The Structure of Vitamin BFormula. II. The Crystal Structure of a Hexacarboxylic Acid Obtained by the Degradation of Vitamin BFormula

摘要: A hexacarboxylic acid, obtained by the degradation of vitamin B 12 Cannon, Johnson & Todd in 1953 has been examined X-ray analytical methods. These lead to a solution both crystal and chemical structure acid. The crystals are orthorhombic, = 24·58, b 15·52, c 13·32 A, space group, P 2 1 , n 4. asymmetric unit is found consist essentially one molecule C 46 H 58 O 13 N 6 . CoCl, two molecules water acetone. acid central cobalt atom approximately octahedral co-ordination attached cyanide chlorine four nitrogen atoms corrin nucleus. nucleus itself substituted acetic propionic groups, lactam ring number methyl groups. position was first from Patterson projections remaining atomic positions then derived series calculated approximations three-dimensional electron density distribution. For these calculations, phases were factors on gradually increasing numbers selected stage ρ 1, where only sites known, 10 73 atoms, not counting hydrogen, had placed. process quite straightforward; particular difficulty experienced finding side-chain which may be affected disorder. parameters have refined cycles least-squares calculations. observations made course analysis bear further use non-centrosymmetric Fourier syntheses study complex structures. An appendix A. Vos deals with intensity anomalies observed photographs provide evidence its absolute configuration. K. N. Trueblood summarizes various aspects seen as whole.