Chemistry · Chapter 17
Study notes aligned to the official NEB syllabus.
Organometallic compounds are compounds that contain at least one direct carbon-metal ($\ce{C-M}$) bond, in which the carbon of an organic group is bonded to a metal atom. Examples include Grignard reagents $\ce{R-Mg-X}$, dimethylzinc $\ce{(CH3)2Zn}$, tetraethyllead $\ce{(C2H5)4Pb}$ and ferrocene.
A compound is not organometallic if the metal is joined to carbon through another atom (for example, sodium ethoxide $\ce{C2H5ONa}$ has a $\ce{C-O-Na}$ link, and sodium acetate $\ce{CH3COONa}$ has a $\ce{C-O-Na}$ link, so neither is organometallic).
Nature of the $\ce{C-M}$ bond. Because carbon is more electronegative than most metals, the bond is polarised $\ce{C^{\delta-}-M^{\delta+}}$, so the carbon behaves as a carbanion-like nucleophile. The more electropositive the metal, the more ionic and reactive the bond (sodium alkyls are essentially ionic; magnesium and zinc alkyls are polar covalent; mercury and lead alkyls are largely covalent and more stable).
Organometallic compounds are compounds that contain at least one direct carbon-metal () bond, in which the carbon of an organic group is bonded to a metal atom. Examples include Grignard reagents , dimethylzinc , tetraethyllead and ferrocene.
A compound is not organometallic if the metal is joined to carbon through another atom (for example, sodium ethoxide has a link, and sodium acetate has a link, so neither is organometallic).
Nature of the bond. Because carbon is more electronegative than most metals, the bond is polarised , so the carbon behaves as a carbanion-like nucleophile. The more electropositive the metal, the more ionic and reactive the bond (sodium alkyls are essentially ionic; magnesium and zinc alkyls are polar covalent; mercury and lead alkyls are largely covalent and more stable).