STRUCTURE OF 4-PIPERIDONE DERIVATIVES .3. 1,3,3-TRIMETHYL-2,6-DIPHENYL-4-PIPERIDONE AND 2,6-BIS(P-CHLOROPHENYL)-1,3,5-TRIMETHYL-4-PIPERIDONE

C20H23NO (I), M(r) = 293.4, triclinic, P1BAR, a = 6.486 (2), b = 10.921 (2), c = 12.542 (1) angstrom, alpha = 79.90 (1), beta = 88.87 (2), gamma = 73.50 (2)-degrees, V = 838.2 (3) angstrom3, Z = 2, D(x) = 1. 16 g cm -3, lambda(Cu Kalpha) = 1.5418 angstrom, mu = 5.15 cm -1, F(000) = 316, T = 295 K, R = 0.051, wR = 0.070 for 2641 unique observed reflections [I > 3sigma(I)]. C20H21Cl2NO (II), M(r) = 362.3, orthorhombic, Pnma, a = 7.420 (2), b = 23.118 (1), c = 10.624 (2) angstrom, V = 1822.4 (2) angstrom3 , Z = 4, D(x) 1.32 g cm-3, lambda(Cu Kalpha) = 1.5418 angstrom, mu = 32.95 cm-1, F(000) = 760, T = 295 K, R = 0.042, wR = 0.048 for 1221 unique observed reflections [I > 3sigma(I)]. The 4-piperidone ring has a slightly distorted chair conformation in both compounds and the mean torsion angles are 54.0 (2) and 52.7 (3)-degrees for (I) and (II), respectively. In (I) the puckering is enhanced in the area of N1 and in (II) it is enhanced in the area of C4. The phenyl rings are planar within six standard deviations and all molecular dimensions and van der Waals interactions are normal in both compounds.