Synthesis and characterization of dodecahedral cerium(IV) and gadolinium(III) complexes with a tetradentate Schiff Base / created by Tulika Ghosh and Samudranil Pal

Reactions of CeCl3⋅6H2O and Gd(NO3)3⋅5H2O with biacetyl bis(benzoylhydrazone) (H2babh) and KOH in 1:2:2 mole ratio in methanol afford the complexes [Ce(babh)2] (1) and [Gd(babh)(Hbabh)]⋅H2O (2⋅H2O), respectively in good yields. Characterization of the complexes has been performed with the help of elemental analysis, magnetic susceptibility, spectroscopic (IR, UV-Vis, EPR and NMR) and X-ray crystallographic measurements. 1 is diamagnetic and NMR active, while 2⋅H2O is paramagnetic (μ eff = 8.03 μ B at 300 K) and EPR active. The complexes crystallize as 1⋅CH2Cl2 and 2⋅H2O. X-ray structures show that the metal centre in each of 1 and 2 is in a distorted dodecahedral N4O4 coordination sphere assembled by two meridionally spanning ONNO-donor ligands. Self-assembly of 1⋅CH2Cl2 via intermolecular C−H⋯N and C−H⋯Cl hydrogen bonds and π- π interactions provides one-dimensional ‘ladder’ type structure. On the other hand, 2⋅H2O assembles into a two-dimensional ‘sheet’ like network through intermolecular N−H⋯O and O−H⋯N hydrogen bonds.