Three cadmium(II) coordination compounds were synthesized via controlling the pH in the in situ [2 + 3] cycloaddition reaction of CdSO4, 4-cyanopyridine, and sodium azide under hydrothermal treatment. Mononuclear 3 was obtained at weak acid solution pH 6.0 similar to 7.0, but 3-D coordination polymers 1 and 2 were preferred in weak alkaline conditions from pH 7.0 to 9.0. Hydrothermal reactions of CdSO4, 4-cyanopyridine, and sodium azide yield three metal coordination compounds via controlling the pH, [Cd-2(4-ptz)(SO4)(OH)(H2O)(2)](H2O) (1) [Cd-2(4-ptz)(SO4)(OH)(H2O)](n) (2), and known [Cd-2(4-...
