Reaction of tri(2-furyl)phosphine with triosmium clusters: C-H and P-C activation to afford furyne and phosphinidene ligands

Addition of tri(2-furyl)phosphine, PFu₃, to [Os₃(CO)₁₀(μ-H)₂] at room temperature gives [HOs₃(CO)₁₀(PFu₃)(μ-H)] (1), while in refluxing toluene the same reactants afford [Os₃(CO)₉{μ₃-PFu₂(C₄H₂O)}(μ-H)] (2) resulting from orthometallatation of a furyl ring. Reaction of PFu₃ with [Os₃(CO)_10−n(NCMe)_n] (n = 0, 1, 2) affords the substituted clusters [Os₃(CO)_12−n(PFu₃)_n] (n = 1-3) (3-5), the phosphine ligands occupying equatorial position in all cases. Heating [Os₃(CO)₁₁(PFu₃)] (3) in refluxing octane gives [Os₃(CO)₉(μ₃-PFu)(μ₃-η²-C₄H₂O)] (6) which results from both carbon-hydrogen and carbon-phosphorus bond activation and contains both μ₃-η²-furyne and furylphosphinidene ligands. All new clusters have been characterized by spectroscopic methods together with single crystal X-ray diffraction for 2, 3 and 6.     

Photocatalytic properties of new cyclopentadienyl and indenyl rhodium(I) carbonyl complexes with water-soluble 1,3,5-triaza-7-phosphaadamantane (PTA) and tris(2-cyanoethyl)phosphine

Reactions of [(η⁵-R)Rh(CO)₂] (R = cp, ind) with water-soluble phosphines (L = 1,3,5-triaza-7-phosphaadamantane and tris(2-cyanoethyl)phosphine) give the new rhodium(I) complexes of the types [Rh(η⁵-cp)(CO)(PTA)] (1), [Rh(η⁵-cp)(CO)(P(CH₂CH₂CN)₃)] (2), [Rh(η⁵-ind)(CO)(PTA)] (3) and [Rh(η⁵-ind)(CO)(P(CH₂CH₂CN)₃)] (4) in isolated yields of 52-75%. All these compounds have been fully characterized by IR, ¹H, ³¹P{¹H} and ¹³C{¹H} NMR, FAB-MS spectroscopies and elemental analyses. Reactivity for the substitution of phosphine is greater for [(η⁵-ind)Rh(CO)(L)] comparing to [(η⁵-cp)Rh(CO)(L)] because of a flexibility of the indenyl ligand to undergo facile η⁵-η³ coordinative isomerizations. The obtained complexes are active catalyst precursors for the dehydrogenation of propan-2-ol, octane and cyclooctane under photoassisted conditions without any organic hydrogen transfer acceptors, giving TOFs of 26-56 using 3 as precatalyst.     

Synthesis of 2,5 -Bis(4-methyl-2-thienyl)thiophene and 2,5-Bis(4-methyl-2-thienyl)pyrrole

Syntheses of 2,5-bis(4-methyl-2-thienyl)thiophene 3 and 2,5-bis(4-methyl-2-thienyl)pyrrole 4 are described. The key step involves Stetter reaction between 4-methyl-2-thiophenecarboxaldehyde and divinyl sulfone. Cyclizaton of the resulting 1,4-bis-(4-methyl-2-thienyl)-1,4-butanedione 2 with Lawesson's reagent gives 2,5-bis(4-methyl-2-thienyl)thiophene 3, whereas condensation with ammonium acetate provides the 2,5-bis(4-methyl-2-thienyl)pyrrole 4.     

PCl3- and organometallic-free synthesis of tris(2-picolyl)phosphine oxide from elemental phosphorus and 2-(chloromethyl)pyridine hydrochloride

In the superbase KOH/H₂O/toluene/phase-transfer catalyst system, 2-picolyl chloride, generated in situ from 2-(chloromethyl)pyridine hydrochloride, reacts with elemental phosphorus at 65–95?°C for 3?h to afford tris(2-picolyl)phosphine oxide in 50% yield. Single crystal X-ray analysis of the latter revealed one polymorph form of this tertiary phosphine oxide.     

Structural studies of two-coordinate complexes of tris(2-methoxylphenyl)phosphine and tris(4-methoxyphenyl)phosphine with gold(I) halides

A series of five gold(I) halide complexes with the two isomeric methoxy-substituted triarylphosphines, tris(2-methoxyphenyl)phosphine [P(oanis)₃], [AuP(oanis)₃X] [for X = Cl, (1); X = Br, (2) and X = I, (3)] and tris(4-methoxyphenyl)phosphine [P(panis)₃], [AuP(panis)₃X] [for X = Br (4) and X = I (5)] have been synthesized and characterized by single crystal X-ray diffraction and solution ³¹P{¹H} NMR spectroscopy. The structure determinations confirm the expected presence of linear two-coordination about the gold centres in all five complexes with bond distance and angle data typical of this type of compound [Au–P, 2.239(2)–2.259(3) Å; Au–Cl, 2.294(2) Å; Au–Br, 2.385(2)–2.402(2) Å; Au–I, 2.546(1)–2.554(1) Å; P–Au–X; 175.3(1)–180°]. All analogues except the iodo complex 5 crystallize with one complex molecule in the crystallographic asymmetric unit. The bromo and iodo complexes 2 and 3 constitute a trigonal isomorphous set while the bromo complex 4 is also isomorphous with the previously determined chloro complex [AuP(panis)₃Cl]. The 2-methoxy analogues are stabilized by significant methoxy-O?Au interactions.     

Reactions of 4-ethoxy-l,l,l-trifluoro-3-buten-2-one with phosphorous nucleophiles: Diethyl phosphite, tributyl phosphine and tris(diethylamino) phosphine

The reaction of (E)-4-ethoxy-l,l,l-trifluoro-3-buten-2-one EtOCHCHCOCF₃1 with diethyl phosphite (EtO)₂P(O)H 2 afforded a 1:1 cis- and trans-mixture of diethyl(l-trifluomethyl-3-ethoxy)allyl-phosphate EtO-CHCH-CH(CF₃)OP(O)(OEt)₂3 via the 1,2-λ⁵-oxaphosphol-4-ene intermediate. While tributyl phosphine Bu₃P added to 1 giving the double addition product Bu₃P⁺CH₂-C⁻(COCF₃)-CHCH-COCF₃5. Its resonance structure was fully identified by spectral methods and single crystal X-ray diffraction analysis. More strong phosphorous nucleophile tris(diethylamino) phosphine (Et₂N)₃P reacted with 1 to give the known compound (E)-4-(diethylamino)-l,l,l-trifluoro-3-buten-2-one Et₂N-CHCH-COCF₃10 in good yield.     

Study on inclusion complexes of meso-tetrakis(2-thienyl)porphyrin and Cu-meso-tetrakis(2-thienyl)porphyrin with cyclodextrins by spectroscopy method

In phosphate buffer solution of pH5.4, the interaction of meso-tetrakis(2-thienyl)porphyrin(H₂TTP) and Cu-meso-tetrakis(2-thienyl)porphyrin(Cu-TTP) with α-cyclodextrin(α-CD), β-CD, γ-CD, heptakis(2,3,6-tri-O-methyl)-β-CD(TM-β-CD) has been studied by means of UV-vis, fluorescence and ¹HNMR spectroscopy, respectively. The H₂TTP and Cu-TTP can form 1:2 inclusion complexes with TM-β-CD and 1:1 inclusion complexes with the other three cyclodextrins. In this paper, the inclusion constants (K) of H₂TTP and Cu-TTP for the formation of the inclusion complexes have been estimated from the changes of absorbance and fluorescence intensity in phosphate buffer solution. The inclusive capabilities of different kinds of cyclodextrins are compared. The result shows that the inclusion ability of α-CD with H₂TTP and Cu-TTP is the strongest among the three native CDs. The inclusion ability of modified β-CD with H₂TTP and Cu-TTP is stronger, compared to the native β-CD, which indicates that the capacity matching plays a crucial role in the inclusion procedure except for the hydrophobic effect. In addition ¹HNMR spectra supports the inclusion conformation of the TM-β-CD-Cu-TTP inclusion complex, indicating the interaction mechanism of inclusion processes.     

EXAFS/FT-IR characterization of tetra-iridium carbonyl clusters bound to tris-(hydroxymethyl)phosphine grafted silica surface catalytically active for propene oxidation to acetone

Structure and catalytic activity of Ir₄(CO)₁₂ bound to tris-(hydroxymethyl)phosphine (THP) grafted silica (THP/SiO₂) was investigated by means of EXAFS, FT-IR and kinetic studies. It was found that Ir₄(CO)₁₂ was uniformly attached on THP/SiO₂ by substitution of CO by THP (Ir₄/THP/SiO₂). The tetra-iridium carbonyl cluster framework was remained during the substitution of THP ligands and two THP ligands coordinated to the iridium carbonyl clusters to form Ir₄(CO)₁₀(THP/SiO₂)₂. species. When Ir₄/THP/SiO₂ was evacuated at 373 K, bridge CO was desorbed and Debye-Waller factor of Ir---Ir contribution derived from EXAFS analysis was increased which suggested that the cluster framework was distorted by the evacuation at 373 K. The resulting sample evacuated at 373 K was an active catalyst for hydroformylation of ethene and partial oxidation of propene, while the Ir₄/THP/SiO₂ without evacuation exhibited poor catalytic activities. The propene oxidation reaction proceed on the Ir₄/THP/SiO₂ evacuated at 323–353 K under subatmospheric pressures to give acetone as a product in high selectivity. The ethene hydroformylation proceed on the evacuated Ir₄/THP/SiO₂ at lower temperatures compared with other conventional iridium catalysts. EXAFS characterization and kinetic studies suggested that the catalytic activities were associated with the structural distortion of the iridium cluster framework due to surface attachment by the bidentate phosphine substitution.     

Reactions of tetrakis(trifluoromethyl) diphosphine and bis(trifluoromethyl) phosphine with ruthenium carbonyl clusters; X-ray structure of tetraruthenium carbonyl cluster derivatives

Reaction of [Ru₃(CO)₁₂ with (CF₃)₂P---P(CF₃)₂ in p-xylene at 140°C yielded the compounds [Ru₄(CO)₁₃{μ-P(CF₃)₂}₂] (1), [Ru₄(CO)₁₄{μ-P(CF₃)₂}₂] (2) and [Ru₄(CO)₁₁{μ-P(CF₃)₂}₄] (3). Reaction with [(μ-H)₄Ru₄(CO)₁₂] under similar conditions yielded [(μ-H)₃Ru₄(CO)₁₂{μ-P(CF₃)₂}] (4). All four compounds have been characterised by X-ray crystallography. The fluxional behaviour of the hydrides in 4 has also been studied by variable-temperature NMR spectroscopy. Compounds 1, 2 and 4 were also obtained from the reactions of Ru₃(CO)₁₂ with (CF₃)₂PH in dichloromethane at 80°C.     

Ambidentate coordination of the tripyridyl ligands 2,2′:6′,2″-terpyridyl,tris(2-pyridyl)-amine,tris(2-pyridyl)methane and tris(2-pyridyl)phosphine to carbonylrhenium centres: Structural and spectroscopic studies

The reactions of [Re(CO)₅Cl] with the ligands tpy (2,2′:6′,2″-terpyridine), py₃N {tris(2-pyridyl)-amine}, py₃CH {tris(2-pyridyl)methane}, and py₃P {tris(2-pyridyl)phosphine} in toluene solution realize compounds with the general formulation [Re(ligand)(CO)₃Cl] in which the tripyridyl ligands are bidentate. X-ray structural determinations of fac-[Re(typ)(CO)₃Cl].H₂O and fac-[Re(py₃N)(CO)₃Cl] confirm these assignments. [Re(tpy)(CO)₃Cl].H₂O (C₁₈H₁₃ClN₃O₄Re) is monoclinic, space group P2₁/n, with cell dimensions a = 7.432(2) Å, b = 17.016(4) Å, c = 14.466(2) Å, β = 93.51(2)°, and Z = 4; full-matrix least-squares refinement on 2435 reflections with I ? 2.5σ(I) converged to a final R = 0.028 and R_w = 0.029. [Re(py₃N)(CO)₃Cl] (C₁₈H₁₂ClN₄O₃Re) is triclinic, space group P1 with cell dimensions a = 13.761(2) Å, b = 14.636(6)Å, c = 11.110(2) Å, α = 110.70(2)°, β = 102.45(2)°, γ = 107.48(2)°, and Z = 4; full-matrix least-squares refinement on 3459 reflections with I ? 2.5σ(I) converged to a final R = 0.038 and R_w = 0.039. If the synthetic procedure is undertaken under irradiation by visible light, for the ligand py₃N a species [Re(py₃N)(CO)₂Cl] (characterized by infrared spectroscopy and conductance measurements) is also formed, in which the ligand py₃N is tridentate. No analogous tridentate species is formed with the ligands tpy or py₃P, although there is evidence that it also forms for py₃CH.     

Encapsulating ruthenium and osmium with tris(2-aminoethyl)amine based tripodal ligands

The reaction of a series of tripodal ligands, H₃L^1,2 and L^3-6, with [M(PPh₃)₂Cl₂] (M = Ru, Os) affords a family of coordination cage compounds of the type [M^IIIL^1,2] (1-4) or [M^IIL^3-6](BPh₄)₂ (5-12). The Schiff base ligands (H₃L¹, L³, L⁵) have been synthesized by condensation of tris(2-aminoethyl)amine with salicylaldehyde, pyridine-2-aldehyde and 1-methyl-2-imidazolecarboxaldehyde. These ligands were further reduced and subsequently methylated to form the new ligands (H₃L², L⁴, L⁶). Single crystal X-ray diffraction studies of 1 and 2 show that the tripodal ligand wraps around the metal center as a hexadentate ligand to form a cage. All the synthesized compounds have been thoroughly characterized by ESI-MS, FT-IR, UV-Vis and NMR spectroscopic methods. To the best of our knowledge, this is the first ever report of osmium complexes with tris(2-aminoethyl)amine based tripodal ligands. DFT calculations were performed to obtain geometry optimized structures of all the other complexes (3-12).     

Facile synthesis,X-ray analysis,and spectroscopic studies of di-iron propanedithiolate complexes with tris(aromatic)phosphine ligands

Three new propanedithiolate-type iron–sulfur complexes containing tris(aromatic)phosphine ligands, [{(μ-SCH₂)₂CH₂}Fe₂(CO)₅L] (L?=?P(PhOMe-p)₃, 1; P(PhMe-p)₃, 2; P(PhF-p)₃, 3), have been prepared through carbonyl substitution in the presence of Me₃NO. The new complexes 1–3 were characterized by elemental analysis, IR, ¹H, ¹³C{¹H}, and ³¹P{H} NMR spectra. The molecular structures of 1–3 were unequivocally determined by single crystal X-ray diffraction, in which the tris(aromatic)phosphine coordinated to Fe resides in an apical position of the pseudo-square-pyramidal geometry. IR spectroscopy and X-ray crystallographic analysis for 1–3 have indicated that the highly electron rich tris(aromatic)phosphine ligands (where the corresponding electron-donating abilities display the following order of P(PhOMe-p)₃?>?P(PhMe-p)₃?>?P(PhF-p)₃) result in a considerable red shift of the CO-stretching frequencies and a clear change of the Fe–Fe bond distances in 1–3.     

Formation of a PIII−C(sp2) bond by addition of diphenyl(trimethylsilyl)phosphine to activated acetylenes

Diphenyl(trimethylsilyl)phosphine reacts with alkoxy(alkyl)acetylenes to give mixtures of addition products, (2-alkoxy-2-trimethylsilylalkenyl)diphenylphosphines and (2-alkoxyalkenyl)diphenylphosphines. The reaction is sensitive to the solvent; in MeCN, it gives only nonsilylated products. (1-Alkoxyethenyl)diphenylphosphines were obtained as the main products upon the reaction of Ph₂PSiMe₃ with terminal alkoxyalkynes, irrespective of the reaction conditions. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1792–1796, September, 1998.     

Hydrogenation of α,β-unsaturated substrates by tris(2-phridyl)amine (tpN) or tris(2-pyridyl)phosphine (tpP)/[Ir(COE)2Cl]2 catalyst systems

This work describes the homogeneous hydrogenation of different α,β-unsaturated substrates by using as catalyst systems the complex [Ir(COE)₂Cl]₂ stabilized by tris(2-pyridyl)amine (tpN) or tris(2-pyridyl)phosphine (tpP) formed in situ under the following reaction conditions: pH₂ = 34 atm; T=373 K; substrate/catalyst ratio = 100, [ligand]/[metal]: 2,1; toluene (50 mL); R.P.M.: 430; t = 6 h. The activities varies from low to moderate range, where both ligands proved to be catalyst systems able to hydrogenate C=C and C=O bonds.     

Tris(2-ethylhexyl)phosphine oxide as an effective solvent mediator for constructing a serotonin-selective membrane electrode

A series of solvent mediators containing a phosphoryl (PO) group, such as tris(2-ethylhexyl)phosphate, bis(2-ethylhexyl) 2-ethylhexylphosphonate, 2-ethylhexyl bis(2-ethylhexyl)phosphinate, and tris(2-ethylhexyl)phosphine oxide, were used to construct serotonin-selective membrane electrodes. We found that replacing the alkoxy groups attached to phosphorus atoms in PO groups with alkyl groups strengthened the response of the electrode to serotonin, suppressing remarkably interference from inorganic cations, such as Na⁺. Thus, an electrode combining tris(2-ethylhexyl)phosphine oxide with an ion-exchanger, sodium tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate, gave a detection limit of 9 × 10⁻⁶ M with a slope of 55.2 mV per concentration decade in physiological saline containing 150 mM NaCl and 10 mM NaH₂PO₄/Na₂HPO₄ (pH 7.4). This is the best detection limit of any serotonin-selective electrode developed to date. The selectivity of this electrode for serotonin was over 10³ times that for inorganic cations, such as Na⁺ and K⁺, and lipophilic quaternary ammonium ions, such as acetylcholine and (C₂H₅)₄N⁺. Using the electrode, we measured the amount of serotonin released from platelets and found that the results agreed well with those obtained by a conventional fluorimetric assay of serotonin.     

Molecular structure of (3,5-diallylisocyanuratomethyl)bis(chloromethyl)phosphine oxide. Synthesis of (3,5-diallylisocyanuratomethyl)phosphine sulfides

X-Ray study of the (3,5-diallylisocyanuratomethyl)bis(chloromethyl)phosphine oxide showed that the phosphorylmethyl group is bonded to the nitrogen atom of the cycle. Reaction of the tris(chloromethyl)phosphine sulfide with sodium diallylisocyanurate gave (3,5-diallylisocyanuratomethyl)bis(chloromethyl)phosphine sulfide, and treatment of the tris(3,5-diallylisocyanuratomethyl)phosphine oxide with phosphorus pentasulfide gave a tris(3,5-diallylisocyanuratomethyl)bis(chloromethyl)phosphine sulfide.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1446–1448, August, 1993.     

Reactions of polyfluoroaromatic compounds with electrophilic agents in the presence of tris(dialkylamino)phosphine

The rate of replacement of the halogen atom in isomers of RC₆F₄X (X=Cl, Br, or I) by the SiMe₃ group under the action of Me₃SiCl and P(NEt₂)₃ depends on the nature and the mutural arrangement of the substituents X and R. In addition to silyldehalogenation, compounds C₆HF₄X (X=Br or I) undergo silyldeprotonation and reduction to tetrafluorobenzenes. For Part 5, see Ref. 1 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 813–818, April, 1997.     

Ultrasound promoted enantioselective transesterification of 3-hydroxy-3-(2-thienyl) propanenitrile catalyzed by lipase

(S)-3-hydroxy-3-(2-thienyl) propanenitrile, which is the key chiral building block for the synthesis of (S)-duloxetine, was successfully prepared via enantioselective transesterification catalyzed by lipase under ultrasound irradiation. Compared with conventional shaking, the enzyme activity and enantioselectivity were dramatically enhanced under ultrasound irradiation. Under optimum reaction conditions (solvent: n-hexane, ultrasound power: 150?W, a_w: 0.33, temperature: 40°C), Pseudomonas sp. lipase exhibited an excellent catalytic performance (enzyme activity: 81.5?μmol?g^?1?min^?1, E-value: 65.4). The reaction achieved its equilibrium in approximately 7?h with a conversion of 53.9% and high enantiopurity (99% ee) of (S)-3-hydroxy-3-(2-thienyl) propanenitrile could be obtained.     

Lipase-catalyzed enantioselective transesterification of 3-hydroxy-3-(2-thienyl) propanenitrile in liquid carbon dioxide

The transesterification of 3-hydroxy-3-(2-thienyl) propanenitrile catalyzed by Pseudomonas fluorescens lipase (PFL) in liquid carbon dioxide (CO₂) was reported. Compared with that in organic solvent (n-hexane), the catalytic performance of PFL was dramatically enhanced in liquid CO₂. Under the optimal reaction conditions, PFL exhibited an excellent enantioselectivity (E-value: 92.9) with a high enzyme activity (82.5?μmol/g/min). Besides, the remained (S)-3-hydroxy-3-(2-thienyl) propanenitrile with high enantiomeric purity (ee?>?99%) was obtained in 4?h when the conversion was about 52%.

Lipase-catalyzed transesterification of 3-hydroxy-3-(2-thienyl) propanenitrile in liquid CO₂     

Synthesis of montmorillonite-based tris(2-ethylamine)-Schiff-base composites with remarkable antibacterial activity

A range of heterogeneous, inexpensive and benign Schiff bases-montmorillonite composites were synthesized and screened for their antibacterial activity against common microbial pathogens. Sodium montmorillonite (Na-MMT) clay was modified with tris(2-ethylamine) in the presence of dilute HCl to yield a quaternary salt of tris(2-ethylamine) modified clay. The Schiff bases were then fabricated from the reaction of the modified montmorillonite using different aldehydes. The structures of the obtained compounds were confirmed by Fourier transformer Infrared (FT-IR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). All the obtained composite materials were screened for their antibacterial activities against the multi-drug resistant (MDR) strains. It was reasoned that the modified MMT-based composites has the ability to absorb the different micro-organisms onto the surface, and accordingly act as an effective antibacterial agent. All the composites showed significant antibacterial activity between 2.5 and 20 mg/mL against the MDR bacterial strains. The benzyl-based/modified MMT and the tertiary amino-based/modified MMT was found to be the most effective antibacterial agent.