Unsaturated Phosphorus Research Articles

Highly selective, reversible water activation by P,N-cooperativity in pyridyl-functionalized phosphinines.

Tetrapyridyl-functionalized phosphinines were prepared and structurally characterized. The donor-functionalized aromatic phosphorus heterocycles react highly selectively and even reversibly with water. Calculations reveal P,N-cooperativity for this process, with the flanking pyridyl groups serving to kinetically enhance the formal oxidative addition process of H2O to the low-coordinate phosphorus atom via H-bonding. Subsequent tautomerization forms 1,2-dihydrophosphinine derivatives, which can be quantitatively converted back to the phosphinine by applying vacuum, even at room temperature. This process can be repeated numerous times, without any sign of decomposition of the phosphinine. In the presence of CuI·SMe2, dimeric species of the type ([Cu2I2(phosphinine)]2) are formed, in which each phosphorus atom shows the less common μ2-bridging 2e--lone-pair-donation to two Cu(i)-centres. Our results demonstrate that fully unsaturated phosphorus heterocycles, containing reactive P[double bond, length as m-dash]C double bonds, are interesting candidates for the activation of E-H bonds, while the aromaticity of such compounds plays an appreciable role in the reversibility of the reaction, supported by NICS calculations.

Selective separation and recovery of vanadium from acid leaching solution of polymetallic black shale as function of aminophosphonic acid

AbstractBACKGROUNDAcid leaching is an effective method to extract vanadium from polymetallic black shale. However, a large amount of metal impurities, especially iron and aluminum, which accompany V, are released during this process.RESULTSIn this study, a aminophosphonic acid chelating resin was used for the differential adsorption and desorption of vanadium, iron and aluminum ions to achieve deep separation and concentration of vanadium ions present in the acid leaching solution of polymetallic black shale. Results showed that vanadium adsorption efficiency reached 90.17% at a pH of 1.8. After differential adsorption and desorption, the V:Fe and V:Al concentration ratios increased from 1.84 to 64.53 and from 0.24 to 37.92, respectively. When a 2.5 mol L−1 NaOH solution was used as desorbent, the separation factors β(V/Fe) and β(V/Al) reached values of 694.22 and 452.29, realizing the selective separation and concentration of vanadium.CONCLUSIONIt was found that the vanadium, iron and aluminum ions were selectively adsorbed onto the phosphonic acid functional groups (PO(OH)2) and amino functional groups (NH). The vanadium ions existed in the form of the polyvanadate (), which can be directionally adsorbed onto PO(OH)2 under POH bond cleavage and coordination of to the unsaturated phosphorus atom and then desorbed through the exchange between hydroxide anions OH− and . The iron and aluminum ions cannot be desorbed by OH− because the iron and aluminum sulfate moieties and were capable of coordinating to the nitrogen atom of the NH group via its lone electron pair. © 2022 Society of Chemical Industry (SCI).

ПОРІВНЯННЯ ПОЛІОЛІВ ЯК КАРБОНІЗУЮЧИХ АГЕНТІВ ВОГНЕЗАХИСНИХ КОМПОЗИЦІЙ ІНТУМЕСЦЕНТНОГО ТИПУ

Purpose. To study the influence of the carbonizing agent structure on the formation of thermal insulating char layer of intumescent system acid donor/polyol and on the fire protection efficiency of the system at high temperatures. Methodology. A fire retardant mixture of an acid donor (phosphates ammonium, urea, melamine)/ polyol was chosen as a model intumescent system. Dispersion of vinyl acetate copolymer with ethylene was used as a polymeric component. The study applied the characteristics of the char layer of the intumescent composition at a certain temperature. The volumetric intumescent coefficient (K, cm3/g), mass of char residue (m, %), structure and density of the char layer are proposed as the main estimated parameters of flame retardant effect. IR spectroscopy was used to identify products of thermolysis of intumescent systems. Determination of fire protection efficiency of intumescent coatings was carried out in a mini-oven under standard fire conditions. Findings. The influence of polyol structure on the formation of thermal insulating char layer of intumescent acid donor/polyol system and the prediction of fire protection efficiency of this system under high temperature conditions has been investigated. It has been shown that under conditions of thermal shock the fire protection efficiency is more dependent on the nucleophilic reactivity of the polyol towards the unsaturated phosphorus atom of the acid donor than on its thermal stability. It has been found that pentaerythritol, dipentaerythritol, starch, dextrin, xylitol and sorbitol are the most effective carbonizing agents, regardless of the structure of the acid donor. It has been proved by infrared spectroscopy that at high temperatures as a result of the decomposition of pentaerythritol one of the reaction products is the aldehydes interacting with pentaerythritol with the formation of oligomeric compounds with a simple ether bond C-O-C. At the same time, pentaerythritol can be considered as a universal source of carbon framework for intumescent flame retardants regardless of the phosphate structure used. Originality. It has been shown that an important factor to increase the fire protection efficiency of intumescent systems is the use of polyols with an increased nucleophilicity in the esterification between polyol and phosphoric acid.Practical value. The optimal polyols as carbonizing agents for formulation of intumescent coatings with enhanced fire protection properties have been determined.

The mechanism behind enhanced reactivity of unsaturated phosphorus(v) electrophiles towards thiols.

Vinyl- and ethynyl phosphorus(v) electrophiles are a versatile class of thiol-reactive reagents suitable for cysteine-selective peptide and protein modifications, especially for the generation of antibody conjugates. Herein we investigated the reactivity of various P(v) reagents towards thiol addition. Complementing previous studies, we observed that the heteroatoms X (X = S, O, NH) as well as the vinyl- vs. ethynyl-substituent bound to phosphorus greatly influence the overall reactivity. These experimentally observed trends, as well as the high Z-selectivity for thiol additions to ethynyl derivatives, were further elucidated using DFT calculations. Hyperconjugation was a key means of stabilizing the intermediate generated upon the thiol addition, thus determining both the reactivity and stereoselectivity of unsaturated P(v) electrophiles. Specifically, the energetically low-lying σ antibonding orbital of the P–S bond more readily stabilizes the electron density from the lone pair (LP) of the generated carbanion, rendering the phosphonothiolates more reactive compared to the derivatives bearing oxygen and nitrogen. Our studies provide a detailed mechanistic picture for designing P(v)-based electrophiles with fine-tuned reactivity profiles.

Uncovering the missing piece of unsaturated two-dimensional phosphorus: a theoretical approach

Hyperconjugation-stabilized phosphorus counterparts of graphyne, phosphoryne, with both sp2 (red) and sp3 (blue) P atoms, could be applied as potential photoelectronic nanodevice building blocks and high efficiency photo- and electro-catalysts.

Ambient Degradation-Induced Spin Paramagnetism in Phosphorene.

The sizeable direct bandgap, high mobility, and long spin lifetimes at room temperature offer black phosphorus (BP) potential applications in spin-based semiconductor devices. Toward these applications, a critical step is creating a magnetic response in BP, which is arousing much interest. It is reported here that ambient degradation of BP, which is immediate and inevitable and greatly changes the semiconducting properties, creates magnetic moments, and any degree of degradation leads to notable paramagnetism. Its Landau factor g measured is ≈1.995, revealing that the magnetization mainly results from spin rather than orbital moments. Such magnetism most likely results from the unsaturated phosphorus in the vacancies which are stabilized by O adatoms. It can be tuned by changing any one of the ambient factors of ambient temperature, humidity, and light intensity, and can be stabilized by exposing BP in argon. The findings highlight the importance of evaluating the effect of ambient degradation-induced magnetism on BP's spin-based devices. The work seems an essential milestone toward the forthcoming research upsurge on BP's magnetism.

CF3 -Inspired Synthesis of Air-Tolerant 9-Phosphaanthracenes that Feature Fluorescence and Crystalline Polymorphs.

9-Phosphaanthracene (dibenzo[b,e]phosphorin, acridophosphine) has attracted interest as one of the heavier acenes. Herein, we demonstrate an efficient synthetic process that provides air-tolerant 1,8-bis(trifluoromethyl)-9-phosphaanthracenes. The sterically encumbered and electron-withdrawing trifluoromethyl (CF3 ) groups are quite advantageous not only to stabilize the intrinsically unstable heavier unsaturated phosphorus atom but also to facilitate construction of the phosphinine skeleton based on a putative increase in aromaticity. The isolated 9-phosphaanthracenes allowed characterization of their fluorescence functionality and planar heteroanthracene frameworks. The crystal structures of 9-phosphaanthracenes are remarkably dependent on the aryl substituents at the 10 position; anthryl-substituted 9-phosphaanthracene showed unique polymorphs that induced different-colored crystals.

The Heavier Analogues of Alkenes: A Theoretical Comparison of Unsaturated Group 15/14 Systems

AbstractIn this comprehensive study on unsaturated phosphorus compounds of the type R–P=CR2, R–P=N–R, and R–P=P–R, we investigated how the electronic, spectroscopic, and geometric parameters are influenced by different substituents by means of ab initio and DFT methods. The parent systems are studied with highly accurate theoretical methods and used to benchmark DFT methods. The substituent effects are rationalized based on orbital analysis of DFT calculations for phosphaalkenes, iminophosphanes, and diphosphenes in comparison with their analogous alkenes and imines. Theoretical data are also compared to experimental data if available. This study provides a broad picture of the use of DFT methods for unsaturated main group systems. Trends obtained from this study will enable a rational molecule design for selective manipulation of electronic and geometric properties.

Synthesis of 2,6-Dimesitylphenyl-C,C-Dibromophosphaalkene

GRAPHICAL ABSTRACT

Low-Energy Electron-Induced Decomposition and Reactions of Adsorbed Tetrakis(trifluorophosphine)platinum [Pt(PF3)4

The effect of ∼500 eV electrons on nanometer-thick films of the platinum precursor tetrakis(trifluorophosphine)platinum [Pt(PF3)4] has been studied in situ under ultra-high-vacuum (UHV) conditions using a combination of X-ray photoelectron spectroscopy (XPS), mass spectrometry (MS), and high-resolution electron energy loss spectroscopy (HREELS). Electron irradiation of adsorbed Pt(PF3)4 molecules initially proceeds through a single Pt—P bond-cleavage event and the ejection of one PF3 ligand, analogous to the electron-stimulated reactions of Pt(PF3)4 in the gas phase. The electron-stimulated deposition cross section of Pt(PF3)4, σPt(PF3)4, is governed by the rate of this initial Pt—PF3 cleavage event, which is calculated to be ∼2.5 × 10–15 cm2 at an incident electron energy of 500 eV. In contrast to the initial deposition step, subsequent electron-stimulated reactions of the surface-bound Pt(PF3)3 intermediate occur exclusively through P—F bond cleavage and the release of fluorine into the gas phase. In this second phase of the decomposition process, oxygen uptake into the film is observed because of reactions between water vapor and the coordinatively unsaturated phosphorus atoms formed by P—F bond cleavage. Electron-beam-induced deposition (EBID) of Pt(PF3)4 was also performed by electron irradiating a substrate at room temperature and at higher electron fluxes, in the presence of a constant partial pressure of Pt(PF3)4. The absence of fluorine in these films underscores the role of electron-stimulated P—F bond cleavage, whereas the absence of oxygen highlights the important role that deposition conditions (e.g., substrate temperature and background gas composition) play in determining the ultimate composition of typical EBID films.

ChemInform Abstract: Highly Unsaturated Phosphorus Compounds: Trimeric and Dimeric Sulfides of a α,β‐Di‐tert‐butyl Vinyl Phosphaalkyne.

AbstractThe first examples of sulfides of a 1,3,5‐triphosphabenzene are synthesized by sulfurization of parent phosphabenzene derivative (I).

Highly unsaturated phosphorus compounds: Trimeric and dimeric sulfides of a α,β‐di‐tert‐butyl vinyl phosphaalkyne

AbstractThe first examples of sulfides of a 1,3,5‐triphosphabenzene were synthesized by the sulfurization of parent 1,3,5‐triphosphabenzene 2. Disulfide 7 was found to be remarkably thermally stable, the stability likely coming from the contribution of resonance forms 7A and 7B. In addition to two hydrolysis products of trisulfide 8, which can be anticipated in unsaturated phosphorus chemistry, a new and not trivial bicyclic bridgehead five‐membered heterocycle 10 was isolated among the decomposition products of 8. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:114–118, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.20664

Phospha‐ and Arsaalkenes RE=C(NMe2)2 (E: P, As) as Novel Phosphinidene‐ and Arsinidene‐Transfer Reagents

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Phospha‐ and Arsaalkenes RE=C(NMe2)2 (E = P, As) as Novel Phosphinidene‐ and Arsinidene‐Transfer Reagents

AbstractPhosphinidenes (phosphanylidenes) (RP) are electronically and coordinatively unsaturated phosphorus compounds, which, as six‐electron species, are formally analogous to the more familiar carbenes and nitrenes. In contrast to carbenes (CR2), the extremely reactive phosphinidenes cannot be isolated without decomposition. Thus, our knowledge on phosphinidenes is mainly limited to trapping reactions and quantum‐chemical calculations. There are a number of synthetic methods for phosphinidenes available, for example photolysis or thermolysis of cyclic phosphanes and oligophosphanes, dehalogenation of organodihalophosphanes, liberation of dinitrogen from organodiazidophosphanes, or decomposition of phosphoranylidene‐σ4‐phosphoranes (arylP=PMe3). A plethora of information is available on the generation of highly reactive terminal phosphinidene complexes [RPW(CO)5] and their chemistry. Many of these methods suffer from comparatively harsh conditions (strong base, heat, etc.) which limit their preparative use. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Reactivity of Terminal Electrophilic Phosphinidene Complexes: Synthesis of the First Rhenium Phosphinidene, [Re(CO)5(η1-PNiPr2)][AlCl4], and Novel Reactions with Azobenzene

The first terminal rhenium phosphinidene complex, [Re(CO)5(η1-PNiPr2)][AlCl4], has been synthesized by chloride abstraction from [Re(CO)5{P(Cl)(NiPr2)}]. The electrophilic character of the terminal phosphinidene ligand is demonstrated by phosphine addition at the unsaturated phosphorus center and by novel reactions with azobenzene, PhNNPh, which generate, via C−H activation and P−N and P−C bond formation, coordinated benzodiazaphosphole ligands. The cations [Re(CO)5P(PPh3)NiPr2]+ and [Re(CO)5{P(PhNNHC6H4)NiPr2}]+ have been crystallographically characterized as their AlCl4- salts. The corresponding late-metal terminal phosphinidene complexes [Co(CO)3(PR3)(η1-PNiPr2)][AlCl4] (R = Ph, Et) also afford coordinated benzodiazaphospholes via reaction with PhNNPh.

η2(π)-Coordination of a Bis-Phosphonio-Benzophospholide Cation: A Novel Complexation Mode for Unsaturated Phosphorus Heterocycles

η2(π)-Coordination of a Bis-Phosphonio-Benzophospholide Cation: A Novel Complexation Mode for Unsaturated Phosphorus Heterocycles

Phosphinidene reactivity toward unsaturated phosphorus heterocycles

Abstract The transient electrophilic phosphinidene complex PhPW(CO)5 reacts in the presence of CuCl at room temperature with phospholene 2 and phospholes 4a–c to give the corresponding W(CO)5 complexed products 3 and 5a–c. The intermediate phosphoranylidene phosphine complexes, formed, from the addition of PhPW(CO)5 to the phosphorus atom of the substrates, are characterized by NMR spectroscopy and by a single crystal X-ray structure determination for the one generated from phospholene 2. This intermediate 8 is a CuCl-complexed dimer, which speculatively results from dissociating the phosphole–CuCl tetramer on insertion of PhPW(CO)5 into the P–Cu bonds. Reacting PhPW(CO)5 with phospholene 2 at 110°C in the absence of CuCl gives besides the W(CO)5-complexed phospholene 3 also a bisphospholene–W(CO)4 complex 13. The formation of 13 is attributed to a ligand exchange reaction in the intermediate phosphinidene–phospholene adduct.

Reactions of an antimony containing cage compound with metal carbonyls: synthesis and structural characterization of [{M(CO)5}2(η1:η1-P4Sb2C4But4)], M = Cr, Mo or W, and [{Fe(CO)4}2{Fe(CO)3(η3:η1-P4Sb2C4But4)}

The antimony containing cage compound, P4Sb2C4But4, was treated with an excess of [M(CO)5(THF)], M = Cr, Mo or W, to produce the 2∶1 adduct complexes, [{M(CO)5}2(η1∶η1-P4Sb2C4But4)], which X-ray crystallographic studies have shown to contain one M(CO)5 fragment co-ordinated to an unsaturated phosphorus centre and one co-ordinated to an antimony centre. In contrast, its reaction with an excess of [Fe2(CO)9] produced [{Fe(CO)4}2{Fe(CO)3(η3∶η1-P4Sb2C4But4)}], which is probably formed by the insertion of an Fe(CO)3 fragment into an Sb–P bond of the cage. Its crystal structure confirms that it contains two η1-co-ordinated Fe(CO)4 groups and a 1,3-diphosphaallyl fragment η3 co-ordinated to an Fe(CO)3 moiety.

Versatile Behavior of a New Class of Bicyclic Compounds: Zirconacyclopentadiene Phosphiranes

Diacetylenic phosphanes are cleanly transformed when reacted with zirconocene into zirconacyclopentadiene phosphiranes. These new cyclic systems are the source of a variety of unsaturated phosphorus compounds like phospharadialene or alkenyl alkynyl phosphanes.

Zirconium Species as Tools in Phosphorus Chemistry, 1 [Cp2ZrHCI]n, a Versatile Reagent

Abstract[Cp2ZrHCl]n was found to be a useful reagent for a number of either ring formation or ring opening reactions involving unsaturated phosphorus compounds. Furthermore, treatment of a variety of phosphorus derivatives with [Cp2ZrHCl]n allowed the preparation of several linear or cyclic mono‐, di‐, trior polyphosphanes as well as optically active diphosphanes.