Nickel vaporization

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). 

The increased cooling efficiency of thin-walled reactors also has permitted the use of more volatile substrates in near molar quantities. (l-3 6-7 10-12-rj 2,6,10-Dodecatriene-l,12-diyl)nickel has been prepared in multiple gram quantities by cocondensation of nickel vapor and 1,3-butadiene. This method has provided a clean one-step route to this complex, which was first isolated and identified by Wilke et al.1 as an intermediate in the cyclotrimerization of 1,3-butadiene by nickel catalysts. 

Similarly, condensation of a mixture of CsHe and C3D6 with nickel vapor resulted in isotopic scrambling. The intraligand isomerizations may be explained in terms of a 1,3-hydrogen shift via a nf-allyl nickel hydride complex in equilibrium with a ir-propene complex, e.g.,... 

Complexation of Ni atoms to CF3CF=CFCF3 occurs in preference to the thermodynamically possible defluorination (see Sections IV and V). However, condensation of nickel vapor with C2F4 gives an explosive material presumably defluorination is the dominant reaction in this case (132). 

Trifluorophosphine is a very convenient ligand in metal atom chemistry to use along with other ligands, e.g., in the stabilization of metal arene complexes (Section III,B). Reaction of a mixture of PF3 and PH3 with nickel vapor yields Ni(PF3)3PH3 and Ni(PF3)2(PH3)2 but no Ni(PH3)4. Attempts to make Ni(PH3)4 lead to hydrogen evolution from the ligand during or after condensation with the nickel vapor (128). 

Manganese, iron, cobalt, and nickel vapors do not give arene complexes with haloarenes. Interactions with hexafluorobenzene have been reported, but the explosive products are unlikely to be complexes containing planar C8F8 rings. The Ni-C8F8 cocondensate is a source of... 

Bis(ir-allyl)nickel is not formed in this reaction, but the compound be made by condensing nickel vapor with tetraallyltin (131) ... 

The reaction between metal atoms and ethers is varied. Deoxygenation occurs with the more electropositive transition metals, e.g., Ti, V, Cr, and probably Fe, but Klabunde has been able to use tetrahydrofuran as a medium to form active nickel slurries by condensing in nickel vapor (56, 60). 

Nickel catalysts exhibit similar activity but are usually less selective than palladium 435-438 In addition to chlorosilanes, however, alkylsilanes also add in the presence of nickel catalysts. Nickel vapor showed an exceptionally high activity and selectivity in hydrosilylation.435 The photocatalytic hydrosilylation of 1,3-dienes with a chromium(O) complex occurs at room temperature to afford regioisomeric 1,4-adducts in quantitative yield.439... 

About 1.5 g of nickel was vaporized at 1823 K over 30 min from a resistively heated alumina-coated molybdenum wire spiral inside an evacuated 200-mm diameter glass vessel which was partly immersed in liquid nitrogen. About 20 g of the allyl halide was simultaneously vaporized into the vessel and condensed with the nickel vapor on the cold walls. During this cocondensation, the pressure in the vessel was below 2 x 10 4Torr so that few gas-phase intermolecular collisions occurred. 

When the nickel had vaporized, the vessel was warmed to room temperature and the excess allyl halide was pumped off. The vessel was then warmed to 343 K and the volatile n-allyl nickel halide pumped out into an adjoining cooled trap. 2.7 g of the n-allyl nickel bromide was isolated, a 60% yield based on nickel vapor. In case of 7t-allyl nickel chloride, a 75% yield was obtained, but the product was contaminated by 1-2% of a complex mixture of C10-C15 hydrocarbons. 

In conjunction with their studies of evaporated barium gettei film, Oda and Tanaka (97) investigated the relationships between the structuie of a nickel film evaporated on a glass plate and the conditions of its preparation. These, nickel films had a remarkable tendency to expose the (110) plane with increasing thickness even if made in a high vacuum. When the support on which the nickel vapor was condensed rvas heated, various kinds of crystal planes were observed to develop parallel to the support as a function of the temperature, e.g., the (110) plane at 100°C., the (110) plane and (200) plane at 200°C., and the (200) plane at 300°C. A non-oriented surface was formed at 350°C. From this, it seems reasonable to conclude, that even ordinary metallic catalysts, including carrier-supported catalysts, may preferentially expose crystal planes of various kinds, depending on their mode of preparation. 

Soon after the initial discovery of this trimerization reaction, Wilke and coworkers found that the versatility and reactivity of such catalyses is enhanced when homogeneous zerovalent nickel catalyst are being used [6b, 13]. Catalysts of this type can either be generated from Ni complexes with ligands that can easily be substituted by BD (eg., Ni[CDT], Ni[COD]2) ( naked Nickel [6b]), or from Ni complexes that are reduced in the presence of BD (almost any reducing agent will serve) [6] a typical example is [Ni(acac)2]-Al(OEt)Et2. Condensed nickel vapor has also been shown to be active [13]. 

Conceptually, the simplest C—X oxidative addition reaction involves a naked metal center. Cocondensation of nickel vapor with pentafluorophenyl bromide yields [NiBr(CgF5)], which can be trapped by reaction with a tertiary phosphine ... 

Dimethylfulvene and 250 mg nickel vapor were co-deposited at — 196°C in a conventional metal atom reactor, and 130 mg of 6,6-dimethylMvene dimmer was isolated upon sublimation of the residue. 

Nickel. The corrosion of Ni by PH3 in the presence of air and humidity proceeds as described for Fe (see above) [82]. The cocondensation at 10 K of nickel vapor with PH3 in Ar yields Ni(PH3)n with n=1 to 4, where n increases with an increasing concentration of PH3 [85]. Ni(PH3)4 presumably forms when Ni vapor and pure PH3 are cocondensed at 60 K [78]. An investigation of this reaction at 77 K showed Hg to be the only volatile product being evolved both during the cocondensation and more rapidly on warming to room temperature. Cocondensation of nickel vapor with a mixture of equal volumes of PH3 and PF3 also frees some H2. Warming of the frozen sample to ambient temperature yields Ni(PF3)2(PH3)2, Ni(PF3)3PH3, and Ni(PF3)4 as volatile products [86]. 

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