Structure of the 4-oxo-2-butenoic acid alkyl ester moiety. IV. Methyl 4-(3-oxo-1-piperazinyl)-4-oxo-2-butenoate

Abstract

C9H12N204, M r = 2122, monoclinic, P21/c, a = 17.022 (2), b = 6.161 (1), c = 10.031 (2)/~, fl = 103.92 (1) °, V = 1021.1/~3, Z = 4, Dx = 1.38 Mg m -3, A(Cu Kc~) = 1.54178 ,~, Ni filter, /~ = 0.89 mm-t, F(000) = 448, T = 293 K, R = 0.066 and wR=0.074 for 1247 observed intensities. Inter- molecular hydrogen bonds join molecules related by a 21 axis to form infinite chains running in the (010) direction, with butenoate groups perpendicular to the chain. Experimental. The compound crystallized from chloroform as large transparent plates. Data collec- tion and accurate cell determination (9 < 0 < 16 °, 25 reflections) were performed on a CAD-4 diffractom- eter. The crystal size was 0-31 x 0-20 x 0.04mm. 1942 independent intensities (1247 considered observed with I___ 3~r(/)) were measured using the o9/20 scan technique (0ma x = 75 °, -21 _ h _ 21, 0 _ k _< 7, 0 _ l <_ 12). Three standards monitored during data collection showed no significant change in their intensities. The data were corrected for Lorentz and polarization effects, and for absorption according to Walker & Stuart (1983) (transmission factors between 0-434 and 0.979). The structure was solved by direct methods (Shel- drick, 1986) and refined by full-matrix least squares (Sheldrick, 1976) with anisotropic temperature fac- tors for non-H atoms, isotropic temperature param- eters for H atoms and an isotropic extinction parameter g = 0.009 (2) (Larson, 1967). Non-H and H atom parameters were refined in separate blocks. The function minimized was Y.w(lFol- IFcl) 2 where w -~= tr2(Fo)+ 000225 Fo 2. The refinement conver- ged to a maximum shift/e.s.d, of 0-03 and 0.04 for non-H and H atom blocks comprising 137 and 50 variables, respectively. The final R = 0.046, wR = 0.053, S -- 0.874. The maximum and minimum peaks in the final difference Fourier synthesis were 0.26 and -0.25 e A-3. All calculations were carried out on an AMSTRAD 1512 microcomputer. Scattering factors were taken from SHELX.