Bis[aminoguanidinium(1+)] hexafluorozirconate(IV): redeterminations and normal probability analysis

Area of Science:

• Inorganic Chemistry
• Crystallography
• Materials Science

Background:

• The crystal structure of bis[aminoguanidinium(1+)] hexafluorozirconate(IV), (CH(7)N(4))(2)[ZrF(6)], was previously reported.
• Aminoguanidinium polyfluorozirconates are known to be susceptible to radiation-induced structural changes.

Purpose of the Study:

• To redetermine the crystal structure of bis[aminoguanidinium(1+)] hexafluorozirconate(IV) using two independent samples.
• To assess the reliability of the previous structural determination and identify potential sources of error.
• To investigate the mechanisms of radiation-induced structural damage in this class of compounds.

Main Methods:

• Single-crystal X-ray diffraction
• Normal probability analysis of refined parameter standard uncertainties
• Comparison of crystallographic data from new and previous studies

Main Results:

• The crystal structure was successfully redetermined, confirming the overall structural framework.
• Normal probability analysis indicated reliable parameter standard uncertainties in the new determinations.
• Systematic errors in the earlier work were identified, leading to differences in atomic positions, particularly for an F-atom y coordinate (max difference of 0.069(6) Å).

Conclusions:

• The redetermination provides a more accurate crystal structure for bis[aminoguanidinium(1+)] hexafluorozirconate(IV).
• Previous structural data contained systematic errors affecting atomic positional parameters.
• Radiation-induced structural damage likely involves H atom displacements in N-H...F bonds and subsequent anionic realignment.