koordinatiotosidokset

Koordinatiotosidokset, also known as coordinate covalent bonds or dative bonds, are a type of covalent bond where both of the shared electrons come from a single atom. In a typical covalent bond, each atom contributes one electron to the shared pair. However, in a coordinate covalent bond, one atom donates both electrons to form the bond. This donation occurs when an atom has a lone pair of electrons and another atom has an empty orbital that can accept these electrons.

This type of bond is commonly observed in the formation of complex ions and in certain molecular compounds. For instance, in the ammonium ion (NH4+), the nitrogen atom in ammonia (NH3) has a lone pair of electrons. When ammonia reacts with a hydrogen ion (H+), which has an empty 1s orbital, the nitrogen atom donates its lone pair to form a coordinate covalent bond with the hydrogen ion. This results in the positively charged ammonium ion, where all four N-H bonds are equivalent once formed.

Another example is seen in the formation of the adduct between boron trifluoride (BF3) and ammonia (NH3). Boron trifluoride is electron-deficient due to boron having an incomplete octet. Ammonia, with its lone pair on nitrogen, can donate these electrons to boron, forming a coordinate covalent bond and satisfying the octets of both atoms. The strength of a coordinate covalent bond is generally similar to that of a regular covalent bond once it has been formed.