Of Tcnq Rare Earth Complexes Synthesis, Characterization And Performance Study

A series of TCNQ (TCNQ = tetracyano-p-quinodimethane) lanthanide(III) complexes, namely, [Ln₂(TCNQ)₄(H₂O)₁₀(EtOH)₂][(TCNQ)₂]·2H₂O [Ln = La (1), Pr (2)], [Ln₂(TCNQ)₄(H₂O)₁₂][(TCNQ)₂]·2H₂O·MeOH [Ln = Ce (3), Nd (4), Sm (5)], [Ln₂(TCNQ)₄(H₂O)₁₀][(TCNQ)₂]·3H₂O [Ln = Gd (6), Dy (7)] and [Ln(TCNQ)₂(H₂O)₆][(TCNQ)_0.5(TCNQ)_0.5]·H₂O·2MeOH [Ln = Er (8), Lu (9)], have been synthesized using standard Schlenk techniques under nitrogen in this paper.Complexes 1-9 have been structurally characterized by single-crystal X-ray crystallographic analysis. In 1-7, two TCNQ molecules bridge two Ln(III) ions and another two TCNQ ligands coordinate to two Ln(III) ions in terminal mode. In 8 and 9, two TCNQ ligands coordinate to one Ln(III) ion in terminal mode. The Ln(III) ions are nine-coordinated in 1-5, while the Ln(III) ions are eight-coordinated in 6-9The electrochemical properties of 1-9 have been investigated by cyclic voltammetry in acetonitrile solution of tetra-n-butylammonium hexafluorophosphate. One reversible one-electron oxidation and one reversible or quasi-reversible one-electron reduction have been observed for complexes 1-8. The differences in half-wave redox potentials of the oxidation and reduction for 1-8 decrease linearly along with decreasing the ion radius of lanthanide metals, indicating the lanthanide contraction law.The variable-temperature magnetic properties of 2 and 6-8 have been investigated over the temperature range 2-300 K at 500 Oe. The complex 6 shows a weak ferromagnetic interaction between Gd(III) ions, while an antiferromagnetic interaction exists between Ln(III) ions in complexes 2, 7 and 8.