Inert gases complexes

LeRoy R J and van Kranendonk J 1974 Anisotropic intermolecular potentials from an analysis of spectra of H2- and D2-inert gas complexes J. Chem. Phys. 61 4750... 

Kreek H, Le Roy RJ (1975) Intermolecular potentials and isotope effects for molecular hydrogen-inert gas complexes. J Chem Phys 63 338-344... 

The present chapter mainly discusses the simplest class of atom-diatom Van der Waals molecules, the molecular hydrogen-inert gas complexes. While experimental information on the vibrational predissociation of these species is as yet relatively limited, our knowledge of the potential energy surfaces which govern their dynamics (9,10) is unequalled for any other systems. Moreover, the small reduced mass and large monomer level spacings make accurate calculations of their properties and propensities relatively inexpensive to perform. For these reasons, these species have come to be treated as prototype systems in theoretical studies of vibrational predissociation (17-25). 

Results and Predictions. Detailed close coupling calculations for "real" Av<0 vibrational predissociation of weak-coupling systems such as the hydrogen-inert gas complexes are more difficult and computationally more expensive than those for predissociation by internal rotation. The computational expense arises simply from the very large increase in the nvmber of channels which must be included in order to obtain converged results. The difficulty, on the other hand, arises from the fact that these resonances have very small widths, usually 10 cm , %jhich makes them very difficult to find. 

A gas—tungsten arc-welding system is more complex. In addition to the components of the shielded-metal arc system, provisions must be made for the inert gas supply and water or air cooling of the welding torch. GTAW systems may range from manual to automatic. 

For example, in Ni(CO) nickel metal having 28 electrons coordinates four CO molecules to achieve a total of 36 electrons, the configuration of the inert gas krypton. Nearly every metal forming a carbonyl obeys the 18-electron rule. An exception is vanadium, forming a hexacarbonyl in which the number of electrons is 35. This carbonyl, which has a paramagnetism equivalent to one unpaired electron, however, readily adds one electron to form a closed valence shell complex containing the V(CO)(, anion. 

The electrophilic carbene carbon atom of Fischer carbene complexes is usually stabilised through 7i-donation of an alkoxy or amino substituent. This type of electronic stabilisation renders carbene complexes thermostable nevertheless, they have to be stored and handled under inert gas in order to avoid oxidative decomposition. In a typical benzannulation protocol, the carbene complex is reacted with a 10% excess of the alkyne at a temperature between 45 and 60 °C in an ethereal solvent. On the other hand, the non-stabilised and highly electrophilic diphenylcarbene pentacarbonylchromium complex needs to be stored and handled at temperatures below -20 °C, which allows one to carry out benzannulation reactions at room temperature [34]. Recently, the first syntheses of tricyclic carbene complexes derived from diazo precursors have been performed and applied to benzannulation [35a,b]. The reaction of the non-planar dibenzocycloheptenylidene complex 28 with 1-hexyne afforded the Cr(CO)3-coordinated tetracyclic benzannulation product 29 in a completely regio- and diastereoselective way [35c] (Scheme 18). 

Isotope effects which give ratios of XH +/XD + less than unity are perhaps more interesting from the standpoint of energy transfer in reactive collisions. If a collision complex between an inert gas X and HD +... 

The eleetronic configuration of the group-IIA elements, [inert gas] ns, render them so reactive that they never occur native but are always combined with other elements. Thus, Be is found in complex silicate minerals Mg, Ca, Sr and Ba, however, occur in carbonate, sulfate or phosphate ores. Consequently, whereas the extractive metallurgy of Be is relatively complex, that for the other elements is quite straightforward. 

Since the demonstration by Schumacher et al ) of the use of alkali metal vapor inclusion into a supersonic beam to produce clusters, there have been a number of attempts to generalize the approach. It has recently been recognized that instead of high temperature ovens, with their concommitant set of complex experimental problems, an intense pulsed laser beam focused on a target could be effectively used to produce metal atoms in the throat of a supersonic expansion valve. ) If these atoms are injected into a high pressure inert gas, such as helium, nucleation to produce clusters occurs. This development has as its most important result that clusters of virtually any material now can be produced and studied with relative ease. 

Our studies at Atomic Weapons Establishment (AWE) have confirmed that at elevated temperatures, especially when using dry inert gas conditions, there is considerable difficulty in pushing the reaction (see scheme 5) to completion.18 Moisture was found to affect the rate of the reaction and the nature of the synthesized polymer. The introduction of additional catalyst to the reaction mixture was found to aid the forward reaction. Overall, our observations suggest the existence of a complex series of reactions, possibly having distinctly different activation energies. 

An explosion and fire occurred in the pipework of a vessel in which dilute butadiene was stored under an inert atmosphere, generated by the combustion of fuel gas in a limited air supply. The inert gas, which contained up to 1.8% of oxygen and traces of oxides of nitrogen, reacted in the vapour phase over an extended period to produce concentrations of gummy material containing up to 64% of butadiene peroxide and 4.2% of a butadiene-nitrogen oxide complex. The deposits eventually decomposed explosively. 

The basic assumption used for the interpretation of the field ion images, viz, the overlapping mechanism, was independently confirmed by the recent atom-probe experiments which have supplied evidence for the formation of a quasichemical complex between an inert gas atom and a metal... 

Arc discharge [25] is initially used for producing C60 fullerenes. Nanotubes are produced by arc vaporization of two carbon rods placed in a chamber that is filled with low pressure inert gas (helium, argon). The composition of the graphite anode determines the type of CNTs produced. A pure graphite anode produce preferably MWNT while catalyst (Fe, Co, Ni, Y or Mo) doped graphite anode produces mainly SWNT. This technique normally produces a complex mixture of components, and requires further purification to separate the CNTs from the soot and the residual catalytic metals present in the crude product. 

The carbonyl complex [Ag(L9)(C0)] (12), also of quite remarkable stability, is obtained by reaction of [Ag(L9)(C2H4)] (11) with CO in hexane. Nevertheless, the CO can be easily removed by increasing the temperature of the solution or by purging with an inert gas. Hence, such a reversible guest encapsulation within a molecular container might find applications for gas separation and storage. Again, one likely reason for the stability of the complexes is the protection offered by the bulky mesityl substituents that surround the ethylene or CO unit. 

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