Metal atom chemistry

Lagowski et al. (79) synthesized a very large series of bis(arene) Cr(0) compounds, thereby providing a good example of the use of metal-atom chemistry in synthesizing homologous series of compounds... 

The relationship between "conventional" and "high energy" processes in organometallic chemistry is defined. The growth of metal atom chemistry is surveyed as a model for the impact of a "high energy process" on the field of organometallic chemistry. 

Spectroscopists also saw the potential of reacting ligands with transition metal under matrix isolation conditions. Photolysis of metal carbonyls in organic (383 or inert gas matrices (39) had already been done, but atoms offered the possibility of step-wise addition of ligands. DeKock (40), Turner (41 ), and Moskovits and Ozin (42) made early contributions, but the work of the last two became dominant (32). By 1972, there were the two distinct branches in transition metal atom chemistry, the preparative and matrix spectroscopic studies. 

However, the cost of setting up for metal atom chemistry like the Oxford group has become quite high—at least 40,000 for a do-it-yourself apparatus and at least 100,000 for a commercial apparatus. This cost factor is quite inhibiting and there are few chemists who can afford to "have a go" at that price without a very clear idea of the value of what they can achieve. 

Let us now turn our attention to the newly emerging field of excited state metal atom chemistry. The discovery of the excited state dimerization reaction (34) ... 

On the other hand to perform excited state metal atom chemistry in the M/CH3Br system is not quite so straightforward (58) ... 

At present two main types of apparatus are in use for preparative-scale, metal atom chemistry. 

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). 

Figure 3.1 Macroscale stationary cocondensation apparatus for investigations of metal atom chemistry. (From Ref. 514, reproduced with permission.)...

Only scattered reports of studies of gas-phase reactions of dimers, such as that shown in equation (3), have appeared. There have been several reports in metal-atom chemistry of formation of dimeric complexes, but the mechanism of dimer formation is not known. 

Cyclooctatetraene is also of some interest in metal atom chemistry. Codeposited with Ti, Fe or Co, are formed uncharacterized polymers ". With Cr a Cr Cr bonded dimer, Cr2(C8Hg)3, is formed (see below) ". With Ti, a novel triple decker sandwich is obtained. ... 

Micro- and macroscale metal atom chemistry methods are described in Chapters 3 and 4 of Volume Ml. 

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