IR STUDIES OF THE THERMAL DECOMPOSITION OF[Rh_6(CO)_(16) Co_4(CO)_(12)]/SiO_2: EVIDENCE FOR THE FORMATION OF RhCo_3(CO)_(12)/SiO_2

IntroductionThepreparativeapproachofaneffectivebilTldslliccatalystisalwaysasubjectofboortantsignificanceinheterogeneouscatalysis.InourrecentstUdies,wefoundthatthebAnetallitcarbonylclustercoCo3(CO)12favorablygivesthebAnetalliccoCo3clusterontheSiOZsubdueaft…     

CO在Sm/Rh(100)模型表面上的吸附与反应

应用AES,LEED,XPS和TDS研究了Rh(100)上Sm膜和Sm/Rh表面合金以及CO在这两类模型表面的吸附与反应.室温下Sm在Rh(100)上的生长遵从SK模式,Sm膜经900K高温退火后可形成有序表面合金.在室温制备的Sm膜/Rh(100)表面上,室温下CO在Sm上的吸附改变了表面结构,生成SmOx和表面碳.随着Sm覆盖度的增加,低温脱附峰(α-CO)面积迅速下降,且峰温向高温方向位移;表明Sm的空间位阻和电子效应同时起作用.在Sm/Rh合金表面上,CO在约590K出现新的脱附峰,可归属为受Sm电正性修饰的Rh原子上的CO脱附峰     

The Selective Reduction of 4-Propylthio-2-nitroaniline with CO Using Ru3（CO）12／PEDPA Complex as Catalyst

The Ru3(CO)12/PEDPA complex was firstly applied in the CO selective reduction of 4-propylthio-2-nitroaniline.The effects of reaction temperature,the pressure of CO and concentration of catalyst on the reduction were investigated.Under the optimum conditions of T=140℃, Pco=5.0MPa and substrate/catalyst=300(molar ratio),the conversion and selectivity were 70% and 98%,respectively.After simple phase separation,the catalyst could be recycled.     

Synthetic and spectroscopic characterization of Rh(I)-( S )-amino acid complexes with diphosphine and triphosphine ligands

Reaction of [Rh(η⁴-cod)(S)-amino-acidato] ((S)-amino acidate?=?(S)-O₂C-CHR-NH₂; cod?=?cycloocta-1,5-diene) with 1,2-bis(diphenylphosphino)ethane (dppe) affords the ionic [Rh(dppe)₂]{(S)-O₂C-CHR-NH₂} (R?=?Me, I; Ph, II) complexes. Reactions with 1,3-bis(diphenylphosphino)propane (dppp) or 2,2,2-tris(diphenylphosphinomethyl)ethane (triphos) give the neutral [Rh(dppp){(S)-O₂C-CHR-NH₂}] (R?=?Me, III; Ph, IV) or [Rh(η²-triphos){(S)-O₂C-CHR-NH₂}] (R?=?Me, V; Ph, VI) complexes. The complexes are characterized by elemental analysis, UV–Vis-, IR-, ¹H/³¹P{¹H} NMR- and mass-spectroscopy. Two molecules of dppe coordinate to the Rh(I) symmetrically by replacing both cod and (S)-amino acidate to give I–II. Only one molecule of dppp (or triphos) coordinate to the Rh(I) asymmetrically by replacing only cod to give III–VI. Two diastereomeric Rh(I)-complexes are present in V and VI. The results further suggest that the ligands are arranged in a distorted square planar geometry around the Rh(I) centre. The use of triphos instead of dppe or dppp yields the same coordination sphere.     

Chemical Reconstruction of Pt-Rh(100) Alloy and Pt/Rh(100), Rh/Pt(100) Bimetallic Surfaces

When Cu(110), Ni(l 10), Ag(110) surfaces are exposed to O₂ at room temperature, one dimensional metal-oxygen strings grow in the < 001 > direction of the (110) surfaces. A similar phenomenon occurs in the adsorption of H₂ on Ni( 110) surface at room temperature, where the one dimensional strings grow along the < 110 > direction. These phenomena are undoubtedly different from the adsorption induced reconstruction but are explained by the chemical reconstruction involving the formation of quasi-compounds and their self-ordering on the metal surfaces. The chemical reconstruction is indispensablly important to understand the structure and catalysis of alloy and bimetallic surfaces. Pt_0.25Rh_0.75(100) alloy surface being active for the reaction of NO with H₂ is an interesting example. When the Pt-Rh(100) alloy surface is exposed to NO or O₂ at arround 500 K, a p(3 × 1) ordered Rh-O over-layer is obtained on a Pt-enriched 2nd layer by the chemical reconstruction. Ordering of Rh-0 in the p(3 × 1) structure on the Pt(100) surface was reproduced by heating a Rh/Pt(100) bimetallic surface in O₂, and the chemical reconstruction making the p(3 × 1) Rh-O overlayer on a Pt enriched 2nd layer was also proved by heating a Pt/Rh(100) bimetallic surface in O₂ or NO. The activation mechanism of the Pt-Rh alloy and the Pt/Rh bimetallic surfaces by the chemical reconstruction was evidently shown by using a Pt deposited Rh(100), Pt/Rh(100), surface. That is, the Pt/Rh(100) is not so active for the reaction of NO with H₂, but the reconstructed p(3 × 1)Rh-O/Pt-layer/Rh(100) surface is very active for the reaction. Therefore, it was concluded that the chemical reconstruction of the Pt-Rh catalyst makes the active surface which is composed of Rh-O and a Pt layer.     

Kinetics and Mechanism of Co Substitution by Phosphites of Co4(CO)12

Abstract

The otherwise very fast CO substitution of Co₄(CO)₁₂ by P(OMe)₃ and P(OEt)₃ in aprotic solvents, affording phosphite-monosubstituted products was retarded by the use of CHCI₃ as solvent. This made it possible to investigate these reactions by conventional methods. Kinetic data were obtained by following changes in IR spectra during reaction. The rates show predominantly a ligand-dependent pathway, with the usual two-term rate law, rate = (k₁ + k₂ [P(OR)₃])C₄(CO)₁₂. It is suggested that the rates are retarded in protonic solvents by decreasing the nucleophilicity of phosphites due to a hydrogen bonding interaction between the H atom of CHCI₃ and the O atoms of the ligands.     

C12簇及其碳管烷C12H12的理论研究

C60和C70等碳笼烯的发现及其在新物质、新材料等研究领域中的重要性，激励人们去探索合成更多新型多面体碳簇化合物与碳元素类似物[1，2]．最近，两类新型多面体碳管笼烯的设想提出来了[3，4]应用HMO和MNDO方法对其稳定性变化规律、结构和成键特征进行了讨论.关于多苯的vanderWaals簇实验上已有广泛的调查[5，6]，理论上对其二聚物（C6H6）。的不同几何构型与稳定性进行了深入的研究[7]．本文采用abinitio计算有效势（effectivecorePotential）方法，对C12碳管元素簇和C12H12，碳管烷的平衡结构、稳定性和价键特征进行了理论预测．1…     

在Rh(111)面上NO+CO反应机理的密度泛函理论研究

应用基于密度泛函理论赝势平面波方法的CASTEP程序, 对Rh(111)上的NO+CO反应机理进行研究. 对于反应中的各个关键步骤: NO离解、CO2生成、通过N2O离解生成N2以及通过N+N反应生成N2都进行了详细讨论, 计算得到各反应步骤的过渡态以及活化能, 从而确立了各步骤的反应路径.     

Synthesis, spectroscopic studies and nonlinear optical behavior of N,N′-bis(2-hydroxy-1-naphthylmethylidene)-1-methyl-1,2-diaminoethane-N,N′,O,O′-nickel(II)

A Schiff base complex N,N′-bis(2-hydroxy-1-naphthylmethylidene)-1-methyl-1,2- diaminoethane-N,N′,O,O′-nickel(II) has been synthesized. The title compound has been characterized by FT-IR and UV–vis spectroscopies. The UV–vis experiments indicate that the compound has solvatochromism in the UV region, implying non-zero molecular first hyperpolarizability. To investigate microscopic second-order nonlinear optical (NLO) behavior of the examined complex, the electric dipole moments (μ) and the first static hyperpolarizabilities (β) were computed using Finite Field second-order Møller Plesset (FF MP2) perturbation procedure. According to ab initio quantum mechanical calculations, the title complex exhibits non-zero β values, revealing microscopic second-order NLO behavior.     

Keggin结构纳米硅钨酸铵的室温固相合成与物性

首次以H4SiW12O40 * 22H2O和(NH4)2C2O4 * H2O为原料,室温固相反应合成出(NH4)4SiW12O40纳米微粒;用元素分析、 FTIR确定产物的组成和结构; XRD、 TEM和BET对产物的形貌、晶粒尺寸和比表面积进行了表征; TG-DTA确定了产物的稳定温区.结果表明,产物为纳米粒子,平均粒径为60 nm,比表面积为108.7 m2/g,在430℃以下具有良好的热稳定性.在固相反应中,研磨和放热反应热效应能加快反应物扩散速率和生成物成核速率,使产物粒径减小;反应物含有结晶水和生成物H2C2O4 * 2H2O,对形成小粒径的(NH4)4SiW12O40纳米粒子起关键作用.     

Synthesis and Crystal Structure of （SiCl3）2Fe（CO）4

The compound （SiCl3）2Fe（CO）4 was synthesized and structurally characterized by X-ray single-crystal diffraction. It crystallizes in monoclinic, space group P2 1/n with α = 8.287（2）, b = 9.829（2）, c = 9.042（2） A, β = 96.19（3）°, V= 732.2（3） A^3, C4Cl6FeO4Si2, Mr = 436.77, Z = 2, Dc = 1.981 g/cm^3, F（000） = 424, μ（MoKα） = 2.282 mm^-1, the final R = 0.048 and wR = 0.164 for 1109 observed reflections （I 〉 2σ（I））. The crystal structure of （SiCl3）2Fe（CO）4 reveals that the Si（l）- Fe-Si（l）^a sequence is linear and perpendicular to the Fe（CO）4 cross-shaped plane.     

Non-empirical pseudopotentials (PSIBMOL algorithm) for molecular calculations: The Rh2Cl2(CO)4 complex

The electronic structure of Rh₂Cl₂(CO)₄ in the ground state is computed using the recently proposed PSIBMOL (Pseudo-potentials + IBMOL/H) formalism. The drawing of the total and differential isoelectronic contour maps supports the idea that there does not exist any rhodium-rhodium bond in such a binuclear complex, the origins of the preferred bent conformation having to be found elsewhere.     

Structural and spectroscopic investigations of europium(III) entrapped by the ethylenediaminetetra(methylenephosphonate) ligand in K12H8[Eu4(EDTMP)4] · 45H2O crystal

The X-ray crystal structure of an anionic octacoordinate Eu³⁺ complex of the formula K₁₂H₈[Eu₄(EDTMP)₄] · 45H₂O, where EDTMP is the ethylenediaminetetra(methylenephosphonate) anion, hereinafter referred to as I, has been determined. The crystal consists of cyclic tetrameric complex anions, in which the surrounding of each Eu³⁺ ion is composed of two nitrogen atoms and six oxygen atoms from phosphonate groups. One of the phosphonate groups in the ligand molecule is tridentate (O:O′,O″), thus giving rise to the formation of the tetramers. The compound was characterized by UV–Vis electronic spectroscopy. At room and liquid nitrogen temperatures the complex shows luminescence from both ⁵D₀ and ⁵D₁ states, the latter one, which is very rare in Eu³⁺ compounds with organic ligands, is probably brought about by the saturation of the coordination sphere with the phosphonate groups.     

Electronic Excitation of [(μ4‐η2‐alkyne)Rh4(CO)8(μ‐CO)2]: An In Situ UV/Vis Spectroscopy,Spectral Reconstruction and DFT Study

Reactions of three alkynes, namely, 1‐heptyne, 3‐hexyne and 1‐phenyl‐1‐butyne, with [Rh₄(CO)₉(μ‐CO)₃] are performed in anhydrous hexane under argon atmosphere with multiple perturbations of alkynes and [Rh₄(CO)₉(μ‐CO)₃]. The reactions are monitored by in situ UV/Vis spectroscopy, and the collected electronic spectra are further analyzed with the band‐target entropy minimization (BTEM) family of algorithms to reconstruct the pure component spectra. Three BTEM estimates of [(μ₄‐η²‐alkyne)Rh₄(CO)₈(μ‐CO)₂], in addition to that of [Rh₄(CO)₉(μ‐CO)₃], are successfully reconstructed from the experimental spectra. Time‐dependent density functional theory (TD‐DFT) predicted spectra at the PBE0/DGDZVP level are consistent with the corresponding BTEM estimates. The present study demonstrates that: 1) the BTEM family of algorithms is successful in analyzing multi‐component UV/Vis spectra and results in good spectral estimates of the trace organometallics present; and 2) the subsequent DFT/TD‐DFT methods provide an interpretation of the nature of the electronic excitation and can be used to predict the electronic spectra of similar transition organometallic complexes.     

Interaction of CO and NO with the spinel CuCr2O4 (100) surface: A DFT study

The characteristics of CO and NO molecules at Cu²⁺ and Cr³⁺ ion sites on the CuCr₂O₄ (100) surface have been studied by first principles calculations based on spin‐polarized density functional theory (DFT). The calculated results show that adsorption energies for X‐down(C, N) adsorption vary in the order: Cu²⁺‐CO>Cr³⁺‐NO≈Cr³⁺‐CO>Cu²⁺‐NO. CO molecules are preferentially adsorbed at Cu sites, whereas NO molecules adsorb favorably at Cu²⁺ and Cr³⁺ ion sites. The C‐O and N‐O stretching frequencies are red‐shifted upon adsorption. Combining the analysis of frontier molecular orbitals and Mulliken charge, for CO and NO X‐down adsorption systems, the 5σ orbitals donate electrons and the 2π^* orbitals obtain back‐donated electrons. Although for NO with O‐down adsorption systems, the NO‐2π^* orbitals obtain back‐donated electrons from substrates without 5σ‐donation. Coadsorption calculations show the CO/NO mixture adsorb selectively at the Cu²⁺ion site but simultaneously at the Cr³⁺ ion site, respectively. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Adsorption of Fe（CO）4 on the Sidewall of Boron Nitride Nanotubes： A Periodic DFT Study

The adsorption of Fe（CO）4 on various types of boron nitride nanotubes （BNNTs） areinvestigated by employing density functional theory. Our results indicate that Fe（CO）4 prefers to adsorb on the top of nitrogen atom via Fe atom, and the electronic property analysis indicates that the adsorption of Fe（CO）4 can reduce the band-gap of BNNTs.     

(p-CH3OC6H4)2TeO存在下M2(CO)10(M=Mn,Re)的CO取代反应动力学研究

测定了(p-CH₃OC₆H₄)₂TeO存在下M₂(CO)₁₀(M=Mn,Re)的CO取代反应速率及活化参数。其表观速率常数分别与M₂(CO)₁₀和(p-CH₃OC₆H₄)₂TeO的浓度的一次方成正比。本文所建议的缔合机理与前人用(CH₃)₃NO作氧原子转移试剂的相应反应所提出的机理相似。讨论了在(CH₃)₃NO和(p-CH₃OC₆H₄)₂TeO存在下影响M₂(CO)₁₀的CO取代反应速率的因素。     

Raney—Ni诱导下氯化钴羰化合成Co2（CO）8的研究

采用Ｒａｎｅｙ－Ｎｉ为活化剂，在３０－５０℃，０．１ＭＰａ条件下，由ＣｏＣｌ２／ＣＯ／ＣＨ２ＯＨ体系可快速高效地合成Ｃｏ２（ＣＯ）８，２．５ｈ内，氯化钴转化率可达９５％，在甲醇中保存了３－５ｄ的Ｒ－Ｎｉ仍有较高活性，经脱氢处理后的Ｒ－Ｎｉ仍对羰化反应有很好促进作用，说明Ｒ－Ｎｉ促进氯化钴转化为羰基钴，主要是由于超细Ｒ－Ｎｉ粉的作用，而不是Ｒ－Ｎｉ吸附氯的还原作用，合成产物经２５％ＮａＯＨ处理，转变     

The reactions of Rh2(CO)4Cl2 with 1,5-cyclooctadiene and tetramethylallene. A combined in-situ vibrational spectroscopies, spectral reconstruction and DFT study

Reactions of Rh₂(CO)₄Cl₂ with 1,5-cyclooctadiene (COD) and tetramethylallene (TMA) were performed separately in anhydrous hexane under argon atmosphere. Multiple perturbations of Rh₂(CO)₄Cl₂, COD and TMA were also performed during the reactions. These two reactions were monitored by in-situ FTIR (FIR and MIR) and/or Raman spectroscopies and the collected spectra were further analyzed with BTEM family of algorithms. DFT calculations were performed to identify the organometallic species present. The known diene complex Rh₂(CO)₂Cl₂(η⁴-C₈H₁₂) and a new allene complex Rh₂(CO)₃Cl₂(η²-C₇H₁₂) were formed as the two primary organo-rhodium products. Their pure component spectra were reconstructed in the three characteristic regions of 200-680, 800-1360, and 1500-2200 cm⁻¹. Their relative concentrations were also obtained by the least square fitting of the carbonyl region 1500-2200 cm⁻¹. The present contribution shows the usefulness of combining in-situ spectroscopic measurements, BTEM analysis and DFT spectral prediction in order to analyze organometallic reactions at high dilution and identify the reaction products.