Abstract
The reaction between mononuclear [Ln(bbpen)Cl] [Ln = Gd or Dy; H2bbpen = N,N'-bis-(2-hy-droxy-benz-yl)-N,N'-bis-(pyridin-2-ylmeth-yl)ethyl-enedi-amine, C28H30N4O2] and potassium oxalate monohydrate in water/methanol produced the solvated centrosymmetric isostructural binuclear (μ-oxalato)bis-{[N,N'-bis-(2-oxidobenzyl-κO)-N,N'-bis-(pyridin-2-ylmethyl-κN)ethyl-enedi-amine-κ2 N,N']dilanthanide(III)}-methanol-water (1/4/4) complexes, [Ln 2(C28H28N4O2)2(C2O4)]·4CH3OH·4H2O, with lanthanide(III) = gadolinium(III) (Ln = Gd) and dysprosium(III) (Ln = Dy), in high yields (ca 70%) directly from the reaction mixtures. In both complexes, the lanthanide ion is eight-coordinate and adopts a distorted square-anti-prismatic coordination environment. The triclinic (P ) unit cell contains one dimeric unit together with four water and four methanol mol-ecules; in the final structural model, two of each type of solvating mol-ecule refine well. In each lanthanide(III) dimeric mol-ecule, the medium-strength O⋯H-O hydrogen-bonding pattern involves four oxygen atoms, two of them from the phenolate groups that are 'bridged' by one water and one methanol mol-ecule. These inter-actions seem to contribute to the stabilization of the relatively compact shape of the dimer. Electron densities associated with an additional water and methanol mol-ecule were removed with the SQUEEZE procedure in PLATON [Spek (2015 ▸). Acta Cryst. C71, 9-18]. These two new compounds are of inter-est with respect to magnetic properties.