Fine structures of 1-(arylethynylselanyl)naphthalenes: Characteristic features brought by the ethynylselanyl group

Fine structures of 1-(p-YC6H4CCSe)C10H7 (1) have been determined by X-ray analysis. The Y dependence of the fine structures are just the opposite to the case of 1-(p-YC6H4Se)C10H7 (3). The factor that controls the fine structures of 1 is called the “ethynyl effect”. Structures in solution are also clarified.