DICOBALT HEXACARBONYL DERIVATIVES OF CHIRAL ACETYLENES

(mu(2)-RC(2)R')Co-2(CO)(6) complexes are prepared where R not equal R' and one of these substituents is a chiral organic group. The structur es of the 11 complexes (10 new) range from the simplest possible chira l acetylenic hydrocarbon derivative (S-3-methyl-1-pentyne 1a) to ethyn ylsteroid (1f, 1g, 1h) and ethynylcodeine (1i, 1j, 1k) derivatives. Th e CD spectra are reported and the results are analysed in terms of a q uadrant rule. The CD spectra show that in all complexes the Co-2(CO)(6 ) fragment of the molecule gets chirally perturbed. The reasons for th e chiral perturbation include apolar repulsing (dominant for the hydro carbon acetylenes) and polar attractive (''autosolvation''; dominant f or acetylenes with polar hetero-atom containing substituents) forces.