THE BONDING STRENGTH OF AG+(C2H4) AND AG+(C2H4)2 COMPLEXES

The association reactions Ag+ (C2H4)n-1 + C2H4 = Ag+ (C2H4)n(n = 1 or 2) were studied using high pressure mass spectrometry (HPMS). The enthalpy and entropy changes determined are - DELTA-H0 = 32.4 kcal/mol, and DELTA-S0 = 30.2 cal/mol K for the n = 2 reaction. In the case of the n = 1 reaction, the Gibbs free energy change at 750 K is measured to be - DELTA-G0 = 17.1 kcal/mol. Using the free energy change and the calculated entropy change DELTA-S0 = 22.1 cal/mol K. we derive an enthalpy change DELTA-H0 = 33.7 kcal/mol for the n = 1 reaction. The bonding in both Ag+ (C2H4) and Ag+ (C2H4)2 complexes is extremely strong, and much higher than expected based on the simple electrostatic-interaction considerations. The strong bonding suggests that covalent interaction or a two-way donor-acceptor interaction dominates in the complexes.