In this chapter, we revise some of the most relevant and widely used synthetic routes available for the preparation of metallic silver nanoparticles. Particular emphasis has been focused in the rationale involved in the formation of the nanostructures, from the early metallic silver atoms formation, passing by atoms nucleation and concluding in the growth of silver nanostructures. We hope the reader will find in this chapter a valuable tool to better understand the relevance of the experimental conditions in the resulting silver nanoparticle size, shape and overall properties.

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Aryl methyl sulfides and diaryl sulfides were prepared by photoinduced reactions of potassium thioacetate with aryl halides under entrainment conditions. Without isolation, the arene thiolates obtained by the aromatic substitution were quenched with methyl iodide to afford the aryl methyl sulfides in 26-59 % yields in a "one-pot" procedure together

The photoinduced reactions of o-iodoanilides (o-IC6H4N(Me)COR, 4a-d) with sulfur nucleophiles such as thiourea anion (1, -SCNH(NH2)), thioacetate anion (2, MeCOS-), and sulfide anion (3, S(2-)) follow different reaction channels, giving the sulfides by a radical nucleophilic substitution or the dehalogenated products by hydrogen atom transfer pathways. After an initial photoinduced electron transfer (PET) from 1 to iodide 4, the o-amide aryl radicals 12 are generated. These aryl radicals 12 afford alternative reaction pathways depending on the structure of the alpha-carbonyl moiety: (a) 12b (R = Me) adds to 1 to render the methylthio-substituted compounds by quenching the thiolate anion intermediate with MeI after irradiation; (b) 12c (R = -CH2Ph) follows a 1,5-hydrogen transfer to give a stabilized alpha-carbonyl radical (17); and (c) 12d (R = t-Bu) affords 1,6-hydrogen transfer, followed by a 1,4-aryl migration to render an amidyl radical (20), which is reduced to the N-benzyl-N,2-dimethylpropanamide (10). Together with this last rearranged product, the ipso substitution derivative was also observed. Similar results were obtained in the PET reactions of 4d (R = t-Bu) with anions 2 and 3 under entrainment conditions with the enolate anion from cyclohexenone (5) or the tert-butoxide anion (6). From this novel rearrangement, and only under reductive conditions by PET reaction with anion 5, iodide 4d (R = t-Bu) affords quantitatively the propanamide 10. The energetic of the intramolecular rearrangements followed by radicals 12b-d were rationalized by B3LYP/6-31+G* calculations.

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