A monoclinic phase of the deoxycholic acid rubidium salt

The title compd., C24H39O4Rb.H2O, is monoclinic, space group P2, with a 13.118(6), b 7.817(3), c 11.788(5) Å, and β 97.74(3)°; Z = 2. R = 0.051 And RW = 0.069 for 1867 obsd. data with I >3σ(I). The side-chain and D-ring conformations of the anion are similar to those of the orthorhombic and tetragonal phases of deoxycholic acid. The anions are held together mainly by ion-ion and ion-dipole interactions between Rb+ and the carboxylate and hydroxyl groups, as well as by a H-bonding scheme to which the H2O mols. contribute. The crystal packing is characterized by an assembly of bilayers, different from those found in the orthorhombic and tetragonal phases, without empty spaces between them. Zigzag chains of Rb+ ions running parallel to b are inside the bilayers