THE STRUCTURES AND VIBRATIONAL FREQUENCIES OF A SERIES OF ALIPHATIC ETHERS OBTAINED USING THE SPECTROSCOPIC POTENTIAL SPASIBA

The SPASIBA potential energy function has been extended to include lin ear ethers, in order to investigate biomolecules related to saccharide s. The parameters of the potential energy function were derived from m inimization of the average error between the observed structures, conf ormational energy differences, vibrational frequencies and the predict ed quantities for a series of aliphatic ethers, including some deutera ted analogues. For several molecules the dipole moment was also calcul ated and compared with experimental or ab initio values. The molecules under investigation are dimethyl ether, trans and gauche forms of met hyl ethyl ether, trans-trans and trans-gauche forms of diethyl ether, methyl isopropyl ether and ethyl isopropyl ether. A set of 32 independ ent force constants was found to be sufficient to correctly describe t heir structures, potential energy surfaces and vibrational frequencies . The average deviation between the predicted and observed frequencies is about 11 cm(-1).