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The preparation and characterization of a series of complexes of the Yb and Eu cations in the oxidation state II and III with the tetradentate N,O-donor tripodal ligands (tris(2-pyridylmethyl)amine (TPA), BPA− (HBPA=bis(2-pyridylmethyl)(2-hydroxybenzyl)amine), BPPA− (HBPPA=bis(2-pyridylmethyl)(3.5-di- tert-butyl-2-hydroxybenzyl)amine), and MPA2− (H2MPA=(2-pyridylmethyl)bis(3.5-di- tert-butyl-2-hydroxybenzyl)amine) is reported. The X-ray crystal structures of the heteroleptic Ln2+ complexes [Ln(TPA)I2] (Ln=Eu, Yb) and [Yb(BPA)I(CH3CN)]2, of the Ln2+ homoleptic [Ln(TPA)2]I2 (Ln=Sm, Eu, Yb) and [Eu(BPA)2] complexes, and of the Ln3+ [Eu(BPPA)2]OTf and [Yb(MPA)2K(dme)2] (dme=dimethoxyethane) complexes have been determined. Cyclic voltammetry studies carried out on the bis-ligand complexes of Eu3+ and Yb3+ show that the metal center reduction occurs at significantly lower potentials for the BPA− ligand as compared with the TPA ligand. This suggests that the more electron-rich character of the BPA− ligand results in a higher reducing character of the lanthanide complexes of BPA− compared with those of TPA. The important differences in the stability and reactivity of the investigated complexes are probably due to the observed difference in redox potential. Preliminary reactivity studies show that whereas the bis-TPA complexes of Eu2+ and Yb2+ do not show any reactivity with heteroallenes, the [Eu(BPA)2] complex reduces CS2 to afford the first example of a lanthanide trithiocarbonate complex. [ABSTRACT FROM AUTHOR]

A new series of complexes of Eu2+ and Yb2+ with tripodal aminophenolate ligands are reported by M. Mazzanti and colleagues in their Full Paper on page 15188 ff. Cyclic voltammetry studies show that these ligands can be effectively used to tune the redox properties and reactivity of lanthanide ions possessing weak reducing power. The increased reducing power of Eu2+ in a homoleptic aminophenolate complex allows the reduction of CS2 and affords the first example of a lanthanide trithiocarbonate complex. [ABSTRACT FROM AUTHOR]