Structure cristalline et moléculaire de l'aminal du dimère de la carbométhoxy-3 méthyl-5 formyl-5 pyrazoline-Δ2, C₁₆H₂₀N₄O₆

Abstract

Crystals of the title compound are triclinic, space group PT, with a=7.815 (3), b=9-434 (3), c= 6.376 (3) A; ~ = 99"31 (3), ,8 = 87" 12 (3), 7 = 105-28 (3) °, Z= 1. The structure was solved by direct methods. The parameters were refined by a block-diagonal least-squares method. The hydrogen atoms were included in the refinement. The final R value is 0.047 for the 1480 reflexions considered observed. The symmetry of the dimer molecule is T, making the two monomers involved in it enantiomorphous; this confirms the stereospecificity of the dimerization. The piperazine ring is distorted from its free configuration. The pyrazoline ring is very near the ',8 envelope' conformation. There is a well defined conjugation from the ester group to the pyrazoline ring. Cohesion of the crystal is the result of van der Waals interactions.

Structure cristalline et moléculaire de l'aminohémiacétal du dimère de la carboéthoxy-3 méthyl-5 formyl-5 pyrazoline-Δ2, C16H24N4O6

“…* Les positions des atomes H ont 6t4 obtenues par synth6se (Fo-Fc). La num6rotation des atomes est diff6rente, par commodit6, de celle de la nomenclature chimique; elle est, par contre, la mSme que celle utilis6e pour la structure (II'b) (Dupont et al, 1975 (20) 1075 (5) 221 (5) 1116 (4) H (21) 698 (4) 658 (4) 972 (4) H (22) 670 (4) 520 (4) 1057 (4) H (51) 283 (5) 365 (-5) 605 (4) H (52) 341 (4) 463 (5) 510 (4) H (6) 1000 (4) 286 (4) 890 (4) H (71) 222 (4) 272 (4) 386 (4) H (72) 368 (4) 168 (5) 525 (4) H (73) 401 (5) 290 (5) 416 (5) H (81) 1051 (5) 484 (4) 1264 (4) H (82) 928 (4) 574 (5) 1259 (5) H (83) 892 (4) 414 (5) 1229 (4) Tableau 2. Principaux programmes utilisOs…”

“…La structure cristalline du compos6 (II'b) qui diff6re de (lib) parla longueur du radical R' a 6t6 publi6e r6cemment* (Dupont, Toussaint, Dideberg, Braham & Noels, 1975).…”