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1.
Novel tetrameric rhenium(V) complexes have been prepared from [ReNCl2(PPh3)2] and [ReN(PMe2Ph)(S2CNEt)2], respectively. [ReNCl2(PPh3)2] reacts with 1.5 equivalents of KS2CNEt2 in methanol to yield the unusual dark red species [{cyclo-ReN}4(S2CNEt2)6(MeOH)2(PPh3)2][BPh4]2 · CH2Cl2 · 2 H2O ( 1 ). The crystal structure of the tetramer (triclinic, space group P1, a = 13.842(2), b = 15.213(2), c = 16.796(3) Å, α = 67.88(1), β = 70.90(1), γ = 88.05(1)°, U = 3080.2(8) Å3, Z = 1) shows four rhenium atoms in a square configuration which are bridged via linear asymmetric Re≡N–Re groups with bond lengths of about 169 and 203 pm. The molecule contains a centre of symmetry with two distinct octahedral rhenium environments. The first rhenium environment contains two bidentate dithiocarbamate ligands which complete the octahedral geometry and the second contains a bidentate dithiocarbamate ligand, coordinated methanol and has retained a single phosphine coligand. A symmetric compound containing the {cyclo-ReN}4 core is obtained from the reaction of [ReN(PMe2Ph)(S2CNEt2)2] with Al2Cl6 in acetone. [{cyclo-ReN}4(S2CNEt2)4Cl4(PMe2Ph)4] · 2 acetone ( 2 ) forms red crystals (monoclinic, space group C2/c, a = 21.432(6), b = 13.700(3), c = 28.060(9) Å, β = 102.37(1)°, U = 8048(4) Å3, Z = 4) with each rhenium atom coordinated by a bidentate dithiocarbamato, a phosphine and a chloro ligand. The non-planar 8-membered {ReN}4 ring contains asymmetric Re≡N–Re bridges (mean values: 1.69 Å and 2.029 Å, respectively). In contrast, reaction of [ReNCl(S2CNEt2)(PMe2Ph)2] with one equivalent of K[S2CN(Me)CH2CH2NMe3]I gave the mixed dithiocarbamato-cation [ReN(S2CNEt2)(S2CN(Me)CH2CH2NMe3)(PMe2Ph)]+ ( 3 ) which was isolated as a tetraphenylborate salt.  相似文献   

2.
Two series of new phosphine derivatives based on C60 protected by borane have been synthesized and characterized. These phosphines were used for two preliminary complexation trials with [RhCl(COD)]2 and [Re(S3CPh)2(S2CPh)] to afford, respectively, the corresponding complexes [RhCl(COD)(PRPh2)] and [Re(S2CPh)3(PRPh2)].  相似文献   

3.
Reactions of Halfsandwich Rhenium(V) Oligochalcogenide Complexes with Dimethyl Acetylene Dicarboxylate. Molecular Structures of the New 1,2-Dicarbomethoxy-ethene-1,2-dichalcogenate Chelate Compounds Cp*Re[S2C2(COOMe)2]2 and Cp*Re(NtBu)[Se2C2(COOMe)2] The reaction of Cp*Re(S3)(S4) ( 1a ) with dimethyl acetylene dicarboxylate (dmad) leads through the blue intermediate Cp*Re(S4)[S2C2(COOMe)2] ( 2a ) to the red bis(ethene-1,2-dithiolato) complex Cp*Re[S2C2(COOMe)2]2 ( 3a ). The product 3a is also formed in the reactions of dmad with the tetrasulfidorhenium complexes Cp*Re(L)(S4) (L = O ( 4a ), NtBu ( 5a )) while the analogous tetraselenidorhenium compounds Cp*Re(L)(Se4) ( 4b and 5b ) are only transformed to Cp*Re(L)[Se2C2(COOMe)2] (L = O ( 6b ), NtBu ( 7b )). According to the X-ray crystal structure analyses, the (ethene-1,2-dithiolato)rhenium chelate rings in 3a are folded along the S …? S vector towards the Cp* ligand (angle between the planes ReS2/S2C2 159.2°), whereas the ReSe2C2 chelate ring in 7b is planar.  相似文献   

4.
In the structure of the title compound, [Ir2Cl3H2(C36H28P2)2]BF4·2CH2Cl2, the bimetallic cation features a confacial bioctahedral structure that is held together by three bridging chloride ions and is very close to C2 symmetric. The hydrides are in a syn orientation (trans to the same halide bridge), and the chelating bis(phosphine) atropisomers display a racemic (R,R)/(S,S) configuration. Because of the high trans‐bond‐weakening influence of the hydride ligands, the Ir—Cl bonds trans to Ir—H [2.5262 (7) and 2.5365 (7) Å] are significantly longer than those opposite the Ir—P linkages [2.4287 (7)–2.4672 (8) Å]. The Ir—P distances vary between 2.2464 (9) and 2.2565 (8) Å. This study illustrates the usefulness of sterically demanding biaryl‐based P2 ligands in the synthesis of halide‐bridged Ir2 complexes, which are valuable precursors of versatile catalysts for homogeneous C=O hydrogenation.  相似文献   

5.
In this study, we theoretically investigated the mechanism underlying the high‐valent mono‐oxo‐rhenium(V) hydride Re(O)HCl2(PPh3)2 ( 1 ) catalyzed hydrosilylation of C?N functionalities. Our results suggest that an ionic SN2‐Si outer‐sphere pathway involving the heterolytic cleavage of the Si?H bond competes with the hydride pathway involving the C?N bond inserted into the Re?H bond for the rhenium hydride ( 1 ) catalyzed hydrosilylation of the less steric C?N functionalities (phenylmethanimine, PhCH=NH, and N‐phenylbenzylideneimine, PhCH=NPh). The rate‐determining free‐energy barriers for the ionic outer‐sphere pathway are calculated to be ~28.1 and 27.6 kcal mol?1, respectively. These values are slightly more favorable than those obtained for the hydride pathway (by ~1–3 kcal mol?1), whereas for the large steric C?N functionality of N,1,1‐tri(phenyl)methanimine (PhCPh=NPh), the ionic outer‐sphere pathway (33.1 kcal mol?1) is more favorable than the hydride pathway by as much as 11.5 kcal mol?1. Along the ionic outer‐sphere pathway, neither the multiply bonded oxo ligand nor the inherent hydride moiety participate in the activation of the Si?H bond.  相似文献   

6.
Synthesis and Structure of [Re(NH)Cl2(PMe2Ph)3][TaCl6] and [(Me2PhP)3Cl2Re≡N]2VOCl2 The products of the reaction of ReNCl2(PMe2Ph)3 with TaCl5 are dependent on the solvent. In CH2Cl2 the solvent protonates the nitrido ligand to yield [Re(NH)Cl2(PMe2Ph)3][TaCl6] as air-stable, reddish brown needles with the space group P21/n and a = 1213.8(3), b = 1358.0(2), c = 2165.9(4) pm, β = 92.88(1)°, Z = 4. The Re atom of the cation exhibits an octahedral coordination with the phosphine ligands in meridional arrangement. The imido ligand is in trans-position to a Cl atom with a distance Re–N = 170.4(4) pm. When the reaction is carried out in toluene the dinuclear nitrido complex [Re(NTaCl5)Cl2(PMe2Ph)3] is obtained instead. The reaction of ReNCl2(PMe2Ph)3 with VCl3(THF)3 in toluene affords the threenuclear complex [Re2N2Cl4(PMe2Ph)5]VCl3, which upon crystallization at air gives air-stable, reddish-brown crystals of [(Me2PhP)3Cl2ReN]2VOCl2. They crystallize in the monoclinic space group P21 with a = 1519.2(5), b = 1257.1(1), c = 1564.3(6) pm, β = 102.86(2)°, and Z = 2. The threenuclear complex shows an almost linear arrangement Re≡N–V–N≡Re with distances Re–N 171(2) pm and V–N of 209(2) pm.  相似文献   

7.
Defluorinative C(sp3)?P bond formation of α‐trifluoromethyl alkenes with phosphine oxides or phosphonates have been achieved under catalyst‐ and oxidant‐free conditions, giving phosphorylation gem‐difluoroalkenes as products. α‐Trifluoromethyl alkenes bearing various of aryl substituents such as halogen, cyano, ester and heterocyclic groups are available in this transformation. The results of control experiments demonstrated that the mechanism of dehydrogenative/defluorinative cross‐coupling reactions was not a radical route, but might be an SN2′ process involving phosphine oxide anion.  相似文献   

8.
Mixed-ligand Complexes of Rhenium. VI. Synthesis and X-Ray Structures of the Rhenium Thionitrosyl Complexes mer-[Re(NS)Cl2(Me2PhP)3] · CH2Cl2 and trans-[Re(NS)Cl3(Me2PhP)2] mer-Dichlorotris(dimethylphenylphosphine)(thionitrosyl)rhenium(I), mer-[Re(NS)Cl2(Me2PhP)3], and trans-Trichlorobis(dimethylphenylphosphine)(thionitrosyl)rhenium(II), trans-[Re(NS)Cl3(Me2PhP)2], are formed during the reaction of rhenium(V) mixed-ligand complexes of the general formula [ReN(Cl)(Me2PhP)2(R2tcb)] with disulphur dichloride (HR2tcb = N-(N,N-dialkylthiocarbamoyl)benzamidine). The chelating ligands are substituted during the reaction. mer-[Re(NS)Cl2(Me2PhP)3] crystallizes monoclinic in the space group P21/n. The dimensions of the unit cell are a = 8.854(2); b = 31.295(3); c = 11.981(3) Å; β = 108.14(1)°; Z = 4. A final R value of 0.033 was achieved on the basis of 5 387 reflections with I ≥ 3σ(I). The rhenium atom is coordinated in a distorted octahedral environment. The Me2PhP ligands are arranged meridionally cis to the linear thionitrosyl group. trans-[Re(NS)Cl3(Me2PhP)2] crystallizes in the monoclinic space group C2/c with an unit cell of the dimensions a = 33.320(9); b = 8.446(1); c = 17.28(5) Å; β = 116.09(1)°, Z = 8. The R value converged at 0.026 on the basis of 5 460 independent reflections. The metal is octahedrally coordinated with the phosphine ligands in trans position to each other. The angle Re? N? S is 175.7(3)°.  相似文献   

9.
The central phosphino group of tripodal tetradentate tris[2-(diphenylphosphino)ethyl]phosphine (pp3) was selectively oxidized by the reaction with diethyl disulfide to give tridentate phosphine ligand pOp3. The terminal phosphino groups were reacted with sulfur to give pOp3 trisulfide (pOp3S3). Three palladium(II) ions were sandwiched in the two pOp3 and pOp3S3 ligands to form the trinuclear complexes with three trans(P) and trans(S) PdX2 (X = Cl, Br, I) moieties, respectively. The tripodal triphosphine, 1,1,1-tris(diphenylphosphinomethyl)ethane (i-p3), and its mono- and tri-sulfide, which have shorter carbon chains compared with pOp3, form the mononuclear dichloro palladium(II) complexes with cis(P) and cis(S) geometries. Difference in the catalytic activity for the C–C coupling reaction was discussed in connection with the coordinated groups and geometries of the complexes.  相似文献   

10.
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 Rw = 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 Rw = 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.  相似文献   

11.
We have developed an on-line digestion device-based on the nano-TiO2-catalyzed photooxidation of arsenic species—for coupling between microbore anion-exchange chromatography (μ-LC) and hydride generation (HG)-inductively coupled plasma mass spectrometry (ICP-MS) systems that can be used for the determination of urinary arsenic species. To maximize the signal intensities of the desired arsenic species, we optimized the photocatalytic oxidation efficiency of the analyte species and developed a rapid on-line pre-reduction process for converting the oxidized species into As(III) prior to HG-ICP-MS determination. Under the optimized conditions for the nano-TiO2-catalyzed photooxidation-i.e., using 1 g of nano-TiO2 per-liter, at pH 5.2, and illuminating for 3 min- As(III), monomethylarsenoic acid (MMA), and dimethylarseinic acid (DMA) can be converted quantitatively into As(V). To attain maximal hydride generation efficiency, 0.5% Na2S2O4 solution, which can reduce As(V) to As(III) virtually instantaneously upon on-line mixing, was added as a pre-reductant prior to performing the HG step. In light of all the HG efficiency of tested arsenicals were improved and a segmented-flow technique was employed to avoid the loss of peak resolution when using our proposed on-line μ-LC-UV/nano-TiO2/HG-ICP-MS, the detection limits for As(III), MMA, DMA, and As(V) were all in the range of sub-microgram-per-liter (based on 3 sigma). A series of validation experiments-analysis of neat and spiked urine samples-indicated that our proposed methods can be applied satisfactorily to the determination of As(III), MMA, DMA, and As(V) in urine samples.  相似文献   

12.
The methylidene complex [(η-C5H5)Re(NO)(PPh3)(CH2)]+PF6?(I) yields kinetically labile sulfonium salts when treated with CH3SCH3, CH3SCH2C6H5, and (η-C5H5)Re(NO)(PPh3)(CH2SCH3) (V);the binuclear adduct formed in the latter case, [(η-C5H5)Re(NO)(PPh3)CH2]2S+CH3 (VI), is substantially more stable than the others and undergoes hydride transfer disproportionation to [(η-C5H5)Re(NO)(PPh3)(CHSCH3)]+PF6?(VII) and (η-C5H5)Re(NO)(PPh3)(CH3) (VIII) when heated.  相似文献   

13.
Abstract

The mechanism of the reactions of diphenyl N-bromosulfilimine (I) with such nucleophiles as sulfides, phosphines and tertiary amines was investigated. In the presence of water, (I) reacts with sulfides or phosphines to afford the corresponding sulfoxides or the phosphine oxides in moderate yields; however, the reaction with tertiary amine gave only the N-t-aminosulfilimine derivative. The effect of ring size in the reaction with cyclic sulfides suggests that the reaction proceeds via initial bromine transfer from the nitrogen atom to the sulfur atom of the cyclic sulfides followed by SN2 type substitution of bromide on the sulfur atom of the cyclic sulfide with the sulfilimino group. The phosphine oxide obtained in the reaction of (I) with optically active methyl n-propyl phenyl phosphine was racemized but retained a small portion of the optical activity. In the case of tertiary amines, even 1,4-diazabicyclo-(2,2,2)-octane (DABCO), in which the back side of the nitrogen atom is blocked, reacted smoothly to afford the corresponding ammonium salts, suggesting the reaction to be of SN2 type on the nitrogen atom of the sulfilimine.  相似文献   

14.
The catalytic performance of ReOx‐modified Ir metal catalyst in the hydrogenolysis of C–O bonds is strongly dependent on the choice of solvent. The acidic property of the Re species becomes obvious in the alkane solvent, and the hydrogenolysis reaction proceeds mainly by acid‐catalyzed dehydration and the subsequent metal‐catalyzed hydrogenation. The acidic property of the Re species is weakened in water; however, the hydrogenolysis reaction proceeds in water via a direct mechanism involving SN2‐like attack of a hydride species at the interface between Ir and ReOx on the adsorbed Re alkoxide species. This mechanism enabled the selective dissociation of the C–O bond neighboring the CH2OH group.  相似文献   

15.
Abstract

Problems associated with using a phosphine /CO2 mixture as a fumigant include oxidation and contamination with P4  相似文献   

16.
Synthesis and Crystal Structure of (PPh4)3[Re2NCl10] The rhenium(V) nitrido complex (PPh4)3[Re2NCl10] ( 1 ) is obtained from the reaction of (PPh4)[ReNCl4] with 1, 3‐dioxan‐(2‐ylmethyl)diphenyl phosphine in CH2Cl2/CH3CN in form of orange red crystals with the composition 1 ·2CH2Cl2 crystallizing in the triclinic space group P1¯ with a = 1210.7(2), b = 1232.5(1), c = 2756.3(5) pm, α = 99.68(1)°, β = 100.24(1)°, γ = 98.59(1)° and Z = 2. The crystal structure contains two symmetry independent, centrosymmetrical complex anions [Re2NCl10]3‐ with a symmetrical nitrido bridge Re=N=Re and distances Re(1) ‐ N(1) = 181.34(5) and Re(2) ‐ N(2) = 181.51(4) pm.  相似文献   

17.
Summary The interaction of hard base chelating agents (LH) such as 8-quinolinol (oxH), salicylaldehyde (salH) andN-nitrosophenylhydroxylamine (NphaH) with ammonium tetrathiomolybdate(VI), (1), in aqueous solution yields disulphidomolybdenum(VI) complexes, [MoS2L2]. The i.r. absorptions at 540 and 510 cm–1 are assigned tov(Mo-S), which indicate that the two sulphido-groups arecis to each other, The interaction of (1) with soft base chelating agents (SS), such as dithiocarbamates (dtc), dithiophosphate (dtp) and xanthates (xan) yields dimeric sulphido-bridged sulphidomolybdenum(V) complexes, [Mo2S4(SS)2] and with potassium ethylthioxanthate (KEttxan) yields a molybdenum(IV) complex, [Mo(Ettxan)4]. The [Mo2S4(R2dtc)2] complexes were also obtained by the interaction of [MoO2(R2dtc)2] with phosphorus pentasulphide in xylene. It was concluded that tetrathiomolybdate(VI) undergoes facile reduction when compared with tetraoxomolybdate(VI).  相似文献   

18.
Monomeric, five-coordinated bis(ethylxanthato)ZnII(phosphine) complexes [phosphine = PPh3, P(o-tolyl)3, P(CH2Ph)3] have been synthesized by addition of the phosphine ligand (1:1 molar ratio) to CH2Cl2 solutions of [Zn(S2COEt)2]. Bidentate ligands Ph2PCH2CH2PPh2 (dppe) and Ph2P(CH2)4PPh2 (dppb) reacted in a 1:2 molar ratio to form dinuclear phosphine-bridged complexes. The Zn—P bonds are very labile and are probably broken in solution. The characterization of all the compounds has been carried out by elemental analyses and spectroscopic methods (i.r. and n.m.r.). The structure of binuclear [(S2COEt)2Zn(-dppb)Zn(S2COEt)2], determined by X-ray crystallography, shows a distorted trigonal bipyramidal environment for the Zn atoms, formed by two chelating xanthate and a bridging dppb ligand.  相似文献   

19.
Sulfide solid electrolytes, which show high ion conductivity, are anticipated for use as electrolyte materials for all-solid-state batteries. One drawback of sulfide solid electrolytes is their low chemical stability in air. They are hydrolyzed by moisture and generate H2S gas. Substituting oxygen atoms for sulfur atoms in sulfide solid electrolytes is effective for suppression of H2S gas generation in air. Especially, the xLi2O·(75-x)Li2S·25P2S5 (mol%) glasses hardly generated H2S gas in air. However, substituting oxygen atoms for sulfur atoms caused a decrease in conductivity. The x?=?7 glass showed high chemical stability in air and maintained high conductivity of 2.5?×?10?4 S cm?1 at room temperature. Performance of cells using the 7Li2O·68Li2S·25P2S5 and the 75Li2S·25P2S5 glasses as solid electrolytes were compared. All-solid-state C/LiCoO2 cell using the 7Li2O·68Li2S·25P2S5 glass produced performance as good as that obtained using the 75Li2S·25P2S5 glass. Capacity retention and change of interfacial resistance of the former cell were superior to those of the latter cell after storage at 4.0 V and 60 °C. The diffusion of oxygen element into the 7Li2O·68Li2S·25P2S5 glass was less than that into the 75Li2S·25P2S5 glass after storage at the voltage of 4.0 V at 60 °C. Improvement of the stability of sulfide solid electrolytes to moisture was related to cell performance as well as an increase in conductivity.  相似文献   

20.
Coordination of a bulky pyridinyl‐phosphine ( P?N ) ligand toward CuBr was investigated. However, this P?N donor behaves as a monodentate via the coordination of phosphine to form a bromide bridged dimeric [( P?N )Cu(μ‐Br)2Cu( P?N )], which was characterized by spectral and crystal structural analysis. It appeared that the “PCu(μ‐Br)2CuP” unit is planar with a short distance between Cu…Cu' [2.7585(9) Å]. The catalytic activity on Sonogashira coupling of phenylacetylene with aryl halides was studied.  相似文献   

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