COMPARATIVE-STUDY OF THE GAS-PHASE BOND STRENGTHS OF CO2 AND N2O WITH THE HALIDE-IONS

Thermodynamic data, DELTAH(n-1,n)degrees and DELTAS(n-1,n)degrees for clustering reactions of halide ions X-(X = F, Cl, Br, and I) with N2O were measured with a pulsed electron beam high-pressure mass spectrometer. In contrast to the fact that CO2 forms a covalent bond with the fluoride ion to yield the fluoroformate ion, FCO2-, the interaction between F- and N2O is mainly electrostatic. It was found that the duster ions F-(N2O)n complete the first shell at n = 6, thus forming an octahedral structure. The difference between F-CO2- and F-...N2O is discussed in terms of Coulombic, exchange, and charge-transfer interactions. The X-(N2O)2 clusters (X = Cl, Br and I) are found to be of C2h symmetry, while F-(N2O)2 is of a twisted form and is slightly asymmetric due to a slight participation of covalency (charge transfer) in the core ion F-...N2O.