A number of polymeric pyrazolato complexes have been prepared and characterized by spectroscopy, thermal analyses (DSC and TGA), and X-ray powder diffraction (XRPD) methods. Ab initio XRPD studies showed that the (isomorphous) [Zn(pz)(2)](n) and [Cd(pz)(2)](n) species(Hpz = pyrazole) are 1-D polymers containing tetrahedrally coordinated metals and M(mu-pz)(2)M (M = Zn, Cd) bridges, much alike [Cu(pz)(2)](n) [orthorhombic, Ibam, a = 7.4829(4), b = 14.3844(6), c = 7.3831(3)Angstrom (Zn) and a = 7.8591(6), b = 13.652(1), c = 7.9165(4) Angstrom (Cd)]; differently, Hg(pz)(2) [triclinic, P1, a = 7.4097(3), b = 9.4474(3), c = 5.8345(3) Angstrom, cr 96.310(2), beta = 96.752 (3), and gamma = 73.694(2)degrees] is best described as a mononuclear complex, containing two monodentate pyrazolato ligands loosely interacting, through long(er) Hg ... N contacts with neighboring molecules. During the synthesis of the latter, an intermediate phase was obtained, and characterized as Hg(pz)NO3, which contains a polymeric polycation, [Hg(pz)](n)(n+) based on Hg(mu-pz)Hg bridges, and uncoordinated NO3- groups (orthorhombic, Pcmn, a 17.2985(9), b = 5.2538(3), c = 7.3912(4) Angstrom). All structures were ultimately refined by the Rietveld method.