ChemInform Abstract: Structure and Energetics of Ammonia Clusters (NH₃)_n (n = 3—20) Investigated Using a Rigid—Polarizable Model Derived from ab initio Calculations.

Abstract

Theory C 1000 Structure and Energetics of Ammonia Clusters (NH3)n (n = 3-20) Investigated Using a Rigid-Polarizable Model Derived from ab initio Calculations. -(JANEIRO-BARRAL, P. E.; MELLA*, M.; CUROTTO, E.; J. Phys. Chem. A 112 (2008) 13, 2888-2898; Sch. Chem., Cardiff Univ., Cardiff CF10 3AT, UK; Eng.) -Schramke 26-002

Experimental Binding Energies for the Metal Complexes [Mg(NH3)n]2+, [Ca(NH3)n]2+, and [Sr(NH3)n]2+ for n = 4–20 Determined from Kinetic Energy Release Measurements

“…Therefore, for the examples being studied here, E b might be expected to converge toward a value of between 12 and 16 kJ mol –1 as n in [M(NH 3 ) n ] 2+ increases. Calculations on ammonia clusters show that, as a function of size, there is considerable variation in values calculated for the binding or evaporation energies of single molecules. , Because all of the calculations concentrate on the most stable structures, there are not data for the breaking of just a single hydrogen bond; the above range comes from dividing calculated binding energies by the number of bonds being broken. This distinction between calculated results for the most stable hydrogen-bonded structures and what is being derived from these experiments emphasizes the fact that the latter records data from the least stable of the structures available to a complex.…”