Organometallic have classically been compounds having bonds between one or more metal atoms and one or more carbon atoms of an organyl group. Organometallic compounds are distinguished by the prefix "organo-". The organopalladium compounds are an example of this.
In addition to the traditional metals and semimetals, elements such as boron, silicon, arsenic and selenium are considered to form organometallic compounds, e.g. organomegnesium compounds MeMgI iodo(methyl)magnesium, Et2Mg diethylmagnesium; an organo-lithium compound BuLi butyllithium; an organozinc compound ClZnCH2C(=0)OEt chloro(ethoxycarbonylmethyl)zinc; an organocuprate Li[CuMe2] lithium dimethylcuprate; an organoborane Et3B triethylborane.
The status of compounds in which the canonical anion has a delocalized structure in which the negative charge is shared with an atom more electronegative than carbon, as in enolates, may vary with the nature of anionic moiety, the metal ion, and possibly the medium; in the basense of direct structural evidence for a carbon-metal bond, such compounds are not considered to be organometallic.
See chelation, acetylides, ferrocenophanes , Grignard reagents, metallocenes.
