Substitutional/positional disorder of biguanide and guanylurea in the structure of a decavanadate complex [(Bg)(HV 10 O 28 5- )] 0.4 [(HGU + )(V 10 O 28 6- )] 0.6 (H 2 Met 2+ ) 2 (H 3 O + )·8H 2 O

• Published in: Acta crystallographica Section B, Structural science, crystal engineering and materials
• Main Authors: Chatkon, Aungkana, Haller, Kenneth J, Haller, Joseph P
• Format: Journal Article
• Language: English
• Published: England 01.10.2024
• Subjects: biguanide; metforminium dication; teaching; monoprotonated decavanadate; substitutional/positional disorder
• ISSN: 2052-5206
• DOI: 10.1107/S2052520624006929

A hydrated salt of decavanadate containing diprotonated metforminium(2+) (H Met ), hydronium (H O ) and either neutral biguanide (Bg) or monoprotonated guanylurea (HGU ) exhibits a previously seen complex charge-stabilized hydrogen-bonded network [Chatkon et al. (2022). Acta Cryst. B78, 798-808]. Charge balance is achieved in two ways through substitutional disorder: a 0.6 occupied HGU cation is paired with a V O anion, and a 0.4 occupied neutral Bg molecule is paired with a HV O anion, with the remaining charge in both cases balanced by two H Met dications and one H O monocation. Bg/HGU moieties exhibit bifurcated N-H...O hydrogen bonding to the H O cation and are substitutionally/positionally disordered along with the H O cation about an inversion center. The HGU V O synthon seen in the previous study occurs again. Bg exhibits bifurcated hydrogen bonding from two amino groups to two rows of cluster O atoms running diagonally across the equatorial plane of the HV O anion with a return hydrogen bond from the cluster H atom to the imino N atom of the Bg. Thus, a Bg...cluster synthon similar to the HGU ...cluster synthon previously reported is found. The disordered moieties occupy spaces with excess volume in the 3-D network structure. Interestingly, when the crystallographic unit cell of the current compound, whose X-ray data was collected at 100 K, is compared with that of a previous compound exhibiting the same supramolecular framework, unit-cell parameter c does not shorten as a and b expectantly do because of the lower data collection temperature. The lack of contraction on unit-cell parameter c is possibly due to the supramolecular structure.