Ab initio theoretical optical rotations of small molecules

Optical rotations of small chiral molecules have been calculated ab initio to evaluate the role of substituents and of conformations. The optical rota tions of oxaziridines provide a nice correlation between the sign of optica l rotation and absolute configuration. Such correlation is not obvious in t he case of diaziridines and tetrahydrofurans. The optical rotations obtaine d for different conformers of 3-butyn-2-ol suggested a possible predominant conformation in liquid solutions. The prediction of optical rotations, as a function of dihedral angle, for H2O2 and H2S2 reveal that the sign of opt ical rotation is negative for counter-clockwise dihedral angles (M-helicity ) and the magnitude is maximum at a dihedral angle of 90 degrees (in H2O2) or 110 degrees (in H2S2). (C) 1999 Elsevier Science B.V. All rights reserve d.