Tetraalkyllead complex

These elements (E) have four valence electrons and are tetravalent as carbon below which they are located. The compounds ER4 thus follow the octet rule which confers them a great stability. The tetraalkyl-element complexes are almost apolar and particularly robust and inert. However, the energy of the E-C bond decreases upon going down in the column of the periodic table. Thus, the tetraalkyllead complexes are less robust towards thermolysis than the lighter analogs. They decompose between 100 and 200°C, which was eventually applied to provide their antiknock properties. The chemistry of these elements is largely dominated by the oxidation state and coordination number 4, but the oxidation state and coordination number 2 is also known for all, and its stability increases upon going down in the column of the periodic table. 

Determination of organolead metabolites of tetraalkyllead in urine can be carried out after solid-phase enrichment and end analysis using reversed-phase HPLC with chemical reaction detector and by LC-MS (thermospray127). The chemical derivation consists of conversion to the dialky Head form, as shown in reaction 1, followed by complex formation with 4-(2-pyridylazo)resorcinol (11) and spectrophotometic measurement at 515 nm128. 

The first, unsuccessful, attempts to prepare alkylsilver compounds were made as early as 1859 by Buckton5a and 1861 by Wanklyn and Carius5b. The reaction of silver chloride with diethylzinc yielded only metallic silver, and a mixture of ethylene, ethane and butane. Due to their low thermal stability alkylsilver compounds were entirely unknown until 1941, when Semerano and Riccoboni6 reported the formation of some alkylsilver complexes by the reaction of silver nitrate with tetraalkyllead in alcoholic solution at low temperatures (equation 1). The yellow to brown precipitates of the formula RAg (R = methyl, ethyl, propyl) were stable at —80 °C for several hours, but upon warming to room temperature rapid decomposition took place with formation of metallic silver and... 

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