AB-INITIO THEORETICAL-STUDY OF THE MONOMER-DIMER EQUILIBRIUM IN LITHIUM AND SODIUM GEM-DIFLUORO ALLYL AND METHYL SYSTEMS

Non-empirical calculations on lithium and sodium gem-difluoroallyl and difluoromethyl systems show that the monomer-dimer equilibrium is shi fted in favour of the dimeric species. The two difluoromethyl systems show geometric and energetic features very close to those found in the larger systems. Difluoromethyl is then used as a model for difluoroal lyl to allow the investigation of the structural and energetic effects of the interaction of a discrete number of water molecules (used to m odel ether molecules) with the counterion in both monomers and dimers. Two dimerization processes were investigated, in which the two cation s present in the dimers are surrounded by a different number of solven t molecules. The dimerization energies obtained by taking into account the oxygen-cation interactions are significantly reduced, but the equ ilibrium is still estimated to lie in favour of the dimeric species.