Question

What are hydrides?

Answer 1

Hydrides, or more likely what you mean is metal hydrides, are compounds containing a metal and an `"H":^(-)` ligand. An `"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:

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

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

• `"LiAlH"_4` (lithium aluminum hydride), a very strong reducing agent used in organic chemistry. It reacts sufficiently with carboxylic acids, amides, and esters, whereas `"NaBH"_4` (sodium borohydride) would be insufficiently reactive.