Die Molekül- und Kristallstrukturen von (CO)4 W(μ-S-t-C4H9)2W(CO)4, η7-C7H7W(μ-SC6H4CH3)3W(CO)3 und η7-C7H7W(μ-S-n-C4H9)3W(CO)(μ-S-n-C4H9)2W(CO)4

Molecular and Crystal Structures of (CO)₄W(μ-S-t-C₄H₉)₂W(CO)₄, η⁷-C₇H₇W(μ-SC₆H₄CH₃)₃W(CO)₃ and η⁷-C₇H₇W(μ-S-n-C₄H₉)₃W(CO)(μ-S-n-C₄H₉)₂W(CO)₄ The molecular structures of the two binuclear complexes (CO)₄W(μ-S-t-C₄H₉)₂W(CO)₄ and η⁷-C₇H₇W(μ-SC₆H₄CH₃)₃W(CO)₃ and of the tungsten cluster η⁷-C₇H₇W(μ-S-n-C₄H₉)₃W(CO)-(μ-S-n-C₄H₉)₂W(CO)₄ respectively are described. In the nonlinear trinuclear cluster the central tungsten atom is connected to the two tungsten atoms by two and three μ-S-n-C₄H₉ bridges respectively and additionally by one W? W bond each. The coordination sphere of the W atoms is completed by a η⁷-C₇H₇ ring and four CO groups respectively; the central tungsten carries an additional CO group.     

配合物Co[S2P(O-i-C3H7)2]3的合成和晶体结构

过渡金属硫配合物可作为加氢脱硫(HDS)和加氢脱氮(HDN)过程的有效催化剂而倍受人们关注[1-3].这类配合物的催化活性、选择性和抗毒性与过渡金属的种类、配合物本身的立体结构和电子分布密切相关[4-5].其中,钴的硫化物在HDS和HDN过程中有很好的催化活性.本文由二元金属羰合物Co2(CO)8和双(硫代磷酸二异丙基酯)二硫化物(A),合成标题配合物Co[S2P(O-i-C3H7)2]3 (B),对配合物B进行XRD表征,并对反应机理进行初步探讨.反应式如下:     

Electrospray ionization mass spectrometric study of the hydrolysis-polycondensation process of Sn(OBu(t))(4)

The oligomerization of Sn(OBu(t))(4) in the sol-gel process has been studied by several different analytical approaches. Electrospray ionization (ESI) mass spectrometry was highly effective in describing the first species produced by the hydrolysis-polycondensation reactions. M?ssbauer spectroscopy has elucidated the fast behavior of the hydrolytic oligomerization process, while calorimetric data have demonstrated the high enthalpy of the reaction in the presence of different solvents.     

Superstructures of Ti2S3(4 H)

Superstructures related to 4H type Ti₂S₃ (hexagonal unit cell: a, c) are examined by the X-ray diffraction work for several compositions, and the ordered arrangements of titanium vacancies are studied. The space group of TiS_1.46 annealed at 500 or 700°C is Cc and the parameters of the monoclinic unit cell are: A = 5.9439(5) Å = √3 a, B = 10.295(1) Å = 3a, C = 22.858(3) Å = 2c and β = 90.0°. The space group of TiS_1.51 annealed at 500, 700 or 900°C is also Cc and the parameters of the rectangular monoclinic unit cell are: A = 10.286(1) Å = 3a, B = 5.9383(6) Å = √3 a, C = 34.924(5) Å = 3c and β = 90.0°.     

Electrospray ionization ion trap mass spectrometry of a tetrahedral supramolecular Ti4L4 cluster

The analysis of self-assembled supramolecular clusters held together by metal-ligand interactions is a relatively new area in mass spectrometry. These complexes may have molecular weights exceeding several kDa, are often highly charged and their composition is most sensitive to their chemical environment. Electrospray ionization appears to be the ionization technique of choice for their mass spectral characterization. The analysis (positive and negative ion detection mode) of the prototype compound [Ti₄L₄]^8? (L = a catechol-based tris-bidentate ligand; MW of cluster = 2293 u) using a Paul trap mass analyzer is reported. The combination of electrospray ionization and high resolution ion trap technology is a powerful tool which provides the unambiguous solution state characterization of this supramolecular cluster. The results are correlated with the known solid state structure of the cluster and reactions previously reported for mononuclear Ti(IV) catecholates.     

Reactivity of the Indenyl Radical (C9H7) with Acetylene (C2H2) and Vinylacetylene (C4H4)

The reactions of the indenyl radicals with acetylene (C₂H₂) and vinylacetylene (C₄H₄) is studied in a hot chemical reactor coupled to synchrotron based vacuum ultraviolet ionization mass spectrometry. These experimental results are combined with theory to reveal that the resonantly stabilized and thermodynamically most stable 1-indenyl radical (C₉H₇^.) is always formed in the pyrolysis of 1-, 2-, 6-, and 7-bromoindenes at 1500 K. The 1-indenyl radical reacts with acetylene yielding 1-ethynylindene plus atomic hydrogen, rather than adding a second acetylene molecule and leading to ring closure and formation of fluorene as observed in other reaction mechanisms such as the hydrogen abstraction acetylene addition or hydrogen abstraction vinylacetylene addition pathways. While this reaction mechanism is analogous to the bimolecular reaction between the phenyl radical (C₆H₅^.) and acetylene forming phenylacetylene (C₆H₅CCH), the 1-indenyl+acetylene→1-ethynylindene+hydrogen reaction is highly endoergic (114 kJ mol⁻¹) and slow, contrary to the exoergic (−38 kJ mol⁻¹) and faster phenyl+acetylene→phenylacetylene+hydrogen reaction. In a similar manner, no ring closure leading to fluorene formation was observed in the reaction of 1-indenyl radical with vinylacetylene. These experimental results are explained through rate constant calculations based on theoretically derived potential energy surfaces.     

Matrix-assisted laser desorption/ionisation mass spectrometry in the study of polycondensation of Ti(OBun)4 in the presence of Si(OEt)4

The hydrolysis-polycondensation behaviour of alcoholic solutions containing Si(OEt)4 and Ti(OBun)4, in different molar ratios (Si/Ti = 10-0.2), was analysed by laser desorption/ionisation (LDI) and matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry. The solutions were prepared using operating conditions usually employed in the sol-gel synthesis of SiO2-TiO2 materials. In accord with the well-known procedures for controlling the different chemical reactivities of the alkoxides, the pre-hydrolysis of the slower reacting silicon ethoxide and the chelation by acetylacetone of the faster reacting titanium butoxide were performed before mass spectrometric analysis. While LDI-MS did not provide evidence for the presence of mixed Si-Ti species in samples obtained from these reactions, MALDI-MS of samples diluted with chloroform and using 2,5-dihydroxybenzoic acid (DHB) as matrix led to detection of various oligomers with different contents of Si and Ti atoms. The results suggest that the formation of Si-Ti mixed oligomers seems to be the favoured process, especially for solutions in which one of the two components is diluted.     

(C_5H_9C_5H_4)_3NdBrLi(THF)_3和(C_5H_9C_5H_4)_3SmTHF的合成与结构

无水三氯化钕与环戊烷基环戊二烯钠、溴化锂(1:2:1摩尔比)反应,除去不溶物和溶剂后,产物在己烷/四氢呋喃溶剂中冷冻得到兰紫色晶体(C5H9C5H4)3NdBrLi(THF)3(配合物1)。其中心金属Nd3+的配位数为10,以η5与3个环戊二烯基相连,并通过单溴原子桥连锂原子,形成双核结构。该晶体属三斜晶系,P`1空间群。晶体学参数为a=12.048(2)、b=13.498(3)、c=13.831(3);α=104.16(3)、β=104.07(3)、γ=95.96(3); V=2083.3(7)3、Z=2、Dc=1.35Mg/m3、Mr=847.01gmol-1、F(000)=874。无水三氯化钐与环戊烷基环戊二烯钠(1:3)反应,产物在-30oC下的己烷溶剂中结晶得桔红色晶体(C5H9C5H4)3SmTHF(配合物2)。该晶体属正交晶系,Fdd2空间群。晶胞参数a=28.175(5) 、b=46.24(2)、c=9.167(4);V=11943(8)3、Z=16、Dc=1.38Mg/m3、 Mr=622.11 g·mol-1、F(000)=5136。10配位的金属Sm3+与3个环戊二烯基以η5相连,并结合一个四氢呋喃溶剂分子。     

Formation of poly(ethylene phosphates) in polycondensation of H3PO4 with ethylene glycol. Kinetic and mechanistic study

Conditions of synthesis of poly(ethylene phosphates) in reaction of H₃PO₄ with HOCH₂CH₂OH (EG), the actual path of polycondensation, and structure of the obtained polymers (mostly oligomers) and kinetics of reaction are described. Preliminary kinetic information, based on the comparison of the MALDI‐TOF‐ms and ³¹P{¹H} NMR spectra as a function of conversion is given as well. Because of the dealkylation process fragments derived from di‐ and triethylene glycols are also present in the repeating units. Structures of the end groups (? CH₂CH₂OH or ? OP(O)(OH)₂) depend on the starting ratio of [EG]₀/[H₃PO₄]₀, although even at the excess of EG the acidic end groups prevail because of the dealkylation process. In MALDI‐TOF‐ms products with P_n equal up to 21 have been observed. The average polymerization degrees (P_n) are lower and have been calculated from the proportion of the end groups. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 830–843, 2008     

VIBRATIONAL SPECTRA OF (t-C4H9 6Li)4 AND (t-C4H9 7Li)4: Raman Intensities and the Question of Li-Li Bonding

Abstract

Raman frequencies and intensities in methylcyclohexane solution and infrared frequencies in Nujol mull, have been obtained and assigned for the skeletal modes of (t-C₄H₉ ⁶Li)₄ and (t-C₄H₉ ⁷Li)₄. A normal coordinate analysis, neglecting hydrogen atoms, gave an overall frequency fit of 2% with a reasonable set of valence force constants. The calculated eigenvectors were used to transform the Raman intensities into bond polarizability derivatives. Because of coordinate mixing and the inherent sign ambiguity of molecular polarizability derivatives, there are eight sets of bond polarizability derivatives which are consistent with the measured intensities. Only one set, however, gives reasonable polarizability derivatives for CC stretching and CCC bending, and also shows the requisite invariance to isotope substitution. This set gives a low value for the Li-Li polarizability derivative, and application of the delta function potential equation suggests that the extent of Li-Li bonding is small, amounting to perhaps 5% of the total bonding electron density in the Li₄C₄ cage. This conclusion is consistent with the failure to observe Li[sbnd]Li spin-spin coupling in (t-C₄H₉Li)₄.     

Electron paramagnetic resonance study of the TiCl4/Al(i-C4H9)3 system

Toluene solutions of titanium tetrachloride-triisobutyl aluminium varying in molar ratio from 1: 3 to 1: 30 are studied by electron paramagnetic resonance spectroscopy at 77 K. It is shown that the stepwise reduction of Ti(IV) to Ti(III) occurs under these conditions, resulting in the formation of TI ₂ ⁷⁺ and TI ₂ ⁶⁺ heterovalent compounds. A feasible mechanism for the interaction between TiCl₄ and Al(i-Bu)₃ is proposed.     

Reaction of Os3H2(CO)9(C6H4) with diphenylacetylene: the formation and structural characterisation of Os3(CO)7(C6H4)[PhCC(H)Ph]2

The reaction of the 'benzyne' cluster Os₃H₂(CO)₉(C₆H₄) with diphenylacetylene affords the new compound Os₃(CO)₇(C₆H₄)[PhCC(H)Ph]₂; a single crystal X-ray analysis of this product shows that two PhCC(H)Ph units and the benzyne moiety are bonded to the Os₃ core as separate ligands, and that under these conditions there is no ligand condensation.     

Activation of the Ti(OC4H9)4-Al(C2H5)3 catalytic system in the selective dimerization of ethylene to 1-butene by the grignard reagent

The effect of an organomagnesium compound on the dimerization of ethylene to 1-butene was studied. The organomagnesium compound increases the catalytic activity of the Ti(OC₄H₉)₄-Al(C₂H₅)₃ system by 5–10 times. A high degree of selectivity (up to 99%) with respect to 1-butene was obtained. This makes it possible to eliminate a series of technological difficulties involved in the industrial production of 1-butene. The kinetics of the reduction of Ti(OC₄H₉)₄ by butylmagnesium chloride were studied by ESR and polarography.Chernogolovka Institute of Chemical Physics, Russian Academy of Sciences, 142432 Chernogolovka. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2277–2283, October, 1992.