Structure of MeCO-Gly psi [NH-CO]NHMe.
N,N'-Methylenediacetamide, C5H10N2O2, Mr = 130.15, orthorhombic, Pna2(1), a = 17.218 (1), b = 4.489 (1), c = 18.124 (1) A, V = 1400.8 A3, Z = 8, D chi = 1.23 g cm-3, lambda(Cu K alpha) = 1.5418 A, mu Rmax much less than 1, mu = 7.19 cm-1, F(000) = 560, T = 293 K, R = 0.044 for 1318 observed reflections. This retro-peptide molecule assumes two nearly identical conformational states (A phi = 93.2, phi' = 77.0; B phi = 90.6, phi' = 79.6 degrees) with planar trans amide functions. The bond lengths and bond angles are very close to the standard dimensions of the peptide group.