title: Conformational richness and multiple Z' in salt co-crystal of N-methylpiperidine betaine with N-methylpiperidine betaine hexafluorosilicate.
abstract: The co-crystal structure of N-methylpiperidine betaine with N-methylpiperidine betaine hexafluorosilicate represents an unusual case of a salt co-crystal with a high Z' value (3), unexpected conformational variability, and with nearly 50% of its contents disordered. The betaine units from the salt and co-crystal formers are paired into several homoconjugated dimers via very short, linear O(-)...H(+)...O(-) bridges. These hydrogen bonds are the dominating interactions in the co-crystal structure, in variance with the simple hexafluorosilicate salt, which has a structure governed by COOH...F hydrogen bonds. The SiF(2-)(6) anion in the co-crystal structure has only C-H...F interactions with the betaine units. The zwitterion:cation:anion stoichiometry is 3:3:1.5. Some of the betaine units display disorder, but each case is different. One of the SiF(2-)(6) anions is ordered while possessing exact crystallographic symmetry. The other one is disordered in a general position. In addition, there are three water molecules in the crystal structure. One is fully ordered, one has an H atom disordered in two positions and the third one occupies two alternative positions with unequal populations.
authors.affiliation: Faculty of Chemistry, A. Mickiewicz University, Poznan, Poland.
authors.forename: Ram
authors.initials: R
authors.lastname: Thaimattam
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Szafran
authors.forename: Zofia
authors.initials: Z
authors.lastname: Dega-Szafran
authors.forename: Mariusz
authors.initials: M
authors.lastname: Jaskolski
mesh_terms: D000838:Anions / Q000737:chemistry; D001622:Betaine / Q000031:analogs & derivatives* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019281:Dimerization; D005459:Fluorides / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008968:Molecular Conformation; D011522:Protons; D012492:Salts / Q000737:chemistry*; D012824:Silicic Acid / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000838:Anions; D011522:Protons; D012492:Salts; D014867:Water; D012824:Silicic Acid; C004832:hexafluorosilicate; D001622:Betaine; D005459:Fluorides