# What are hydrides?

Aug 24, 2017

Hydrides, or more likely what you mean is metal hydrides, are compounds containing a metal and an $\text{H} {:}^{-}$ ligand. An $\text{H} {:}^{-}$ is a hydride.

The hydrogen atom has a significantly higher electronegativity than many transition metals, so we can treat the interaction as a complete electron transfer (i.e. ~100% ionic character).

Some example metal hydrides are:

• $\text{NaH}$ (sodium hydride), used in organic chemistry often to remove an ${\text{H}}^{+}$ from acetylene for reaction with alkyl halides, a $\text{C"-"C}$ bond-making reaction.

• "HCo"("CO")_4 (tetracarbonylhydridocobalt(I)), a trigonal bipyramidal transition metal complex.

• ${\text{LiAlH}}_{4}$ (lithium aluminum hydride), a very strong reducing agent used in organic chemistry. It reacts sufficiently with carboxylic acids, amides, and esters, whereas ${\text{NaBH}}_{4}$ (sodium borohydride) would be insufficiently reactive.