(N/A) Organometallic compounds: Compounds in which a carbon atom is bonded to a metal atom are called 'organometallic' compounds. Most organic chlorides,bromides,and iodides react with certain active metals to form these compounds.
$(b)$ Grignard reagent: Organic halide compounds react with magnesium metal in dry ether to form alkyl magnesium halides $(RMgX)$,which are known as Grignard reagents.
$R - X + Mg \xrightarrow{\text{dry ether}} R^{-\delta} - Mg^{+\delta} - X^{-\delta}$
$CH_3CH_2Br + Mg \xrightarrow{\text{dry ether}} CH_3CH_2MgBr$
Victor Grignard discovered $RMgX$ in $1900$. It belongs to the class of organometallic compounds.
$(c)$ Reactivity and reactions: In Grignard reagents,the carbon-magnesium bond is not purely covalent but polar $(R^{-\delta} - Mg^{+\delta} - X^{-\delta})$ because magnesium is an electropositive metal. The carbon atom pulls electrons from magnesium,making the carbon partially negative. This makes the carbon highly reactive.
Grignard reagents react with any source of protons to form hydrocarbons:
$RMgX + H^+ \xrightarrow{OH^-} RH + Mg(OH)X$
They react with water,alcohols $(R'OH)$,and amines $(R'NH_2, R'_2NH)$,which act as proton donors.
$RMgX + H_2O \rightarrow RH + Mg(OH)X$
Example: $CH_3Br + Mg$ $\rightarrow CH_3MgBr$ $\xrightarrow{H_2O} CH_4 + Mg(OH)Br$