Crystal engineering via C-H...F and C-H...pi interactions in two substituted indoles.

The crystal structures of 1-(4-fluorophenyl)-2-phenyl-4,5,6,7-tetrahydro-1H-indole, C20H18FN, and 1-(4-fluorophenyl)-6,6-dimethyl-2-phenyl-4,5,6,7-tetrahydro-1H-indole, C22H22FN, have been determined in order to study the role of 'organic fluorine' in crystal engineering. These molecules pack in the crystal structure via different types of molecular motifs utilizing weak C-H...F and C-H...pi interactions.