BOND STRENGTHS OF THE GAS-PHASE CLUSTER IONS X-(CS2)N (X = F, CL, BR AND I)

Thermodynamic quantities, DLETAH(n-1,n)0 and DELTAS(n-1,n)0, for the c lustering reactions, X-(CS2)n-1+CS2=X-(CS2)n, X=F, Cl, Br and I, were measured with a pulsed electron-beam high-pressure mass spectrometer. A large binding energy, 35.0 kcal/mol, for F-...CS2 has been obtained, whereas those for other X-...CS2 species are approximately 7-9 kcal/m ol. Except the C2v F- (CS2)1 geometry, linear X- (CS2)1 geometries are found, arising from the S(delta+)-C(delta-)-S(delta+) electronic natu re and an effective polarization of ''soft'' atoms.