Two-dimensional square-grid frameworks formed by self-associating copper(II) complexes with 1-(3-pyridyl)- and 1-(4-pyridyl)-substituted butane-1,3-diones.

In bis[1-(3-pyridyl)butane-1,3-dionato]copper(II) (the Cu atom occupies a centre of inversion), [Cu(C9H8NO2)2], (I), and bis[1-(4-pyridyl)butane-1,3-dionato]copper(II) methanol solvate, [Cu(C9H8NO2)2].CH3OH, (II), the O,O'-chelating diketonate ligands support square-planar coordination of the metal ions [Cu-O=1.948 (1)-1.965 (1) A]. Weaker Cu...N interactions [2.405 (2)-2.499 (2) A], at both axial sides, occur between symmetry-related bis(1-pyridylbutane-1,3-dionato)copper(II) molecules. This causes their self-organization into two-dimensional square-grid frameworks, with uniform [6.48 A for (I)] or alternating [4.72 and 6.66 A for (II)] interlayer separations. Guest methanol molecules in (II) reside between the distal layers and form weak hydrogen bonds to coordinated O atoms [O...O=3.018 (4) A].