Synthesis metal vapor condensation

The metal-vapor synthesis, involving co-condensation of nickel vapors, r-BuC = P, and 1,2,4-triphospholyl system leads to the mixed-ligand species 178 (94AGE2330). 

Co-condensation of Hf and Zr atoms from an electron-gun evaporation device, with P(Me)3 and arenes at 77K gave good yields of the species [M(arene)2P(Me3)]. Metal vapor synthesis led to Fe(i7 -arene)L2 and Fe(i7 -arene)-(i7 -diene), where L is a phosphorus ligand. In addition, complexes of stoichiometry Fe(T) -diene)L3 (where L is again a... 

The general technique of the metal vapor experiments described below was to co-condense the vapors of the transition metal with those of the chosen hydrocarbon or hydrocarbon mixtures. In this paper we briefly outline the technique of metal atom synthesis and then show how it can be applied to alkane activation reactions. 

Ullrafine particles (UFPs) of metal and semiconductor nitrides have been synthesized by two major techniques one is the reactive gas condensation method, and the other is the chemical vapor condensation method. The former is modified from the so-called gas condensation method (or gas-evaporation method) (13), and a surrounding gas such as N2 or NII2 is used in the evaporation chamber instead of inert gases. Plasma generation has been widely adopted in order to enhance the nitridation in the particle formation process. The latter is based on the decomposition and the subsequent chemical reaction of metal chloride, carbonate, hydride, and organics used as raw materials in an appropriate reactive gas under an energetic environment formed mainly by thermal healing, radiofrequency (RF) plasma, and laser beam. Synthesis techniques are listed for every heal source for the reactive gas condensation method and for the chemical vapor condensation method in Tables 8.1.1 and 8.1.2, respectively. 

The synthetic potential of transition metal atoms in organometallic chemistry was first demonstrated by the formation of dibenzenechrom-ium (127). Apart from chromium, Ti, V, Nb, Mo, W, Mn, and Fe atoms each form well-defined complexes with arenes on condensation at low temperatures. Interaction has also been observed between arenes and the vapors of Co, Ni, and some lanthanides. Most important, the synthesis of metal-arene complexes from metal vapors has been successful with a wide range of substituted benzenes, providing routes to many compounds inaccessible by conventional reductive preparations of metal-arene compounds. 

Cobalt-silicon bonds, in hydridocobalt complexes, 7, 5 Cobalt—tin bonds, in hydridocobalt complexes, 7, 5 Co-catalyst effects, in olefin polymerization, 4, 1111 (—)-Goccinine, via Alder-ene reactions, 10, 593 Co-condensation sites, in metal vapor synthesis technique,... 

Not surprisingly, in recent years the technique of metal vapor synthesis, in which the metal vapor and PF3 are cocondensed at liquid nitrogen temperatures, has found general application since PF3 is readily condensible (in contrast to CO) and the high volatility of the resulting metal-PF3 complexes facilitates their isolation (method H). 

The homoleptic (see Homoleptic Compound) titanium diene complex (j " -r-BuCH=CHCH=CHBu-t)2Ti (11) has been prepared by the condensation ofelectron-beam vaporized titanium with an excess of 1,4-di-t-butylbuta-1,3-diene" (see Metal Vapor Synthesis of Transition Metal Compounds). The bis-diene dmpe complex Ti(dmpe)( " -C4H6)2Ti (12) has been prepared by the reduction of TiCl4(dmpe) with Na/Hg in the presence of butadiene, and by the reduction of TiCLi with CH2=CHLi in the presence of dmpe. ... 

Atypical synthesis of naAed NHC-containing complexes has been reported by Cloke and coworkers. As shown in equation (7), the co-condensation of nickel, paUadium, and platinum vapor with the free NHC, TBu, provided two-coordinated homoleptic complexes of Ni(0), Pd(0), and Pt(0) (43). Unfortunately, in addition to the poor yield of the isolated product, this original methodology required a metal vapor synthesis apparatus. 

There are numerous approaches to the synthesis of highly dispersed metal oxides in addition to those discussed. These include some methods that have been less commonly used to prepare metal oxides, such as vapor condensation methods, spray pyrolysis and templated techniques. 

Figure 12.4 Evaporation-condensation generator for the synthesis of ultrafine metal particles. The cylindrical glass chamber was 0.34 m in diameter and 0.45 m in height. Metal vapor from the alumina crucible mixes with the inert gas. The vapor nucleates particles grow by condensation and deposit on the cooled copper plate by thcrmophorcsis. (After Granqvisi and Buhrman. 1976.)...

Recently, the matrix co-condensation technique has been used to synthesize a number of unstable and transient coordination compounds. For example, a series of nickel carbonyls of the type Ni(CO), where x= 1, 2, 3, and 4, have been synthesized by allowing metal vapor to react with CO diluted in Ar on a cold window and warming the matrix carefully. Figure 1-21 shows the result obtained by DeKock. The structures of Ni(CO)2 and Ni(CO)3 were concluded to be linear and trigonal-planar, respectively, since these compounds exhibit only one CO stretching band in the infrared. Similar methods have been applied to the synthesis of a number of coordination compounds ML , where M is Pt, Pd, Ni, and so on, and L is CO, Nj, O2, PFj, and so on. More detailed discussions of individual compounds will be given in Part 111. ... 

Production of preformed nanoparticles in the gas phase Several methods have been found to produce gas-phase nanoparticles. However, they all involve the production of a supersaturated metal vapor that condenses into particles. This method is the most flexible technique for the synthesis of metal nanoparticles and it is the way to produce tightly mass-selected nanoparticles of virtually any material or alloy in environments ranging from free particles... 

Techniques for the preparation of metal cluster/nanoparticles can be classified into three primary categories condensed phase, gas phase, and vacuum methods. In condensed phase synthesis, metal and semiconductor nanoparticles are prepared by means of chemical synthesis, which is also known as wet chemical preparation. In gas phase synthesis, metal is vaporized, and the vaporized atoms are condensed in the presence or absence of an inert gas. In vacuum methods, the metal of interest is vaporized with high-energy Ar, Kr ions, or laser beams in a vacuum, and thus generated metal vapor is deposited on a support. 

Condensation of metal vapors with various 6e ligands (cf. preparation of diene complexes, Chapter 8) allows the synthesis of many complexes which would be difficult or impossible to obtain by other methods owing to the reactivity of substituents. The following bisarene complexes were obtained in this manner [Cr(arene)2], where arene = PhX (X = F, Cl, CF3, COOMe, Me, /-Pr) or (X = F, Cl, CF3,... 

The co-condensation, using metal vapor deposition (MVD) techniques, between the vapors of nickel and di-Bu NHC ligand l,3-di-N-Bukimidazol-2-ylidene proved to be a straightforward path for the synthesis of the 14-electron... 

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