Carbonyl halides atomic charges

Alkyl halides and sulfonates are the most frequently used alkylating acceptor synthons. The carbonyl group is used as the classical a -synthon. O-Silylated hemithioacetals (T.H. Chan, 1976) and fomic acid orthoesters are examples for less common a -synthons. In most synthetic reactions carbon atoms with a partial positive charge (= positively polarized carbon) are involved. More reactive, "free carbocations as occurring in Friedel-Crafts type alkylations and acylations are of comparably limited synthetic value, because they tend to react non-selectively. 

So the only remaining question is when thioamides combine with a-haloketones, which atom (N or S) attacks the ketone, and which atom (N or S) attacks the alkyl halide Carbonyl groups are hard electrophiles—their reactions are mainly under charge control and so they react best with basic nucleophiles (Chapter 12). Alkyl halides are soft electrophiles—their reactions are mainly under frontier orbital control and they react best with large uncharged nucleophiles from the lower rows of the periodic table. The ketone reacts with nitrogen and the alkyl halide with sulfur. 

Diorgano ditellurium compounds react with transition metal salts and carbonyl complexes to form coordination compounds (Table 5, p. 283). Complexes with the following transition metals have been reported Ti, Cr, Mo, W, Mn, Re, Fe, Ir, Ni, Pd, Pt, Cu, Ag, Cd, Hg, Yb, and U. In many of these complexes, the organyltelluro group bridges the metal atoms in binuclear complexes. The Te —Te bond seems to remain intact upon complexation to mercury halides, rhenium carbonyls, and uranium pentachloride. For details on tellurolatO bridged complexes see p. 212. Complexes with SnCl are also known. Diphenyl ditellurium and bis[4-ethoxyphenyl] ditellurium formed charge-transfer complexes when equimolar amounts of the ditellurium compound and tetracyano-p-quinodime-thane were refluxed in acetonitrile. ... 

Carbonyl compounds are capable of undergoing another completely different sort of reaction, in which the carbonyl oxygen is replaced, not by a heteroatom as we saw above, but by an sp carbon atom. When triphenylphosphine is treated with a secondary aliphatic halide, a normal substitution reaction occurs, resulting in the replacement of the halide by the phosphorus compound. This phosphonium salt adduct may then be treated with a very strong base, such as phenyllithium, to produce an ylid. An ylid is a compound in which there is a positive charge adjacent to a negative charge. Write down this reaction sequence. 

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