Synthesis, Characterization, and Thermal Properties of Cd(II) and Hg(II) Complexes Containing N,N'-bis(2-hydroxyethyl)piperazine and Saccharinate

New complexes of Cd(II) and Hg(II) incorporating N,N'-bis(2-hydroxyethyl)piperazine (bheppz) as a ligand, along with saccharinate (sac), were synthesized. The characterization of these complexes, proposed to have the general structure [M(sac)₂(bheppz)]n (M = Cd(II) or Hg(II)), was conducted using elemental composition determination, FT-IR spectral analysis, and thermal analysis techniques. The complexes were synthesized by reacting [Cd(sac)₂(H₂O)₄]·2H₂O and [Hg(sac)₂] with bheppz. Based on the IR spectra, it has been suggested that the sac ligand coordinates through the N atom, which is its most common coordination mode. Additionally, the bheppz ligand was proposed to act as a bridging ligand via its nitrogen and oxygen donor atoms, leading to the formation of polymeric structures. The immediate precipitation of the complexes as powders during synthesis and their low solubility in common solvents further support their polymeric nature. The IR spectra of the complexes exhibited characteristic absorption bands corresponding to both bheppz and sac ligands. Thermal dissociation studies revealed that the bheppz ligand was exothermically eliminated in the first step, while the sac ligand dissociated in two exothermic steps at higher temperatures. The final decomposition products were identified as CdO for [Cd(sac)₂(bheppz)]n (1) and elemental mercury for [Hg(sac)₂(bheppz)]n (2), with mercury volatilizing from the system at elevated temperatures.