Synthesis, crystal structure, magnetic properties and EPR spectra of copper(II) acetate derivatives: Tetra-(μ-acetato)bis(2-methylaminopyridine) copper(II) and catena-poly(aquadiacetato-μ-3-aminomethylpyridine)copper(II). Sheets formed by chains connected through hydrogen-bonds

The derivatives of Cu(OAc)₂·H₂O with 2-methylaminopyridine and 3-aminomethylpyridine, [Cu₂(μ-OAc) ₄(MeNHpy)₂] (1) and [Cu(OAc)₂(μ-NH ₂CH₂py)(H₂O)]_n (2), respectively, have been synthesized and characterized. Compound 1 shows the dimer structure of [Cu₂(μ-OAc)₄(H₂O)₂], with four syn-syn bridging acetate groups and the MeNHpy ligand coordinated in the axial positions. It is antiferromagnetic (2J=-285 cm^-1). Signals of the triplet state are observed in its EPR spectrum and the zero-field splitting parameter has been calculated (D=0.36 cm^-1; g_∥=2.35; g_⊥=2.07). Otherwise, the ligand 3-aminomethylpyridine acts as bridging bidentate ligand in compound 2, forming infinite zig-zag chains. Each copper atom lies in a square-planar pyramidal coordination, determined by two nitrogen atoms of two bridge ligands, two oxygen atoms of two monodentate terminal acetate groups and a water molecule. The parallel chains form a sheet because of the hydrogen bonds between them. The shortest Cu-Cu distances are: 5.1270, 6.0952 and 6.2163 Å (inter-chains) and 7.875 Å (intra-chain). Compound 2 shows a slight antiferromagnetic effect below 30 K. The EPR spectra show an orthorhombic signal (g₁=2.26; g ₂=2.08; g₃=2.06).