and tricarbonyl complexes with tertiary phosphine ligands

Rhenium(i) di- and tri-carbonyl complexes of the form fac-[Re(CO)3(L,L'-Bid)X] and [Re(CO)2(L,L'-Bid)X2], where X = aqua (H2O), methanol (CH3OH), triphenylphosphine (PPh3), 1,3,5-triaza-7-phosphaadamantane (PTA), tricyclohexylphosphine (PCy3) and L,L'-Bid = O,O' bidentate ligands (tropolone = TropH and 3-hydroxyflavone = FlavH) and N,O bidentate ligands (8-hydroxyquinoline = QuinH, 5,7-chloro-8-hydroxyquinoline = diCl-QuinH and quinoline-2,4-dicarboxylic acid = QuinH2), were synthesized and unambiguously characterized by 1H-, 13C-and 31P-NMR, IR, UV/Vis and micro-analysis. The crystal structures of four complexes, namely fac-[Re(CO)3(QuinH)(H2O)]·H2O (5), fac-[Re(CO)3(Quin)(PPh3)] (11), fac-[Re(CO)3(diCl-Quin)(PPh3)] (12) and [Re(CO)2(Trop)(PPh3)2]·2C6H5CH3 (20) were obtained. Re-P bonding distances for 11 and 12 are 2.4948(8) and 2.4908(8) Å, respectively, indicating the effect of the electron-withdrawing substituents of the diCl-Quin- ligand. The second-order rate constants for the substitutions of methanol at 25.1 °C in fac-[Re(CO)3(L,L'-Bid)(CH3OH)] (L,L'-Bid = Trop, Flav and QuinH) type complexes by different entering phosphine ligands (PPh3, PCy3, and PTA) varied between 7.23(7) × 10-5 and 1.32(3) × 10-3 M-1 s-1 and were found to depend on the coordinated bidentate ligand (in general k1 (QuinH) < k1 (Trop) < k1 (Flav)). The toxicity of fac-[Re(CO)3(QuinH)(PTA)], fac-[Re(CO)3(Trop)(PTA)], fac-[Re(CO)3(Trop)(PPh3)] and fac-[Re(CO)3(Flav)(PPh3)] on the cervical cancer HeLa and epithelial RPE-1 cell lines was then evaluated. Complex fac-[Re(CO)3(Flav)(PPh3)] (16) and fac-[Re(CO)3(Trop)(PPh3)] (13) displayed the highest cytotoxicity with IC50 values of 12.21 ± 0.17 μM and 13.35 ± 0.94 μM, respectively in HeLa cells. Interestingly, a small selectivity towards cancer over non-cancerous cells was observed for these compounds (IC50 = 18.41 ± 3.16 μM and >25 μM in RPE-1 cells).

The construction of three C–P bonds of P-stereogenic tertiary phosphines containing (l)-menthyl

A wide range of RP or SP-(l)-menthyl-containing SPOs were prepared via the reaction of 1,1′-bi(2-naphthol) derived phosphonite with a metallic reagent with excellent yield and dr.

Synthesis, reactivity and catalytic activity of Au-PAd3 complexes.

Tri(1-adamantyl)phosphine (PAd3) possesses unique steric and electronic properties positioning it at the border between tertiary phosphines and N-heterocyclic carbenes (NHC). Novel Au-PAd3 complexes were synthesized from the known [Au(PAd3)Cl]. We have optimised reaction conditions for the synthesis of this useful synthon in order to circumvent the formation of the [Au(PAd3)2]Cl. [Au(PAd3)Cl] was used to access a number of derivatives and some were deployed as catalysts. The hydration of alkynes was targeted to gauge the reactivity of Au-PAd3 complexes and permit comparison with NHC and tertiary phosphine congeners.

Radical reactions promoted by trivalent tertiary phosphines

The background and recent breakthroughs in the single-electron-transfer (SET) reactions with trivalent tertiary phosphines are summarized and discussed in detail, and an outlook in the developments within this field is provided.