Metal/vapour reactions

The complex SmCpj was synthesized by metal vapour reaction of samarium with Cs(CH3)5H as a green product or by desolvation of the red SmCpj 2THF by sublimation. The crystal structure of the complex SmCpj shows it to be decamethyl samarocene with bent metallocene disposition [138], The Cg-Sm-Cg angle of 140.1° is greater than 136.7 in the desolvated analogue. The Sm-C bond distance is reduced, 2.79(1) A compared to 2.86 (3) A and the structure of SmCpj is shown in Fig. 6.12. 

There are many good reasons for applying ionic liquids as alternative solvents in transition metal catalysed reactions. Besides their very low vapour pressure and then-good thermal stability [33], an important advantage is the possibility of tuning then-solubility [34] and acidity/coordination properties [35] by varying the nature of the anions and cations systematically. 

The reaction of tris(jr-allyl)chromium with the jr-acceptor ligand PF3 produces stable crystals of [Cr(PF3)6] via [(C3H5)3Cr(PF3)] (Scheme 9). At high pressure, only [Cr(PF3)6] is isolated 60 it can also be obtained by metal vapour synthesis, 1 and its He(I) PE spectrum has been assigned.62... 

Alkali metal vapours will also induce reaction between chlorine and a hydrocarbon, a process which presumably occurs in the following way ... 

This is a very restricted oxidation state of copper but may be considered to occur in the polynuclear copper species Cu2, Cu3 and Cus, which have been characterized by matrix isolation techniques. Copper(O) also occurs in species formed by the reaction of copper metal vapour and carbon monoxide gas. Matrix isolation techniques have characterized a monomeric [Cu(CO)3] trigonal planar species and a dimeric [(CO)3CuCu(CO)3] species.32... 

P. L. Timms, Chemistry of Transition-metal Vapours. Part I. Reactions with Trifluoro-phosphine and Related Compounds, J. Chem. Soc. A, 1970, 2526-2528. 

The chemiluminescence, which is possibly best, understood is that emitted in the reaction of alkali metal vapours with halogens. When streams of alkali metal vapours and halogens at pressures of 10"2 to 10-3 nm Hg are mixed, alkali halides are formed with the emission of luminescence. The probable mechanism suggested is ... 

Chemical reactions whose product is gaseous and contains the element to be determined have proved useful. The determination of Hg as metal vapour... 

Metal-vapour-deposition methods have begun to provide new low-valent complexes of uncommon stoichiometry. The preparation of gram quantities of paramagnetic (ji = 2.02 BM) [Co(bipy)2] has been reported and its reactions with Br2, tetracyanoethylene and tetracyanoquinodimethane studied.283 Electrochemically it behaves identically to [Co(bipy)3]2+ (equation 47).283... 

To illustrate the feasibility of the proposed closed loop process, pure iron oxide FejOt was subjected to a producer gas from a 100 kW fluidised bed gasifier (reaction 1) and subsequently exposed to water vapour (reaction 2). For the reduction, Fej04 powder was placed in alumina cmcibles and heated in a tubular furnace at 900 °C and 1000 C, respectively while being exposed to a flow of producer gas for at least 25 minutes. The characterisation of the product by powder X-ray diffractometry and thermal analysis revealed that Fci. O indeed is the main product. Metallic iron and carbonaceous materials were identified as by- products. Generally, samples prepared at... 

The sensitivity to air of alkali-metal-doped fullerenes (A C ) limits the choice of sample preparation and characterization techniques. To avoid sample degradation, we carried out reactions with the alkali metal vapour and Ceo in sealed tubes either in high vacuum or under a partial pressure of helium. The Cso was purified by chromatography of fullerite and was heated at 160 °C under vacuum to remove solvents. 

Superbasic Surface Centres with Ionic Character. - As mentioned earlier reactions between alkali metal atoms and surface acceptor centres such as hydroxyl groups or holes near cationic vacancies lead to the creation of centres of higher basicity. In the first of these examples the reason is the replacement of a hydrogen atom by a more electropositive element, such as an alkali metal atom in the second example it is the result of introduction of an electron from the alkali metal to the hole trapped on the O " anion, the vacancy being filled by a univalent cation. It should be noted that both of the surface configurations so formed can cause strong one-electron or two-electron donor activity. Closer physico-chemical examination has shown that these centres tend to be electron pair rather than one-electron donating in character. They mostly occur on surfaces on which alkali-metal vapours have reacted with oxides heated at the lower temperatures, e.g., MgO calcined... 

Table 9.2 Reaction products observed in the vapour phase hydrogenation of croton-aldehyde over various supported metal catalysts. (Reaction conditions H2 crotonalde-hyde = 14 1, Pressure = 1 bar.)...

RATE COEFFICIENTS AND REACTION MECHANISMS FOR THE REACTIONS OF HALOGENS AND INORGANIC HALIDES WITH ALKALI METAL VAPOURS... 

REACTION OF METAL VAPOURS WITH INORGANIC COMPOUNDS... 

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