首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The dimeric rhodium precursor [Rh(CO)2Cl]2 reacts with quinoline (a) and its three isomeric carboxaldehyde ligands [quinoline-2-carboxaldehyde (b), quinoline-3-carboxaldehyde (c), and quinoline-4-carboxaldehyde (d)] in 1:2 mole ratio to afford complexes of the type cis-[Rh(CO)2Cl(L)] (1a-1d), where L = a-d. The complexes 1a-1d have been characterised by elemental analyses, mass spectrometry, IR and NMR (1H, 13C) spectroscopy together with a single crystal X-ray structure determination of 1c. The X-ray crystal structure of 1c reveals square planar geometry with a weak intermolecular pseudo dimeric structure (Rh?Rh = 3.573 Å). 1a-1d undergo oxidative addition (OA) with different electrophiles such as CH3I, C2H5I and I2 to give Rh(III) complexes of the type [Rh(CO)(COR)Cl(L)I] {R = -CH3 (2a-2d), R = -C2H5 (3a-3d)} and [Rh(CO)Cl(L)I2] (4a-4d) respectively. 1b exhibits facile reactivity with different electrophiles at room temperature (25 °C), while 1a, 1c and 1d show very slow reactivity under similar condition, however, significant reactivity was observed at a temperature ∼40 °C. The complexes 1a-1d show higher catalytic activity for carbonylation of methanol to acetic acid and methyl acetate [Turn Over Frequency (TOF) = 1551-1735 h−1] compared to that of the well known Monsanto’s species [Rh(CO)2I2] (TOF = 1000 h−1) under the reaction conditions: temperature 130 ± 2 °C, pressure 33 ± 2 bar, 450 rpm and time 1 h. The organometallic residue of 1a-1d was also isolated after the catalytic reaction and found to be active for further run without significant loss of activity.  相似文献   

2.

Naphthphosphacyclophanes based on symmetrical dihydroxynaphthalenes linked by diethylamidophospite groups were used to synthesize rhodium(I) complexes containing carb-onyl and acetylacetonato fragments. The physicochemical and spectral characteristics of the synthesized coordination systems were studied.

  相似文献   

3.
The chelate complexes of the types (1) and (2) have been synthesized and characterized by IR and NMR spectroscopy. The lower shift of the ν(P-Se) bands and downfield shift of the 31P-{1H}NMR signals for both P(III) and P(V) atoms in 1 and 2 compared to the corresponding free ligands indicate chelate formation through selenium donor. 1 and 2 show terminal ν(CO) bands at 1977 and 1981 cm−1, respectively, suggesting high electron density at the metal center. The molecular structure of 2 has been determined by single-crystal X-ray diffraction. The rhodium atom is at the center of a square planar geometry having the phosphorus and selenium atoms of the chelating ligand at cis-position, one carbonyl group trans- to selenium and one chlorine atom trans- to phosphorus atom. 1 and 2 undergo oxidative addition (OA) reaction with CH3I to produce acyl complexes (3) and (4), respectively. The kinetics of the OA reactions reveal that 1 undergoes faster reaction by about 4.5 times than 2. The catalytic activity of 1 and 2 in carbonylation of methanol was higher than that of the well known species [Rh(CO)2I2] and 2 shows higher catalytic activity compared to 1.  相似文献   

4.
The reactions of dimeric complex [Rh(CO)2Cl]2 with hemilabile ether‐phosphine ligands Ph2P(CH2) nOR [n = 1, R = CH3 (a); n = 2, R = C2H5 (b)] yield cis‐[Rh(CO)2Cl(P ~ O)] (1) [P ~ O = η 1‐(P) coordinated]. Halide abstraction reactions of 1 with AgClO4 produce cis‐[Rh(CO)2(P ∩ O)]ClO4 (2) [P ∩ O = η 2‐(P,O)chelated]. Oxidative addition reactions of 1 with CH3I and I2 give rhodium(III) complexes [Rh(CO)(COCH3)ClI(P ∩ O)] (3) and [Rh(CO)ClI2(P ∩ O)] (4) respectively. The complexes have been characterized by elemental analyses, IR, 1H, 13C and 31P NMR spectroscopy. The catalytic activity of 1 for carbonylation of methanol is higher than that of the well‐known [Rh(CO)2I2]? species. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

5.
Summary Rhodium(I) carbonyl complexes, namely [Rh(CO)2ClL] where L = thiourea (Tu), 1,3-diphenyl-2-thiourea (DTu), dithizone (Dtz), indole (Id), 3-chloropyridine (Clpy), 3-hydroxypyridine (HOpy), 3-methylpyridine (Mepy), 2,5-dimethylpyridine (Me2py) or 2,5-dichloropyridine (Cl2py)] were prepared. [Rh(CO)2Cl(Clpy)2] has also been isolated. In the (Tu) complex, (C-S) occurs at ca. 710cm-1, indicating the presence of a metal-sulphur bond. The carbonyl stretching frequencies in [Rh (CO)2ClL] and [Rh(CO)2CIL2] occur at ca. 2100–1990 and 1830–1800 cm-1, respectively. PPh3 reacts with the complexes to form trans-[Rh(CO)Cl(PPh3)2]. The complexes were characterized by elemental analyses, conductivity measurements and by their i.r. spectra.  相似文献   

6.
Summary Complexes of the [Rh(N-N)(CO)2][RhCl2(CO)2], [Rh(N-N)(CO)2]BF4 and Rh(N-N)(CO)2Cl types where (N-N) = 2,9-dimethyl-1,10-phenanthroline (Me2Phen), 4,7-diphenyl-1,10-phenanthroline (Ph2Phen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (Me22Ph2Phen) or 2,2-biquinoline (biq), have been prepared and investigated. Benzidine (benz) ando-tolidine (tol) also form complexes of the first type. The complexes of the first two types behave as 11 electrolytes. While Ph2Phen forms the four coordinate monocarbonyl Rh(Ph2Phen)(CO)Cl complex, benzo(f)-quinoline (Q) yields the Rh(CO)2 (Q)Cl compound. Triphenyl-phosphine and triphenylarsine react with the above complexes to form the well knowntrans-Rh(CO)ClL2 where L = PPh3 or AsPh3. The i.r. and u.v.-visible spectra of the compounds are discussed.  相似文献   

7.
The syntheses of Co(π-all)(PF3)2(PPh3) complexes (π-all = π-allyl, anti-1-Me-π-allyl, syn-1-Me-π-allyl, 1,1-dimethyl-π-allyl, anti-1,2-diMe-π-allyl, syn,syn-1,3-diMe-π-allyl, 2Et-π-allyl, π-cyclooctenyl, h3-π-cycloheptadienyl) are described. 1H and 19F NMR data are presented and discussed in relation to the structures of the complexes. The compound Co(π-C5H9)(PF3)(PPh3)2 is also reported. Several of the π-allylic complexes are found to be active catalysts for the isomerisation of 1-octene to 2-octene under a hydrogen atmosphere.  相似文献   

8.
The complexes CoH(PF3)4?n (PPh3)n (n = 1–3) have been prepared by low from the reaction between CoH(PF3)(PPh3)3 and butadiene. The hydrido complexes are active catalysts for the isomerisation of 1-octene to 2-octene under hydrogen or nitrogen.  相似文献   

9.
Summary Rhodium(I) carbonyl complexes, namely Rh(CO)X(R2SO)2 (R = Me, n-Pr or n-Bu) and Rh(CO)X(R2S)2 (R = Me, Et or i-Pr) and X = CI or Br, have been prepared and characterized. The compounds Rh(CO)X[P(OPh)3]2 X = Cl or Br, have also been isolated. In the R2SO and R2S complexes, the carbonyl stretching frequencies occur atca. 2020–2025 cm–1 andca. 1950–1980 cm–1 respectively. In the R2SO ligand containing complexes v(S-O) occurs atca. 1100–1125 cm–1 indicative of metal-sulphur coordination. In presence of HBF4, the addition of an excess of Me2SO to (OC)2Rh(-Cl)2Rh(CO)2 gives [Rh(Me2SO)6]3+ in which the central metal atom undergoes spontaneous oxidation from Rh1(d8) to RhIII(d6). The complexes have been characterized additionally by u.v.vis. spectra, conductivity measurements and by elemental analyses.  相似文献   

10.
Thermal treatment of three monobridged biscyclopentadienes (C5H5)R(C5H5) [R = C(CH3)2 (1), C(CH2)5 (2), Si(CH3)2 (3)] with Re2(CO)10 in refluxing mesitylene gave the corresponding complexes [(η 5-C5H4)2R][Re(CO)3]2 [R = C(CH3)2 (4), C(C5H10) (5), Si(CH3)2 (6)], which were separated by chromatography, and characterized by elemental analysis, IR, and 1H NMR spectroscopy. The molecular structures of complexes 5 and 6 were characterized by X-ray crystal diffraction analysis and show that both are monobridged bis(cyclopentadienyl)rhenium carbonyl complexes in which the molecule consists of two [(η 5-C5H4)Re(CO)3] moieties linked by a single bridge, in which each of the two Re(CO)3 units is coordinated to the cyclopentadienyl ring in an η 5 mode. All three of these monobridged bis(cyclopentadienyl)rhenium carbonyl complexes have good catalytic activities in Friedel–Crafts alkylation reactions.  相似文献   

11.
Rhodium(I) complexes with 1,5-cyclooctadiene (COD) and disiloxydiphosphines {O[Si(CH3)2(CH2)nPPh2]2 where n = 1–3; (B-1, B-2, B-3, respectively)}; and/or with trisiloxytriphosphine Ph2P(CH2)3(CH3)Si[OSi(CH3)2(CH2)2PPh3]2 (C-2) were synthesized. Their composition and structure were determined using elemental analysis, molecular weight measurements and spectroscopic (IR, 1H NMR and vis) methods, and were then compared with the corresponding data for RuCl(COD)PPh3 (A) and RhCl(COD)2 (D). The analytical and physico-chemical data all confirm the square planar geometry of the rhodium siloxyphosphine (the same as for rhodium triphenylphosphine) complexes with the general formula [(COD)RhCl(PPh2)(CH2)n]mZ where m = 2 and Z = (CH3)2SiOSi(CH3)2 or m = 3 and Z = (CH3)2SiOSi(CH3)OSi(CH3)2. The structure is independent of the type of phosphine ligand, and the molar ratio of Rh:P is always 1:1. Catalytic activity of the complexes prepared was tested in the hydrosilylation of 1-hexene by triethoxysilane which showed a slight decrease in turnover number (A–C) compared with Wilkinson's catalyst (E) but the activation energies for the rhodium-siloxyphosphine complexes (B and C) are higher than those for the rhodium phosphine complexes (A and E).  相似文献   

12.
The preparation of cationic indazole (HIdz) rhodium(I) complexes of the types [(diolefin)Rh(HIdz)2]ClO4 and [(CO)2Rh(HIdz)2]ClO4 is described. Neutral binuclear rhodium(I) complexes of the type [Y2Rh(μ-Idz)]2 (Y2  COD, TFB, NBD, (CO)2 or (CO)(PPh3)) are obtained by treating the corresponding complexes [Y2RhCl]2 with indazole and organic or inorganic bases. The cationic mononuclear derivatives react with the solvated species [Y2Rh(acetone)x]ClO4 in the presence of triethylamine to give neutral binuclear complexes of the types [(CO)2Rh(μ-Idz)2Rh(diolefin)], [(Ph3P)(CO)Rh(μ-Idz)2Rh(diolefin)] and [(diolefin)Rh(μ-Idz)Rh(diolefin′)] (diolefin  COD, TFB or NBD; diolefin′  COD or TFB). Alternative methods for the synthesis of the binuclear complexes are also described.  相似文献   

13.
14.
15.
16.
Several Rh(I) and Ir(I) complexes containing an N-heterocyclic carbene-pyrazolyl chelate ligand have been synthesised. Determination of the single-crystal X-ray structure of the Ir(I) complex showed a novel binding mode with the iridium centre coordinated to two ligands via two carbene donors in preference to one ligand forming the entropically favoured chelate. The hydrogenation activity of several of these complexes was investigated along with that of previously synthesised Rh(I) and Ir(I) complexes containing an analogous phosphine-pyrazolyl chelate.  相似文献   

17.
E. Delgado  E. Hernandez 《Polyhedron》1992,11(24):3135-3138
The reaction of [AuCl(PPh3)] with Pb(SR)2(R = C2H5, C6H5, CH2C6H5, C6F5, C6H2Me3-2,4,6, Pri and But) provides a clean method to obtain complexes of the type [Au(SR)(PPh3)] in good yields. The new compounds have been characterized by IR, 1H, 31P, 19F and 31C NMR. A study by FAB mass spectrometry indicates that an ion-molecule aggregation process takes place.  相似文献   

18.
The complexes [Rh(CO)2ClL]( 1 ), where L = 2‐aminophenol ( a ), 3‐aminophenol ( b ) and 4‐aminophenol ( c ), have been synthesized and characterized. The ligands are coordinated to the metal centre through an N‐donor site. The complexes 1 undergo oxidative addition ( OA ) reactions with various alkyl halides ( RX ) like CH3I, C2H5I and C6H5CH2Cl to produce Rh(III) complexes of the type [Rh(CO)(COR)XClL], where R = ? CH3( 2 ), ? C2H5( 3 ), X = I; R = C6H5CH2? and X = Cl ( 4 ). The OA reaction with CH3I follows a two‐stage kinetics and shows the order of reactivity as 1b > 1c > 1a . The minimum energy structure and Fukui function values of the complexes 1a–1c were calculated theoretically using a DND basis set with the help of Dmol3 program to substantiate the observed local reactivity trend. The catalytic activity of the complexes 1 in carbonylation of methanol, in general, is higher (TON 1189–1456) than the species [Rh(CO)2I2]? (TON 1159). Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

19.
The reactions of hydrogen transfer from 2-propanol on acetophenone in the presence of the system [Rh(cod)Cl]2–L] (L is bisaldimine ligands based on (R,R)-1,2-cyclohexanediimine and pyridine-, quinoline-, and thiophenecarboxaldehyde) were studied. Rhodium(I) complexes with optically active ligand showed a high catalytic activity (up to 345 h–1) and moderate enantioselectivity [up to 55% ee of (R)-1-phenyethanol]. The structure of rhodium complex with N,N'-(1R,2R)-cyclohexane-1,2-diyl-bis[1-(pyridine-2-yl)methanimine] was determined on the basis of the data of 1H and 13C NMR spectroscopy and quantum chemical calculations.  相似文献   

20.
Reactions of Rh(ClO4)(CO)(PPh3)2 with dicyano olefins, cis-NCCHCH-CH2CH2CN (c-DC1B), rans-NCCHCHCH2CH2CN (t-DC1B), trans-NCCH2CHCHCH2CN (t-DC2B), and NCCH2CH2CH2CN (DCB) produce the binuclear dicationic rhodium(I) complexes, [(CO)(PPh3)2RhNCACNRh-(PPh3)2(CO)](ClO4)2 (NCACN = c-DC1B 1), t-DC1B (2), t-DC2B (3), DCB (4). Complexes 1 and 2 are catalytically active for the hydrognation of c-DC1B and t-DC1B, respectively, to give DCB, while complex 3 catalyze the isomerization of t-DC2B to give c-DC1B and t-DC1B, and the hydrogenation of t-DC2B to DCB at 100°C.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号