Synthesis, structure, terahertz spectroscopy and luminescent properties of copper(I) complexes with mercaptan ligands and triphenylphosphine

• Seven new complexes were synthesized and characterized.
• Complexes 1–5 represent first examples of HMNBT and HAMTD with copper(I) halides.
• The complexes 1, 5, 6 and 7 exhibit interesting fluorescence in the solid state.
• THz-TDS of starting materials and complexes were investigated.
• Our results show several factors can affect the THz spectra of the complexes.

The reactions of copper(I) halides with triphenylphosphine (PPh3) and mercaptan ligand [2-mercapto-6-nitrobenzothiazole (HMNBT), 2-amino-5-mercapto-1,3,4-thiadiazole (HAMTD) and 2-mercapto-5-methyl-benzimidazole (MMBD)] yielded seven complexes, [CuCl(HMNBT)(PPh3)2] (1), [CuX(HMNBT)(PPh3)]2 (X = Cl, Br) (2–3), [Cu(MNBT)(HMNBT)(PPh3)2] (4), [CuBr(HAMTD)(PPh3)2]·CH3OH (5) and [CuX(MMBD)(PPh3)2]·2CH3OH (X = Br, I) (6–7). These complexes were characterized by elemental analysis, X-ray diffraction, 1H NMR and 31P NMR spectroscopy. In these complexes the mercaptan ligands act as monodentate or bridged ligand with S as the coordination atom. In complexes 1 and 4, hydrogen bonds CH⋯X and weak interactions CH⋯π lead to the formation of chains and 2D network respectively, while complexes 2 and 3 are dinuclear. In 5–7, intramolecular hydrogen bonds link the [CuX(thione)(PPh3)2] molecules and the solvated methanol molecules into centrosymmetric dimers. Complexes 1–5 represent first copper(I) halide complexes of HMNBT and HAMTD. The complexes 1, 5, 6 and 7 exhibit interesting fluorescence in the solid state at room temperature and their terahertz (THz) time-domain spectroscopy was also studied.