Structures and dynamic stereochemistry of 9-arylselanyltriptycenes: X-ray crystallographic, spectroscopic and theoretical investigations

9-(Arylselanyl)triptycenes (1: p-YC6H4SeTpc) should supply the planar structure (pl) around the p-YC6H4Se (ArSe) group in the ground state, irrespective of the p-Y substituents. 1 with Y = H (a), NMe2 (b), OMe (c), Cl (d), CN (e) and NO2 (f) are prepared. Structures of 1a–d and 1f are determined by X-ray analysis and dynamic 1H NMR spectroscopy is applied to 1a, 1c, 1e and 1f. For convenience of discussion, the structure of 1 is defined as...