Structures of a spiro[3.3]heptane and a related dispiro[3.1.3.1]decane derivtive

2,2,6,6-Tetrakis(mesyloxymethyl)spiro[3.3]heptane (1), C15H28O12S4, Mr = 528.64, triclinic, P1, a = 10.319 (1), b = 14.233 (2), c = 8.5187 (9) A, alpha = 97.87 (1), beta = 104.08 (1), gamma = 98.86 (1) degrees, V = 1179.0 (6) A3, Z = 2, Dm = 1.46 (1), Dx = 1.489 Mg m-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.44 mm-1, F(000) = 556, T = 298 (1) K, R = 0.036 for 2411 reflections. Diethyl 8,8-bis(mesyloxymethyl)dispiro[3.1.3.1]decane-2,2-dicarboxyl ate (2) C20H32O10S2, Mr = 496.60, triclinic, P1, a = 12.168 (1), b = 16.789 (2), c = 5.9411 (6) A, alpha = 90.416 (8), beta = 94.294 (9), gamma = 87.590 (9) degrees, V = 1209.2 (4) A3, Z = 2, Dm = 1.35 (1), Dx = 1.364 Mg m-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.26 mm-1, F(000) = 528, T = 292 (1) K, R = 0.037 for 2530 reflections. The cyclobutane rings in both structures are puckered. Dihedral angles of these rings in the spiroheptane derivative (1) [12.9 (7) and 21.2 (5) degrees], and in the end rings of the dispirodecane derivative (2) [18.9 (5) and -18.5 (4) degrees], are significantly smaller than that for the central cyclobutane ring in (2) [29.0 (3) degrees]. Ring puckering in (2) gives the molecule a decided bow shape when viewed normal to the best plane of the central four-membered ring.