Two new nickel phosphonate compounds: different supramolecule structures constructed by 1-aminoethylidenediphosphonic acid and ammonium counterions

Abstract

Hydrothermal reactions of 1-aminoethylidenediphosphonic acid (AEDPH₄), Ni(OH)₂ and ammonium counterions afforded two nickel phosphonate compounds, (enH₂)₃[Ni(AEDP)₂] · 6H₂O (1) and (NH₄)₆[Ni(AEDP)₂] · 4H₂O (2) (en = ethylenediamine). Compounds 1 and 2 both contain [Ni(AEDP)₂]⁶⁻ while having different three-dimensional (3-D) supramolecular structures. In 1, the [Ni(AEDP)₂]⁶⁻ anion and cations interconnected via various hydrogen bonds and form a 3-D porous supramolecular network with extended one-dimensional channels, in which an interesting T4(2)6(2) water tape penetrates. Compared to 1, the [Ni(AEDP)₂]⁶⁻ anion and cations in 2 constitute an enclosed 3-D supramolecular framework without obvious channels; two water-ammonium clusters with different structural motifs are observed. The magnetism of 1 exhibits weak antiferromagnetic interaction via the hydrogen bonds. The effect of protonated ammonium counterions on the structural types of the final products is also discussed.

Keywords:

• Nickel phosphonate compound
• Water tape
• Water-ammonium clusters
• 1-Aminoethylidenediphosphonic acid

Acknowledgement

This work was supported by grants of the National Nature Science Foundation of China (No. 20671074).