Organosilver chemistry in chemistry is the study of organometallic compounds containing a carbon to silver chemical bond and the study of silver as catalyst in organic reactions. In the group 11 elements silver is the element below copper. The chemistries have much in common but organosilver catalysis is much less common (mostly academic study) than organocopper chemistry due both to the relatively high price of silver and to the poor thermal stability of organosilver compounds. The oxidation state for silver in organosilver compounds in exclusively +1 with the notable exception of Ag(III) in the trifluoromethyl silver anion Ag(CF3)4− because of the electron-withdrawing effect of the trifluoromethyl groups. Poor thermal stability is reflected in decomposition temperatures of AgMe (-50 °C) versus CuMe (-15 °C) and PhAg (74 °C) vs PhCu (100 °C).
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The first attempts in organosilver were recorded by Buckton in 1859 and by J. A. Wanklyn & L. Carius in 1861. The first synthesis of an organosilver compound (methyl silver) was described by Semerano and Riccoboni in 1941.
Compounds
Phenylsilver can be obtained by reaction of silver nitrate with an trialkylphenyllead compound:
AgNO3 + R3PhPb → PhAgAlternatively, diphenylzinc may be used:
Ph2Zn + AgNO3 → PhAg + PhZnNO3The silver mesitylene adduct is a tetramer. it can be formed from silver chloride and the Grignard reagent:
AgCl + MesMgBr → Ag4(Mes)4 + MgClBrSilver forms stable complexes with ylides such as triphenylphosphonium methylide:
AgCl + Ph3P=CH2 → AgCl(Ph3P=CH2)The C-Ag bond is stabilized by perfluoroalkyl ligands:
AgF + CF2=CF(CF3) → AgCF(CF3)2Alkenylsilver compounds are also more stable than their alkylsilver counterparts. Vinylsilver can be obtained by reaction of silver nitrate with tetravinyllead:
AgNO3 + (CH2=CH)4Pb → (CH2=CH)Ag + (CH2=CH)3PbNO3Silver-NHC complexes are easily prepared, and are commonly used to prepare other NHC complexes by displacing labile ligands. For example, the reaction of the bis(NHC)silver(I) complex with bis(acetonitrile)palladium dichloride or chlorido(dimethyl sulfide)gold(I):
Catalysis
In catalysis silver is active as silver oxide in the Wolff rearrangement. Silver nitrate is used to separate out alkenes as the η2-alkene complex. Silver is also present in other carbon-carbon bond skeletal rearrangements such as the quadricyclane to norbornadiene rearrangement, the cubane to cuneane rearrangement and the rearrangement of the cyclobutadiene dimer to cyclooctatetraene.