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At least 19 recordsLinked to original sources
PubMed2006

Novel palladium complexes employing mixed phosphine phosphonates and phosphine phosphinates as anionic chelating [P,O] ligands.

A route to various substituted phosphine phosphonic acid compounds of the general form Ar(2)PC(6)H(4)PO(OH)(2) (Ar = Ph, o-MeC(6)H(4), o-MeOC(6)H(4)) has been investigated. These compounds were employed as bidentate anionic [P,O] ligands in neutral palladium complexes. The [P,O] chelating coordination was determined by X-ray crystallography of a representative palladium complex. Furthermore, the bifunctional ligand Ph(2)PC(6)H(4)PO(OH)Ph represents the first example of a chelating anionic [P,O] ligand resulting from the combination of a phosphine and a phosphinate moiety.

Journal Article↗
PubMed2006

Comparative toxicity of fumigants and a phosphine synergist using a novel containment chamber for the safe generation of concentrated phosphine gas.

BACKGROUND: With the phasing out of ozone-depleting substances in accordance with the United Nations Montreal Protocol, phosphine remains as the only economically viable fumigant for widespread use. However the development of high-level resistance in several pest insects threatens the future usage of phosphine; yet research into phosphine resistance mechanisms has been limited due to the potential for human poisoning in enclosed laboratory environments. PRINCIPAL FINDINGS: Here we describe a custom-designed chamber for safely containing phosphine gas generated from aluminium phosphide tablets. In an improvement on previous generation systems, this chamber can be completely sealed to control the escape of phosphine. The device has been utilised in a screening program with C. elegans that has identified a phosphine synergist, and quantified the efficacy of a new fumigant against that of phosphine. The phosphine-induced mortality at 20 degrees C has been determined with an LC(50) of 732 ppm. This result was contrasted with the efficacy of a potential new botanical pesticide dimethyl disulphide, which for a 24 hour exposure at 20 degrees C is 600 times more potent than phosphine (LC(50) 1.24 ppm). We also found that co-administration of the glutathione depletor diethyl maleate (DEM) with a sublethal dose of phosphine (70 ppm, <LC(5)), results in a doubling of mortality in C. elegans relative to DEM alone. CONCLUSIONS: The prohibitive danger associated with the generation, containment, and use of phosphine in a laboratory environment has now been substantially reduced by the implementation of our novel gas generation chamber. We have also identified a novel phosphine synergist, the glutathione depletor DEM, suggesting an effective pathway to be targeted in future synergist research; as well as quantifying the efficacy of a potential alternative to phosphine, dimethyl disulphide.

Animals↗
PubMed2002

The response of phosphine-resistant lesser grain borer Rhyzopertha dominica and rice weevil Sitophilus oryzae in mixed-age cultures to varying concentrations of phosphine.

The response of Rhyzopertha dominica and Sitophilus oryzae (both phosphine-resistant) in mixed-age cultures to phosphine at fixed concentration-time products (CT) of 10,500 to 168,000 microliters litre 1 h (ppm h) with either constant, rising or falling concentrations for 7 days was studied at 27 (+/- 2) degrees C. At lower CT products, rising concentrations of phosphine led to significantly fewer survivors of R dominica and S oryzae. Conversely, exposure to falling concentrations of phosphine resulted in significantly more survivors. The influence of changing concentrations of phosphine was more pronounced in S oryzae than in R dominica. In the latter, at the lower CT products of 21,000 and 42,000 microliters-1 h, the adult stage proved to be most tolerant, contrary to the accepted belief that the egg or pupal stage are always more tolerant to phosphine. The results indicate that application of phosphine in rising concentrations is more effective than in constant or falling concentrations.

Animals↗
PubMed2003

Insertion of carbon fragments into P(III)-N bonds in aminophosphines and aminobis(phosphines): synthesis, reactivity, and coordination chemistry of resulting phosphine oxide derivatives. Crystal and molecular structures of (Ph(2)P(O)CH(2))(2)NR (R = Me, (n)Pr, (n)Bu), Ph(2)P(O)CH(OH)(n)()Pr, and cis-[MoO(2)Cl(2)((Ph(2)P(O)CH(2))(2)NEt-kappaO,kappaO)].

Reactions of N-aryl and N-alicyclic derivatives of aminophosphines with paraformaldehyde lead to methylene insertion into P-N bond followed by oxidation of phosphorus from the P(III) to P(V) state. When N-alkyl derivatives are reacted with paraformaldehyde, dimerization takes place to afford bis(phosphine oxide)s of the type Ph(2)P(O)CH(2)N(R)CH(2)P(O)Ph(2) (R = Me, (n)Pr, (n)Bu). Aminobis(phosphines) also undergo methylene insertion when treated with paraformaldehyde to give bis(phosphine oxides) Ph(2)P(O)CH(2)N(R)CH(2)P(O)Ph(2) (R = Me, Et, (n)()Pr, (i)()Pr, (n)Bu) in good yield. The reaction of aminophosphines with aromatic aldehydes ArCHO leads to insertion of "ArCH" into the P-N bond to give Ph(2)P(O)CH(R)N(H)Ph (R = C(6)H(5), furfuryl, o-C(6)H(4)OH), but with aliphatic aldehydes such as butanal, P-N bond cleavage takes place to afford alpha-hydroxy phosphine oxide. The reaction of aminobis(phosphines) with both aromatic and aliphatic aldehydes leads to the formation of alpha-hydroxy phosphine oxides through P-N bond cleavage whereas the reaction with furfural leads to the P-N bond insertion. The structure of the alpha-hydroxy derivative Ph(2)P(O)CR(H)(OH)(n)()Pr shows intermolecular hydrogen bonding between OH and P=O oxygen. The phosphine oxide derivatives act as bidentate ligands and form chelate complexes with Co(II), Mo(VI), Th(IV), and U(VI) derivatives. The crystal structure of the molybdenum complex, cis-[MoO(2)Cl(2)((OPPh(2)CH(2))(2)NEt-kappaO,kappaO)], shows the distorted octahedral geometry around Mo with two oxo groups cis to each other.

Journal Article↗
PubMed1996

Water-Soluble Phosphines. 6.(1) Tailor-Made Syntheses of Chiral Secondary and Tertiary Phosphines with Sulfonated Aromatic Substituents: Structural and Quantum Chemical Studies.

Chiral water-soluble secondary phosphines (2-6) were obtained by nucleophilic phosphination of FC(6)H(4)-4-SO(3)K (1a), FC(6)H(3)-2,4-(SO(3)K)(2) (1b), and FC(6)H(4)-2-SO(3)K (1c) with RPH(2) (R = Ph, 2,4,6-Me(3)C(6)H(2), 2,4,6-iPr(3)C(6)H(2)) in the superbasic medium DMSO/KOH by employing steric control of substitution at phosphorus by bulky substituents R and sulfonic groups in the ortho position of the aromatic ring systems in 1b or 1c. The secondary phosphines may be deprotonated in DMSO/KOH to give phosphido anions which on reaction with alkyl halides (PhCH(2)Cl, Br(CH(2))(3)Br, and C(12)H(25)Br) yield mono- or bidentate tertiary phosphines (7-10). Ligands of this type are alternatively accessible by nucleophilic arylation of secondary phosphines, e.g. Ph(Me)PH or Ph(H)P(CH(2))(3)P(H)Ph with 1a or 1b, respectively. The crystal structure of the starting material 1b.H(2)O (space group P2(1)/m) has been determined. In the solid state of 1b.H(2)O the individual molecules are interconnected by ionic interactions between the potassium cations and the SO(3)(-) anions. The C-F bond (C(1)-F 1.347(4) Å) is shorter than that in C(6)H(5)F (1.356(4) Å). The unit cell of 7a.0.5H(2)O (space group P&onemacr;), the first structurally characterized chiral phosphine with a sulfonated phenyl substituent, contains the two enantiomers. Due to the asymmetrical substitution at phosphorus the PC(3) skeletons are significantly distorted (P(1)-C(1,11,31) 1.864(10), 1.825(8), 1.841(7) Å). The electronic structure of sulfonated fluorobenzenes FC(6)H(5)(-)(n)()(SO(3)M)(n)() (M = K, NH(4), n = 1-3) is discussed on the basis of quantum chemical calculations. In particular, the reactivity difference toward nucleophilic phosphination within the series is rationalized in terms of steric factors and of the -I effect of the sulfonic groups.

Journal Article↗
PubMed2004

Sterically hindered and robust pnictogen ligands derived from carboranes: synthesis and X-ray structure determination of tris(1'-methyl(1,2-dicarba-closo-dodecaboran-1-yl))phosphine, tris(1'-methyl(1,2-dicarba-closo-dodecaboran-1-yl))arsine and chloro(tris(1'-methyl(1,2-dicarba-closo-dodecaboran-1-yl))phosphine)gold(I).

Sterically hindered phosphine and arsine ligands derived from ortho-carborane were synthesized and characterized by X-ray crystallography. Tris(1'-methyl(1,2-dicarba-closo-dodecaboran-1-yl))phosphine, 2 (crystal data, hexagonal, space group P6(3), a = b = 12.251(3) A, c = 11.514(4) A, alpha = beta = 90 degrees, gamma = 120 degrees, V = 1496.6(7) A(3), Z = 2, R(1) = 0.0568) and tris(1'-methyl(1,2-dicarba-closo-dodecaboran-1-yl))arsine, 3 (crystal data, hexagonal, space group P6(3), a = b = 12.330(3) A, c = 11.474(4) A, alpha = beta = 90 degrees, gamma = 120 degrees, V = 1510.7(7) A(3), Z = 2, R(1) = 0.0930) were prepared in 82% and 68% yield, respectively. The phosphine ligand is resistant to air-oxidation but was converted to corresponding oxide when heated with hydrogen peroxide. The tertiary carboranyl phosphine reacted with (Tht)AuCl to yield chloro(tris(1'-methyl(1,2-dicarba-closo-dodecaboran-1-yl))phosphine)gold(I), 4 (crystal data, monoclinic, space group P2(1)/c, a = 19.101(4) A, b = 12.167(2) A, c = 13.846(3) A, alpha = gamma = 90 degrees, beta = 91.13(3) degrees, V = 3217.2(11) A(3), Z = 4, R(1) = 0.0396) in 82% yield. From the X-ray structure of the gold complex, the cone angle of the phosphine was determined to be 213(2) degrees, which is among the largest values reported to date.

Journal Article↗
PubMed2004

Predicting mortality of phosphine-resistant adults of Sitophilus oryzae (L) (Coleoptera: Curculionidae) in relation to changing phosphine concentration.

Adults of a phosphine-resistant strain of Sitophilus oryzae (L) were exposed to constant phosphine concentrations of 0.0035-0.9mg litre(-1) for periods of between 20 and 168h at 25 degrees C, and the effects of time and concentration on mortality were quantified. Adults were also exposed to a series of treatments lasting 48, 72 or 168 h at 25 degrees C, during which the concentration of phosphine was varied. The aim of this study was to determine whether equations from experiments using constant concentrations could be used to predict the efficacy of changing phosphine concentrations against adults of S oryzae. A probit plane without interaction, in which the logarithms of time (t) and concentration (C) were variables, described the effects of concentration and time on mortality in experiments with constant concentrations. A derived equation of the form C(n)t = k gave excellent predictions of toxicity when applied to data from changing concentration experiments. The results suggest that for resistant S oryzae adults there is nothing inherently different between constant and changing concentration regimes, and that data collected from fixed concentrations can be used to develop equations for predicting mortality in fumigations in which phosphine concentration changes. This approach could simplify the prediction of efficacy of typical fumigations in which concentrations tend to rise and then fall over a period of days.

Animals↗
PubMed2006

Diligating tripodal amido-phosphine ligands: the effect of a proximal antipodal early transition metal on phosphine donor ability in a building block for heterometallic complexes.

The ligand precursors P(CH2NH-3,5-(CF3)2C6H3)3 (1a), P(CH2NHPh)3 (1b), and P(CH2NH-3,5-Me2C6H3)3 (1c), react with the reagents Ti(NMe2)4 and tBuN=Ta(NEt2)3 to generate metal complexes of the type P(CH2NAr(R))3TiNMe2 (2a-c) and P(CH2NAr(R))3Ta=NtBu (3a-c) (where Ar(R) = 3,5-(CF3)2C6H3, Ph, and 3,5-Me2C6H3). Due to ring strain, the phosphine lone pair cannot chelate and is available to bind a second metal, and this feature can be utilized to synthesize heterometallic polynuclear complexes. The 31P chemical shifts observed upon complexation of the early transition metals to the amido donors are large and in the opposite direction expected for the increased C-P-C bond angles in these complexes; these unusual shifts are due to P-Ti and P-Ta distances that are significantly shorter than the sum of van der Waals radii. The reaction of 2c with Ni(CO)4 produces at first the bimetallic complex (CO)3Ni[P(CH2N-3,5-Me2C6H3)3TiNMe2] (4c), which gradually converts to the trimetallic complex (CO)2Ni[P(CH2N-3,5-Me2C6H3)3TiNMe2]2 (5c). The effect of the complexation of Ti and Ta fragments on the donor ability of the phosphine ligand was determined by the preparation of the bis-phosphine complexes trans-L(2)Rh(CO)Cl, (where L = 1a-c, 2a-c, and 3a-c) prepared by the reaction of the appropriate phosphine with [Rh(CO)2(mu-Cl)]2, and a measurement of the resultant CO stretching frequencies. Surprisingly, the complexes with the larger C-P-C angles are significantly poorer donors. Density functional theory calculations were performed to determine what factors affect the donor ability of the phosphine and if through-space interactions might play an important role in the observed electronic properties.

Journal Article↗
PubMed2002

Determination of dissociation constant of phosphinate group in phosphinic pseudopeptides by capillary zone electrophoresis.

Capillary zone electrophoresis (CZE) was used for determination of dissociation constant of phosphinate group in phosphinic pseudopeptides, i.e. peptides where one peptide bond is substituted by phosphinic acid moiety -PO2--CH2-. The dissociation constants were determined for a set of newly synthesized pseudopeptides derived from a structure N-Ac-Val-Ala(psi)(PO2--CH2)Leu-His-NH2 by nonlinear regression of experimentally measured pH dependence of their effective electrophoretic mobilities. CZE experiments were carried out in Tris-phosphate background electrolytes in the pH range 1.4-3.2. The pseudopeptides were synthesized as a mixture of four diastereomers, the separation of which was achieved in most cases. Moreover, differences of the effective mobilities of the pseudopeptide diastereomers enabled simultaneous determination of the dissociation constant of their phosphinate group without necessity of previous isolation of individual isomers.

Electrophoresis, Capillary↗
PubMed2001

Lanthanide chemistry with (bis[[bis(carboxymethyl)amino]methyl]phosphinate: what does an extra phosphinate group do to EDTA?

H5XT (bis[[bis(carboxymethyl)amino]methyl]phosphinic acid) is an EDTA(4-)-like ligand containing an extra phosphinate group. [Co(II)(XT)]3-, [Co(III)(XT)]2-, and a series of [Ln(XT)]2- complexes have been prepared. The phosphinate group is not coordinated in the Co complexes but is bound in the lanthanide complexes. Solid state and solution behaviors of Ln-XT species are consistent: both monoprotonated and nonprotonated species have been found. Protonation of the metal complex does not lead to dissociation of a carboxylate; rather, the proton distributes around the molecular ion. The pM values of Ln-XT are comparable to those of Ln-EDTA but are higher than those of Ln-TMDTA. The inclusion of a phosphinate eases the selectivity of an EDTA-type ligand for late lanthanides.

Contrast Media↗
PubMed2004

Gas-phase ion chemistry of the allene-phosphine and silane-allene-phosphine systems.

The gas-phase ion chemistry of allene-phosphine and silane-allene-phosphine mixtures was studied by ion trap mass spectrometry. Rate constants of the main processes were measured and compared with the collisional rate constants to determine the reaction efficiencies. For the binary mixture, the highest yield of C- and P-containing ions is obtained with a 1 : 1 partial pressure ratio among the reagents. In the ternary mixture, formation of ion species containing Si, C and P together is mainly achieved in reactions of Si/P ions with allene, with a lower contribution from reactions of Si/C and C/P ions with phosphine and silane, respectively. The formation of ternary ion clusters is related to their possible role as precursors of amorphous silicon carbides doped with phosphorus, obtained by deposition from properly activated silane-allene-phosphine mixtures.

Journal Article↗
PubMed2002

Water-soluble phosphines. 17.(1) novel water-soluble secondary and tertiary phosphines with disulfonated 1,1'-biphenyl backbones and dibenzophosphole moieties.

Reaction of 2,2'-difluoro-1,1'-biphenyl with chlorosulfonic acid and subsequent hydrolysis followed by neutralization with potassium or sodium hydroxide affords disodium or dipotassium 5,5'-disulfonato-2,2'-difluoro-1,1'-biphenyl (1a, 1b). On treatment of 1b with diphenyl- or phenylphosphine in the superbasic medium DMSO/KOH, phosphine ligand 2 or 3 with a disulfonated 1,1'-biphenyl backbone or a dibenzophosphole moiety is formed. The structure of the oxide of 5-phenyldibenzophosphole 3, which crystallizes as 4.2.5H(2)O in the monoclinic space group P2(1)/n with a = 13.799(3) A, b = 19.246(4) A, c = 17.764(4) A, beta = 105.63(3) degrees, and Z = 4, has been determined by X-ray analysis. Nucleophilic phosphination of 1a with NaPH(2) in liquid ammonia yields the sodium phosphide 5a which on protonation gives the water-soluble 5H-dibenzophosphole 5. Reaction of 1b with PH(3) in the superbasic medium DMSO/KOtBu affords 5b in addition to the oxidation product 6a. On oxidation of 5a or 5b with H(2)O(2), the sodium or potassium salts of the sulfonated phosphinic acids 6a or 6b, respectively, are formed. Alkylation of the sodium dibenzophospholide 5a with 2,2'-bis(chloromethyl)-1,1'-biphenyl or 1,4-di-O-p-toluenesulfonyl-2,3-O-isopropylidene-D-threitol yields the chiral water-soluble bidentate phosphine ligands 8 and 9, respectively.

Journal Article↗
PubMed1998

Metal-Ligand Bonding in Coinage Metal-Phosphine Complexes: The Synthesis and Structure of Some Low-Coordinate Silver(I)-Phosphine Complexes.

Reaction of AgBF(4) with 2 equiv of Ph(3)P in acetonitrile followed by recrystallization from dichloromethane/hexane yields the mixed phosphine-nitrile complex [(Ph(3)P)(2)AgNCCH(3)]BF(4) (I) as its dichloromethane solvate, I.0.5CH(2)Cl(2). This solvate crystallizes in the monoclinic space group C2/c with a = 22.928(5), b = 12.700(3), c = 25.156(5) Å, beta = 97.53(3) degrees, and Z = 8. The acetonitrile ligand in I is loosely bound to the metal center and easily lost, even in the solid state, without decomposition. Hence, recrystallization of dried samples of I.0.5CH(2)Cl(2) from CH(2)Cl(2)/hexane results in isolation of the novel low-coordinate phosphine complex [(Ph(3)P)(2)Ag]BF(4) (II). II crystallizes in the monoclinic space group C2/c with a = 21.733(9), b = 12.272(4), c = 24.356(9) Å, beta = 95.01(3) degrees, and Z = 8. In both cases, a weak interaction is present between a fluorine atom of the BF(4)(-) anion and the silver cation. However, these interactions appear to be essentially electrostatic rather than dative in nature, implying that I is best considered a three-coordinate silver complex and that II is a rare, structurally characterized example of a two-coordinate silver-phosphine complex. These solid-state geometric assignments are supported by (31)P NMR studies, which reveal a Ag-P coupling constant of 550 Hz for II, consistent with the presence of a linear two-coordinate complex in solution. The NMR data also indicate that the phosphine ligands are involved in exchange processes, which are accelerated by the presence of a donor solvent such as acetonitrile. Comparison of II with its gold analogue supports the previously stated concept that gold atoms are smaller than silver atoms. An analysis of 13 other isostructural pairs of silver and gold complexes culled from the crystallographic database lends further support to this concept.

Journal Article↗
PubMed1996

Protection of the Hydroxyphosphinyl Function of Phosphinic Dipeptides by Adamantyl. Application to the Solid-Phase Synthesis of Phosphinic Peptides.

To develop solid-phase synthesis of phosphinic peptides, different FmocXaaPsi{PO(OAd)CH(2)}XaaOH building blocks have been prepared, where Fmoc is (fluorenylmethoxy)carbonyl. In this respect, the protection of the hydroxyphosphinyl function in these phosphinic dipeptides by the adamantyl group turns out to be convenient. The phosphinic adamantyl esters are completely stable in basic conditions and can be removed under relatively mild acidic conditions. Using these building blocks, despite the bulkiness of the adamantyl group, no particular problem of coupling was observed during the solid-phase synthesis of phosphinic peptides by the Fmoc strategy. The developed methodology is of particular interest to facilitate the development of potent inhibitors of zinc-metalloproteases.

Journal Article↗
PubMed2006

A novel method for the separation of bis(alpha-hydroxyalkyl)phosphinic acid diastereoisomers via formation of novel cyclic phosphinic acids.

The reaction of aromatic and aliphatic aldehydes with hypophosphorus acid under microwave irradiation was examined. The reaction gave a mixture of a racemic pair of bis(alpha-hydroxyalkyl)phosphinic acids and acetal derivatives from the corresponding bis(alpha-hydroxyalkyl)phosphinic acids of meso-stereochemistry in good yield. The difference in solubility in organic solvents due to polarity allowed us to readily separate these compounds. This method constitutes an easy, rapid, and good-yielding preparation and separation of bis(alpha-hydroxyalkyl) phosphinic acid diastereoisomers from simple starting materials using microwave irradiation.

Aldehydes↗
PubMed2005

Novel polymer incarcerated palladium with phosphinated polymers: active catalyst for Suzuki-Miyaura coupling without external phosphines.

[reaction: see text] Immobilization of a palladium catalyst with use of new phosphinated polymers was carried out utilizing the polymer incarcerated (PI) method. This phosphinated PI Pd catalyst showed excellent activity in Suzuki-Miyaura couplings without addition of external phosphine ligands. No leaching of Pd was observed in this reaction, and the catalyst was recovered quantitatively by simple filtration and reused several times without loss of activity.

Catalysis↗
PubMed2006

Bis(trifluoromethyl)phosphinous acid (CF3)2P-O-H: an example of a thermally stable phosphinous acid--synthesis, gas-phase structure, and rotational isomers.

The bis(trifluoromethyl)phosphinous acid, (CF3)2P-O-H, is the only known example of a thermally stable phosphinous acid. Although this compound has been known since 1960, little is known about the chemistry of this extraordinary compound; this might be due to the tedious, and in some part risky, synthesis that was originally published. An improved, simple, and safe synthesis that is based on the treatment of the easily accessible (CF3)2PNEt2, with at least three equivalents of p-toluene sulfonic acid, is presented. The reaction results in a complete conversion to the phosphinous acid, which is isolated in almost 90 % yield. The compound exists in an equilibrium of two P--OH rotational isomers, a fact which is supported by quantum chemical calculations. The relative enthalpy difference of 6.4 kJ mol(-1), calculated at the B3PW91/6-311G(3d,p) level, is in excellent agreement with the experimental value of 5.9 kJ mol(-1), which was determined from the temperature dependence of the nu(OH) bands of the two rotational isomers. The complete experimental vibrational spectra of both rotamers, their predicted vibrational spectra obtained by using quantum chemical calculations, and an attempt at photoinduced isomerization of matrix-isolated (CF3)2POH is presented. The experimental structure, obtained from an electron-diffraction study in the gas phase, is reproduced very well by ab initio and density functional theory (DFT) methods.

Journal Article↗