Syntheses, structures, electrochemical and optical properties of four transition metal complexes based on the 1-triazolyl-3-benzimidazolyltriazene ligand

Abstract

Four transition metal complexes based on the 1-triazolyl-3-benzimidazolyltriazene (H₃TBIT) ligand of [Co(H₂TBIT)(HTBIT)] (1), {[Cu(H₂TBIT)(SCN)]·H₂O} (2), [Cd₂(H₃TBIT)₂(H₂O)₂Cl₄] (3) and {[Ni₃(H₂TBIT)₂(HTBIT)₂(en)₂]·IPA·2H₂O} (en = ethylenediamine, IPA = isopropanol) (4) have been synthesized and characterized by single crystal X-ray diffraction analysis. In 1–4, the triazene ligand acts in different coordinating or bridging modes resulting in two mononuclear structures for 1 and 2, one dinuclear structure for 3 and one trinuclear structure for 4. Different structural 1–4 are further self-assembled through hydrogen bonds or π–π, C–H⋯π or metal–π interactions to form 3D supramolecular structures. The electrochemical properties in aqueous solutions as well as the photoluminescent properties in ethanol of H₃TBIT and 1–4 are investigated. The TD-DFT calculations at the B3LYP/6-311++G(d,p) level for H₃TBIT has been used to demonstrate the characteristic absorption spectrum.