COORDINATION COMPLEXES OF BERYLLIUM(II) WITH VARIOUS ANTIHISTAMINIC SUBSTANCES - THEIR STABILITIES AND THERMODYNAMIC VALUES

Stepwise formation constants for the Be(II) complexes with adrenaline, antistine, ephedrine, benadryl and pyribenzamine are reported at five different temperature. The Gibbs free energy, entropy and enthalpy values for these reactions are discussed in terms of coordination number of the metal ion, complexing ability and steric hinderance of ligands, and possible tetrahedral structures for these complexes. Results show that all the antihistamines form stable compounds with Be(II), demonstrating thereby the validity of nitrogen-beryllium coordination bond. It is also observed that Be(II)-antihistamine complex formation results in greater free energy change than is associated with the formation of Be(II)-histamine complex. The data from this work substantiates the theory of competitive binding between histamine and antihistamine for the electrophilic site of a metal ion. © 1969.