PMe3 Research Articles

2,6-Bis(diphenylphosphinooxy)phenyl]bis(trimethylphosphine)cobalt(I)

The title compound, [Co(C30H23O2P2)(C3H9P)2], was synthesized by the addition of a Co(PMe3)4 solution to (PPh2O)2C6H4. The CoI atom displays a trigonal-bipyramidal geometry with the two P atoms of the ‘PCP’ pincer ligand and the P atom of one of the trimethyl phosphine ligands forming the basal plane, whereas the metalated C atom and the P atom of the second phospine ligand occupy the apical sites. The Co—C distance is 1.961 (2) Å and the C—Co—P angle is 171.96 (6)°.

An ab initio investigation of some hydrogen-bonded complexes of methanethiol

The hydrogen-bonded complexes formed between methanethiol, as proton donor, and trimethyl amine, dimethyl ether, methyl fluoride, trimethyl phosphine, dimethyl sulphide and methyl chloride, as proton acceptors, have been studied by means of ab initio calculations at the second order level of Møller–Plesset perturbation theory and using the 6-311++G(d,p) basis set. The hydrogen bond energies were found to correlate with the gas phase basicities of the proton acceptors. The increases of the SH bond lengths, the shifts of the wavenumbers of the SH stretching modes and the increases of their infrared intensities were also found to be dependent on the interaction energies. The results for the CH 3SH·S(CH 3) 2 complex are anomalous, and this is attributed to deficiencies with the basis set used for sulphur. The data for the CH 3SH complex closely mirror the behaviour of the corresponding complexes of CH 3OH and (CH 3) 2NH, with the perturbations of the various properties varying consistently in the order CH 3OH > (CH 3) 2NH > CH 3SH.

An ab initio investigation of some hydrogen-bonded complexes of methanol and dimethylamine

The hydrogen-bonded molecular complexes formed between methanol and dimethylamine, as proton donors, and the series of proton acceptors trimethylamine, dimethyl ether, methyl fluoride, trimethyl phosphine, dimethyl sulphide and methyl chloride, have been studied by means of ab initio molecular orbital theory, at the second order level of Møller–Plesset perturbation theory, and using the 6-311++G(d,p) basis set. The properties determined were the molecular structures, the interaction energies and the vibrational spectra. The results show that, based on the trends in the values of these properties, the order of strength of interaction per proton donor is methanol > dimethylamine and the order per proton acceptor is trimethylamine > dimethyl ether > methyl fluoride for the first row bases and trimethyl phosphine > dimethyl sulphide > methyl chloride for the second row. The first row proton acceptors consistently form stronger hydrogen-bonded complexes than their counterparts from the second row.

Metal-organic chemical vapour deposition of (BInGa)P: Density-functional calculations to the mechanisms

Using the density-functional method and clusters modelling steps of (BInGa)P(0 0 1) surfaces, chemisorption and desorption energies as well as related barriers are calculated for probable chemisorption structures formed by precursor molecules XZ 3 (X: B, Ga, In, P; Z: H, Me=CH 3) during the metal-organic chemical vapour deposition (MOCVD). Reaction mechanisms, especially the stability of surface structures, the efficiency of the precursor molecules, and the rate-limiting steps, are obtained. In most cases, the final removal of hydrogen or methyl groups is the rate-limiting step. The deposition with hydrogen precursors (XH 3) is faster than the analogous deposition with methyl precursors (XMe 3). The deposition rate decreases from indium over gallium to boron. The rate of phosphorus deposition in surface dimers decreases from indium over gallium to boron dimers. Trimethylphosphine (TMP) is a less suitable precursor. Boron antisite deposition and formation of BGa and BIn alloys is less probable. The formation of an elementary boron phase by BH 3 is less probable and can be fully prevented by using trimethylboron (TMB) precursors. The differences in the reaction behaviour in comparison with (BInGa)As, investigated previously, are discussed.

Group-Transfer Reactions of Ni(II)−Ni(II) Bridging Imido Complexes. Catalytic Formation of Carbodiimides and Isocyanates via Nitrene Transfer from Organoazides

The NHC-supported Ni(I) dimer {(IPr)Ni(μ-Cl)}2 (1; IPr = 1,3-di(2,6-di-isopropylphenyl)imidazolin-2-ylidene) yields the bridging d8−d8 imido complex {(IPr)NiCl}2(μ-NMes) (2; Mes = 2,4,6-Me3C6H2) up...

Interactions of phosphorous molecules with the acid sites of H-Beta zeolite: Insights from solid-state NMR techniques and theoretical calculations

The local structures of various Brønsted and Lewis acid sites in H-Beta zeolite were resolved with the combined 31P MAS NMR, 31P– 27Al TRAPDOR NMR experiments and theoretical calculations at different levels. In addition, the interacting mechanisms of these acid sites with probe molecules such as trimethylphosphine (TMP) and trimethylphosphine oxide (TMPO) were clarified, which greatly aids the understanding of acid catalysis. Owing to the narrow chemical shift range and close Brønsted acid strengths, only an average resonance at −4.5 ppm was observed in TMP adsorbed H-Beta zeolite, consistent with the calculated data of acidities (substitution energies and proton affinities), geometries, adsorption energies as well as 31P chemical shifts. However, two types of Brønsted acids were distinguished by TMPO, and the HF/DZVP2 (MP2/DZVP2) chemical shifts were calculated at 68.1 (69.5) and 69.7–72.1 (71.7–74.9) ppm, respectively. Two types of Lewis acids were identified at −32.0 and −47.0 ppm with the latter exhibiting strong 31P– 27Al TRAPDOR effects. With theoretical calculations, these two peaks were attributed to the extra-lattice oxo-AlOH 2+ species and the three-fold coordinated lattice-Al, extra-framework Al(OH) 3, oxo-AlO + species, respectively. The peak at −60.0 ppm was conventionally assigned to the TMP physisorption, but the calculations indicated that the EFAL monovalent Al(OH) 2 + species coordinating with two lattice-O atoms near the framework Al atom can contribute to it as well.

Substituent Effect on Oxygen Atom Transfer Reactivity from Oxomolybdenum Centers: Synthesis, Structure, Electrochemistry, and Mechanism

Dioxo molybdenum complexes of general formula Tp*MoO(2)(S-p-RC(6)H(4)) (1), where Tp* = hydrotris(3,5-dimethyl-1-pyrazolyl)borate and R = OMe, Me, SMe, NHCOMe, H, Cl, CF(3), NO(2), were reacted with trimethyl phosphine (PMe(3)) to convert into complexes of general formula Tp*MoO(S- p-RC(6)H(4))(OPMe(3)) (2) (where R = OMe, Me, SMe, H, Cl, and CF(3)). These complexes were isolated and characterized by NMR, IR, UV/vis, and single crystal X-ray crystallography. Electronic and NMR spectra, as well as redox potentials vary as a function of substituent on the thiophenolato ligand. When viewed entirety of the oxygen atom transfer (OAT) reactivity, the reaction of Tp*MoO(2)(S-p-RC(6)H(4)) with PMe(3) shows a biphasic behavior, indicating the formation of at least one intermediate. The kinetics of the both steps, that is, the formation of the phosphoryl intermediate and the formation of the solvent coordinated species have been investigated by UV-vis spectroscopy. The first step follows a second order process, first order with respect to both the complex and PMe(3), and the overall second order rate constants at 25 degrees C range from 98.2 (+/-0.01) x 10(-2) M(-1) s(-1) (for R = OMe) to 223.0 (+/-0.20) x 10(-2) M(-1) s(-1) (for R = CF(3)); activation parameters were in the ranges DeltaH(++) = 49.3(+/-4.1) kJ x mol(-1) (for R = OMe) to 34.0 (+/-7.5) kJ x mol(-1) (for R = CF(3)), DeltaS(++) = -154.0 (+/-14.2) J x mol(-1) x K(-1) (for R = OMe) to -184.3 (+/-26.1) J x mol(-1) K(-1) (for R = CF(3)), and DeltaG(++) = 95.0 kJ x mol(-1) (for R = OMe) to 88.7 kJ x mol(-1) (for R = CF(3)). Formation of the acetonitrile complex from the phosphoryl complex follows a first order process with respect to the complex. The first order rate constants at 25 degrees C range from 3.60 (+/-0.01) x 10(-4) sec(-1) (for R = OMe) to 6.32 (+/-0.11) x 10(-4) sec(-1) (for R = CF(3)), and the enthalpy of activation and entropy of activation show variation; DeltaH(++) = 62.5 (+/-2.2) to 67.8 (+/-1.0) kJ x mol(-1), DeltaS(++) = -82.5 (+/-3.3) to -101.3 (+/-7.5) J x mol(-1) x K(-1), but the free energy of activation remains constant DeltaG(++) approximately 92 (+/-1) kJ x mol(-1). Large entropies of activation associated with both steps are consistent with associative transition states. The comparable magnitude of the activation energy of the two steps underscores the difficulty in identifying the rate-limiting step in the overall OAT reaction. The first step, however, is more sensitive toward the substituent effects than the second step. Therefore, a change in the substituent can play an important role in deciding the rate-limiting step involved in a two-step OAT reaction.

1H and 31P solid-state NMR of trimethylphosphine adsorbed on heteropolytungstate supported on silica

Trimethylphosphine (TMP) has been used as an NMR probe in order to determine the acidity of Keggin-type 12-tungstophosphoric heteropolyacid (HPW), pure and supported on silica, dehydrated at 473 K. Adsorption of TMP on pure dehydrated HPW leads to the formation of trimethylphosphonium ions (TMPH +) characteristic of the presence of strong Brönsted acid sites. TMP replaces the water molecules lost by dryness and allows the Keggin secondary structure to recover. Silica interacts with TMP by two kinds of acid sites: with weak acid support sites through the isolated silanol groups and with strong Brönsted acid, which lead to the formation of TMPH +, through the hydrogen-bonded silanol groups. Silica only interacts with HPW through its isolated silanol groups.

Coadsorption of trimethyl phosphine and thiocyanate on colloidal silver: a SERS study combined with theoretical calculations

AbstractThe adsorption of trimethyl phosphine (TMP) on colloidal silver has been investigated by means of surface‐enhanced Raman scattering spectroscopy (SERS). On the basis of surface selection rules, it is deduced from the SERS results that TMP adsorbs on silver surface via its P atom. The electron donor effect of TMP can be sensitively probed by the coadsorbed SCN−. The Raman wavenumber of νCN of the adsorbed SCN− shifts to lower wavenumbers when TMP is coadsorbed with SCN− and the red shift of C≡N stretching wavenumber is found to increase with increasing surface coverage of TMP. This could be explained in terms of the electron donor effect of TMP. Density functional theory (DFT) calculations further confirm the experimental results that the charge transfer is from TMP to silver surface rather than reversely. Natural bond orbital (NBO) analysis indicates that the red shift of C≡N stretching mode is due the increase of electronic populations of π* orbital of C≡N bond induced by coadsorbed TMP, consequently the C≡N bond is weakened, and the νCN shifts to lower wavenumbers. An NBO analysis also indicates that the conjugated effect between S atom and C≡N bond could easily make the charge transfer from silver surface to C≡N bond. Copyright © 2008 John Wiley & Sons, Ltd.

Reactions of an (Arylimido)vanadium(V)−Alkylidene, V(CHSiMe3)(N-2,6-Me2C6H3)(N═CtBu2)(PMe3), with Nitriles, Diphenylacetylene, and Styrene

Reactions of a vanadium(V)−alkylidene, (ArN)V(CHSiMe3)(N═CtBu2)(PMe3) (1, Ar = 2,6-Me2C6H3), with various nitriles, diphenylacetylene, and styrene have been explored. Treatment of 1 with RC≡N (R = ...

Synthesis, electrochemistry, geometric and electronic structure of oxo-molybdenum compounds involved in an oxygen atom transferring system

The oxygen atom transfer reactivity of Tp∗MoO2(SPh) (1) (where Tp∗=hydrotris-(3,5-dimethylpyrazol-1-yl)borate) with trimethyl phosphine (PMe3) has been investigated. The reaction proceed through a diamagnetic phosphoryl intermediate complex, Tp∗MoO(SPh)(OPMe3) (2), which has been isolated and characterized by IR, NMR, UV–visible spectroscopy, and mass spectrometry. The molecular structure of 2 has been determined by X-ray crystallography. The complex crystallizes in monoclinic (P21/n) space group, a=19.81 (1)Å, b=11.1 (4)Å, c=18.416 (5)Å, β=121.2 (3)°, V=3463.8 (25)Å3 with Z=4. In acetonitrile, complex 2 exchanges its phosphoryl ligand with a solvent molecule resulting in Tp∗MoO(SPh)(MeCN) (3), which has been isolated and also characterized spectroscopically and by X-ray crystallography. Compound 3 crystallizes in triclinic (P1¯) space group, a=10.159 (6)Å, b=18.563 (5)Å, c=7.986 (3)Å, α=96.22 (3)°, β=121.2 (3)°, γ=84.64 (3)°, V=1452.4 (11)Å3 with Z=2. The electronic structures of the complexes have been investigated by density functional theory and the redox chemistry has been investigated by cyclic and differential pulse voltammetry. In acetonitrile, complex 2 spontaneously transforms to complex, 3 at a rate of 5.6×10−4s−1.

A joint experimental–theoretical study on trimethylphosphine adsorption on the Lewis acidic sites present in TS-1 zeolite

31P MAS NMR desorption experiments and density functional calculations were combined to study the interactions between TS-1 zeolite and probe molecules. Two types of Lewis acidic sites at −34.2 and −32.0 ppm in the 31P MAS NMR spectra were identified, which correspond to the Ti(OSiO 3) 4 and (OSiO 3) 3Ti(OH) species with the Ti atoms at the T12 sites. Trimethylphosphine (TMP) was chemisorbed on the Lewis acidic sites with the adsorption energies calculated to be −6.2 and −19.6 kJ mol −1, respectively. On all the other T sites, TMP was physisorbed with slightly positive adsorption energies, in the range 0.82–5.92 kJ mol −1. The two types of Lewis acidic sites are responsible for the catalytic reaction of TMP oxidation, with their catalytic activities explained by structural and Mulliken charge analyses. It was also found that further hydrolysis of Si–O–Ti links to form (SiO) 2Ti(OH) 2 or (SiO)Ti(OH) 3 species were not observed in TS-1 zeolite.

Base-induced Brönsted Acid Sites on Dealuminated HY Zeolite: A Solid-state NMR Spectroscopy Study

Using trimethylphosphine (TMP) and d 5-pyridine(deuterated pyridine) as the basic probe molecules, the concentrations of Brönsted acid sites on both HY zeolite and dealuminated HY zeolite have been quantitatively determined using solid-state 1H and 31P magic-angle spinning (MAS) NMR. After adsorption of the probe molecules, the concentration of Brönsted acid sites on the dealuminated HY zeolite increases by about 25%, whereas that in the parent HY sample remains almost unchanged. The increase in the concentration of Brönsted acid sites is due to the appearance of base-induced Brönsted acid sites in the dealuminated HY zeolite. The terminal SiOH in the vicinity of the aluminum atom is “induced” to form a bridging hydroxyl group (SiOHAl) in the presence of the basic probe molecules. The mechanism of formation of the induced Brönsted acid sites has also been discussed.

Acid sites in mesoporous Al-SBA-15 material as revealed by solid-state NMR spectroscopy

The nature of acid sites in Al-SBA-15 materials with various Si/Al ratios was studied by various NMR techniques including 27Al, 29Si, 1H, 31P MAS (magic-angle spinning), and some double-resonance methods such as 1H/ 27Al transfer of population in double resonance (TRAPDOR). XRD and 27Al NMR results indicate that Al has been successfully incorporated into the framework of SBA-15 materials by post-synthesis method. The bridging hydroxyl groups (SiOHAl) associated with Brönsted acid sites are invisible either in 1H MAS or in 1H/ 27Al TRAPDOR spectra of the dehydrated Al-SBA-15 materials. However, after the adsorption of basic probe molecules, such as trimethylphosphine oxide (TMPO), trimethylphosphine (TMP) and acetone, 31P MAS and 13C CP MAS NMR experiments strongly support the presence of Brönsted acid sites. NMR results suggest that Brönsted acid sites in dehydrated Al-SBA-15 materials are in the form of terminal silanol groups in the vicinity of aluminum atoms that can be induced to generate the bridging hydroxyl groups by the adsorbed basic probe molecules. Although the acid strength of Al-SBA-15 materials detected by different probe molecules is different, it is comparable to that of microporous zeolites. It is noteworthy that no Lewis acid site can be found in the Al-SBA-15 materials.

Structural/bonding insights from new geometrical varieties of two Pt–Au carbonyl/phosphine clusters, [Pt3(AuPPh3)5(μ2-CO)2L3]+(L3= (CO)2PPh3) and [(μ6-Au){Pt3(μ2-CO)3L4}2]+(L = PMe3)

Structural/bonding considerations of two new Pt-Au clusters, [Pt3(AuPPh3)5(mu2-CO)2(CO)2PPh3]+ (1) and [(mu6-Au){Pt3(mu2-CO)3(PMe3)4}2]+ (2) isolated (as chloride salts), revealed: (i) that the heretofore unknown 20-electron Pt-centered Pt2Au5 icosahedral cage fragment (five missing vertices) of is best viewed as a 44-electron triangular Pt3 adduct of a nearly planar 39-electron [Pt3(mu2-CO)2L3]+ (L3 = (CO)2PPh3) and five one-electron donating AuPPh3 ligands; and (ii) that the geometrically distorted trimethylphosphine "full" Pt3AuPt3 sandwich of is the first example of two nucleophilic 44-electron triangular Pt3(mu2-CO)3L4 (3 : 3 : 4) units (L = PMe3) which asymmetrically encapsulate a central electrophilic Au(I).

A Practical One‐Pot Synthesis of New S‐Glycosyl Amino Acid Building Blocks for Combinatorial Neoglycopeptide Synthesis

S‐Glycosyl L‐aspartic acid building blocks were synthesized starting from 1‐thiosugars by reaction with 5‐aminopentanol and suitably protected L‐aspartic acid pentafluorophenyl ester in a one‐pot procedure under Mitsunobu conditions using 1,1′‐azodicarbonyl dipiperidine and trimethyl phosphine. The method allowed for the preparation of S‐glycosyl amino acid building blocks in one step without protection of the amino function for the Mitsunobu condensation. Alternatively, the title compounds were prepared by a stepwise approach via 5‐aminopentyl 1‐thioglycosides. This paper is dedicated to Joseph Lloyd Stiles.

Growth and characterization of phosphorus‐doped diamond using organophosphorus gases

AbstractPhosphorus‐doped diamond films were grown by plasma‐enhanced chemical vapor deposition using organophosphorus gases, tertiarybutylphosphine (TBP) and trimethylphosphine (TMP). The electronic properties are characterized based on secondary ion mass spectroscopy, Hall‐effect, and cathodoluminescence measurements and compared with data deduced for samples which have been doped using PH3. The technical potential of P‐doping using TBP is discussed and the high potential of TBP and TMP as alternative P precursors for P‐doping of diamond is shown. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Growth and characterization of P-doped CVD diamond (1 1 1) thin films homoepitaxially grown using trimethylphosphine

We have homoepitaxially grown phosphorus-doped chemical-vapor-deposited (CVD) diamond (1 1 1) films using trimethylphosphine (TMP) as a more convenient dopant gas and have measured their electrical properties. On one hand, sheet Hall coefficients, R H, obtained at various temperatures, T, above room temperature (RT) by AC Hall method were all negative and had the maximum in the | R H|–1/ T plots, suggesting that two types of electrons with substantially different mobilities existed in the P-doped specimens. On the other hand, a hopping conduction with an activation energy of 0.013 eV was observed below RT. A two-carrier model was proposed to consistently explain all of these data obtained. From a curve fitting procedure, we deduced the RT electron mobility of 100 cm 2/V s in the conduction band, the activation energy of 0.59 eV from the donor to the conduction band and the compensation ratio of 1.6%. The smaller carrier mobility was estimated to be ≈1 cm 2/V s. It is found that TMP yields a much higher doping efficiency for n-type diamond synthesis, as compared with PH 3.

On the Parallel Mechanism of the Dissociation of Energy-Selected P(CH3)3+ Ions

Energy selected trimethyl phosphine ions were prepared by threshold photoelectron photoion coincidence (TPEPICO) spectroscopy. This ion dissociates via H, CH(3), and CH(4) loss, the latter two involving hydrogen transfer steps. The ion time-of-flight distribution and the breakdown diagram are analyzed in terms of the statistical RRKM theory, which includes tunneling. Ab initio and DFT calculations provide the vibrational frequencies required for the RRKM modeling. CH(3) loss could produce both the P(CH(3))(2)(+) by a simple bond dissociation step, and the more stable HP(CH(2))CH(3)(+) ion by a hydrogen transfer step. Quantum chemical calculations are extensively used to uncover the reaction scheme, and they strongly suggest that the latter product is exclusively formed via an isomerization step in the energy range of the experiment. The data analysis, which includes modeling with the trimethyl phosphine thermal energy distribution, provides accurate onset energies for both H (E(0K) = 1024.1 +/- 3.5 kJ/mol) and CH(3) (E(0K) = 1024.8 +/- 3.5 kJ/mol) loss reactions. From this analysis, we conclude that the Delta(f)H(298K) degrees [HP(CH(2))(CH(3))(+)] = 783 +/- 8 kJ/mol and Delta(f)H(298K) degrees [P(CH(2))(CH(3))(2)(+)] = 711 +/- 8 kJ/mol.

トリメチルホスフィンを用いたリンドープ気相合成ダイヤモンド薄膜の作製と評価

We have homoepitaxially grown phosphorus-doped chemical-vapor-deposited (CVD) diamond (111) films using trimethylphosphine (TMP) as a more convenient dopant gas and have measured their electrical properties. On one hand, sheet Hall coefficients, RH, obtained at various temperatures, T, above room temperature (RT) by AC Hall method were all negative and had the maximum in the |RH|-1/T plots, suggesting that two types of electrons with substantially different mobilities existed in the P-doped specimens. On the other hand, a hopping conduction with an activation energy of 0.013 eV was observed below RT. A two-carrier model was proposed to consistently explain all of these data obtained. From a curve fitting procedure, we deduced the RT electron mobility of 100 cm2/Vs in the conduction band, the activation energy of 0.59 eV from the donor to the conduction band and the compensation ratio of 1.6%. The smaller carrier mobility was estimated to be ≈ 1 cm2/Vs. It is also found that TMP yields a much higher doping efficiency for n-type diamond synthesis than PH3 does.