NMR spectrometric study of molecular complex formation of [60]- and [70]fullerenes with a number of phosphine oxides

Molecular complex formation between [60]- and [70]fullerenes with a series of phosphine oxides, namely, tri-n-octyl phosphine oxide, triphenyl phosphine oxide and tri-n-butyl phosphine oxide has been studied in CCl4 medium by NMR spectrometric method. Both [60]- and [70]fullerenes have been shown to form 1:1 adducts with the above series of phosphine oxides. Formation constants (K) for all the complexes have been determined from the systematic variation of NMR chemical shifts of specific protons of the donors in presence of [60]- and [70]fullerenes. Trends in the values of K suggest that [70]fullerene binds stronger with the phosphine oxides relative to [60]fullerene.     

Synthesis and resolution of 2-(diphenylphosphino)heptahelicene

Palladium catalysed Heck couplings have been applied to the two-step synthesis of a stilbene derivative bearing a diphenylphosphine oxide function which represents a suitable precursor for the photochemical generation of the corresponding [7]-helicene. After reduction of the phosphine oxide, resolution of the monodentate helical phosphine has been performed by means of the ortho-metallated (R)-1-(naphthyl)ethylamine-palladium complex. A ruthenium complex of (heptahelicen-2-yl)diphenylphosphine has also been prepared and fully characterized.     

Markovnikov hydroformylation catalyzed by ROPAC in the presence of phosphine and phosphine oxide ligands

Rhodium-catalyzed hydroformylation of 1-octene in the presence of different phosphine and phosphine oxide ligands has been investigated. The molecular structure of new phosphine ligand, fluorenylidine methyl phenyl diphenylphosphine, was determined by single-crystal X-ray crystallography. Parameters such as different ligands, molar ratio of ligand to rhodium complex, ratio of olefin to rhodium complex, pressure of CO : H₂ mixture, and time of the reaction were studied. The linear aldehyde was the main product when the phosphine ligands were used as auxiliary ligands while the selectivity was changed to the branched products when the related phosphine oxide ligands were used. Under optimized reaction conditions, in the presence of [Rh(acac)(CO)(Ph₃P)]-di(1-naphthyl)phenyl phosphine oxide, conversion of 1-octene reached 97% with 87% selectivity of branched aldehyde.     

Synthesis of polymers containing tertiary phosphine oxides using complex bases

Tertiary phosphine oxides have been prepared in excellent yield from primary alkyl halides or aromatic halides and activated sodium phosphinates obtained by reaction of dialkyl phosphine oxides with complex bases (NaNH₂/tBuONa). This reaction has been successfully applied to soluble and cross-linked bromopolystyrenes and to macroporous polystyrenes with bromooctyl substituents giving polymers which contain pendant phosphine oxide groups.     

Study of Electron Donor–Acceptor Complex Formation of o-Chloranil With a Series of Phosphine Oxides and Tri- n-butyl Phosphate by the Absorption Spectrometric Method

Electron donor–acceptor (EDA) complex formation of o-chloranil with six different phosphine oxides and tri-n-butyl phosphate (TBP) has been studied in CCl ₄ solution by the UV-VIS absorption spectrophotometric technique. An absorption band due to a charge–transfer (CT) transition is observed in the visible region. Utilizing the CT transition energy, the electron affinity of o-chloranil in solution has been calculated. Degrees of charge transfer, and oscillator and transition dipole strengths have also been calculated for all of the investigated EDA complexes. Except for TBP, other phosphine oxides, viz., tri-n-octyl phosphine oxide, tri-n-butyl phosphine oxide, triphenyl phosphine, octyl(phenyl)-N,N-diisobutylcarbamoylphosphine oxide, octyl(phenyl)-N,N-dicyclohexylcarbamoylmethylphosphine oxide and octyl(phenyl)-N,N-diisopropylcarbamoylmethylphosphine oxide have been shown to form stable 1:1 EDA complexes with o-chloranil. The complex of TBP with o-chloranil decays slowly into a secondary product. Formation constants of the EDA complexes have been determined.     

Mixed (PS/PO)‐Stabilized Geminal Dianion: Facile Diastereoselective Intramolecular C?H Activations by a Related Ruthenium–Carbene Complex

A new unsymmetrical geminal dianion that contained both a phosphine oxide moiety and a phosphine sulfide moiety has been synthesized. Its reactivity towards Ru^II was explored, which led to the formation of a highly reactive carbene complex that evolved at room temperature to yield a kinetic orthometalated Ru^II complex through C? H activation of the phenyl group of the phosphine oxide moiety. This insertion was found to be thermally reversible and a second C? H insertion occurred at a phenyl group of the phosphine sulfide moiety to form the thermodynamic orthometalated Ru^II complex in a diastereospecific manner. DFT calculations fully rationalized the experimental findings in terms of the relative energies of the kinetic and thermodynamic products and allowed the mechanism of this process to be fully understood.     

A new rhodium complex with a nitrogen‐containing bis(phosphine oxide) ligand as an efficient catalyst for the hydroformylation of styrene

A new rhodium complex with a nitrogen‐containing bis(phosphine oxide) ligand has been synthesized. The complex was applied to hydroformylation of styrene and displayed high activity and regioselectivity towards the branched aldehyde, which was found to be higher than those of the tertiary bis(phosphine) analogue. Copyright © 2006 John Wiley & Sons, Ltd.     

Unexpected formation of a scrambled aryl-phosphine oxide under modified sonogashira conditions

A phosphine oxide ruthenium complex has been obtained by aryl-phenyl exchange on a Pd(PPh₃)₄ catalyst in the presence of NaOH and CuI.     

Isolation, characterization of an intermediate in an oxygen atom-transfer reaction, and the determination of the bond dissociation energy

The synthesis and structure of a phosphine oxide-bound intermediate molecule originating from a dioxo-molybdenum(VI) complex is described. The loss of phosphine oxide has been followed by surface-induced dissociation mass spectrometry that gave the bond dissociation energy of 29.5 (+/- 3.5) kcal/mol. Considering the bond dissociation energy for a Mo=O bond to be 100 kcal/mol, this value suggests that the primary driving force for the reaction is the formation of the intermediate complex.     

Synthesis,Molecular, and Crystal Structure of Tris(2-carbamoylmethoxyphenyl)phosphine Oxide

Russian Journal of General Chemistry - New tripodal ligand, tris(2-carbamoylmethoxyphenyl)phosphine oxide, has been synthesized via the alkylation of tris(2-hydroxyphenyl)phosphine oxide with...     

Tripodal Phosphine Oxide Ligand with Tetrazole Functionality

Russian Journal of General Chemistry - Tris[2-(3′-cyanopropoxy)phenyl]phosphine oxide has been obtained via the alkylation of tris(2hydroxyphenyl)phosphine oxide with 4-bromobutyronitrile in...     

Charge effects on oxygen atom transfer

The rhenium(V) complex [(HCpz3)ReOCl2]+ ([1]+), the tris(pyrazolyl)methane analogue of the known tris(pyrazolyl)borate complex (HBpz3)ReOCl2 (2), has been prepared. The two complexes are strikingly similar, as are the phosphine oxide adducts [(HCpz3)ReCl2(OPPh3)]Cl ([3]Cl) and (HBpz3)ReCl2(OPPh3) (4), which have been characterized by X-ray crystallography. Comparison of the bimolecular reduction of [1]BF4 and 2 by triarylphosphines reveals a pronounced charge effect, with the cationic species being reduced by PPh3 about 1,000 times faster than its neutral analogue in CH2Cl2 at room temperature. Ligand substitution of the adducts [3]+ and 4 is dissociative, with the cationic complex dissociating phosphine oxide about 56 times more slowly than the neutral compound. The relative impact of charge on ground and transition states in atom transfer reactions is discussed.     

Conversion of alcohols to bromides using a fluorous phosphine

Reaction of alcohols with the fluorous phosphinecarbon tetrabromide complex in toluene or in a two-phase toluene-FC-72 system afforded the corresponding bromides in good yields. The fluorous-phosphine oxide is readily separated by liquid-liquid extraction, providing an alternative to the homogeneous triphenylphosphine-carbon tetrachloride conversion, as well as to the polymer-supported phosphine method. The fluorous phosphine oxide could be reduced and the product reused.     

The Concept of P--H Protection Extended to Phosphine Oxides: Preparation of Functional,Unsymmetrical Secondary and Tertiary Phosphine Oxides

Phosphine oxide analogues of Triazole fungicides and protected Threonine have been prepared. The enzymatic hydrolysis of phosphine oxide di-acetates has been investigated.     

Meso-porphyrinylphosphine oxides: mono- and bidentate ligands for supramolecular chemistry and the crystal structures of monomeric {[10,20-diphenylporphyrinatonickel(II)-5,15-diyl]-bis-[P(O)Ph(2)] and polymeric self-coordinated {[10,20-diphenylporphyrinatozinc(II)-5,15-diyl]-bis-[P(O)Ph(2)]}

A series of porphyrins substituted in one or two meso positions by diphenylphosphine oxide groups has been prepared by the palladium-catalyzed reaction of diphenylphosphine or its oxide with the corresponding bromoporphyrins. Compounds {MDPP-[P(O)Ph2]n} (M = H2, Ni, Zn; H2DPP = 5,15-diphenylporphyrin; n = 1, 2) were isolated in yields of 60-95%. The reaction is believed to proceed via the conventional oxidative addition, phosphination, and reductive elimination steps, as the stoichiometric reaction of eta(1)-palladio(II) porphyrin [PdBr(H2DPP)(dppe)] (H2DPP = 5,15-diphenylporphyrin; dppe = 1,2-bis(diphenylphosphino)ethane) with diphenylphosphine oxide also results in the desired mono-porphyrinylphosphine oxide [H2DPP-P(O)Ph2]. Attempts to isolate the tertiary phosphines failed due to their extreme air-sensitivity. Variable-temperature 1H NMR studies of [H2DPP-P(O)Ph2] revealed an intrinsic lack of symmetry, while fluorescence spectroscopy showed that the phosphine oxide group does not behave as a "heavy atom" quencher. The electron-withdrawing effect of the phosphine oxide group was confirmed by voltammetry. The ligands were characterized by multinuclear NMR and UV-visible spectroscopy, as well as mass spectrometry. Single-crystal X-ray crystallography showed that the bis(phosphine oxide) nickel(II) complex {[NiDPP-[P(O)Ph2]2} is monomeric in the solid state, with a ruffled porphyrin core and the two P=O fragments on the same side of the average plane of the molecule. On the other hand, the corresponding zinc(II) complex formed infinite chains through coordination of one Ph2PO substituent to the neighboring zinc porphyrin through an almost linear P=O...Zn unit, leaving the other Ph2PO group facing into a parallel channel filled with disordered water molecules. These new phosphine oxides are attractive ligands for supramolecular porphyrin chemistry.     

SYNTHESIS OF HYDROPHILIC ULTRAFINE NANOPARTICLES COORDINATED WITH CARBOHYDRATE CLUSTER

A hydrophilic phosphine oxide (1) as a suitable ligand for semiconductor nanoparticles was synthesized. The hydrophilicity of the phosphine oxide was enhanced by introduction of three mannose moieties to the end of the molecule via amide linkages. The ligand 1 was able to coordinate to the CdSe/ZnS nanoparticle making the newly formed hydrophilic complex.     

Effect of oxidant on the reaction of [RhCl(cyclooctadiene)(phosphine)] with 1-hexene

Summary A promoting role of an oxidant, present in commercial 1-hexene, in the substitution of phosphine in the complex [RhCl(COD)(phosphine)] (1) where the phosphine is PPh₃ or 1/2 BPS-2 [bis(diphenylphosphinoethyl)tetra-methyldisiloxane] and COD=cycloocta-1,5-diene, has been detected and explained. When [oxidant]>[(1)] two reaction steps are distinguished: an oxidation of phosphine to phosphine oxide with generation of [RhCl(COD)], followed by its fast dimerization, and an oxidation of the dimer to Rh^III species. When [oxidant]<[(1)] the latter step is not observed and the reaction of [RhCl(COD)] with 1-hexene is favoured, particularly when an excess of phosphine (even at high oxidant concentration) is present. Most rate constants of the individual steps were evaluated.     

Synthesis and use of borane and platinum(II) complexes of 3‐diphenylphosphino‐1‐ phenylphospholane (LuPhos)

3‐Diphenylphosphinoyl‐1‐phenylphospholane 1‐oxide ( 2 ) obtained by the Michael addition of diphenylphosphine oxide to the double‐bond of 1‐phenyl‐2‐phospholene 1‐oxide ( 1 ) was subjected to double deoxygenation to afford the corresponding bisphosphine ( 3 , LuPhos) that was converted to bis(phosphine borane) 4 and to cis chelate platinum(II) complex 6 . A mixed phosphine oxide–phosphine borane 5 was also prepared. Stereostructures of the bidentate P‐ligand 3 and the ring platinum(II) complex ( 6 ) were evaluated by quantum chemical calculations. Complex 6 used as a catalyst showed modest activity, but unusual regioselectivity in the hydroformylation of styrene and its 4‐substituted analogues. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:730–736, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20741     

Synthesis of hydrolytically stable phosphorus-containing polymers via polycondensation and their utilization in polymer blends

Amorphous polyarylene ether homo- and copolymers were synthesized which were based upon bisphenol A and either 4, 4'-dichlorodiphenylsulfone, 4, 4'-difluorobenzophenone or 4, 4'-difluorodiphenyl phenylphosphine oxide. Solution blends were prepared from these homo- and copolymers with linear bisphenol A based polyhydroxyether, which was used as a model for the epoxy or vinyl ester thermosetting matrix resins for composite materials. It was observed that transparent, single Tg blends could be prepared from the phosphine oxide containing homopolymer and a 50/50 phosphine oxide/dichlorodiphenylsulfone copolymer. The other homopolymers produced materials with two Tg's, implying that they were definitely phase separated systems. Thermogravimetric analysis was also conducted and the phosphine oxide blends produced high char yields suggesting utilization in fire-resistant applications. The miscibility of the phosphine oxide material has been attributed to specific hydrogen bonding interactions observed between the phosphine oxide bond and the secondary hydroxyl group in the polyhydroxy ether. This hydroxyl functionality is also present in the epoxy and vinylester precursors and it is suggested that these materials could be utilized as interface sizings for carbon fibers, which would produce a graded microstructure between the fiber and the polymer matrix systems.     

Catalytic Asymmetric Synthesis of Phosphine Boronates

The first catalytic enantioselective synthesis of ambiphilic phosphine boronate esters is presented. The asymmetric boration of α,β‐unsaturated phosphine oxides catalyzed by a copper bisphosphine complex affords optically active organoboronate esters that bear a vicinal phosphine oxide group in good yields and high enantiomeric excess. The synthetic utility of the products is demonstrated through stereospecific transformations into multifunctional optically active compounds.