# What is a "coordinate covalent bond"?

$N {H}_{3} \left(a q\right) + {H}_{2} O \left(l\right) r i g h t \le f t h a r p \infty n s N {H}_{4}^{+} + H {O}^{-}$
In the forward equilibrium, ammonia has bound a proton to form the ammonium ion. In $N {H}_{4}^{+}$ all the hydrogen atoms are equivalent, yet the 2 electrons that form one of the $N - H$ derive from the lone pair on the nitrogen. Coordination chemistry is replete with examples of $\text{coordinate covalent bonds}$, or $\text{donative}$ or $\text{dative}$ bonds, i.e. the hexaqua transition metal complexes, ${\left[M {\left(O {H}_{2}\right)}_{6}\right]}^{2 +}$, in which a lone pair on the oxygen donor forms a covalent bond with the metal centre.