Organolead compounds are

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

s containing a chemical bond between

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...

and

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, ...

. Organolead chemistry is the corresponding science. The first organolead compound was hexaethyldilead (Pb₂(C₂H₅)₆), first synthesized in 1858.''Main Group Metals in Organic Synthesis'' Yamamoto, Hisashi / Oshima, Koichiro (eds.) 2004 Sharing the same group with carbon, lead is tetravalent. Going down the carbon group the C–''X'' (''X'' = C, Si, Ge, Sn, Pb) bond becomes weaker and the bond length larger. The C–Pb bond in tetramethyllead is 222 pm long with a

dissociation energy The bond-dissociation energy (BDE, ''D''0, or ''DH°'') is one measure of the strength of a chemical bond . It can be defined as the standard enthalpy change when is cleaved by homolysis to give fragments A and B, which are usually radical s ...

of 49 kcal/ mol (204 kJ/mol). For comparison the C–Sn bond in tetramethyltin is 214 pm long with dissociation energy 71 kcal/mol (297 kJ/mol). The dominance of Pb(IV) in organolead chemistry is remarkable because inorganic lead compounds tend to have Pb(II) centers. The reason is that with inorganic lead compounds elements such as

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements ...

and the halides have a much higher electronegativity than lead itself and the partial positive charge on lead then leads to a stronger contraction of the 6s orbital than the 6p orbital making the 6s orbital inert; this is called the inert pair effect. By far the organolead compound that has had the greatest impact is

tetraethyllead Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula Pb( C2H5)4. It is a fuel additive, first being mixed with gasoline beginning in the 1920s as a patented octane rating booster that ...

, formerly used as an

antiknock agent An antiknock agent is a gasoline additive used to reduce engine knocking and increase the fuel's octane rating by raising the temperature and pressure at which auto-ignition occurs. The mixture known as gasoline or petrol, when used in high com ...

gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic c ...

intended for internal combustion engines. The most important lead reagents for introducing lead are

lead tetraacetate Lead(IV) acetate or lead tetraacetate is an organometallic compound with chemical formula . It is a colorless solid that is soluble in nonpolar, organic solvents, indicating that it is not a salt. It is degraded by moisture and is typically st ...

and

lead(II) chloride Lead(II) chloride (PbCl2) is an inorganic compound which is a white solid under ambient conditions. It is poorly soluble in water. Lead(II) chloride is one of the most important lead-based reagents. It also occurs naturally in the form of the m ...

. The use of organoleads is limited partly due to their toxicity.

Synthesis

Organolead compounds can be derived from

Grignard reagent A Grignard reagent or Grignard compound is a chemical compound with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide . ...

s and

lead chloride Lead chloride may refer to: * Lead(II) chloride (plumbous chloride), mineral name: cotunnite. * Lead(IV) chloride (plumbic chloride) {{Short pages monitor