Assertion:- Organo metallic compounds are those which have one or more metal -  carbon bonds
Reason:-  Metallic carbonyls are organometallic compounds having both $\sigma$ and $\pi$ – bonds.

Organometallic Compounds are chemical compounds which contain at least one bond  between a metallic element and a carbon atom belonging to an organic molecule.All  carbonyls are and bonded in nature because the metal - carbon bond in metal carbonyls  possesses both σ and π character. The M−C bond is formed by the donation of ion pair of  electrons on the carbonyl carbon into a vacant orbital of the metal.