Tungsten di

Tungsten Di-iodide, WI, is formed on passing iodine vapour over the metal heated to redness, or by heating the hexachloride at 400° to 450 C. in a current of dry hydrogen iodide. The substance is... 

Although the reaction of an aryl Grignard reagent with the metal halide (Hein s reaction) sometimes successfully yields the chromium, molybdenum, and tungsten di-arene 7r-complexes, it is only recommended as a good preparative method for Ti-arene chromium complexes. Equation (2-29) shows... 

The potential of Fischer carbene complexes in the construction of complex structures from simple starting materials is nicely reflected in the next example. Thus, the reaction of alkenylcarbene complexes of chromium and tungsten with cyclopentanone and cyclohexanone enamines allows the di-astereo- and enantioselective synthesis of functionalised bicyclo[3.2.1]octane and bicyclo[3.3.1]nonane derivatives [12] (Scheme 44). The mechanism of this transformation is initiated by a 1,4-addition of the C -enamine to the alkenylcarbene complex. Further 1,2-addition of the of the newly formed enamine to the carbene carbon leads to a metalate intermediate which can... 

Electronic Structure and Spectroscopic Properties of Molybdenum and Tungsten N2, NNH, NNH2, and NNH3 Complexes with Diphosphine Co-Ligands Insights into the End-on Terminal Reduction Pathway of Di nitrogen Felix Tuczek... 

Tungsten aryloxo complexes have been shown to catalyze the intramolecular metathesis reactions of di- and tri-substituted co-unsaturated glucose and glucosamine derivatives to yield bicyclic carbohydrate-based compounds containing 12- and 14-membered rings [108,214,215]. An example is shown in Eq. 37. The tolerance for amides and esters is noteworthy, as are the yields and the size of the rings that are formed. 

Yao, Z. Di, J. Yong, Z. Zhao, Z. G. Li, Q., Aligned coaxial tungsten oxide/carbon nanotube sheet A flexible and gradient electrochromic film. Chem. Commun. 2012, 48, 8252-8254. 

A. A. Holscher and W. M. H. Sachtler, Chemisorption and surface corrosion in the tungsten + carbon monoxide system, as smdied by field emission and field on microscopy, Dis. Faraday Soc. 41, 29 (1966). 

The properties and reactions of the molybdenum and tungsten complexes [(Tt-Cp)M(CO)2(N CPhBu )] Ci.sely resemble those of the corresponding di-t-butylmethyleneamino-complexes, steric hindrance preventing bridging by the methyleneamino-groups. The complexes react with iodine to form [(jr-Cp)-M(CO)l2(NCPhBu )] as expected however, in contrast to all other such... 

Electrochemical recognition, 39 80 anions, macrocyclic and acyclic polycobalti-cinium ligand systems, 39 134-140 cations, 39 81-133 ammonium cation, 39 128-133 crown ether and bis crow ether ligands containing bipyridyl transition metal recognition sites, 39 111 crown ether dithiocarbamate and dithi-olene complexes, 39 123-124 di-h-cyclopentadienyl-molybdenum(IV) and -tungsten(IV) crown ether complexes, 39 107-108... 

Both W(CO)5[C(C6Hs)2] and the analogous di-p-tolylmethylene complex have been used in model studies of the olefin metathesis reaction.2 3 In contrast to heteroatom-stabilized carbene complexes such as W(CO)s [C(OCH3)(C6Hs)], pentacarbonyl(diphenylmethylene)tungsten(0) reacts with alkenes to give cyclopropanes and 1,1-diphenylalkenes.2 The compound W(CO)5 [C(C6H5)2] is the best reported catalyst for the metathetical polymerization of 1-methylcyclo-butene.4... 

NBFjOsWCmH, Tungsten(l +) pentacar-bonyl-[(diethylamino)methylidyne]-tetrafluoroborate( 1 -), 26 40 NBr04SCraHls, Bicyclo(2.2.l)heptane-7-methanesulfonate, 3-bromo-l, 7-di-methyl-2-oxo-... 

N,05WCii)H(h, Tungsten, tetracarbonyl[(di-ethylamino)methylidyne](isocyanato)-trans-, 26 42... 

KF]MnSCt. Manganese(I), pentacarbonyl-(trifluoromethanesulfonato)-, 26 114 0 F,ReSCfi, Rhenium(I), pentacarbonyl-(trifluoromethanesulfonato)-, 26 115 OsF]2W2C , Tungsten(II), tetrakis(trifluoro-acetato)di-(W-4-W), 26 222... 

Many theories of adsorption, following Langmuir, have assumed that the rate of adsorption is proportional to (1 — 0), i.e., to the fraction of the surface which is bare or not yet covered. Langmuir first proved the (1 — 0) law by measuring experimentally how the thermionic work function

changed with time as thorium reached the surface of a tungsten filament at a constant rate (10). He then assumed that tp decreased linearly with 0 and thus deduced that dd/di was proportional to (1 — 0). But this assumption has been shown to be incorrect for such cases as Cs on W, Ba on W, SrO on W, and other systems. Hence it follows that the (1 — 0) law is not valid. The experiments described above for N2 on W not only show that dQ/dt is not proportional to (1 — 0), but they show by a direct experiment that dd/dt for a constant arrival rate is independent of 0 between 0 = 0 and 1.0. 

A copper(O) complex, electro-generated from Cu(acac)2, is able to undergo an oxidative addition with benzyl and allyl bromides. Further reduction leads to the coupling products bibenzyl and 1,5-hexadienes Methyl-3-hexene-l,6-dicarb-oxylate can be prepared from butadiene and CO by electroreduction if di-Fe dicyclopentadienyl tetracarbonyl is used as redox catalyst Electro-generated low-valent tungsten species are able to reductively dimerize benzaldehyde to stilbene according to Eq. 83. The reduction potential was controlled at the third wave of the WClg catalyst (V = -1900 mV/SCE)... 

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