hard acid

hard acid

[′härd ′as·əd]
(chemistry)
A Lewis acid of low polarizability, small size, and high positive oxidation state; it does not have easily excitable outer electrons; some examples are H+, Li+, and Al+.
References in periodicals archive ?
In this communication the HSAB concept is employed to link the hard acid metal Pr to the soft acid metal Cu by using isonicotinic acid (INA) as a connecting ligand.
INA has two coordination sites; one is N which is suitable to coordinate to a soft acid metal (Cu) and the other is O which is suitable to coordinate with hard acid metal (Pr).