Two new hydrothermally synthesised L–M–L type cobalt(II) hydrogen bonded co-ordination complexes with mixed ligands: Characterisation and magneto-structural correlation

Two new hydrogen bonded polymeric L–M–L type Co(II) metal co-ordination complexes [{Co(hmt)2(NCS)2(H2O)2}{Co(NCS)2(H2O)4}(2H2O)] (1) and [Co(hmt)(NNN)2(H2O)2]n (2) have been synthesised under controlled hydrothermal condition and characterised by elemental analyses, FT-IR, UV/vis spectroscopy and thermal analyses. Here 1,3,5,7-tetraazatricyclo [3.3.1] decane [or hexamethylenetetramine (hmt)] has been used as a neutral organic bidentate spacer molecule. The structures of the complexes have been confirmed unequivocally from single crystal X-ray diffraction studies which reveals the presence of weak covalent and H-bonding interactions between octahedral Co(II) complexes. Magneto-structural correlations have been drawn from cryo-magnetic susceptibility measurements over a wide range of temperature (2–300 K) under 0.5 T magnetic fields. A weak antiferromagnetic interaction of J = −0.77 cm−1 found is as expected from X-ray structure determination. The high dimensionality of the structures is probably a manifestation of extensive weak covalent interactions and H-bondings.

Graphical abstractTwo new hydrogen bonded 2-D polymeric L–M–L type Co(II) metal coordination complexes have been synthesised under controlled hydrothermal condition and spectroscopically characterised. X-ray study reveals the presence of weak covalent and extensive inter/intra molecular H-bonding interactions within the chains responsible for polymeric network. Both the complexes are found to be weakly antiferromagnetic in nature corroborating well with their structures.Figure optionsDownload full-size imageDownload as PowerPoint slide