⁷⁷Se NMR Chemical Shifts of 9-(Arylselanyl)triptycenes: New Standard for Planar Structures of ArSeR and Applications to Determine the Structures in Solutions

A set of new δ(Se) parameters is proposed as a standard for the planar (pl) orientational effect of p-YC6H4 (Ar) in ArSeR, employing 9-(arylselanyl)triptycenes (1: p-YC6H4SeTpc). The Se−CR bond in ArSeR is placed on the Ar plane in pl and it is perpendicular to the plane in pd. Large upfield shifts are observed for Y = NMe2, OMe, and Me (−22 to −6 ppm) and large downfield shifts for Y = COOEt, CN, and NO2 (19−37 ppm), relative to Y = H, with...