Table 4. Key structural data for the cations in (I), (II) and related phases.
φ is the dihedral angle (°) between the pyridoxal ring and the pendant ring and ζ is the conformation of the C1—C5—C7—O2 grouping (our numbering scheme). The atom designations in the N1, N3 and O2 columns are the hydrogen-bond acceptors for these protonated atoms in the respective cations; Np = pyridine, Ow = water; OD = DMSO (dimethylsulfoxide). Atom O1 forms an intramolecular O—H⋯N hydrogen bond in every case.
| Compound | Space group | φ | ζ | N1 | N3 | O2 |
|---|---|---|---|---|---|---|
| (I) | Ia | 12.63 (12) | gauche | Np | Cl− | Cl− |
| (II) |
P
|
6.11 (15) | anti | Cl− | Ow | Cl− |
| IGELOW | Cc | 5.4 | anti | Cl− | Cl− | Ow |
| PYPICZ | Cc | 5.1 | anti | Cl− | Cl− | Ow |
| VUYPOW |
P
|
7.6 | anti | Cl− | OD | Cl− |
| XARHUX | P21/c | 3.5 | anti | Cl− | Ow | Cl− |