Fine structures of 8-G-1-(arylethynylselanyl)naphthalenes (G = H, Cl, Br): Factors to control the linear alignment of five G⋯Se–C C–CAr atoms in crystals and the behavior in solution

8-G-1-(p-YC6H4CCSe)C10H6 [2 (G = Cl) and 3 (G = Br): Y = H (a), OMe (b), Me (c), F (d), Cl (e), CN (f) and NO2 (g)] have been prepared and the NMR spectra measured, in addition to 1 (G = H). Structures have been determined by X-ray crystallographic analysis for 2b, 2e and 2g, which are all type B (B), where the Se–Csp bond is placed in the naphthyl plane in B. The type is classified as A if the Se–Csp bond is perpendicular to the naphthyl plane....