Prismanes constitute a fascinating family of (CH) n polyhedra, [1] several members of which, namely, prismane, [2] cubane, [3] and pentaprismane, [4, have been successfully synthesized. Recently, attention has focused on the challenging objective of synthesizing the higher prismanes, in particular, hexaprismanes 1. Despite many efforts, they have so far eluded synthesis, mainly because of the lack of proper synthetic routes and the expected higher strain energies than the lower prismanes. In our approach to construct the hexaprismane skeleton by photolysis of multibridged [3 n ]cyclophanes (n 3 ± 6) we first optimized the reaction conditions using the lowest homologue 3 3 cyclophane (2), diffractometer, Mo Ka radiation (l 0.71073 ), and a graphite monochromator. A total of 14 022 reflections were measured using a w/2V scan mode (3.38 2V 54.08). Crystal system: tetragonal, space group P4 2 /n, Z 8, a 24.846(3), b 24.846(3), c 7.8219(13) ; V 4828.6(12) 3 ; 1 calcd 1.262 g cm À3 ; m 0.084 mm À1 . The structure was solved directly with SHELXS 97 with 7011 independent reflections, the structure was refined according to full-matrix least-squares procedures (SHELXL 97); wR 2 0.1919 for 7011 reflections, R 1 0.0986 for 2706 observed reflections [I 0 b 2.0s(I 0 )] and 311 refined parameters. The positions of the hydrogen atoms were calculated according to geometric considerations and refined isotropically.
X-ray crystal structure analysis of 4 a: A yellow crystal 0.57 Â 0.48 Â 0.34 mm 3 in size was measured at room temperature with a STADI4 diffractometer, Mo Ka radiation (l 0.71073 ), and a graphite monochromator. A total of 13 516 reflections were measured using a w/2V scan mode (3.38 2V 54.98). Crystal system: triclinic, space group P1 Å , Z 2, a 9.6489(3), b 9.8280(5), c 13.2209(6) , a 82.092( ), b 69.261(5), g 84.237(4)8; V 1159.53(10) 3 ; 1 calcd 1.313 g cm À3 ; m 0.088 mm À1 . The structure was solved directly with SHELXS 97 using 6758 independent reflections, the structure was refined according to full-matrix least-squares procedures (SHELXL 97); wR 2 0.1340 for 6758 reflections, R 1 0.0477 for 5035 observed reflections [I 0 b 2.0s(I 0 )] and 405 refined parameters. The positions of the hydrogen atoms were calculated geometrically and refined isotropically.