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Migrating hydrogen in 2,4,6‐triaminopyrimidinium(1+) x hydrogen trioxofluorophosphate(−) x monohydrate/2,4,6‐triaminopyrimidinium(2+) 1– x trioxofluorophosphate(2–) 1– x monohydrate (0.0 < x < 0.73) with changing temperature
Author(s) -
Matulková Irena,
Fábry Jan,
Němec Ivan,
Císařová Ivana,
Vaněk Přemysl
Publication year - 2017
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520617014007
Subject(s) - hydrogen atom , crystallography , hydrogen bond , hydrogen , atom (system on chip) , chemistry , molecule , group (periodic table) , organic chemistry , computer science , embedded system
The data of the title structure of 2,4,6‐triaminopyrimidinium(1+) x hydrogen trioxofluorophosphate(1−) x monohydrate/2,4,6‐triaminopyrimidinium(2+) 1− x trioxofluorophosphate(2−) 1− x monohydrate (0.0 < x < 0.73), with the sum formula C 4 H 11 FN 5 O 4 P, were collected in 10 K intervals between 290 and 150 K, as well as at 100 K. The most interesting feature is the presence of a moderate though still strong O—H…N/O…H—N hydrogen bond. Its bridging H atom was found to be disordered over two positions in the temperature interval 290–220 K, with the larger occupation towards the O atom. The occupation in the latter position decreased with decreasing temperature, though not monotonously. At 210 K and below, the difference electron‐density maps showed just one maximum which was closer to the N atom. Though difference scanning calorimetry (DSC) revealed no anomaly in the interval 303–93 K, the dependence of the length of the unit‐cell axes b and c on temperature showed a kink in the slope at about 190 K. The N…O distance of the mentioned hydrogen bond or the occupational parameter of the electron density of the disordered H atom indicate less pronounced anomalies for the temperatures 270 and 230 K. The cation and the anion, as well as the water molecules, form layers which are parallel to (10) and which are interconnected by O—H…N (in the interval 290–220 K), N—H…O and O—H…O hydrogen bonds of moderate strength. The layers are arranged into centrosymmetric double layers in which the F atoms are directed outwards. The layers are interconnected by water–acid O—H…O hydrogen bonds, weak N—H…F interactions and π‐electron ring…π‐electron ring interactions. The dependence of P—F bond lengths on bonding properties of the trioxofluorophosphate or hydrogen trioxofluorophosphate anions is discussed. It has been recognized that a carbon‐bonded F atom avoids participation in a hydrogen‐bond pattern; however, this property seems to be also common to fluorine bonded to P, As and S, especially if an oxygen ligand is also present in a molecule. The deposited material contains an overview of the determined structures with trioxofluorophosphate or hydrogen trioxofluorophosphate anions.