The thermal decomposition reactions of [Co(en)n(phen)m]Cl3 complexes

The thermal behaviour of [Co(en)_n(phen)_m]Cl₃ complexes has been studied using thermogravimetry (TG), differential thermogravimetry (DTG) and differential thermal analysis (DTA) in air, nitrogen and oxygen atmospheres. The effect of the stoichiometry of the complexes and that of the gas atmosphere in the furnace chamber on the thermal decomposition reaction is evidenced and discussed. The following thermal stability order has been found [Co(en)₃]Cl₃ [Co(en)₂(phen)]Cl₃ > [Co(en)(phen)₂]Cl₃ [Co(phen)₃]Cl₃     

Reactions of some 2H-Chromenes and 2H-Thiochromenes with triazolinediones

Simple 2H-chromenes and 2H-thiochromenes form the [2+2]-adducts, tetrahydro[1]benzo(thio)pyrano[3,4-c] [1,2]diazeto[1,2-a][1,2,4]triazoles, with triazolinediones, whereas their 3- and 4-bromo and the corresponding cycloalkylamino derivatives undergo an overall etectrophilic substitution sequence.     

Asymmetric hydroboration of [E]- and [Z]-2-methoxy-2-butenes. Synthesis of (−)-[2R,3R]-butane-2,3-diol in >97% ee

Asymmetric hydroboration of [E]- and [Z]-2-methoxy-2-butene, using (−)-diisopinocampheylborane at −25°C in THF solvent, followed by oxidation using H₂O₂/NaOH, gave (−)-[2R,3R]- and (+)-[2R,3S]-3-methoxy-2-butanols in >97 and 90% ee, respectively. (−)-[2R,3R]-3-Methoxy-2-butanol was converted to (−)-[2R,3R]-butane-2,3-diol (>97% ee, in an overall yield of 65%).     

A localized molecular orbital study on the bonding of> Mo3S4]2Mo> and> Mo3S4]CuI> versus (C6H6)2Cr and C6H6Cr(CO)3

The energy-localized CNDO/2 molecular orbitais have been calculated for the clusters containing molybdenum, > {Mo₃S₄₂Mo}⁸⁺ and> Mo₃S₄]CuI> ⁴⁺, versus the prototype arene-metal sandwich (C₆H₆)₂Cr and half-sandwich complexes C₆H₆Cr(CO)₃. The bonding characteristics of these compounds are described from a localization bonding viewpoint. There are two typical M-arene and M-[Mo₃S₄] bondings. One is formed by electron donation from the three-center two-electron π-bonds in the arene or [Mo₃S₄]⁴⁺ ligands into the vacant hybrid orbitais of the “stranger” metal atom. In the other M-arene or M-[Mo₃S₄] bond there is very little donation by the lone electron pair occupying the d AOs of the “stranger” metal atom to the arene or [Mo₃S₄]⁴⁺ ligands. The analogy of the ligand [Mo₃S₄]⁴⁺ in the clusters studied with the ligand benzene is also briefly discussed.     

Tetrakis(triphenylphosphine oxide) complexes of the lanthanide nitrates; synthesis, characterisation and crystal structures of [La(Ph3PO)4(NO3)3]·Me2CO and [Lu(Ph3PO)4(NO3)2]NO3

The reaction of Ln(NO₃)₃·6H₂O (Ln=La, Ce, Pr or Nd) with a sixfold excess of Ph₃PO in acetone formed [Ln(Ph₃PO)₄(NO₃)₃]·Me₂CO. The crystal structure of the La complex shows a nine-coordinate metal centre with four phosphine oxides, two bidentate and one monodentate nitrate groups, and PXRD studies show the same structure is present in the other three complexes. In CH₂Cl₂ or Me₂CO solutions, ³¹P NMR studies show that the complexes are essentially completely decomposed into [Ln(Ph₃PO)₃(NO₃)₃] and Ph₃PO. Similar reactions in ethanol gave [Ln(Ph₃PO)₃(NO₃)₃] only. In contrast for Ln=Sm, Eu or Gd, only the [Ln(Ph₃PO)₃(NO₃)₃] are formed from either acetone or ethanol solutions. For the later lanthanides Ln=Tb–Lu, acetone solutions of Ln(NO₃)₃·6H₂O and Ph₃PO gave [Ln(Ph₃PO)₃(NO₃)₃] only, even with a large excess of Ph₃PO, but from cold ethanol [Ln(Ph₃PO)₄(NO₃)₂]NO₃ (Ln=Tb, Ho–Lu) were obtained. The structure of [Lu(Ph₃PO)₄(NO₃)₂]NO₃ shows an eight-coordinate metal centre with four phosphine oxides and two bidentate nitrate groups. In solution in CH₂Cl₂ or Me₂CO the tetrakis-complexes show varying amounts of decomposition into mixtures of [Ln(Ph₃PO)₃(NO₃)₃], [Ln(Ph₃PO)₄(NO₃)₂]NO₃ and Ph₃PO as judged by ³¹P{¹H} NMR spectroscopy. The [Ln(Ph₃PO)₃(NO₃)₃] also partially decompose in solution for Ln=Dy–Lu, forming some tetrakis(phosphine oxide) species.     

Copper thioether chemistry: The synthesis and single crystal X-ray structures of [Cu2([18]aneS6)(NCMe)2](ClO4)2 and [Cu([9]aneS3)(AsPPh3)](ClO4)

Reaction of [18]aneS₆ with two molar equivalents of [Cu(NCMe)₄](ClO₄) in CH₂Cl₂-MeCN affords the binuclear copper(I) complex [Cu₂([18]aneS₆)(NCMe)₂](ClO₄)₂. The single crystal X-ray structure of the complex shows a centrosymmetric cation with two tetrahedral copper(I) centres each coordinated to three thioether S-donors of [18]aneS₆,Cu---S(1) = 2.3200(15), Cu---S(4) = 2.3415(16), Cu---S(7) = 2.3250(15) Å, and to one MeCN molecule, Cu---N(1) = 1.939(5) Å, to give an overall NS₃-donation at the metal centres. Additionally, S(7′) shows a long-range interaction, Cu …S(7′) = 3.318(2) Å thus distorting the coordination geometry of the metal ion towards trigonal bipyramidal. The metal-metal separation of 4.428(2) Å suggests that there is no significant interaction between the copper centres of the dimer. Reaction of [9]aneS₃ with one molar equivalent of [Cu(NCMe)₄](ClO₄) in refluxing MeCN in the presence of ligands, L, affords the adducts [Cu([9]aneS₃)L]⁺ (L = PPh₃, AsPh₃). The single crystal X-ray structure of the complex [Cu([9]aneS₃)(AsPh₃)](ClO₄) shows tetrahedral AsS₃ coordination at copper(I) with [9]aneS₃ bound facially to the metal centre, Cu---S = 2.303(6), Cu---As = 2.322(4) Å.     

The transition-metal assisted synthesis of the anti-octadecaborate Anion [B18H21] from the Nido-dodecahydrononaborate anion [B9H12]

When heated under reflux in CH₂Cl₂ solution with [Os(CO)₃Cl₂]₂, two nido-[B₉H₁₂]⁻ units edge-fuse to form anti-[B₁₈H₂₁]⁻.     

Synthesis and X-ray crystal structures of [Ru4H4(CO) 11(PPh3)] and [Ru4−x IrxH2−x(CO) 12(PPh3) ] (x = 0 or 1)

Three tetranuclear clusters [Ru₄H₄(CO)₁₁(PPh₃)] (1), [Ru₄H₂(CO)₁₂(PPh₃)] (2) and [Ru₃IrH(CO)₁₂(PPh₃)] (3) were formed in the reaction of [Ir(CO)Cl(PPh₃)₂] and Na[Ru₃H(CO)₁₁] in tetrahydrofuran. Complexes 1–3 were characterized by IR and ¹H and ³¹P NMR, and the structure of the clusters was confirmed by single crystal X-ray analysis. In 2 and 3 one of the carbonyls bridges between two ruthenium atoms; otherwise the compounds contain only terminal carbonyls.     

Synthesis and molecular structure of Ba5(μ5-OH)[μ3-OCH(CF3)2]4[μ2-OCH(CF3)2]4 [OCH(CF3)2](THF)4(H2O)·THF: a source of barium fluoride

The reaction between metallic barium and fluoroisopropanol or alcoholysis of [Ba(OPrⁱ)₂] produces a pentanuclear fluoroalkoxide. Its X-ray structure determination showed its formulation to correspond to Ba₅(μ₅-OH)[μ₃-OCH(CF₃)₂]₄[μ₂-OCH(CF₃)₂]₄ [OCH(CF₃)₂](THF)₄(H₂O)·THF. The metallic core is based on a square pyramid encapsulating an hydroxo ligand. In addition to the barium---alkoxide bonds [2.53(3)–2.86(3) Å] neutral O-donors, four THF [2.82(2)–2.86(3) Å] and one H₂O [2.79(3) Å] and secondary barium---fluorine interactions [2.99(2)–3.31(2) Å] ensure high coordination numbers, from 9 to 11 for the metal centers. Hydrogen bonding between the apical fluoroisopropoxide, the water molecule and one THF molecule, non-bonded to a metal center, accounts for the stability of the hydrate and illustrates the Lewis acidity of fluoroalkoxides. Thermal decomposition leads to BaF₂.     

One-pot synthesis of fluorine containing 3-cyano/ethoxycarbonyl-2-methyl-benzo[b]furans

Fluoro-substituted 3-cyano-2-methyl-benzo[b]furans and ethyl 2-methyl-benzo[b]furan-3-carboxylates are conveniently prepared in a single step in good yield by the microwave induced tandem intramolecular Wittig and Claisen rearrangement reactions of the corresponding [(aryloxyacetyl) (cyano) methylene] triphenylphosphorane and [(aryloxyacetyl) (ethoxycarbonyl) methylene] triphenylphosphoranes, respectively.     

Theoretical study of tricyclo[3,3,1,1]decane, tricyclo[3,3,1,1]decsilane molecules and their halogen derivatives, C10H12X4 and Si10H12X4 (X=F, Cl, Br, I)

The B3LYP/3-21G* ab initio molecular orbital method from the program package was applied to study tricyclo[3,3,1,1^3,7]decane and tricyclo[3,3,1,1^3,7]decsilane molecules and their halogen derivatives (1,3,5,7-tetrahalotricyclo[3,3,1,1^3,7]decane and 1,3,5,7-tetrahalotricyclo[3,3,1,1^3,7]decsilane, C₁₀H₁₂X₄ and Si₁₀H₁₂X₄ respectively). The optimized structures of these compounds were obtained. Ionization potentials, HOMO and LUMO energies, energy gaps, heats of formation, atomization energies and vibration frequencies were calculated. The calculations indicate that these molecules are stable and have T_d symmetry. Tricyclo[3,3,1,1^3,7]decsilane and its halogen derivatives (Si₁₀H₁₂X₄) are found to have higher conductivity than tricyclo[3,3,1,1^3,7]decane and its halogen derivatives (C₁₀H₁₂X₄). 1,3,5,7-Tetrafluorotricyclo[3,3,1,1^3,7]decane (C₁₀H₁₂F₄) and 1,3,5,7-tetrafluorotricyclo[3,3,1,1^3,7]decsilane (Si₁₀H₁₂F₄) were found to be the easiest compounds to form and the most difficult to dissociate of all 1,3,5,7-tetrahalotricyclo[3,3,1,1^3,7]decane and 1,3,5,7-tetrahalotricyclo[3,3,1,1^3,7]decsilane compounds, respectively.     

钛铝载体的合成及负载CuO对NO催化性能研究

以TiCl4为原料合成了TiO2/[[alpha]]-Al2O3载体. 在色谱-微反流动法反应装置上考察了CuO/15%(w, 下同)TiO2/[alpha]-Al2O3系列催化剂对NO+CO 的反应性能. 结果表明上述催化剂对NO+CO 反应表现出较好的活性, 其中12%CuO/15%TiO2/[alpha]-Al2O3反应活性最佳. 空气和H2 预处理后, NO 完全转化的温度分别为300C[[deg]]和275C[deg].通过H2-TPR、XRD 和FT-IR 等技术表征, 发现适量TiO2能促进CuO 在钛铝载体上的分散. TPR 结果显示12%CuO/15%TiO2/[alpha]-Al2O3在整个TPR 过程中出现四个还原峰, 琢和酌还原峰分别是钛铝载体表面裸露的TiO2上高度分散的CuO 和晶相CuO 的还原；茁和啄还原峰为钛铝载体上高度分散的CuO 和晶相CuO 的还原. FT-IR实验表明NO和CO 在经H2气氛预处理的催化剂表面上吸附较强, 且生成了N2O 和NO2等物种；NO+CO混合气在经空气和H2预处理的催化剂表面吸附时, 出现了N2O吸收峰, 峰温分别为200C[deg]和150C[deg].     

Oxidative addition of 2,2′-dipyridyl disulfphide to the cluster [Os3(CO)10(MeCN)2]

The cluster [Os₃(CO)₁₀(MeCN)₂] reacts with 2,2′-dipyridyl disulphide (1, pySSpy) to give a range of oxidative addition products which were separated by TLC on silica and crystallization : [Os₃(pyS)₂(CO)₁₀] (2), [Os₃(pyS)₂(CO)₉] (3), [Os₂(pyS)₂(CO)₆] (4) and [Os(pyS)₂(CO)₂] (5), together with some of the hydride [Os₃H(pyS)(CO)₉] (6), which is not an expected oxidative addition product. The X-ray crystal structures of compounds 2, 3, 4 and 6 (compounds 2 and 6 occurring within a single crystal), together with the known structure of compound 5, reveal several modes of pyS bonding : chelating pyS, μ₂-pyS (both sulphur-bonded and nitrogen, sulphur-bonded) and μ₃-pyS.     

Substrate-induced anisotropy of c-axis textured NaxCoO2 thin films

Na_xCoO₂ [x = 0.51, 0.54, and 0.59] thin films have been grown on SrTiO₃ (100)-oriented single crystals with a 5° vicinal cut towards [010] by pulsed laser deposition. We analysed the films by X-ray diffractometry, atomic force microscopy (AFM), and dc-transport measurements. X-ray diffraction patterns of the films show single phase and c-axis textured growth with the film plane closely aligned to the [001]-direction of 5° miscut SrTiO₃ (001) substrates. In addition to the structural analysis of these films we performed transport measurements along and perpendicular to the substrate tilt direction and determined the resistivity anisotropy as a function of temperature. The results enable the development of a strategy for the fabrication of Na_xCoO₂ based thermoelectric thin film devices.     

Ein beitrag zur darstellung und reaktivität der η-allyliridium-komplexe [Ir(η-2-RC3H4) (PPr3)2]

The η³-allyliridium complexes [Ir(η³-2-RC₃H₄)(PⁱPr₃)₂] (2, 3) have been prepared in a one-pot reaction from [IrCl(C₂H₄)₂]₂, 2-RC₃H₄Li and PⁱPr₃ in 70% yield. Compounds 2 and 3 react spontaneously with H₂ to give [IrH₅(PⁱPr₃)₂] (7) and with excess PhC=CH and MeCCH to give [Ir(CCPh)₃(PⁱPr₃)₂] (5) and [Ir(CCMe)₂(CMe=CH₂)(PⁱPr₃)₂] (6), respectively. From 2 (or 3) and two equivalents of PhCCH the complex [IrH(CCPh)₂(PⁱPr₃)₂] (4) has been obtained. Treatment of 2 or 3 with CF₃CO₂H does not lead to a cleavage of the allyl-metal bond but affords the allyl(hydrido)-iridium(III) complexes [IrH(η³-2-RC₃H₄)(η¹-P₂CCF₃)(PⁱPr₃)₂] (8, 9) in almost quantitative yield.     

Syntheses of low-valent nitrosyl complexes of rhenium and X-ray structure oftrans-[ReCl(NO)(Ph2PCH2CH2PPh2)2][NO3]2 with nitrosyl derived nitrates

The nitrosyl complexes trans-[ReCl(NO)(dppe)₂]A₂ (1; A = BF₄ or NO₃; dppe = Ph₂PCH₂CH₂₋PPh₂) and trans-[ReCl(NO)(dppe)₂][BF₄] (2) have been prepared from the reactions of NO[BF₄] or NO with trans-[ReCl(N₂)dppe)₂]. An unusual facile oxidation of NO to nitrate is involved in the formation of (1, A = NO₃), the X-ray structure of which is reported.     

Syntheses of gold-manganese and gold-rhenium clusters, [(Ph3PAu)3M(CO)4] and [(Ph3PAu)4M(CO)4] (M = Mn, Re), and the crystal structure of [(Ph3PAu)4Mn(CO)4]BF4

The specific additions of one, three or four Ph₃PAu groups to [M(CO)₅]⁻ (M=Mn, Re) are described. Thus [M(CO)₅] ⁻ in THF reacts with [(Ph₃PAu)₃O]BF₄ to give [(Ph₃PAu)₄Mn(CO)₄]BF₄. An X-ray crystal structure of the M = Mn example shows the cation to have a trigonal bipyramidal Au₄Mn core with the Mn in an equatorial site. The previously known neutral (Ph₃PAu)₃M(CO)₄ clusters are formed by addition of two Ph₃PAu groups, using the mixed reagent [(Ph₃PAu) ₃O]BF₄/[ppn][Co(CO)₄], to Ph₃PAuM(CO)₅, which itself is readily prepared from [M(CO)₅]⁻ and Ph₃PAuCl.     

A bis(phosphinimino)methanide lanthanum amide as catalyst for the hydroamination/cyclisation, hydrosilylation and sequential hydroamination/hydrosilylation catalysis

[La[N(SiHMe2)2]2[CH(PPh2NSiMe3)2]], which was obtained via an amine elimination starting from [CH2(PPh2NSiMe3)2] and [La[N(SiHMe2)2]3(THF)2], was used as catalyst for the hydroamination/cyclisation, the hydrosilylation and the sequential hydroamination/hydrosilylation reaction.     

Reactions of cyclo-(t-Bu4Sb4) with alkali metals; syntheses and crystal structures of [M(L)n(t-Bu4Sb3)] (M=Na, K; n=1, 2) and [K(L)(t-Bu3Sb2)] (L=(Me2NCH2CH2)2NMe)

Reduction of cyclo-(t-Bu₄Sb₄) (1) with sodium or potassium in boiling tetrahydrofuran leads to the anions [t-Bu₄Sb₃]⁻ and [t-Bu₃Sb₂]⁻. Crystallization with pentamethyldiethylenetriamine (L) gives [M(L)_n(t-Bu₄Sb₃)] (n=1, M=Na (2), K (3); n=2, M=K (4)) and [K(L)(t-Bu₃Sb₂)] (5). Crystal structure analyses reveal coordination of the anionic antimony ligands on the alkali metal ions for 2, 3, and 5. In contrast, no Sb---K interactions were observed in the structure of 4.     

Formation of [C60C5H5] adduct cations and theoretical study of the isomers

We study here the reactions between C₆₀ and planar C₅H₅⁺ cations that lead to the formation of [C₆₀C₅H₅]⁺ adduct cations in the chemical ionization source of the mass spectrometer. The structures, stabilities and charge locations of some possible isomers of [C₆₀C₅H₅]⁺: σ-adduct, π-complex, [1,4]- and [l,2]-addition cations, are studied by AM1 semiempirical molecular orbital calculations. We find that the most stable is the σ-addition cation. Another interesting and stable structure is the π-complex cation which is bonded by the electrostatic interaction at the inter-ring distance of 1.589 Å with the C_5v symmetry. The C₅H₅⁺ cyclopentadienium cation seems to be an “inverted umbrella” sitting on a five-membered ring of the C₆₀ cage.