# Can the hydride ion act as a ligand?

Hydride ion, as I know is a pretty powerful base, much stronger than hydroxide ion and cannot exist in an aqueous phase.

Can it act as a ligand in coordination compounds? Hydride ion has its electronic configuration as $\mathrm{1s^2}$ in a symmetrical s orbital so the tendency to donate a lone pair into a metal atom would be less. But can its high nucleophilicity allow it to bind to the metal atom despite the symmetry of its orbital?

• Does the model of the bonding matter? In $\ce{MnF6^{2-}}$ the best model is probably ionic while in $\ce{PtI6^{2-}}$ covalent is probably nearer to the truth, and then you have $\ce{{Cu(NH3)_4}^{2+}}$ where some kind of dative bond is the most intuitive model. But I think we'd all be happy to call them metal complexes, which are examples of coordination compounds. – Ian Bush Apr 20 '17 at 8:07
• There’s also the nice case of pentacarbonyl iron which, when hydroxide ions are added, reacts to give $\ce{[Fe(CO)4(COOH)]-}$ which then rearranges and liberates $\ce{CO2}$ to give $\ce{[FeH(CO)4]-}$. This compound is Brønsted amphotheric: it can be protonated to give neutral $\ce{[FeH2(CO4)]}$ or deprotonated to give $\ce{[Fe(CO)4]^2-}$. I think it’s fascinating! – Jan Jun 18 '17 at 17:25