Heteromolecular insertion of EtNCX (X = O, S) and RCN (R = CH3, C6H5) into tungsten hexachloride

The interactions of tungsten hexachloride with EtNCX (X = O, S) and RCN (R = CH₃, C₆H₅) were studied. In the case of E = CH₃, heterocumulenes are inserted at the W-Cl bond, while in the case of R = C₆H₅, they were inserted at a multiple tungsten-nitrogen bond of an intermediate imido complex [WCl₄(NCPh)(CNCl₂Ph)]. The IR, MALDI TOFF mass spectroscopy, and elemental analysis data confirmed that these interactions yielded the products of heteromolecular insertion, namely, [WCl₄{(EtNCO)₂(MeCN)Cl}], [WCl₄(EtNCS)₂(MeCN)Cl], [WCl₄N(CCl₂Ph)C(=NEt)O}], and WCl₄N(CCl₂Ph)C(=NEt)S}], whose compositions and structures were determined by the nature of the organic nitrile radical.     

Über die Reaktion von 2,2-Dimethylpropylidinphosphan mit Wolframhexachlorid; die Kristallstrukturen von [(Cl3PO)WCl4(H9C4?CC?C4H9)] und [(H5C6)4As][WCl6]

Reaction of 2,2-Dimethylpropylidynephosphane with Tungsten Hexachloride as well as the Crystal Structures of [(Cl₃PO)WCl₄(H₉C₄? C?C—C₄H₉)] and [(H₅C₆)₄As][WCl₆] The reaction of 2,2-dimethylpropylidynephosphane, (CH₃)₃C? C?P|, with tungsten hexachloride suspended in POCl₃ results, with oxidation of the phosphorus atom, in 2,2,5,5-tetramethylhex-3-yne. This compound reacts with tungsten tetrachloride simultaneously formed to give the alkyne complex [(Cl₃PO)WCl₄(H₉C₄? C?C—C₄H₉)], which is dark green in colour. A small amount of tungsten hexachloride is reduced merely to tungsten pentachloride; after the addition of tetraphenyl arsonium chloride it can be isolated as [(H₅C₆)₄As][WCl₆]. For this compound, a new and very simple synthesis from WCl₆, [(H₅C₆)₄As]Cl and C₂Cl₄ as reducing agent is described. The structure of [(Cl₃PO)WCl₄(H₉C₄? C?C? C₄H₉)] has been determined from X-ray diffraction data (R = 5.8%). The complex crystallizes in the monoclinic space group P2₁/n with: {a = 1510; b = 1517; c = 849 pm; β = 93.1°; Z = 4}. The tungsten atom is sevenfold coordinated by four equatorial chlorine atoms, by the C°C group of the acetylene ligand and by the oxygen atom of the POCl₃ molecule in trans position. The bulky acetylene ligand which is nearly symmetrically bound shifts the chlorine atoms towards the solvated POCl₃ molecule so that no common plane with the tungsten atom is possible. With 130 pm the C°C bond length of the 2,2,5,5-tetramethyl-3-yne ligand corresponds to a C°C double bond. The i.r. spectrum of [(H₅C₆)As][WCl₆] shows two WCl₆ strectching vibrations and therefore proves a reduction of octahedral symmetry. In agreement with the results of a crystal structure determination (space group P4/n; a = 1301; c = 780 pm; Z = 2.7%) the [WCl₆]^?-anion has nearly exact C_4V symmetry with somewhat shorter W? Cl bond lengths parallel to the fourfold axis of rotation.     

Electrochemically reduced tungsten‐based active species as catalysts for cross‐metathesis reactions: cross‐metathesis of non‐functionalized olefins

The electrochemical reduction of WCl₆ results in the formation of an active olefin (alkene) metathesis catalyst. The application of the WCl₆–e^?–Al–CH₂Cl₂ catalyst system to cross‐metathesis reactions of non‐functionalized acyclic olefins is reported. Undesirable reactions, such as double‐bond shift isomerization and subsequent metathesis, were not observed in these reactions. Cross‐metathesis of 7‐tetradecene with an equimolar amount of 4‐octene generated the desired cross‐product, 4‐undecene, in good yield. The reaction of 7‐tetradecene with 2‐octene, catalyzed by electrochemically reduced tungsten hexachloride, resulted in both self‐ and cross‐metathesis products. The cross‐metathesis products, 2‐nonene and 6‐tridecene, were formed in larger amounts than the self‐metathesis products of 2‐octene. The optimum catalyst/olefin ratio and reaction time were found to be 1 : 60 and 24 h, respectively. The cross‐metathesis of symmetrical olefins with α‐olefins was also studied under the predetermined conditions. Copyright © 2003 John Wiley & Sons, Ltd.     

Beiträge zur Chemie der Alkylverbindungen von Übergangsmetallen. XIV. Untersuchungen über Benzylwolframverbindungen-Darstellung und Charakterisierung des Wolframtetrabenzyls

Contributions to the Chemistry of Transition Metal Alkyl Compounds. XIV. Investigations on Benzyl Tungsten Compounds. – On the Formation and Characterization of Tetrabenzyl Tungsten Unstable benzyl tungsten pentachloride is formed from tribenzyl boron and tungsten hexachloride. Other benzylating agents yield only less defined reduction products. – Reacting WCl₄ · 2 THF with dibenzyl magnesium W(CH₂C₆H₅)₄ can be obtained. The new compound is stable at room temperature and is thoroughly characterized.     

Bis[(tert-butylnitren)tetrachlorowolfram] Synthese,IR-Spektrum und Kristallstruktur

Bis[(tert-butylnitrene)tetrachlorotungsten]: Synthesis, I.R. Spectrum, and Crystal Structure The title compound, forming red crystals, is prepared by the reaction of tungsten hexachloride with the iminoborane Me₃CB?NCMe₃. With PPh₄Cl it forms the chloro complex PPh₄[WCl₅(NCMe₃)]. Both complexes are characterized by their i.r. spectra. The crystal structure of [WCl₄(NCMe₃)]₂ was determined by the aid of X-ray diffraction (space group P2₁/c, Z = 2 dimeric units, 1938 independent, observed reflexions, R = 0.028, a = 636, b = 1537, c = 1124 pm; β 104.74°). The compound forms centrosymmetric molecules in which the tungsten atoms are bridged via chloro atoms with W? Cl bond lengths of 241 and 275 pm. In position trans to the longer WCl bond the nitrene ligand is attached with a WN distance of 170 pm which corresponds to a triple bond; the W?N? C bond angle is 173°.     

[WCl4(Me3Si?CC?SiMe3)]2 Synthese,IR-Spektrum und Kristallstruktur

[WCl₄(Me₃Si? C?C? SiMe₃)]₂. Synthesis, I.R. Spectrum, and Crystal Structure The title compound is obtained from tungsten hexachloride and bis-trimethylsilyl acetylene in the presence of C₂Cl₄ in dichloro methane, forming green crystals. The complex is characterized by the mass spectrum, the i.r. spectrum, and by a structural analysis with the aid of X-ray diffraction data. [WCl₄(Me₃Si? C?C? SiMe₃)]₂ crystallizes triclinic in the space group P1 with one dimeric formula unit per unit cell (2 231 observed, independent reflexions, R = 4.6%). The cell dimensions are a = 928, b = 938, c = 1 080 pm; α = 115.3°, β = 91.9°, γ = 100.0°. The complex forms centrosymmetric dimers, the units being linked by chloro bridges of bond lengths W? Cl 244 and 272 pm. The trans-position to the long W? Cl bridge is occupied by the acetylene ligand which is bonded side-on with identical W? C bond lengths of 203 pm. Together with the three terminal chlorine ligands (mean W? Cl distance 231 pm) the tungsten atom achieves coordination number seven.     

钨氧化物纳米结构的合成与表征

采用溶剂热法以WCl₆作为前体合成出了一维和二维的钨氧化物纳米结构,研究了反应溶剂和前体浓度对钨氧化物物相和形貌的影响并评价了各种钨氧化物纳米结构对NO₂气体的敏感性能。XRD、SEM、TEM和XPS的表征结果表明,通过改变溶剂和调整WCl₆浓度,可分别获得单斜的W₁₈O₄₉纳米棒、W₁₈O₄₉纳米线和WO₃纳米片结构。气敏性能测试结果表明,钨氧化物纳米结构对NO₂气体表现出良好的可逆性,与W₁₈O₄₉纳米棒和WO₃纳米片相比,W₁₈O₄₉纳米线对NO₂具有更高的灵敏度。     

Efficient synthesis of vinyl chlorides and/or gem-dichlorides from ketones by treatment with tungsten hexachloride

Treatment of cyclic ketones, e.g. 4, with tungsten hexachloride (WCl₆) provided good yields of vinyl chlorides, e.g. 5, and/or gem-dichlorides. A trans-diequatorial dichloride 9 was prepared by treatment of the corresponding epoxide 8 with WCl₆.     

Organotin(IV) isothiocyanatochromates

Summary Several new compounds of the type [R₃Sn]₃[Cr(NCS)₆] and [R₃Sn][Cr(NCS)₄L₂], where R = Ph or n-Bu and L = NH₃, PhNH₂ or CO(NH₂)₂, have been synthesized and characterized by analytical data, i.r. and electronic spectral studies. Conductance measurements indicate that the compounds are ionic.     

Diorganotin(IV) and triorganotin(IV) derivatives of diphenic acid

The diorganotin(IV) and triorganotin(IV) derivatives R₂SnA (R = Me, n-Pr, n-Bu, n-Oct) and (R₃Sn)₂A [R = Me, Ph, cyclohexyl (Cyh); A = an anion of diphenic acid] have been prepared and characterized by elemental analysis, IR, ¹H and ¹³C NMR spectroscopies. Tetrahedral tin forms a part of a diphenate cyclic ring in the diorganotin complexes with unidentate carboxylates, which have further been used for the synthesis of cyclic acid anhydrides. The soluble dinuclear triorganotin complexes (Me, Ph) possess symmetrically bonded carboxylates while the less soluble compound (Cyh₃Sn)₂A has two asymmetrically bonded carboxylates. All have a trigonal bipyramidal structure with R₃Sn units remote from each other.     

Etudes sur le mecanisme de la metathese des olefines : II. Coupure des alkyltungstenes,amorçages anormaux

With a view to elucidating the mode of action of tungsten containing catalyst of the olefin metathesis, the thermal decomposition of various alkyltungsten derivatives was examined. It was shown that n-alkyltungsten derivatives (i.e. n-alkylmagnesium halides + WCl₆) are decomposed to lighter alkenes and alkanes (i.e. propyl to ethylene, ethane and methane). With methyl or neopentyl derivatives of tungsten, alkenes are observed, which derive from alkylation and fission of the metathesis substrate (i.e. Me₃CCH₂MgBr + WCl₆ + 2-pentene give inter alia 2,2-dimethyl-4 hexene). Metathesis of tetramethylethylene was also observed, as evidenced by the formation of 2-methyl-2-pentene in the presence of 3-hexene.All these facts agree with the intermediacy of a tungsten hydride as the key step in the formation of a metathesis catalyst, intermediacy which is linked with the formation of tungstacarbene (alkylidene tungsten).     

Detection and Characterization of Compounds in the Mn‐W‐Cl System through a Combined Thermal Scanning ‐ XRD Approach

A procedure combining thermal analyses and XRD powder diffraction is used to scan and detect a series of new compounds in the Mn‐W‐Cl system. Four new ternary Mn‐W‐Cl compounds are formed in a progressive reaction of tungsten hexachloride (WCl₆) with manganese powder, in which tungsten is gradually reduced from W⁶⁺ to W²⁺. Among several DSC signals, the new compounds Mn_xWCl₆, MnW₂Cl₁₀, (Mn, W)_1–xCl₂, and MnW₆Cl₁₄ are detected and their crystal structures are assigned or identified by X‐ray diffraction techniques. Magnetic properties are reported for MnW₂Cl₁₀ and MnW₆Cl₁₄.     

Diiodacetylenkomplexe von Wolfram(IV). Die Kristallstruktur von PPh4[WCl5(C2l2)] · 0,5 CH2Cl2

Diiodoacetylene Complexes of Tungsten(IV). Crystal Structure of PPh₄[WCl₅(C₂I₂)] · 0.5 CH₂Cl₂ Tungsten hexachloride and diiodoacetylene react in CCl₄ solution forming [WCl₄(I? C?C? I)]₂ which has a dimer structure with chloro bridges. In CH₂Cl₂, it reacts with PPh₄Cl yielding PPh₄[WCl₅(I? C?C? I)] · 0.5 CH₂Cl₂. In both compounds the C₂I₂ ligands attain a marked increase in thermal stability by their side-one coordination to the tungsten atoms. The crystal structure of the PPh₄^⊕ salt was determined with X-ray diffraction data (3879 observed reflexions, R = 0.050). PPh₄[WCl₅(C₂I₂)] · 0.5 CH₂Cl₂ crystallizes in the space group P2₁/n with 8 formula units per unit cell. The lattice constants are a = 1723.0, b = 1681.2, c = 2214.6 pm and β = 94.38°. There are two crystallographically independent [WCl₅(C₂I₂)]^? ions which differ only slightly from one another. The C₂I₂ ligand has a staggered arrangement relative to the W? Cl groups, with C? C bond lengths of 127 pm. The infrared spectra are discussed.     

Biocidal Organotin Compounds. Part 2. Synthesis,Characterization and Biocidal Properties of Triorganotin(IV) Hydantoic Acid Derivatives and the Crystal Structures of Triphenyltin and Tricyclohexyltin Hydantoates

The preparation and spectroscopic (¹H NMR, UV and IR) characterization of three R₃Sn(O₂CCH₂N(H)C(O)NH₂) [R=Ph, c-Hex (cyclohexyl) or n-Bu] compounds are reported. A different mode of coordination is indicated for the hydantoate ligand in the R=Ph compound compared with the R=c-Hex and R=n-Bu compounds, as confirmed by a crystallographic analysis. The structure of [Ph₃Sn(O₂CCH₂N(H)C(O)NH₂)] is polymeric owing to the presence of bridging hydantoate ligands such that each ligand coordinates one tin atom, via one of the carboxylate oxygen atoms, and a symmetry-related tin atom via the carbonyl group at the other end of the molecule. The structure features distorted trigonal-bipyramidal tin atom geometries with a trans -R₃SnO₂ motif. The structure of [c-Hex₃Sn(O₂CCH₂N(H)- C(O)NH₂)], by contrast, is monomeric, distorted tetrahedral, as the carboxylate group is monodentate and there are no additional tin–ligand interactions. The structures are each stabilized by a number of intermolecular hydrogen bonds. Fungitoxicity and phytotoxicity studies indicate that the R=n-Bu derivative is the more active compound.     

Chlorthionitrenkomplexe des Wolframs Die Kristallstruktur von [WCl4(NSCl)]2

Chlorothionitrene Complexes of Tungsten. Crystal Structure of [WCl₄(NSCl)]₂ Tungsten hexachloride reacts with trithiazyl chloride, (NSCl)₃, yielding the chlorothionitrene complex [WCl₄(NSCl)]₂, from which AsPh₄[WCl₅(NSCl)] can be obtained by reaction with AsPh₄Cl. Both complexes are characterized by their i.r. spectra. The crystal structure of [WCl₄(NSCl)]₂ was determined and refined with X-ray diffraction data (1059 reflexes, R = 0.055). It crystallizes in the monoclinic space group P2₁/n with the lattice constants a = 1523, b = 904, c = 583 pm and β = 91.35°. In the unit cell there are two centrosymmetric [WCl₄(NSCl)]₂ molecules in which the W atoms are linked via two chloro bridges; short and long W? Cl distances (244 and 265 pm) alternate in the W₂Cl₂ ring, the NSCl groups are found in the trans positions to the longer W? Cl bonds. The WNS bond angle (175°) and short bond distances correspond to a formulation .     

In situ catalyst systems for ring-opening metathesis polymerization

Several new in situ tungsten catalyst systems for ring-opening metathesis polymerizations (ROMP) by reaction injection molding (RIM) have been developed by adding BF₃ promoter to binary catalyst systems, by using metal hydride cocatalysts, and by altering the ligands on the procatalyst metal center. BF₃ etherates improved catalyst efficiency and reduced induction times for formation of active catalysts from reaction of aryloxytungsten complexes [e.g., (ArO)_y(WX_x)] with organotin hydrides. Coordinatively unsaturated cationic intermediates, such as [(ArO)_yWX_x-1]⁺ BF₃X⁻, are proposed to facilitate formation of the active catalysts. Tougher poly(dicyclopentadiene) (polyDCPD) composites were produced using < 5 wt % of styrene-butadiene block copolymers due to formation of small “shell-core” rubber morphologies when BF₃ promoter was added to the catalyst system. Nonalkylating metal hydrides besides R₃SnH, including (PPh₃)₂CuBH₄, (PPh₃CuH)₆, and Cp₂ZrClH, were shown to be cocatalysts. The optimum 2 : 1 stoichiometric ratio of organotin hydride cocatalyst to tungsten, revealed by BF₃-promoted catalyst systems, and W^V EPR resonances (g ∼ 1.7) observed in the reaction of aryloxytungsten with organotin hydride are consistent with an overall reduction and reoxidation mechanism for formation of the active metathesis catalysts. Some tungsten complexes derived from 9-hydroxyfluorene, 2,2′-(and 4,4′)-biphenols, and 1,4-hydroquinones were found to be very reactive procatalysts, even in the absence of cocatalyst in some cases. These procatalysts also were paramagnetic, characterized by unusual EPR spectra consistent with W^V (g = 1.6–1.9) and “ligand-centered” (g = 2.003) resonances. Valence tautomeric species, analogous to catecholate-semiquinonate complexes, are proposed. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3027–3047, 1997     

Biocidal organotin compounds: Part 1. Preparation and characterization of triorganotin(IV) 4-pyridyl- and 2-pyrimidyl- thioacetates and the crystal structure of triphenyltin(2-pyrimidylthioacetate)

The preparation and spectroscopic characterization of [R₃Sn(O₂CCH₂SC₅H₄N-4)], R == Ph, benzyl (Bz), cyclohexyl (c-Hex) and n-Bu, and of [R₃Sn(O₂CCH₂SC₄H₃N₂-2,6)], R == Me, Ph and n-Bu, are reported. The 2-pyrimidyl compounds feature trigonal bipyramidal tin centres with trans-R₃SnO₂ geometries as was confirmed by X-ray crystallography for [Ph₃Sn(O₂CCH₂SC₄H₃N₂-2,6)]. ¶ By contrast the 4-pyridyl compounds have trigonal bipyramidal geometries in the solid state (arising from intermolecular Sn…N interaction) and tetrahedral geometries in solution. The biocidal activity of these compounds against the fungi Helminthosporium maydis (ITCC 2675) and H. oryzae (ITCC 2675), both of which damage crops such as maize and rice, shows promise. Encouraging is the observation that the compounds show no adverse phytotoxicity at concentrations to 10^?3M.     

Structural studies in main group chemistry : XIX. Organotin(IV) derivatives of tetracyanoethylene, 7,7,8,8-tetracyanoquinodimethane and 2,3,5,6-tetrachlorobenzoquinone. The isolation of stable organotin-substituted radicals

The reaction of organotin chlorides with the lithium salt of 7,7,8,8-tetracyanoquinodimethane (TCNQ) or hexaalkylditins with TCNQ yield stable organotin-substituted free radicals of the types R₃SnTCNQ^. (R = Me, n-Pr, n-Bu) and Me₂Sn(TCNQ^.)₂. The reaction of hexaphenylditin with TCNQ yields a (σ → π) charge transfer complex of stoichiometry (Ph₃SnSnPh₃)·TCNQ, whilst [Me₂SnCl(terpyridyl)⁺](TCNQ^-·) was isolated from the reaction of [Me₂SnCl(terpyridlyl)⁺][Me₂SnCl₃^-] and LiTCNQ. The oxidation of hexaalkylditins by tetracyanoethylene (TCNE) yields stable free radicals of the type R₃SnTCNE·, but treatment with 2,3,5,6-tetrachlorobenzoquinone yields either R₃SnOC₆Cl₄O·-p (R = Me) or R₃SnOC₆Cl₄OSnR₃-p (R = n-Bu, Ph). Tin-119 Mössbauer spectroscopy shows that the derivatives R₃SnTCNQ· and R₃TCNE· have trigonally-bipyramidally coordinated tin with planar [SnC₃] skeletons and bridging [TCNQ·] and [TCNE·] groups forming infinite one-dimensional chain structures. Me₃SnOC₆Cl₄O·-p was inferred to possess a similar structure but with oxy bridges forming chains with a Sn---O---Sn---O backbone. Me₂Sn(TCNQ·)₂ has a structure intermediate between tetrahedral and octahedral with a non-linear MeSnMe unit and anisobidentate chelation by two TCNQ groups. The TCNQ derivatives were of two types: (i) “green” or “brown”, indicative of delocalisation of the Ione electron over the cyanoquinone ligand, and (ii) a “blue” form in which spin-pairing of the Ione electron between adjacent organic groups takes place. Me₃SnTCNQ· may exist in both forms depending upon the mode of preparation.     

Ring-opening polymerization of 2-azabicyclo-[2,2,1]-hept-5-en-3-one using metathesis catalysts

The ring-opening polymerization of an unsaturated bicyclic lactam, 2-azabicyclo-[2,2,1]-hept-5-en-3-one (ABHEO), was carried out using metathesis catalysts under various reaction conditions. It is observed that the best results (34% conversion and η_inh: 0.18 dL/g) were obtained when the mole ratios of ABHEO to WCl₆ as a catalyst and WCl₆ to AlEt₃ as a cocatalyst were 200 and 4, respectively. The infrared (IR) and nuclear magnetic resonance (¹H- and ¹³C-NMR) spectra of the polymer obtained indicated that the ABHEO was transformed to the ring-opened polymer, poly(2-pyrrolidone-3,5-diylvinylene) [poly(ABHEO)]. The resulting polymer was amorphous as determined by DSC analysis, which showed only secondary transition at 100°C.     

Komplexkatalyse. XIX. Zur Synthese von Nitrosylkomplexen des Wolframs und deren Eignung als Präkatalysatoren für die Olefinmetathese

Complex Catalysis. XIX. Synthesis of Nitrosyl Complexes of Tungsten and their Usefulness as Precatalysts for Olefin Metathesis Nitrosylating reduction of WCl₆ with NO leads to WCl₃(NO)₄ that on addition of different donor ligands L yields complexes of the types WCl₃(NO)L₂ (L = OOh₃, HMPT, pyridine) and WX₂(NO)₂ L₂ (L = PPh₃, X = Cl; XL = acac) or mixtures of products (L = Dipy, RCN, Et₄NCl), respectively. Whereas by carbonylation of WCl₃(NO)(OPPh₃)₂ in the presence of EtAlCl₂ only chloro carbonyl tungsten complexes are formed, the reaction of W(CO)₆ with NOAlCl₄ and subsequent addition of PPh₃ gives, in analogy to molybdenum, the nitrosyl carbonyl complexes W(NO)(CO)₄(AlCl₄) and WCl(NO)(CO)₂(PPh₃)₂. All the nitrosyl tungsten complexes in combination with EtAlCl₂ catalyze the metathesis of pent-2-ene, however, with a significantly lower activity than the corresponding nitrosyl molybdenum systems.