coordinatecovalent

A coordinate covalent bond, also known as a dative bond, is a type of covalent bond in which one atom contributes both of the electrons to the shared pair. In a typical covalent bond, each atom involved contributes one electron to form the shared pair. However, in a coordinate covalent bond, one atom donates a lone pair of electrons to form a bond with another atom that has an empty orbital.

This type of bond is commonly observed in Lewis acid-base reactions. A Lewis base is a species that can donate an electron pair, while a Lewis acid is a species that can accept an electron pair. When a Lewis base reacts with a Lewis acid, a coordinate covalent bond is formed. For instance, the reaction between ammonia (NH3) and boron trifluoride (BF3) results in the formation of an adduct, H3N→BF3, where the nitrogen atom of ammonia donates its lone pair of electrons to the boron atom of boron trifluoride.

Coordinate covalent bonds are fundamentally similar to regular covalent bonds in that they involve the sharing of electrons between atoms. However, the origin of the shared electrons distinguishes them. Once formed, a coordinate covalent bond is indistinguishable from a regular covalent bond in terms of its properties, such as bond length and strength. The arrow notation (→) is sometimes used to represent coordinate covalent bonds, indicating the direction of electron donation from the donor atom to the acceptor atom. Examples include the formation of complex ions, such as [Cu(NH3)4]2+, where the ammonia molecules act as Lewis bases and donate electron pairs to the central copper ion.