New Coordination Compounds of CuII with Schiff Base Ligands-Crystal Structure, Thermal, and Spectral Investigations

The new mono-, di- and tetranuclear coordination compounds [Cu(HL1)]center dot H2O (1), [Cu-2(L-1)(OAc)(MeOH)]center dot 2H(2)O center dot MeOH (2), [Cu-4(L-2)(2)(OAc)(2)]center dot 4MeOH (3), and [Cu-4(L-2)(2)(OAc)(2)]center dot 4H(2)O center dot 4MeOH (4) were synthesized by the direct reaction of 2,2 '-{(2-hydroxypropane-1,3-diyl)bis[nitrilomethylidene]}bis(4-bromo-6-methoxyphenol) (H3L1) or 2,2 '-{(2-hydroxypropane-1,3-diyl)bis(nitriloeth-1-yl-1-ylidene)}diphenol (H3L2) and the Cu(II) salt. They were characterized by elemental analysis, X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, simultaneous thermal analysis and differential scanning calorimetry (TG/DSC), and thermal analysis coupled with Fourier transform infrared spectroscopy (TG-FTIR) techniques and the single crystal X-ray diffraction study. In the dinuclear complex 2, the copper(II) ions are bridged by an alkoxo- and a carboxylato bridges. The tetranuclear complexes 3 and 4 are formed from dinuclear species linkage through the phenoxo oxygen atoms of the fully deprotonated H3L2. Compounds 1-4 are stable at room temperature. During heating in air, at first, the solvent molecules (water and/or methanol) are lost and after that, the organic part undergoes defragmentation and combustion. The final decomposition solid product is CuO. The main gaseous products resulting from the thermal degradation of 1-4 in a nitrogen atmosphere were: H2O, MeOH, CH3COOH, CH4, C6H5OH, CO2, CO, and NH3.