Two new hydrothermally synthesised hexamine bridged L–M–L type coordination polymers: Characterisation and magneto-structural correlation

Two new L–M–L type transition metal coordination polymers [M(C6H12N4)(NCO)2(H2O)2]n, where M = Co(II) (1) and Ni(II) (2), have been synthesised under controlled hydrothermal condition and characterised spectroscopically and by thermal analyses. Here hmt or hexamethylenetetramine has behaved as a neutral organic bidentate spacer molecule. Both the complexes crystallise in the monoclinic system as confirmed from single crystal X-ray diffraction studies. Cryomagnetic susceptibility measurements over a wide range of temperature (2–300 K) under 0.5 T magnetic fields show a weak antiferromagnetic interaction of J = −0.65 cm−1 for 1 and −1.6 cm−1 for 2. The values have been given a favorable support by weak covalent and H-bonding interactions between octahedral M(II) metal centers as revealed from X-ray structure determination. The high dimensionality of the structures is probably a manifestation of extensively weak covalent interactions and H-bondings.

Graphical abstractTwo new extensively hydrogen bonded polymeric L–M–L type metal coordination complexes [M(hmt)(NCO)2(H2O)2]n [M = Co(II) and Ni(II)] have been synthesised under controlled hydrothermal condition and thoroughly characterised. Here hmt (hexamethylenetetramine) has been used as a neutral organic bidentate spacer molecule. The structures reveal the presence of weak covalent and H-bonding interactions. A very weak antiferromagnetic interaction between the metal centers is found from cryomagnetic susceptibility measurements. The increase in the dimensionality of the structures is probably due to the presence of extensive weak covalent interactions and H-bondings.Figure optionsDownload full-size imageDownload as PowerPoint slide