Structure of 1,1-dichloro-2-(4-methoxyphenyl)-2,3-diphenylcyclopropane.

C22H18Cl2O, M(r) = 369.3, monoclinic, P2(1)/a, a = 16.585(1), b = 17.328(1), c = 13.192(3) A, beta = 107.443(8) degrees, V = 3616.8 A3, Z = 8, Dx = 1.356 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 3.2 cm-1, F(000) = 1536, T = 138 K, R = 0.039 for 5450 observed reflections. The structural features of the two independent molecules are quite similar except in the orientation of the methoxy group. The cyclopropane ring shows the expected bond-length asymmetry with C(2)-C(3) as the longest bond. The two cis-arranged phenyl rings adopt similar conformations as observed in diaryl-cyclopropanes, with one ring in the bisecting position and the other near the perpendicular position. The conformation of the third aryl ring is also near the perpendicular position. The overall conformation of the three aryl rings is different from the helical propeller conformation consistently observed in tamoxifen and all other known tri(tetra)aryl-vinyl systems.