Hybride interactions (stacking plus H-bonds) between molecules bearing benzyl groups

In this paper, the crystal structure of the 3-O-benzyl-1,2-O-isopropylidene-5,6-dideoxy-alpha-D-ribo-hex-5-yno-1,4-furanose is presented. This is the first noticed example in which weak hydrogen bonds prevail over the pi-pi stacking interactions of the aromatic rings. As a result, the hybride interactions an formed by the pi-sigma stacking and the C-H...pi hydrogen bonds. The analysis of molecular packing of crystal structures collected in the Cambridge Crystallographic Database shows that hybride interactions occur in infinite columns of benzyl groups or in binary complexes of organic molecules. Semiempirical calculations suggest that the pi-sigma stacking interactions and the C-H...pi hydrogen bonds have a synergic character. Probably they are the key factor which stimulates the growth of crystals. (C) 1998 Elsevier Science B.V.