Synthesis and characterization of Cu(I) and Zn(II) complexes with new sulfur-bearing isoxazole- or pyrazole-based ligands

The synthesis of the new ligands 6-(5-methyl-1,2-oxazol-3-yl)-2,3-dihydro-5H-[1,4] dithiino[2,3-cipyrrole-5,7(6H)-dione (isox') and 6-(3-methyl-1H-pyrazol-5-yl)-2,3-dihydro-5H-(1,4]dithiino[2,3-cipyrrole-5,7(6H)dione (pyraz' and their coordination chemistry toward Cu(I) and Zn(II), was studied. The ligands and their complexes were characterized using a combination of either multinuclear NMR (H-1 and C-13{H-1}), HRMS, FTIR or Uv-Vis spectroscopy. The solid state structures of ligand isox' and complexes [Cu(pyraz')(2)]OTf and [Zn(OOCCF3)(2)(pyraz')(2)] were determined. Interestingly, isox', presents a yellow luminescence in its free form. Additionally, the ability of isox' to coordinate as an N-O bidentate ligand or as an N-S bridge between two copper centers, forming a coordination polymer, is studied. The solid state structure of this Cu(I)-isox' 1D coordination polymer is also reported. (C) 2015 Elsevier B.V. All rights reserved.