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(mu-ac)(2)(Hpz)(2)}(n)], as well as the [{Cd(mu-ac)(2)(Hdmpz)(2)}(n)] species (Hac= acetic acid), were obtained by solution chemistry, while the two-dimensional [{Cd-3(mu(3)-ac)(4)(mu-pz)(2)(Hpz)(2)}(n)] and [{Cd(mu-ac)(mu-pz)}(n)] polymers were prepared upon controlled thermal treatment of one of the [{Cd(mu-ac)(2)(Hpz)(2)}(n)] forms. Two mercury derivatives, [{Hg-3(mu-ac)(3)(mu-pz)(3)}(n)] and [{Hg(ac)(mu-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 C-13 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.