Crystal XRD analysis. Crystals for compounds (3) and (4) were obtained by crystallization from chloroform/methanol at room temperature, obtaining transparent, needleshaped crystals. In both cases π … π stacking between pyrene rings of neighboring molecules was not observed. The structure of p-BrPh-oC-PhEPy (3) (Figure ) is a V-shaped structure with the o-carborane cage at the apex and the bromo-phenyl group taking up one leg. The pyrene moiety, including the phenyl group and the acetylenic goup make up the other leg. As can be seen in the packing diagram (Figure ), two molecules of (3) are seen head-to-toe, with close contacts of 3.552(3) and 3.900(3) Å between the carborane moiety and the pyrene carbon atoms of an adjacent molecule (generated by symmetry) (see Figure , and the distances in Table ) in the SI. The acetylenic distance between C15 and C16 is 1.202(3) Å (a normal CC distance) and the distance between the o-carbon atoms in the carborane is 1.732(3) Å, which is a very long single bond C-C distance (perhaps because of the substituents on these two carbon atoms). The phenyl rings of the p-BrPh-oC-PhEPy (3) units, however, exhibit an almost perpendicular orientation with respect to the pyrene planes: 86.11 (5)° between the phenyl and the pyrene, and 86.02 (5) o between the pyrene and the substituted phenyl ring.