Synthesis, thermogravimetric study and crystal structure of an N-rich copper(II) compound with tren ligands and nitrate counter-anions

• A novel N-rich copper(II)-tren complex has been crystallized as a 3-hydrated nitrate salt.
• Tren acts both as tripodal tetradentate and as μ3-tren bridging ligand.
• Copper(II) centers exhibit distorted trigonal bipyramidal coordination.
• Coupled thermogravimetry and FT-IR spectra of evolved gases have been used.
• Decomposition of nitrate anions and tren ligands occurs in an overlapped step.

The compound [{Cu(tren)}3(μ3-tren)]2(NO3)12·3H2O has been synthesized, crystallized and characterized by single crystal X-ray diffraction, thermogravimetry (TG) coupled to FT-IR spectroscopy of the evolved gases, TG–differential scanning calorimetry (DSC) and electronic (diffuse reflectance) and FT-IR spectroscopies. The sample loses the crystallization water between room temperature and 200 °C. The decomposition of the salt begins with an overlapped decomposition of nitrate anions and some tren ligands where CO2, H2O, CO, NH3, N2O, NO and NO2 are evolved (205–235 °C). Then decomposition of additional tren ligands takes place (235–725 °C). Finally a non-pure CuO residue is obtained at 725 °C.

Figure optionsDownload as PowerPoint slideThe N-rich salt [{Cu(tren)}3(μ3-tren)]2(NO3)12·3H2O has been studied by XRD and by coupled TG and FT-IR spectroscopy of the evolved gases. After water loss, thermal decomposition of the nitrate ions and some tren ligands in the salt are overlapped.