**5. Crystallographically independent molecules and ions**

Different orientations resulting from non-rigid units in some molecules and ions and the presence of different H-bonds or the other short contacts may result in two or more conformers (or symmetrically independent molecules (or ions)) in solid state. Compound C6H5C(O)NHP(O)[NH(*tert*-C4H9)]2, exists as two conformers in crystalline lattice (which are detectable in solution, too by NMR experiment) [27]. They are due to different spatial orientations of *tert*-butyl amido groups. One of the two conformers has two NH units (of *tert*-butyl amido moieties) which are *syn*, but not in the other. Another example is the presence of disorder in the cyclic amido moiety. For example, C6H5C(O)NHP(O)[NC4H8]2 appears as two crystallographically independent molecules [55]. This is based on the conformational forms of the pyrrolidinyl groups and the orientation of the phenyl ring. The dimmeric aggregate in this case, between two independent molecules, is not centrosymmetric. The structure of [NH2(C6H11)(*tert*-C4H9)][PO2Cl2] consists of two symmetrically independent dichlorophosphate anions as well as cyclohexyl-*tert*butylammonium cations [75]. In the crystal structure of [*tert*-C4H9NH3][CF3C(O)NHP(O)(O)(*tert*-C4H9NH)].0.333CH3CN.0.333H2O [79], there are three symmetrically independent trifluoroacetyl-N-(*tert*-butylamino) phosphate anions and three independent cations of *tert*-butyl- ammonium; one of the anion indicates disorder in the *tert*-C4H9 moiety. There are some other examples of disordered components for the groups such as *tert*-C4H9, cyclopentyl and cyclohexyl etc. in the deposited cifs.
