Weak hydrogen bonding .3. A benzyl group accepting equally strong hydrogen bonds from O-H and C-H donors: 5-ethynyl-5H-dibenzo[a,d]cyclohepten-5-ol

In the crystal structure of the title compound, one of the benzyl groups accepts hydrogen bonds from a hydroxy and an ethynyl group, one to each face of the ring. For both hydrogen bonds, energies around -1.3 kcal mol(-1) have been calculated. The bond donated by the hydroxy group has unusual geometry and is directed almost linearly at a C atom with H...C = 2.36 Angstrom.