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1.
The kinetics of oxidative addition of CH3I to [Rh(FcCOCHCOCF3)(CO)(PPh3)], where Fc = ferrocenyl and (FcCOCHCOCF3)− = fctfa = ferrocenoylacetonato, have been studied utilizing UV/Vis, IR, 1H and 31P NMR techniques. Three definite sets of reactions involving isomers of at least two distinctly different classes of RhIII-alkyl and two different classes of RhIII-acyl species were observed. Rate constants for this reaction in CHCl3 at 25 °C, applicable to the reaction sequence below, were determined as k1 = 0.00611(1) dm3 mol−1 s−1, k−1 = 0.0005(1) s−1, k3 = 0.00017(2) s−1 and k4 = 0.0000044(1) s−1 while k−3 ? k3 and k−4 ? k4 but both ≠0. The indeterminable equilibrium K2 was fast enough to be maintained during RhI depletion in the first set of reactions and during the RhIIIalkyl2 formation in the second set of reactions. From a 1H and 31P NMR study in CDCl3, Kc1 was found to be 0.68, Kc2 = 2.57, Kc3 = 1.00, Kc4 = 4.56 and Kc5 = 1.65. 相似文献
2.
Elizaveta P. Shestakova Viktor N. Khrustalev Ivan S. Podkorytov Aleksei B. Nikolskii 《Journal of organometallic chemistry》2011,696(20):3214-3222
The oxidative addition of CH3I to planar rhodium(I) complex [Rh(TFA)(PPh3)2] in acetonitrile (TFA is trifluoroacetylacetonate) leads to the formation of cationic, cis-[Rh(TFA)(PPh3)2(CH3)(CH3CN)][BPh4] (1), or neutral, cis-[Rh(TFA)(PPh3)2(CH3)(I)] (4), rhodium(III) methyl complexes depending on the reaction conditions. 1 reacts readily with NH3 and pyridine to form cationic complexes, cis-[Rh(TFA)(PPh3)2(CH3)(NH3)][BPh4] (2) and cis-[Rh(TFA)(PPh3)2(CH3)(Py)][BPh4] (3), respectively. Acetylacetonate methyl complex of rhodium(III), cis-[Rh(Acac)(PPh3)2(CH3)(I)] (5), was obtained by the action of NaI on cis-[Rh(Acac)(PPh3)2(CH3)(CH3CN)][BPh4] in acetone at −15 °C. Complexes 1-5 were characterized by elemental analysis, 31P{1H}, 1H and 19F NMR. For complexes 2, 3, 4 conductivity data in acetone solutions are reported. The crystal structures of 2 and 3 were determined. NMR parameters of 1-5 and related complexes are discussed from the viewpoint of their isomerism. 相似文献
3.
Yu.S. Varshavsky M.R. Galding S.N. Smirnov 《Journal of organometallic chemistry》2007,692(26):5788-5794
Selective oxidation of one (trans to N) carbonyl group in [Rh(8-Oxiquinolinato)(CO)2] with stoichiometric amount of Me3NO in MeCN produces a solution containing [Rh(Oxq)(CO)(Me3N)] and [Rh(Oxq)(CO)(MeCN)]. The ammonia complex, [Rh(Oxq)(CO)(NH3)], has been prepared by action of NH3 gas on this solution and characterized by IR, 1H and 13C NMR, and X-ray data. Spectral parameters, ν(CO), δ13C, and 1J(CRh), were measured in situ for a series of complexes [Rh(Oxq)(CO)(L)] (L = NAlk3, Py, PBu3, PPh3, P(OPh)3, C8H14) formed upon action of L on [Rh(Oxq)(CO)(NH3)] in THF. A new ν(CO) and δ13C based scale of σ-donor/π-acceptor properties of ligands L is proposed including NH3 and CO as the natural endpoints. 相似文献
4.
Rhodium(I) complexes [Rh(TropNMe)(CO)(PPh3)] (TropNMe = 2-(N-methylamino)tropone, ONC8H9) (1) and [Rh(Trop)(CO)(PPh3)] · Acetone (Trop = Tropolone, O2C7H6) (2) have been synthesized and characterized by single-crystal X-ray diffraction analysis. A distorted square planar geometry about the rhodium(I) metal centre is observed in both compounds 1 and 2. Substitution of an oxygen atom with a methyl functionalized nitrogen atom does not significantly alter the bond distances and angles in the rhodium(I) complex. A theoretical study at B3LYP/6-31G(d) (main group) and LANL2DZ (Rh) level is presented to clarify the solid state behaviour of these complexes. 相似文献
5.
Marrigje M. Conradie 《Journal of organometallic chemistry》2010,695(18):2126-101
The transition state for the oxidative addition reaction [Rh(acac)(P(OPh)3)2] + CH3I, as well as two simplified models viz. [Rh(acac)(P(OCH3)3)2] and [Rh(acac)(P(OH)3)2], are calculated with the density functional theory (DFT) at the PW91/TZP level of theory. The full experimental model, as well as the simplified model systems, gives a good account of the experimental Rh-ligand bond lengths of both the rhodium(I) and rhodium(III) β-diketonatobis(triphenylphosphite) complexes. The relative stability of the four possible rhodium(III) reaction products is the same for all the models, with trans-[Rh(acac)(P(OPh)3)2(CH3)(I)] (in agreement with experimental data) as the most stable reaction product. The best agreement between the theoretical and experimental activation parameters was obtained for the full experimental system. 相似文献
6.
The reaction of [Ru(CO)2(PPh3)3] (1) with o-styryldiphenylphophine (SP) (2) gave [Ru(CO)2(PPh3)(SP)] (3) in 83% yield. This styrylphosphine ruthenium complex 3 can also be synthesized by the reaction of [Ru(p-MeOC6H4NN)(CO)2(PPh3)2]BF4 (4) with NaBH4 and 2 in 50% yield. When “Ru(CO)(PPh3)3” generated by the reaction of [RuH2(CO)(PPh3)3] (8) with trimethylvinylsilane reacted with 2, [Ru(CO)(PPh3)2(SP)] (10) was produced in moderate yield as an air sensitive solid. The spectral and X-ray data of these complexes revealed that the coordination geometries around the ruthenium center of both complexes corresponded to a distorted trigonal bipyramid with the olefin occupying the equatorial position and the C-C bonding in the olefin moiety in 3 and 10 contained a significant contribution from a ruthenacyclopropane limiting structure. Complexes 3 and 10 showed catalytic activity for the hydroamination of phenylacetylene 11 with aniline 12. Ruthenium complex 3 in the co-presence of NH4PF6 or H3PW12O40 proves to be a superior catalyst system for this hydroamination reaction. In the case of the reaction using H3PW12O40 as an additive, ketimines (13) was obtained in 99% yield at a ruthenium-catalyst loading of 0.1 mol%. Some aniline derivatives such as 4-methoxy, 4-trifluoromethyl-, and 4-bromoanilines can also be used in this hydroamination reaction. 相似文献
7.
Ramachandran Gnanasekaran 《Vibrational Spectroscopy》2011,57(2):288-293
The cyclooctatetraenyl dianion (C8H82−) π-conjugated system forms a stable complex system with alkali and some transition metals. The results of vibrational analysis for C8H8M2 (M = Na, K) complexes were reported here. The geometries of C8H8M2 (M = Na, K) were optimized using ab initio (HF, MP2, CCSD(T)) and DFT (B3LYP) methods with 6-311G** and 6-311++G** basis sets and the harmonic frequencies were obtained. To reproduce and compare with the experimental values the structurally similar molecules C5H5M (M = Na, K) and benzene were studied. The scale factors obtained from these systems were applied to predict the experimental frequencies of C8H8M2 (M = Na, K). The force field and vibrational spectra are analyzed and the most probable assignments are proposed for all the fundamentals based on the potential energy distribution. 相似文献
8.
Somayyeh Rostamzadehmansor Shahriare Ghammamy Kheyrollah Mehrani 《Journal of fluorine chemistry》2008,129(8):674-679
The reaction of VOF3 with (C2H5)4NF, (CH3)4NCl and (C4H9)4NBr salts in anhydrous CH3CN produced new complexes with the anion general formula [VOF3X]− in that (X = F−, Cl−, Br−). These were characterized by elemental analysis, IR, UV/Visible and 19F NMR spectroscopy. The optimized geometries and frequencies of the stationary point are calculated at the B3LYP/6-311G level of theory. Theoretical results showed that the VX (X = F, Cl, Br) bond length values for the [VOF3X]− in compounds 1-3 are 1.8247, 2.4031 and 2.5595 Å, respectively. Also, the VF5 bond length values in [VOF3X]− are 1.824, 1.812 and 1.802 Å, respectively. These results reveal that the bond order for VX bonds decrease from compounds 1 to 3, while for VF5 bonds, the bond orders increase. It can be concluded that the decrease of VX bonds lengths and the increase of VF5 bond lengths in compounds 1-3 result from the increase of the hyperconjugation from compounds 1 to 3. Harmonic vibrational frequencies and infrared intensities for VOF4−, VOF3Cl− and VOF3Br− are studied by means of theoretical and experimental methods. The calculated frequencies are in reasonable agreement with the experiment values. These data can be used in models of phosphoryl transfer enzymes because vanadate can often bind to phosphoryl transfer enzymes to form a trigonal-bipyramidal structure at the active site. 相似文献
9.
Benjamin Folch Yannick Guari Christian Guérin 《Journal of solid state chemistry》2005,178(7):2368-2375
Single-crystalline nanorods of γ-MnOOH (manganite) phase with diameters of 120 nm and lengths of 1100 nm have been prepared using a new cluster growth route under low-temperature hydrothermal conditions starting from [Mn12O12(CH3COO)16(H2O)4]·2CH3COOH·4H2O or [Mn12O12(C2H5COO)16(H2O)3]·4H2O without any catalyst or template agents. The so-obtained nanorods were studied by X-ray diffraction (XRD), infrared (IR) spectroscopy, Raman spectroscopy and high resolution transmission electron microscopy (HRTEM). Their thermal conversion opens an access to Mn3O4 (hausmannite) and β-MnO2 (pyrolusite) nanorods, respectively, under argon or air atmosphere. A coercive field of 12.4 kOe was obtained for the Mn3O4 nanorods. 相似文献
10.
采用共沉淀法合成了ZrO2与Al2O3的不同质量比的ZrO2-Al2O3复合氧化物,并以此为载体通过等体积浸渍法制备了1.5% Pt/ZrO2-Al2O3(w/w)催化剂。以C3H6和CO为反应物的催化性能评价显示,在系列催化剂中以Pt/Zr(0.4)-Al催化剂催化氧化活性最为优异,其C3H6和CO的起燃温度(T50)小于125℃,完全转化温度(T90)小于150℃。采用XRD、低温N2吸附、H2-TPR、CO脉冲吸附等分析表征技术探索了催化剂物相结构、比表面积、颗粒尺寸等对催化活性的影响规律。结果发现,ZrO2-Al2O3复合氧化物具有Al2O3材料的介孔织构和大比表面积特性,且产生了AlxZr1-xOy固溶体新物相。适当的ZrO2与Al2O3的质量比,是改善Pt与ZrO2-Al2O3的相互作用强度,促进贵金属Pt的分散,提升Pt/ZrO2-Al2O3催化剂的低温氧化活性的关键。 相似文献
11.
采用共沉淀法合成了ZrO2与Al2O3的不同质量比的ZrO2-Al2O3复合氧化物,并以此为载体通过等体积浸渍法制备了1.5% Pt/ZrO2-Al2O3(w/w)催化剂。以C3H6和CO为反应物的催化性能评价显示,在系列催化剂中以Pt/Zr(0.4)-Al2O3催化剂催化氧化活性最为优异,其C3H6和CO的起燃温度(T50)小于125℃,完全转化温度(T90)小于150℃。采用XRD、低温N2吸附、H2-TPR、CO脉冲吸附等分析表征技术探索了催化剂物相结构、比表面积、颗粒尺寸等对催化活性的影响规律。结果发现,ZrO2-Al2O3复合氧化物具有Al2O3材料的介孔织构和大比表面积特性,且产生了AlxZr1-xOy固溶体新物相。适当的ZrO2与Al2O3的质量比,是改善Pt与ZrO2-Al2O3的相互作用强度,促进贵金属Pt的分散,提升Pt/ZrO2-Al2O3催化剂的低温氧化活性的关键。 相似文献
12.
Ab initio method is employed to study the structures of twelve aromatic ketones at HF/3-21G, HF/6-31G and HF/6-31G* levels, respectively.
A theoretical analysis is also carried out to study the regioselectivity and reactivity of aromatic ketones in the addition
with olefin catalyzed by RuH2(CO)(PPh3)3. The results indicate that a U shape LUMO conjugation of aromatic ketones in a plane plays an important role in regioselectivity
on the cleavage of β C-H bond and is a necessary factor to success of addition with olefin, and that steric effect is an indispensable
factor in forming additional ortho-product. Meanwhile, electronic effect may influence the rate of addition for the structures
alike which only have different replacements in the same site of aromatic ring, such as furan, thiophene and pyrole. A possible
catalytic reaction mechanism is proposed that the addition of C-H bond may be carried out by a coordination of aromatic ketones
with Ru complex. 相似文献
13.
O.L. Sologub L.P. Salamakha H. Noël A.P. Gonçalves 《Journal of solid state chemistry》2007,180(10):2740-2746
Two new compounds, La3Ru8B6 and Y3Os8B6, were synthesized by arc melting the elements. Their structural characterization was carried out at room temperature on as-cast samples by using X-ray diffractometry. According to X-ray single-crystal diffraction results these borides crystallize in Fmmm space group (no. 69), Z=4, a=5.5607(1) Å, b=9.8035(3) Å, c=17.5524(4) Å, ρ=8.956 Mg/m3, μ=25.23 mm−1 for La3Ru8B6 and a=5.4792(2) Å, b=9.5139(4) Å, c=17.6972(8) Å, ρ=13.343 Mg/m3, μ=128.23 mm−1 for Y3Os8B6. The crystal structure of La3Ru8B6 was confirmed from Rietveld refinement of X-ray powder diffraction data. Both La3Ru8B6 and Y3Os8B6 compounds are isotypic with the Ca3Rh8B6 compound and their structures are built up from CeCo3B2-type and CeAl2Ga2-type structural fragments taken in ratio 2:1. They are the members of structural series R(A)nM3n−1B2n with n=3 (R is the rare earth metal, A the alkaline earth metal, and M the transition metal). Structural and atomic parameters were also obtained for La0.94Ru3B2 compound from Rietveld refinement (CeCo3B2-type structure, P6/mmm space group (no. 191), a=5.5835(9) Å, c=3.0278(6) Å). 相似文献
14.
A new 1,6-hexyldiamine heptaborate, [H3N(CH2)6NH3][B7O10(OH)3] (1), has been solvothermally synthesized and characterized by single-crystal X-ray diffraction, FTIR, elemental analysis, and thermogravimetric analysis. Compound 1 crystallizes in monoclinic system, space group P21/n with a=8.042(2) Å, b=20.004(4) Å, c=10.103(2) Å, and β=90.42(3)°. The anionic [B7O10(OH)3]n2n− layers are interlinked via hydrogen bonding to form a 3D supramolecular network containing large channels, in which the templated [H3N(CH2)6NH3]2+ cations are located. 相似文献
15.
Konstantinos A. Chatziapostolou Alexios Grigoropoulos Aris Terzis Panayotis Kyritsis Georgios Pneumatikakis 《Journal of organometallic chemistry》2007,692(19):4129-4138
The complexes [Rh(CO)(PPh3){Ph2PNP(O)Ph2-P,O}] (3), [Rh(CO)2{Ph2P(Se)NP(Se)Ph2-Se,Se′}] (5), and [Rh(CO)(PPh3){Ph2P(Se)NP(Se)Ph2-Se,Se′}] (6), were synthesised by stepwise reactions of CO and PPh3 with [Rh(cod){Ph2PNP(O)Ph2-P,O}] (2) and [Rh(cod){Ph2P(Se)NP(Se)Ph2-Se,Se′}] (4), respectively. The complexes 3, 5 and 6 have been studied by IR, as well as 1H and 31P NMR spectroscopy. The ν(CO) bands of complexes 3 and 6 appear at approximately 1960 cm−1, indicating high electron density at the RhI centre. The structure of complexes 3 and 6 has been determined by X-ray crystallography, and the 31P NMR chemical shifts have been resolved via low temperature NMR experiments. Both complexes exhibit square planar geometry around the metal centre, with the five-membered ring of complex 3 being almost planar, and the six-membered ring of complex 6 adopting a slightly distorted boat conformation. The C-O bond of the carbonyl ligand is relatively weak in both complexes, due to strong π-back donation from the electron rich RhI centre. The catalytic activity of the complexes 2, 3 and 6 in the hydroformylation of styrene has been investigated. Complexes 2 and 3 showed satisfactory catalytic properties, whereas complex 6 had effectively no catalytic activity. 相似文献
16.
Miaojun Wang 《Journal of solid state chemistry》2005,178(4):1182-1189
Lithium substituted Li1+xMn2−xO4 spinel samples in the entire solid solution range (0?x?1/3) were synthesized by solid-state reaction. The samples with x<0.25 are stoichiometric and those with x?0.25 are oxygen deficient. High-temperature oxide melt solution calorimetry in molten 3Na2O·4MoO3 at 974 K was performed to determine their enthalpies of formation from constituent binary oxides at 298 K. The cubic lattice parameter was determined from least-squares fitting of powder XRD data. The variations of the enthalpy of formation from oxides and the lattice parameter with x follow similar trends. The enthalpy of formation from oxides becomes more exothermic with x for stoichiometric compounds (x<0.25) and deviates endothermically from this trend for oxygen-deficient samples (x?0.25). This energetic trend is related to two competing substitution mechanisms of lithium for manganese (oxidation of Mn3+ to Mn4+ versus formation of oxygen vacancies). For stoichiometric spinels, the oxidation of Mn3+ to Mn4+ is dominant, whereas for oxygen-deficient compounds both mechanisms are operative. The endothermic deviation is ascribed to the large endothermic enthalpy of reduction. 相似文献
17.
S. Chandrasekhar G. Chandrashekar K. Vijeender M. Srinivasa Reddy 《Tetrahedron letters》2006,47(20):3475-3478
B(C6F5)3 as a catalyst and polymethylhydrosiloxane as a hydride source have been employed for the reductive dehydroxylation of Baylis-Hillman adducts wherein the hydride adds in an SN2′ manner onto the unactivated allyl alcohol moiety with concomitant elimination of the hydroxy group along with double bond migration. The products formed were found to be E in the case of ester adducts and Z in the case of nitrile adducts. 相似文献
18.
Sihai Yang Shujian Tian Fuhui Liao Jianhua Lin 《Journal of solid state chemistry》2005,178(12):3703-3707
By hydrothermal reaction of In2O3 with H2C2O4·2H2O in the presence of H3BO3 at 155 °C, an open-framework three-dimensional indium oxalate of formula [In(OH)(C2O4)(H2O)]3·H2O (1) has been obtained. The compound crystallizes in the trigonal system, space group R3c with , , , Z=6, R1=0.0352 at 298 K. The small pores in 1 are filled with water molecules. It loses its filled water at about 180 °C without the change of structure, then the bounded water at 260 °C, and completely decompounds at 324 °C. The residue is confirmed to be In2O3. 相似文献
19.
F. Goubin P. Deniard M.-H. Whangbo S. Jobic 《Journal of solid state chemistry》2004,177(12):4528-4534
Various compositions of solid solutions K3P(Mo1−xWx)12O40 (0?x?1) were prepared using two solid state synthetic routes. The crystallite size was determined by linewidth refinements of X-ray diffraction patterns using the Warren-Averbach method, and the grain size distribution by laser scattering experiments. Optical properties were determined by diffuse reflectance measurements in the UV-visible range. The optical gap Eg was found to increase exponentially from ∼2.5 to ∼3.30 eV with increasing x, and is systematically shifted to a higher energy when the grain size decreases. The relation between Eg and x was analyzed by calculating the HOMO-LUMO gaps of the [P(Mo1−xWx)12O40]3− anions on the basis of tight-binding electronic structure calculations. 相似文献
20.
Anshita Gairola Girish V. Kunte Deepak Chopra T.N. Guru Row A.M. Umarji S.A. Shivashankar 《Polyhedron》2010
A detailed study, involving the synthesis of a single-source precursor containing two metal ions sharing the same crystallographic site, has been undertaken to elucidate the use of such a single-source precursor in a CVD process for growing thin films of oxides comprising these two metals, ensuring a uniform composition and distribution of metal ions. The substituted complexes Cr1−xAlx(acac)3, where acac = acetylacetonate, have been prepared by a co-synthesis method, and characterized using UV–Vis spectroscopy, TGA/DTA measurements, and single crystal X-ray diffraction at low temperature. All the studied compositions crystallize in the monoclinic space group P21/c with Z = 4 in the unit cell. It was observed that the ratio (Al:Cr) of the site occupancy for the metal ions, obtained from single crystal refinement, is in agreement with the results obtained from complexometric titrations. All the solid state structures have the metal in an octahedral environment forming six-membered chelate rings. M–O acac bond lengths and disorder in the terminal carbon have been studied in detail for these substituted metal–organic complexes. One composition among these was chosen to evaluate their suitability as a single-source precursor in a LPMOCVD process (low-pressure metal–organic chemical vapour deposition) for the deposition of a substituted binary metal oxide thin film. The resulting thin films were characterized by X-ray diffraction, scanning electron microscopy, and infrared spectroscopy. 相似文献