Reaction Of Phosphine Research Articles

Co-Catalyzed P-H Activation and Related Cp*Co(III) Phosphine Complexes.

This study reports that the well-known Co(III) precursor Co(η5-Cp*)I2(CO) (1) is an effective precatalyst for dehydrocoupling reactions of phosphines. Reaction monitoring by NMR, complemented by ESI-MS and EPR, suggests that Co(III) complexes containing secondary and primary phosphine ligands play an important role in this catalysis but that redox chemistry is also facile for these complexes, resulting in paramagnetic species. Representative examples of the mono(phosphine) complexes Co(η5-Cp*)I2(PR2H) (2) and Co(η5-Cp*)I2(PRH2) (4) and bis(phosphine) complexes [Co(η5-Cp*)I(PR2H)2] I (3) have been prepared. The characterization of these complexes through structural, computational, spectroscopic, and electrochemical analysis is reported and serves as a foundation for considering their mechanistic significance in the observed catalytic dehydrocoupling chemistry.

Reactions of Benzyl Phosphine Oxide/Sulfide with (COCl)2: Synthesis of Novel Acyl Chloride-Substituted Chlorophosphonium Ylides.

New reactions of benzyl phosphine oxide/sulfide with oxalyl chloride are presented. The resulting reactive intermediates, acyl chloride-substituted chlorophosphonium ylides, are capable of undergoing esterification and Friedel-Crafts acylation reactions, ultimately yielding either methyl 2-(2-bromophenyl)-2-(diphenylphosphoryl)acetate or β-carbonyl-diarylphosphine oxide derivatives. Additionally, when an alkynyl group is contained in the acyl chloride-substituted chlorophosphonium ylide, intramolecular cyclization occurs, leading to the formation of a pair of trans- and cis-dichlorophosphonyl benzofulvene isomers. The generation process of acyl chloride-substituted chlorophosphonium ylide was carefully monitored by using 31P{1H} NMR spectroscopy, and a plausible reaction mechanism was proposed.

A supramolecular photosensitizer based on triphenylamine and pyrazine with aggregation-induced emission properties for high-efficiency photooxidation reactions

Recently, there has been a great interest in the study of photocatalysts (PCs) and photosensitizers (PSs) in the field of organic photocatalysis. In the present study, a pure organic thermally activated delayed fluorescence (TADF) molecule 4,4′-(12-(pyridin-4-yl)dibenzo[f,h]pyrido[2,3-b]quinoxaline-3,6-diyl)bis(N,N-diphenylaniline) (DPQ-TPA) was designed and synthesized, which not only have excellent TADF property and small energy splitting (ΔEST), but also can self-assembly in water to form cross-linked nanoparticles with exceptional aggregation-induced emission (AIE) characteristics. DPQ-TPA exhibits excellent remarkable selectivity and notably enhances the production capacity of reactive oxygen species (ROS), particularly 1O2, which was employed as a highly effective photocatalyst in the photooxidation reaction of phosphine and hydroazobenzenes under blue light irradiation with high yields up to 94% and 91%, respectively. This work expands the potential application of (donor-acceptor) D-A type AIE-TADF molecules in photocatalytic organic transformations through supramolecular self-assembly.

Non-Classical Molecular Activation by Phosphines and N-Heterocyclic Carbenes and Its Application to Catalytic Reactions

Abstract This Award Account reports our recent studies concerning the catalytic transformations that involve a non-classical mode of molecular activation by tertiary phosphines and N-heterocyclic carbenes (NHCs). Regarding organophosphine catalysis, we successfully designed reactions based on a P(III)/P(V) redox couple. A catalytic protocol for generating pentacoordinate P(V) species was devised by the reaction of tertiary phosphines, acyl fluorides and alkynoates. The ability of the thus generated fluorophosphoranes to participate in ligand coupling and ligand metathesis with organosilicon nucleophiles enables synthetic transformations that are otherwise unattainable, including the intermolecular carbofluorination of alkynes and the hydroalkenylation of enol ethers. Regarding nucleophilic NHC catalysis, the use of imidazolium-based NHCs can generate deoxy-Breslow intermediates that are sufficiently nucleophilic to promote the aromatic substitution of aryl halides, aryl ethers and anilides. The protocol can also be used for the nucleophilic activation of styrene derivatives, allowing for the generation of a series of ylide intermediates that can serve as non-stabilized vinyl anion equivalents. These results demonstrate that synthetic transformations involving non-stabilized carbanions can be conducted under catalytic conditions without the use of strong organometallic nucleophiles.

Green Emissive Copper(I) Coordination Polymer Supported by the Diethylpyridylphosphine Ligand as a Luminescent Sensor for Overheating Processes.

Tertiary diethylpyridylphosphine was synthesized by the reaction of pyridylphosphine with bromoethane in a suberbasic medium. The reaction of phosphine with the copper(I) iodide led to the formation of a copper(I) coordination polymer, which, according to the X-ray diffraction data, has an intermediate structure with a copper-halide core between the octahedral and stairstep geometries of the Cu4I4 clusters. The obtained coordination polymer exhibits a green emission in the solid state, which is caused by the 3(M+X)LCT transitions. The heating up of the copper(I) coordination polymer to 138.5 °C results in its monomerization and the formation of a new solid-state phase. The new phase exhibits a red emission, with the emission band maximum at 725 nm. According to the experimental data and quantum chemical computations, it was concluded that depolymerization probably leads to a complex that is formed with the octahedral structure of the copper-halide core. The resulting solid-state phase can be backward-converted to the polymer phase via recrystallization from the acetone or DMF. Therefore, the obtained coordination polymer can be considered a sensor or detector for the overheating of processes that should be maintained at temperatures below 138 °C (e.g., engines, boiling liquids, solar heat systems, etc.).

Reaction of Amide and Sodium Azide for the Synthesis of Acyl Azide, Urea, and Iminophosphorane.

Amides reacted with NaN3 to give the acyl azides in DMF at 25 °C and produce the symmetrical ureas in THF/H2O at 80 °C via the sequential reaction of acyl substitution and Curtius rearrangement. All acyl azides were also obtained from the secondary amides via sequential reaction of p-toluenesulfonyl chloride and NaN3. In addition, keto-stabilized iminophosphoranes were prepared from a one-pot reaction of amides, NaN3, and phosphines.

Synthesis, Crystal Structures and NMR Characterization of Molecular Silver Tin Chalcogenide Complexes

AbstractA series of heteronuclear silver tin chalcogenide complexes has been synthesized by reaction of phosphine coordinated silver acetate and diorganotin acetate with bis(trimethylsilyl)chalcogenide. In addition to the silver complexes with the general formula [(iPr3PAg)2(SnR2)E2]2 (1–6, R=Me, Ph, tBu and E=S, Se), [(iPr3PAg)3(SnPh2)(SnPh)S4] (7) and [(iPr3PAg)(SnPh2)(SnPh)Se2]2 (8) were obtained by exchange of phenyl groups in solution and redox processes, respectively. In addition to single crystal X‐ray structure analyses, NMR spectra involving the nuclei 1H, 31P, 77Se, 117/119Sn and 107/109Ag allowed a structural analysis of these complexes in solution. Each element present in complexes 5–8 consists of at least one isotope with nuclear spin I=1/2. In co‐thermolysis experiments of these complexes together with Zn(SC2H4S) or Zn(SeC2H4Se) as zinc sources binary and ternary chalcogenides as well as elemental silver are found.

Experimental and Computational Studies on the Physicochemical Behavior of Phosphine Induced by Reactions with H and D Atoms on Interstellar Ice Grains

Abstract Phosphine (PH3) is an important molecule in the chemistry of phosphorus (P)-bearing species in the interstellar medium. Interstellar PH3 is thought to primarily form on icy grains, where several surface processes may occur during and after its formation. To better understand the physicochemical behavior of PH3 on icy grains in dense molecular clouds, we performed experimental and computational studies on the reactions of phosphine with H and D atoms at low temperatures. We found that phosphine and its deuterated isotopologue PD3 are released into the gas phase from icy surfaces (porous amorphous, compact amorphous, and crystalline ice) via chemical desorption. Even though the effective desorption cross section did not vary between the different icy surfaces, the desorption fraction was smallest for porous amorphous ice. We confirmed that, at 10 K on icy surfaces, H–D substitution reactions of PH3 and D–H substitution reactions of PD3 occurred following reactions with D and H atoms, respectively. Because the activation barrier for the abstraction of H or D atoms from phosphine is ∼1500 K, quantum tunneling should play a role at low temperatures. Under the present experimental conditions, the H–D substitution reaction of PH3 was slightly slower than the D–H substitution reaction of PD3. Therefore, the rates of the H–D and D–H substitution reactions should not be constrained by tunneling reactions but rather by other elementary processes such as atom diffusion on ice. Our experimental results suggest the possible presence of a deuterated phosphine isotopologue (PH2D) in PH3-rich interstellar environments.

NiCl2 as a Cheap and Efficient Precatalyst for the Coupling of Aryl Fluorosulfonate and Phosphite/Phosphine Oxide

AbstractHerein, NiCl2 is employed as a cheap precatalyst in the formation of C(sp2)–P bond via cross-coupling reaction of phenol derivatives and phosphine oxides/phosphites. This catalytic system allows a variety of phenols with diverse functional groups to transform into phosphates with good yields. No additional additive is used in this reaction.

Multicomponent Reaction of Phosphines, Benzynes, and CO2: Facile Synthesis of Stable Zwitterionic Phosphonium Inner Salts.

The first synthesis of benzyne-derived stable zwitterions is reported. Benzynes generated in situ from 2-(trimethylsilyl)aryl triflates undergo a multicomponent reaction with phosphines and CO2 to produce the stable 1,5-zwitterionic species in moderate to excellent isolated yields, which provides a novel method for the preparation of phosphonium inner salts under mild and transition-metal-free conditions.

Photo-promoted Skeletal Rearrangement of Phosphine-Borane Frustrated Lewis Pairs Involving Cleavage of Unstrained C-C σ-Bonds.

An unprecedented photo-promoted skeletal rearrangement reaction of phosphine-borane frustrated Lewis pairs, o-(borylaryl)phosphines, involving cleavage of an unstrained sp2 C-sp3 C σ-bond is reported. The reaction realizes an efficient synthesis of cyclic phosphonium borate compounds. The reaction mechanism via a boranorcaradiene intermediate is proposed based on theoretical calculations. This work sheds light on the new photoreactivity of phosphine-borane FLPs.

Photo‐promoted Skeletal Rearrangement of Phosphine–Borane Frustrated Lewis Pairs Involving Cleavage of Unstrained C−C σ‐Bonds

AbstractAn unprecedented photo‐promoted skeletal rearrangement reaction of phosphine–borane frustrated Lewis pairs, o‐(borylaryl)phosphines, involving cleavage of an unstrained sp2C–sp3C σ‐bond is reported. The reaction realizes an efficient synthesis of cyclic phosphonium borate compounds. The reaction mechanism via a boranorcaradiene intermediate is proposed based on theoretical calculations. This work sheds light on the new photoreactivity of phosphine–borane FLPs.

Practical synthesis of phosphonium salts with orthoformates and their application as flame retardants in polycarbonate

An efficient and practical approach to phosphonium salts has been developed. By the reaction of phosphines and different acid sources with orthoformates in one-step operation, the process allowed rapid access to phosphonium salts with diverse counterions in high yield after the purification by recrystallization. The flame retardant performance in PC has also been examined by blending several phosphonium salts to PC respectively. Phosphonium phosphates showed excellent flame retardancy in PC with only 2 phr blending.

Rare Au···H Interactions in Gold(I) Complexes of Bulky Phosphines Derived from 2,6-Dibenzhydryl-4-methylphenyl Core.

Gold(I) complexes of sterically demanding phosphines derived from 2,6-dibenzhydryl-4-methylphenyl core viz: 2,6-dibenzhydryl-N,N-bis((diphenylphosphane)-methyl)-4-methylaniline (1), (2,6-dibenzhydryl-4-methylphenyl)-diphenylphosphane (2), N-(2,6-dibenzhydryl-4-methylphenyl)-1,1-diphenylphosphanamine (3), and (2,6-dibenzhydryl-4-methylphenoxy)-diphenylphosphane (4) are described. The reaction of 1 with 2 equiv of [AuCl(SMe2)] in dichloromethane yielded [{AuCl}2{Ar*N(CH2PPh2)2}] (5), which on further treatment with 2 equiv of AgSbF6 and 1 equiv of 1 produced 12-membered dimeric complex [Au2{μ-(Ar*N(CH2PPh2)2)2}][(SbF6)2] (6). A similar reaction of 5 with AgSbF6 in CH3CN afforded [{Au(NCCH3)}2{Ar*N(CH2PPh2)2}][(SbF6)2] (7). Equimolar reactions of bulky phosphines 2, 3, and 4 with [AuCl(SMe2)] resulted in [AuCl(PPh2Ar*)] (8), [AuCl(PPh2NHAr*)] (9), and [AuCl(PPh2OAr*)] (10). Complexes 9 and 10 on treatment with AgSbF6 in CH3CN produced the cationic complexes [Au(NCCH3)(PPh2NHAr*)][(SbF6)] (11) and [Au(NCCH3)(PPh2OAr*)][(SbF6)] (12), respectively. The molecular structure of complex 6 revealed the presence of a strong intramolecular aurophilic interaction with a Au···Au distance of 2.9720(4) Å. Careful analysis of molecular structure of 5 revealed the presence of rare Au···H-C (sp3) interactions between the gold(I) atom and one of the methylene protons of -NCH2PPh2 groups. The solution 1H NMR signals of the methylene protons of 5 showed a considerable downfield shift (∼1 ppm) compared to that of the free ligand indicating their interactions (Au···H) with the Au atom. Complexes 8 and 10 also showed Au···H interactions in their molecular structures. The existence of the Au···H interaction was studied by variable temperature 1H NMR data in the case of complex 5 and further evinced by the QTAIM analysis in complexes 5, 8, and 10.

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.

Cross-linked poly(4-vinylpyridine-N-oxide) as a polymer-supported oxygen atom transfer reagent

Oxygen atom transfer (OAT) reagents are common in biological and industrial oxidation reactions. While many heterogeneous catalysts have been utilized in OAT reactions, heterogeneous OAT reagents have not been explored. Here, cross-linked poly(4-vinylpyridine-N-oxide), called x-PVP-N-oxide, was tested as a heterogeneous OAT reagent and its oxidation chemistry compared to its molecular counterpart, pyridine-N-oxide. The insoluble oxidant x-PVP-N-oxide demonstrated comparable reactivity to pyridine-N-oxide in direct oxidation reactions of phosphines and phosphites in acetonitrile, but x-PVP-N-oxide did not react in other solvents. The polymer backbone of x-PVP-N-oxide, however, allowed for easy filtering and recycling in sequential oxidation reactions. In addition, x-PVP-N-oxide was tested as the stoichiometric oxidant in a copper-catalyzed OAT reaction to α-diazo-benzeneacetic acid methyl ester. The heterogeneous oxidant was much less reactive than pyridine-N-oxide, indicating that interaction with the metal catalyst was challenging. These results demonstrated a proof-of-concept that recyclable, polymer-supported OAT reagents could be a viable OAT reagents in direct oxidation reactions without metal catalysts.

Divergent intramolecular reactions between phosphines and alkynes

A divergent intramolecular reaction of phosphine tethered alkyne in protic solvent was developed. This provided a novel and simple access to a large variety of (Z)-alkenylphosphine oxides and phospholane oxides. Our preliminary studies suggested that these divergent reactions are closely related to the reaction condition and molecular structure. A possible mechanism of C-P bond cleavage of a pentacoordinated hydroxyphosphorane intermediate was proposed.

Synthesis of cationic gold(III) complexes using iodine(III)

We report the synthesis and characterization of cationic Au(III) complexes supported by nitrogen-based ligands. The syntheses are achieved by reacting Au(I) complexes [Au(N-Me-imidazole)2]+ and [Au(pyridine)(NHC)]+ with iodine(III) reagents PhI(OTf)(OAc) and [PhI(pyridine)2]2+ yielding a series of cationic gold(III) complexes. In contrast, reactions of phosphine ligated gold(I) complexes with iodine(III) reagents results in the oxidation of the phosphine ligand.

Cyclooctadiene iridium complexes with phosphine and pentadienyl ligands

Reaction of [(η4-COD)Ir(μ2-Cl)]2 (1) with tin CH2CRCHCRCH2SnR′3 (R = H, Me; R' = Me, n-Bu) or lithium pentadienide reagents gives the corresponding acyclic pentadienyl sandwich compounds [(η4-COD)Ir(η5-CH2CMeCHCMeCH2) (2) and [(η4-COD)Ir(η5-CH2CHCHCHCH2) (3). Treatment of 1 with different phosphines affords the well-known mononuclear phosphine complexes [(η4-COD)IrClPR3] [R = Ph, 4; i-Pr, 5; Me, 6] which react with lithium pentadienide to give the exclusive formation of [(η4-COD)Ir(1-3-η-CH2CHCHCHCH2)PR3] [R = Ph, 7; P(i-Pr), 8], whereas the less steric trimethylphosphine shows an equilibrium mixture of the pseudo iridacyclic [(η4-COD)Ir(1,4-5′-η-CH2CHCHCHCH2)PMe3] (9a) and [(η4-COD)Ir(1-3-η-CH2CHCHCHCH2)PMe3] (9b) in a 2:1 ratio. Additionally, the addition reaction of phosphines to compound 2 gives the dimethyl-pentadienyl complexes [(η4-COD)Ir(1-3-η-CH2CMeCHCMeCH2)PPh3] (10) and the mixture of isomers [(η4-COD)Ir(1,4-5′-η-CH2CMeCHCMeCH2)PMe3] (11a) and [(η4-COD)Ir(1-3-η-CH2CMeCHCMeCH2)PMe3] (11b) in a 2:1 ratio. Compounds 2, 4, 5, 6, 7, 8, 9b, 10 and 11a have been structurally characterized by single-crystal X-ray diffraction studies. The influence of the electronic and steric effects of the different ligands, as well as the preference of the bonding modes in the pentadienyl ligands is analyzed and contrasting to pentadienyl electron rich complexes, derived from IrCl(PR3)3, previously described in the literature.

Reactivity of phosphines with iodomethane analog fluoroiodomethane

Reactions of phosphines with iodomethane are well known and well investigated. The resulting phosphonium salts are used in Wittig reactions or to form ionic liquids. Reaction rates depend on the Tollman parameter as well as on steric factors. Reactions with iodomethane occur spontaneously within a few hours. We have found that the corresponding reactions of phosphines with fluoroiodomethane are significantly slower. Reaction times range from one day up to 11 days. The resulting phosphonium salts are stable towards air and water and show also low aqueous toxicity with respect to Vibrio fisheri bacteria. Due to the strong electronegativity of the fluorine atom and its similarity to an OH group, interesting crystal structures were observed.