The Grignar reaction, named for the French chemist François Auguste Victor Grignard, is an organometallic chemical reaction in which alkyl- or aryl-magnesium halides (Grignard reagents), which act as nucleophiles, attack electrophilic carbon atoms that are present within polar bonds (e.g., a carbonyl group, see below) to yield a carbon-carbon bond (compare to Wittig reaction), thus altering hybridization about the reaction center. The Grignard reaction is an important tool in the formation of carbon-carbon bonds and for the formation of carbon-phosphorus, carbon-tin, carbon-silicon, carbon-boron and other carbon-heteroatom bonds.