what are electron rich hydrides?
Dihydrogen under certain reaction conditions combines with almost all elements except noble gases to form compounds called hydrides. Electron –rich hydrides, as the name suggest, are compounds of hydrogen with other elements that have excess electrons present as lone-pairs. For example ammonia –NH3 is a hydride of nitrogen that has one lone pair, water (H2O) is a hydride of oxygen that has two lone pairs etc. As these are electron rich species, they can donate electrons that is they are lewis bases.