Synthesis, Solid-State NMR, and X-ray Powder Diffraction Characterization of Group 12 Coordination Polymers, Including the First Example of a C-Mercuriated Pyrazole

Cadmium and mercury acetates have been reacted with pyrazole (Hpz) and 3,5-dimethylpyrazole (Hdmpz), affording
distinct mixed-ligand species, selectively prepared upon slightly modifying the reaction conditions. Two polymorphs
of [{Cd(μ-ac)2(Hpz)2}n], as well as the [{Cd(μ-ac)2(Hdmpz)2}n] species (Hac = acetic acid), were obtained by
solution chemistry, while the two-dimensional [{Cd3(μ3-ac)4(μ-pz)2(Hpz)2}n] and [{Cd(μ-ac)(μ-pz)}n] polymers were
prepared upon controlled thermal treatment of one of the [{Cd(μ-ac)2(Hpz)2}n] forms. Two mercury derivatives,
[{Hg3(μ-ac)3(μ-pz)3}n] and [{Hg(ac)(μ-dmpz)}n], were also prepared, the latter containing one-dimensional chains
of Hg(II) ions bridged by C-mercuriated Hdmpz ligands. All their crystal structures (but one) were determined by
powder diffraction methods using conventional X-ray laboratory equipment, supported by 13C CPMAS NMR
measurements. The latter method helped in assigning a C-metalated nature to an amorphous material of [Hg(ac)(pz)] formula, obtained by employing EtOH as a solvent. A few other Hdmpz-containing cadmium acetates were
also prepared, but their polyphasic nature, evidenced by diffraction methods, hampered their complete structural
characterization.