Hydrothermal synthesis, structural characterisation and magnetic behaviour of hybrid complexes of N-(phosphonomethyl)iminodiacetate

Two new compounds containing multidentate chelating organic residues of N-(phophonomethyl)iminodiacetic acid (H4pmida), [M(pyr) (H2O)4][M2(Hpmida)2(pyr)(H2O)2]$2(H2O) (where pyrZpyrazine and MZCo2C or Ni2C for I and II, respectively) have been synthesised and structurally characterised by single-crystal and powder X-ray diffraction, elemental analysis, infrared spectroscopy, thermal analysis and solid-state 31P MAS NMR. The compounds contain discrete binuclear anionic [M2(Hpmida)2(pyr)(H2O)2]2K units in which one pyrazine ligand bridges two M2C cations which are completely trapped inside three five-membered chelate rings formed by the Hpmida3K ligands. These moieties close pack in the ac plane via a series of strong and highly directional O–H/O hydrogen bonds leading to the formation of anionic ½Co2ðHpmidaÞ2ðpyrÞðH2OÞ2 2nK n layers. One-dimensional cationic ½MðpyrÞðH2OÞ4 2nC n coordination polymers are placed in-between and strongly hydrogen-bonded to these layers. The magnetic properties of these two materials are also reported. q 2005 Elsevier B.V. All rights reserved.