Novel lanthanide(III) complex [LaL2(NO3) (H2O)2]·5H2O with 2-pyridine carboxaldehyde isonicotinoyl hydrazine exhibiting a 3D supramolecular topology 3,6T49

Abstract

A new coordination compound, namely [LaL2(NO3)(H2O)2]·5H2O (1), has successfully been synthesized from La(NO3)3·6H2O, 2-pyridinecarboxaldehyde isonicotinoylhydrazone (HL) and NaOH, as a deprotonated agent, in the CH3OH medium under mild solvothermal conditions at 120 °C. Both HL and 1 were characterized by FTIR spectroscopy and elemental analysis. Complex 1 was also studied by the simultaneous TG-DSC, powder and single crystal X-ray diffraction analyses. According to the single crystal diffraction analysis, the lanthanum (III) ion adopts a deca-coordinated mode, and five lattice water molecules exist in the asymmetric unit. The crystal structure of 1 is mainly stabilized by strong O–H⋯N and O–H⋯O and weak π⋯π and C–H⋯π interactions. As a result of hydrogen bonding, a 3D supramolecular structure is formed with a binodal (3,6)-connected network with a 3,6T49 topology having point symbol of {4∙62}{47∙65∙83}. As evidenced from the Hirshfeld surface analysis of [LaL2(NO3)(H2O)2], intermolecular H⋯H (40.1%), H⋯C (15.4%), H⋯N (12.2%) and H⋯O (20.3%) contacts occupy an overwhelming majority of a molecular surface of the complex molecule. Highly favoured intermolecular C⋯C (6.5%) and C⋯N (4.0%) contacts also play a vital role in the supramolecular structure of complex. Upon heating, complex 1 decomposes in few steps, consistently losing lattice water molecules, coordinated water molecules followed by the decomposition of organic ligands, yielding La(NO3)3 followed by the formation of a final residue La2O3.