Halides group

Metal alkyls can be prepared in a simple manner from the main group halides (X = Cl, Br, I) and the appropriate alkyl Grignard reagent (RMgl) or the alkyllithium salt (RLi), as shown for the cadmium alkyls (Equation (2)).13 The elimination of impurities from the precursor source is of great importance, as any remaining impurities are invariably carried over into the growing semiconductor layers. Incorporation of impurities, even at levels as low as 1015 free carriers per cubic centimeter (one part in ca. 107), can drastically affect the electronic properties of the... 

When acido groups, halides, thiocyanate, azide, acetate, and nitrate are present in the coordination sphere of cobalt(III), they appear to be oxidized in preference to coordinated ammonia. Many of the radicals thus produced are capable of oxidizing ammonia released from the complex or of interfering in other ways with the reduction process, and these systems have proved very difficult to understand even in general terms. Quantum yield and other data for a number of acidopentammine and certain other complexes are given in Table IV the data on the aquation reactions of some of the complexes are considered in Section I1I-D. 

The wealth of information that has accumulated regarding the UPS of the main group halides is not considered here, since it falls outside the purview of this Chapter. Of the transition metal halides the largest amount of work has been done with the halides of the Group 2B metals and their monomethyl derivatives (28, 33, 63, 108, 112, 129, 233). In these studies it was found that the zinc and cadmium dihalides require significantly higher vaporization temperatures than the mercury compounds hence specialized high-temperature techniques were necessary. A summary of these and related methods may be found in a recent review article by Schweitzer (255). 

Metal carbonyl anions react with main group halides and oxides to yield a number of main-group transition-metal carbonyl complexes in good yields. These complexes serve as starting materials for a number of higher nuclearity cluster complexes. 

Carbonyl Compounds I. Aldehydes and Ketones. Addition Reactions of the Carbonyl Group halides). The naming of these compounds is described in Sections 7-4 to 7-7. 

The review will be restricted to systems carrying strong Ji-acceptors such as carbonyl, cyano, or sulfonyl groups halide, phenyl, vinyl, or related groups will not be regarded as activating substituents. With respect to the donor function oxy-, amino-, and thio-cyclopropanes will be considered. The trimethylsilylmethyl unit is the weakest donor dealt with, whereas processes as illustrated in Eq. 3 are beyond the scope of this article. 

Identify the leaving group (halides, sulfonate and related esters, or hydroxy groups under acidic conditions). 

Jutzi and Galow (21) found the aluminacarborane 2,3-(CH3)2-l-C2H5-1,2,3-A1C2B9H9 to be a convenient carbollyl transfer agent when reacted with a number of main group halides as outlined in Scheme 1. The structures of the products were inferred from NMR data. These investigators... 

The distinction between between mono- and dinuclear metal complexes is only a formal one in terms of bonding (consider one substituent at silicon the second metal atom instead of an organic group, halide, or hydride substituent). The structural and spectroscopic features related to the three-center bond should therefore be more or less the same as previously discussed. 

A strong base abstracts a proton on a carbon next to the one bearing a halogen. The leaving group (halide) leaves simultaneously. 

These carbonyl anions are strong nucleophiles (see Nucleophile) and can be used to form a diverse range of new compounds. Protonation gives the /t-hydride (see Bridging Ligand) [(/u.-H) Mo(CO)5 ]. Reactions with other metal carbonyls lead to CO substitution and the formation of metal metal-bonded heteronuclear anions, for example, [Mo(CO)s Fe(CO)4] and [Mo(CO)5-Co(CO)4] . Reaction with main group halides is shown in Scheme 1. The dianion reacts similarly. 

In comparison with classic Lewis acids derived from main group halides (e.g., B, Al, Sn), f-elements, and early transition metal halides, late transition metal Lewis acids often are more inert to ubiquitous impurities such as water, offer higher stability, tunable properties by ligand modification, and a well-defined structure and coordination chemistry, thus allowing detailed studies of reaction mechanisms, and a rational basis for catalyst optimization. Among this new class of late transition metal Lewis acids, ruthenium complexes - the subject of this chapter - display remarkable properties... 

A prominent application of TiCp2S5 involves its reactions with main group halides according to the following stoichiometry... 

Very soon after the reactivity of Cd(CF3)2DME toward main group halides (31) and group 10 dihalides (32) had been established, we set out to determine if the cadmium reagent was effective in trifluoromethylating representative organometallic compounds. One of the first substrates chosen was CpCo(CO)I2, which was selected because the mono-trifluoro-methyl derivative was known, but the disubstituted compound was not. The results of this reaction are (60)... 

The choice of oxidant remains. Our reasoning has been that we wish to avoid inner sphere electron transfer reagents since the group (halide, oxalate, etc.) which bridges during electron transfer can also stabilize the oxidized unknown against quantitative gas evolution. Examples include conversion of Fe(C0)j to Fe(C0) I2. 

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