STRUCTURE OF 10,11-DIHYDRO-5,10-ETHANO-5H-DIBENZO(A,D)CYCLOHEPTENE

C17H16 (1), M(r) = 220.3, monoclinic, P2(1)/n, a = 8.465 (1), b = 6.509 (2), c = 21.305 (8) angstrom, beta = 93.44 (2)-degrees, V = 1171.6 (5) angstrom-3, Z = 4, D(x) = 1.249 g cm-3, Mo K-alpha (lambda = 0.71073 angstrom), mu = 0.65 cm-1, F(000) = 472, T = 193 K, R = 0.0461 and wR = 0.0679 for 2200 reflections [I-greater-than-or-equal-to 3-sigma(I)]. The molecule consists of two benzene rings fused on opposite sides of a cycloheptane ring with an ethano group bridging C(5) and C(10). The 4-membered chain of C(5), C(13), C(12) and C(10) is nearly planar [angle C(5)--C(13)--C(12)--C(10) is -5.7 (2)-degrees], but is considerably different from its counterpart in a similar compound, 10,11-dihydro-5,10-ethano-5H-dibenzo[a,d]cyclohepten-11-one (2), studied in our laboratory, which has an angle of 6.8 (3)-degrees. The chain forms dihedral angles of 114.6 (4) and 127.4 (4)-degrees with the C(1) and the C(6) benzene rings, respectively. The dihedral angle between the phenyl rings is 118.0 (3)-degrees. These three dihedral angles differ significantly from their counterparts in (2) where values of 118.0 (4), 128.9 (4) and 112.9 (4)-degrees were observed. The ring conformations are the same as in (2). The two 7-membered rings [C(11a), C(4a), C(5), C(13), C(12), C(10), C(11) and C(11a), C(4a), C(5), C(5a), C(9a), C(10), C(11)] are in boat-sofa conformations, BS11aBAR and BS11a, respectively, with Cremer & Pople [J. Am. Chem. Soc. (1975), 97, 1354-1358] puckering parameters q(2), q(3), phi-(2), phi-(3) and the total puckering amplitude, Q, of 0.953, 0.331 angstrom, 177.8, 355.7-degrees, 1.009 angstrom, for the former, and 0.888, 0.332 angstrom, 0.4, 177.6-degrees, 0.948 angstrom, for the latter. The 6-membered ring [C(5), C(13), C(12), C(10), C(9a), C(5a)] is in a boat conformation, B-5,B-10, and its puckering parameters q(2), q(3), phi-(2), and the puckering amplitude, Q, are 0.695, -0.032 angstrom, 182.5-degrees, 0.695 angstrom.