Dimeric copper(II) 3,3-dimethyl­butyrate adducts with ethanol, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine and 3,3-dimethylbutyric acid

In the crystals of the five title compounds, tetrakis-(μ-3,3-dimethylbutyrato-O:O′)bis(ethanol-O)dicopper(II)–ethanol (1/2), [Cu₂(C₆H₁₁O₂)₄(C₂H₆O)₂]·2C₂H₆O, (I), tetrakis(μ-3,3-dimethylbutyrato-O:O′)bis(2-methylpyridine-N)di­copper(II), [Cu₂(C₆H₁₁O₂)₄(C₆H₇N)₂], (II), tetrakis-(μ-3,3-dimethylbutyrato-O:O′)bis(3-methylpyridine-N)di-copper(II), [Cu₂(C₆H₁₁O₂)₄(C₆H₇N)₂], (III), tetrakis-(μ-3,3-dimethylbutyrato-O:O′)bis(4-methylpyridine-N)di-copper(II), [Cu₂(C₆H₁₁O₂)₄(C₆H₇N)₂], (IV), and tetrakis-(μ-3,3-dimethylbutyrato-O:O′)bis(3,3-dimethylbutyric acid-O)dicopper(II), [Cu₂(C₆H₁₁O₂)₄(C₆H₁₂O₂)₂], (V), the di­nuclear Cu^II complexes all have centrosymmetric cage structures and (IV) has two independent molecules. The Cu⋯Cu separations are: (I) 2.602 (3) Å, (II) 2.666 (3) Å, (III) 2.640 (2) Å, (IV) 2.638 (4) Å and (V) 2.599 (1) Å.