(3S,6S)-3-ISOPROPYL-1,4-DIAZABICYCLO[4.4.0]DECANE-2,5-DIONE, C11H18N2O2 - BAYESIAN STATISTICS IN DATA-ANALYSIS

C11H18N2O2, M(r) = 210.3, monoclinic, P2(1), a = 10.503 (4), b = 10.464 (7), c = 11.012 (4) angstrom, beta = 110.74 (2)-degrees, V = 1132 (1) angstrom 3, Z = 4, D(x) = 1.234 Mg m-3, lambda(Mo K-alpha) = 0.71073 angstrom, mu = 0.10 mm-1, F(000) = 456, room temperature, wR = 0.058, R = 0.102 for 2518 observed reflections out of 2538 measured, and 270 variables. The compound, for which the synthesis is also reported, consists of a piperidine ring in the chair conformation and a diketopiperazine ring in a very shallow boat form with C(3) and C(6) as bowsprits. The two rings are cis fused. The isopropyl group, pseudo-axially bonded, is folded over the diketopiperazine ring. The unit cell contains two symmetrically independent molecules A and B. Infinite chains, consisting exclusively either of type A or type B molecules, are linked by intermolecular N(4)-H...O(1) bonds. To compensate for the systematic weakness of reflections with h + l = odd, a new data analysis scheme was employed, based on Bayesian statistics. It led to an employed, based on Bayesian statistics. It led to an increase in the number of observed reflections from 1155 to 2518. The comparison between a refinement based on 1155 and one based on 2518 reflections showed that the Bayesian re-evaluation of data decreases the final e.s.d.'s considerably and does not create any detectable artefacts.