Attempted Syntheses of Lanthanide(III) Complexes of the Anisole- and Anilinosquarate Ligands

A new cadmium croconate (C5O5 2-) complex, [Cd2(C5O5)2(4,4ʹ-bpy)(H2O)](infinity) (4,4-bpy = 4,4ʹ-bipyridine) with an extended network has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction studies. The title compound crystallizes in the monoclinic system, space group P2 1/n, with empirical formula C20H12Cd2N2O12, a = 15.9623(3) A, b = 7.5837(1) A, c= 18.1181(3) A, (beta) = 99.95(2)°, and Z = 4. Structural determination reveals that the title compound has a bilayered network, containing two crystallographically independent Cd(II) ions in different coordination environments. Cd(1) lies in a distorted pentagonal bipyramidal environment, consisting of three croconate ions and one 4,4ʹ-bpy nitrogen donor, while Cd(2) lies in a distorted octahedral environment, consisting of two croconate anions, one 4,4ʹ-bpy nitrogen donor, and one water molecule. Of the two crystallographic independent croconate ligands, one presents a bis-bidentate adjacent (mu)3-coordination mode and the other a new bidentate/three-adjacent (mu)5-coordination mode. A two-dimensional hybrid layer is formed by two rectangular boxes as the building units through the connectivity between Cd(II) and croconate and 4,4ʹ-bpy ligands.