Synthesis and characterization of dodecahedral cerium(IV) and gadolinium(III) complexes with a tetradentate Schiff Base

Abstract

Reactions of CeCl 3 •6H 2 O and Gd(NO 3) 3 •5H 2 O with biacetyl bis(benzoylhydrazone) (H 2 babh) and KOH in 1:2:2 mole ratio in methanol afford the complexes [Ce(babh) 2 ](1) and [Gd(babh)(Hbabh)]•H 2 O (2•H 2 O), 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•H 2 O is paramagnetic (μ eff = 8.03 μ B at 300 K) and EPR active. The complexes crystallize as 1•CH 2 Cl 2 and 2•H 2 O. X-ray structures show that the metal centre in each of 1 and 2 is in a distorted dodecahedral N 4 O 4 coordination sphere assembled by two meridionally spanning ONNO-donor ligands. Self-assembly of 1•CH 2 Cl 2 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•H 2 O assembles into a two-dimensional 'sheet' like network through intermolecular N−H•••O and O−H•••N hydrogen bonds.

Synthesis and Structural Characterization of a Double Helical Dinuclear Copper(II) Complex With Tetradentate Biacetyl Bis(benzoylhydrazone)

“…32 The C1-O1 and C8-O4 bond lengths of complex (1.289(3) and 1.283(3) Å, respectively) and C1-N1 and C8-N8 (1.331(3) and 1.314(3) Å, respectively) are similar and are in good agreement with analogous Cu(II) complexes observed in the literature where a hydrazone ligand coordinates to the Cu(II) center in its iminolate form. 2,13,14,25,33 The average of Cu-O bond lengths in the dinuclear complex (1.978 Å) is very similar to the corresponding distances in previously reported mononuclear copper(II) complex (1.978 Å).…”