Phosphine Selenides Research Articles

Catalyst-free selenylation of acylacetylenes with secondary phosphine selenides and water: A short-cut to bis(2-acylvinyl) selenides

Secondary phosphine selenides react with acylacetylenes in water to form bis(2-acylvinyl) selenides. The reaction proceeds without catalyst and organic solvent under mild conditions (70–72 °C, 3 h), the corresponding divinyl selenides being isolated as a mixture of (Z,Z)- and (E,Z)-isomers in a yield of up to 78%.

Catalyst- and Solvent-Free Addition of the P–H Species to Alkenes and Alkynes: A Green Methodology for C–P Bond Formation

Traditional methods for C–P bond formation via direct addition of P–H species to unsaturated compounds are usually implemented in the presence of base and metal catalysts or radical initiators in various organic solvents. During the last five years, a novel efficient and general catalyst/initiator- and solvent-free version of the hydrophosphination and hydrophosphinylation of multiple C–C bonds with H-phosphines and their chalcogenides has begun to develop and it is attracting growing attention. This approach corresponds to the recently emerged pot-, atom-, and step-economy (PASE) green paradigm. This review covers the literature on the synthesis of useful and in-demand organophosphorus compounds via catalyst- and solvent-free addition of P–H species to alkenes and alkynes.1 Introduction2 Addition of Secondary Phosphines to Alkenes3 Hydrophosphinylation of Alkenes with Secondary Phosphine Chalcogenides3.1 Oxidative Addition of Phosphine Oxides to Vinyl Sulfides3.2 Addition of Secondary Phosphine Sulfides and Phosphine Selenides to Alkenes3.3 Addition of Secondary Phosphine Sulfides and Phosphine Selenides to Divinyl Chalcogenides3.4 Hydrophosphinylation of Alkenes with Secondary Phosphine/Chalcogen Pair (Three-Component Reactions)4 Addition of Secondary Phosphines to Alkynes5 Addition of Secondary Phosphine Chalcogenides to Alkynes6 Conclusion

Reactivity of cyrhetrenylphosphines: Synthesis and characterization of oxides, boranes and selenides

Reaction of cyrhetrenylphosphines, of general formula (η5-C5H4PR2)Re(CO)2L (R=Ph, L=CO (1); R=Cy; L=CO (2); R=Ph, L=PMe3 (3) and R=Ph, L=P(OMe)3 (4)), with H2O2, BH3·THF or selenium gives the respective cyrhetrenylphosphine oxides, boranes and selenides. These species were characterized by standard spectroscopic techniques (FT-IR, 1H and 31PNMR). Based on the 31P77Se coupling constant (1JP-Se) of the phosphine-selenides, we established the following order of basicity of the parent cyrhetrenylphosphine 2>3>4>1. We also confirmed the opposite electronic effects of the cyrhetrenyl and ferrocenyl groups attached to a –PR2 unit. Finally, phosphine selenides 2c and 4c were structurally characterized by X-ray diffraction.

A cyclopalladated phosphine selenide with an anionic acylselenourea ligand

The chloro-bridged cyclometallated palladium(II) complex [PdCl{κC,Se-C6H4P(Se)Ph2}]2 reacts with 4-MeC6H4C(O)NHC(Se)NEt2 in the presence of base to give [Pd{κC,Se-C6H4P(Se)Ph2}{κO,Se-4-MeC6H4C(O)NC(Se)NEt2}] in high yield. The complex was fully characterised by spectroscopic methods and also X-ray diffraction. This compound represents one of the few examples of a metal complex containing two different selenium-containing ligands.

Zirconium-Catalyzed Reactions of 1-Alkynyl Phosphine Oxides and Sulfides with Et3Al

The interaction of 1-alkynyl phosphine oxides, sulfides, and selenides with Me 3 Al and Et 3 Al under zirconocene catalysis was studied. It has been found that the pathway of the reaction of 1-alkynyl phosphine derivatives with Et 3 Al strongly depends on the nature of the substrate and the solvent. The ethylalumination takes place in the case of 1-alkynyl phosphine oxides in hexane solvent. The reaction of 1-hexynyl phosphine oxide with Et 3 Al failed when dichloromethane was used as a solvent. Zirconium-catalyzed reaction of 1-heptynyl phosphine sulfide with Et 3 Al proceeds as the cycloalumination followed by the desulfurization under the action of low-valent zirconium complexes. 1-Heptynyl phosphine selenide was subjected to full deselenation under the reaction conditions.

Synthesis and conformational analysis of phosphine selenides

Methods of preparation of complex phosphine selenide via the original Trofimov–Gusarova reaction are described. The results of the products conformational analysis by means of a set of physical methods (IR spectroscopy, dipole moments, and quantum chemical calculation) are presented.

Tetrathia[7]helicene Phosphorus Derivatives: Experimental and Theoretical Investigations of Electronic Properties, and Preliminary Applications as Organocatalysts

AbstractCombined experimental and theoretical study on the electronic characteristics of tetrathiahelicene (7‐TH) alkyl and aryl phosphorus derivatives, including phosphanes, phosphine–borane complexes, phosphine oxides, and phosphine–selenides, is described. The collected data give useful information on the σ‐donor ability of the phosphorus atoms, which mainly depends on the aryl or alkyl nature of the substituents at the phosphorus atom. Electrochemical investigations provide the relationships between the electronic and structural properties, and quantum chemical calculations show a clear dominance of the 7‐TH scaffold on the electronic properties of all investigated molecules. Finally, different electronic and steric properties of 7‐TH phosphanes strongly influenced their catalytic behavior, for example, as Lewis base organocatalysts in typical [3+2] annulation reactions.

Air-Stable PbSe Nanocrystals Passivated by Phosphonic Acids.

We developed a new chemical strategy to enhance the stability of lead selenide nanocrystals (PbSe NCs) against oxidation through the surface passivation by P-O- moieties. In the synthesis of PbSe NCs, tris(diethylamino)phosphine (TDP) selenide (Se) was used as a Se precursor, and the resulting PbSe NCs withstood long-term air exposure while showing nearly no sign of oxidation. Nuclear magnetic resonance (NMR) spectroscopy reveals that TDP derivatives passivate the surface of PbSe NC. Through a series of ligand cleavage reactions, we found that the TDP derivatives are bound on NC surface through the P-O- moiety. Based on such understanding, it turned out that direct addition of various PAs during the synthesis of PbSe NCs also results in the NCs whose absorption spectrum remains nearly intact after air exposure for weeks. The P-O- moieties render the NCs stable in the operation of field effect transistors, suggesting that our findings can enable the use of air stable PbSe NCs in wider array of optoelectronic applications.

Tris(pyrazolyl)phosphines with copper(i): from monomers to polymers.

The parent tris(pyrazolyl)phosphine and its 3,5-Me2, 3-Ph, and 3-t-Bu derivatives have been prepared by a simple procedure and show modest Lewis basicity of the phosphorus apex as was established by the magnitude of the (1)JP,Se coupling constant of the phosphine selenides. Because of the chelating properties of both the N- and P-sites, neutral phosphorus-centered scorpion ligands allow coordination modes that are unavailable to the abundantly used anionic tris(pyrazolyl)borate scorpionates as we established for Cu(I)-complexation. The substituted P-scorpion ligands only allow for N-coordination, as the P-apex is presumably less accessible. Two X-ray crystal structures were obtained for the Cu-complex of tris(3,5-dimethylpyrazolyl)-phosphine with acetonitrile and triphenylphosphine in the fourth coordination site. The parent P-scorpion ligand can chelate with both its pyrazolyl groups and its P-apex with the product depending on the ratio in which it is mixed with the Cu(I) complex. Reacting two equivalents of the ligand with [Cu(MeCN)4][PF6] resulted in a complex in which Cu is coordinated to the three pyrazolyl groups of one ligand and to the P-apex of the other ligand as confirmed by an X-ray crystal structure determination and a DFT computational analysis. Reacting the ligand and the Cu(I) complex in an equimolar ratio resulted in a remarkable one-dimensional P-scorpion coordination polymer for which a single crystal X-ray structure could be determined. A detailed analysis of the structural features is presented.

Synthesis, properties and group 10 metal complexes of a bis(dipyridylphosphinomethyl)phenyl pincer ligand

The synthesis, properties and coordination behaviour of the bis(dipyridylphosphinomethyl)phenyl pincer ligand 1,3-C6H4(CH2PPy2)2 (Py=2-pyridyl) are reported. The basicity of the phosphorus atoms in the ligand is explored through the synthesis of the phosphine selenide and a protonation study. The 1JPSe value of 742Hz indicates that this ligand is less basic than PPh3 and the protonation study confirms the nitrogen atoms are more basic than the phosphorus atoms. Protonation of the ligand also renders it water-soluble. The ligand reacts with [PtXY(hex)] (X=Y=Me; X=Cl Y=Me, hex=hexa-1,5-diene) at 50°C to give pincer [PtX(PCP)] complexes (X=Me, Cl). In contrast, when reaction with [PtXY(hex)] (X=Y=Me, Cl; X=Cl Y=Me) occurs at ambient temperature, dimeric complexes of the type [PtXY(μ-PP)]2 are observed in the NMR spectra. The presence of a methyl ligand appears to facilitate metalation: when there is no methyl ligand present formation of the platinum pincer complex does not occur even after prolonged thermolysis. However, reaction with [PdCl2(MeCN)2] proceeds readily at 50°C from the dimer to the [PdCl(PCP)] complex.

Green synthesis of tertiary alkylselanylphosphine chalcogenides via catalyst- and solvent-free addition of secondary phosphine chalcogenides to vinyl selenides

Secondary phosphine sulfides and phosphine selenides react with vinyl selenides under mild conditions (80–82°C, without catalyst and solvent) to form regioselectively functionalized anti-Markovnikov adducts in high yield.

Relativistic Effects in NMR of New Prospective Water-Soluble Ligands SeP(CH2OH)3 and H[Se2P(CH2OH)2

We present the synthesis of new phosphine selenide SeP(CH2OH)3 and diselenophosphinate H[Se2P(CH2OH)2] and their characterization with nuclear magnetic resonance (NMR) spectroscopy and quantum chemistry methods. DFT calculations show large relativistic spin–orbit effects in NMR shielding of phosphorus nuclei. We discuss the impact of Se lone pairs and electrons of P–Se and P–C bonds on the 31P NMR shift and, especially, its relativistic part. The description of P–Se bonds and characterization of electron lone pairs on Se atoms are carried out with the help of natural localized molecular orbitals analysis and topological analysis of electron localization function.

Synthesis of new N-substituted chiral phosphine–phosphoramidite ligands and their application in asymmetric hydrogenations and allylic alkylations

Phosphine–phosphoramidite ligands containing a 2,4-pentanediyl backbone, BINOL moieties, and Me, Bn or Ph substituent on the nitrogen were synthesized and fully characterized. The electronic effect of the N-substituents was examined by 31P NMR of their corresponding seleno-phosphate-amide and phosphine–selenide derivatives. The new ligands together with their earlier reported derivatives were tested in the palladium catalyzed asymmetric allylic alkylation of rac-(E)-1,3-diphenylallyl acetate. Remarkably high activity (up to 1780h−1 turnover frequency) and first order kinetics were observed by facilitating nucleophile formation. The substituent at the nitrogen and the configuration of chiral moieties had a high impact on the enantioselectivity. The new ligands were also tested in the rhodium-catalyzed asymmetric hydrogenation of methyl (Z)-α-acetamidocinnammate, dimethyl itaconate (up to 99.9% ee’s) and methyl 2-acetamidoacrylate (up to 99.5% ee).

Chiral Wide-Bite-Angle Diphosphine Ligands: Synthesis, Coordination Chemistry, and Application in Pd-Catalyzed Allylic Alkylation

A series of diphosphine ligands bearing ester- and ether-modified diphenylether backbones have been prepared. The introduction of carboxylic acid or ether auxiliaries in the ortho-positions relative to the diphenylphosphine groups was achieved via straightforward four-step synthetic protocols, prior to introduction of the phosphines. The electronic properties of these backbone-modified DPEPhos ligands were evaluated by probing the relevant carbonyl stretching frequencies (νCO) of Ni(CO)2(PP) species (PP = diphosphine) using IR spectroscopy and by determining the phosphorus–selenium coupling constant JSe–P of phosphine selenide derivatives using 31P{1H} NMR spectroscopy. Also, the X-ray structure for the bis(carbonyl)nickel(0) species with one of the ligands is reported. The [Pd(η3-allyl)(PP)] complexes were characterized by multinuclear NMR spectroscopy and applied in the asymmetric allylic alkylation of l,3-diphenyl-2-propenyl acetate and cyclohex-2-enyl acetate with dimethyl malonate in order to benchmark their catalytic potential. The enantioselectivity (ranging from 3 to 70%) was found to depend on the size of the chiral auxiliary introduced within the diphenyl ether backbone and its proximity to the phosphorus donor groups and hence to the active metal center.

ChemInform Abstract: Catalyst‐Free and Solvent‐Free Addition of P(Se)—H Species to Alkenes: A Straightforward Access to Tertiary Phosphine Selenides.

Under catalyst- and solvent-free conditions, secondary phosphine selenides easily add to diverse alkenes [acrylonitrile, allyl alcohol, styrene, vinyl ethers, vinyl sulfides, and trimethyl(vinyl)silane] at 80 °C (3–20 h) to give anti-Markovnikov adducts in 70–95% yield.

Dual reactivity of secondary phosphines and their chalcogenides towards 1-(vinyloxy)alkylferrocenes: the switch between α- and β-addition

The secondary phosphines and their sulfides regioselectively add, under free radical conditions (AIBN, 65 °C or UV-irradiation, rt), to (vinyloxy)methyl- and 1-(vinyloxy)ethylferrocenes to give anti-Markovnikov adducts in high yields. Without any initiator, the secondary phosphine selenides, when reacted with the above alkenes (rt, 24 h), selectively form Markovnikov adducts, which readily decompose upon handling to afford diorganyl[1-(ferrocenyl)alkyl]phosphine selenides, R2P(Se)CH(R′)Fc (R=Ph; R′=H or Me) in 28–39% isolated yields. The synthesized compounds were characterized using 1H, 13C, 31P NMR, and FTIR spectroscopy as well as X-ray diffraction analysis.

Chlorination of secondary phosphine chalcogenides with carbon tetrachloride in the absence of bases

The interaction of bis(2-phenylethyl)phosphine sulfide, bis(2-phenylethyl)phosphine selenide and bis[2-(2-phenyl)propyl]phosphine selenide with carbon tetrachloride under heating (80°C, 8–20 h) leads to the formation of the corresponding chlorophosphine chalcogenides with the yield of 80–90%.

Perfluoropropenyl-containing phosphines from HFC replacements.

A series of new perfluoropropenyl-containing phosphines of the type R3-nP(E-CF[double bond, length as m-dash]CFCF3)n (R = Ph, iPr, n = 1, 2; R = tBu, n = 2) have been prepared from the reaction of the hydrofluoroolefin Z-CF3CF[double bond, length as m-dash]CFH (HFO-1225ye) with base and the appropriate chlorophosphine, while reaction with Cl2PCH2CH2PCl2 gave (CF3CF[double bond, length as m-dash]CF)2PCH2CH2P(CF[double bond, length as m-dash]CFCF3)2, the first example of a bidentate perfluoroalkenyl-containing phosphine. An alternative route to these phosphines based on the room- or low-temperature deprotonation of CF3CF2CH2F (HFC-236ea) gives mainly the E-isomer, but also a small amount of the Z-isomer, the ratio of which depends on the reaction temperature. All of the phosphines could be readily oxidised with either H2O2 or urea·H2O2, and the phosphine selenides R3-nP(Se)(E-CF[double bond, length as m-dash]CFCF3)n (R = Ph, n = 1,2; R = iPr, n = 1; R = tBu, n = 2) were also prepared. The steric and electronic properties of these ligands were determined based on their platinum(ii), palladium(ii) and molybdenum carbonyl complexes. The crystal structures of (CF3CF[double bond, length as m-dash]CF)2PCH2CH2P(CF[double bond, length as m-dash]CFCF3)2, (CF3CF[double bond, length as m-dash]CF)2P(O)CH2CH2P(O)(CF[double bond, length as m-dash]CFCF3)2, iPr2P(Se)(CF[double bond, length as m-dash]CFCF3)2, trans-[PtCl2{Ph(3-n)P(E-CF[double bond, length as m-dash]CFCF3)n}2] (n = 1 or 2), trans-[PdCl2{R2P(E-CF[double bond, length as m-dash]CFCF3)}2] (R = Ph, iPr) and [Mo(CO)4{(CF3CF[double bond, length as m-dash]CF)2PCH2CH2P(CF[double bond, length as m-dash]CFCF3)2}] are reported.

Reaction of secondary phosphine chalcogenides with diallylamine

Diphenyl- or bis(2-phenylethyl)phosphine sulfides and -phosphine selenides react with diallylamine under radical initiation (UV or AIBN) to afford the corresponding diadducts and tetrahydropyrrolylmethyl phosphine chalcogenides. The yield and the ratio of the products depend on the structure of the starting secondary phosphine chalcogenides.

Catalyst-Free and Solvent-Free Addition of P(Se)–H Species to Alkenes: A Straightforward Access to Tertiary Phosphine Selenides

Under catalyst- and solvent-free conditions, secondary phosphine selenides easily add to diverse alkenes [acrylonitrile, allyl alcohol, styrene, vinyl ethers, vinyl sulfides, and trimethyl(vinyl)silane] at 80 °C (3–20 h) to give anti-Markovnikov adducts in 70–95% yield.