High-resolution X-ray diffraction data were collected at 80K for guanidinium hydrogen oxalate monohydrate to obtain accurate crystal data and experimental charge density. The measurements were carried out using Nonius KappaCCD diffractometer equipped with Oxford 700 Cryostream Cooler. The studies were performed to explore inter- and intramolecular interactions. The crystal structure is built of layers, parallel to (-101), ~3.2 Å apart, formed by hydrogen oxalate anions, monoprotonated guanidinium cations and water molecules. In the crystal structure hydrogen oxalate anion is surrounded by three monoprotonated guanidinium cations and water molecule. All possible donors are involved in intermolecular hydrogen bonding. The hydrogen bonds are of N-H···O and O-H···O types. The guanidinium cation, with pseudo 3m symmetry, interacts with the hydrogen oxalate anions and water molecules through relatively strong hydrogen bonds of N-H···O type. The water molecules play exceptional function in the structure holding the layers together through O(4)_water-H···O(22)_oxalate and O(4)_water-H···O(21)_oxalate strong hydrogen bonds. O(22) atom accepts three hydrogen bonds (two N-H···O and one O-H···O type), whereas the remaining oxygen atoms of hydrogen oxalate carbonyl groups, O(11) and O(21), accept two hydrogen bonds of N-H···O type each. O(12) atom of hydroxyl group is a donor of hydrogen bond to oxygen atom O(4) of water molecule. Evaluation of experimental electron density and related properties such as moments and electrostatic potential was performed using Hansen-Coppens multipole formalism [1]. According to Bader's AIM theorem [2] topological analysis charge density led to determine quantitative parameters of the interactions, like value of electron density and Laplacian ρ(r) at the bond critical point's (BCP). Multipole refinement and the analysis of static densities was performed using the XD program suite [3] and all topological interactions (atomic volumes, atomic charges) were evaluated with program TOPXD [4].

[1] N. K. Hansen, P. Coppens, Acta Cryst. A 1978, 34. 909.

[2] R. F. W. Bader, Atoms in Molecules - A Quantum Theory, Oxford University Press, 1995.

[3] T. S. Koritsanszky et al., XD - A Computer Program Package for Multipole Refinement and Analysis of Electron Densities from Diffraction Data, 2003

[4] A. Volkov, C. Gatti, Y. Abramov, P. Coppens, Acta Cryst. A 2000, 56, 332.

• Legal notice:
  

  Copyright (c) Pielaszek Research, all rights reserved.
  The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
  In every case, proper references including Author(s) name(s) and URL of this webpage: https://science24.com/paper/8315 must be provided.