Dysprosium- and Ytterbium-Based Complexes Involving Tetrathiafulvalene Derivatives Functionalised with 2,2′-Bipyridine or 2,6-Di(pyrazol-1-yl)-4-pyridine.

Two new tetrathiafulvalene-based ligands { L¹ = 4,5-bis[2,6-di(pyrazol-1-yl)-4-pyridylmethylthio]-4′,5′-bis(methylthio)tetrathiafulvene, L³ = 4-(4′-methyl-2,2′-bypiridin-4-ylmethylthio)-5-(2-cyanoethylthio)-4′,5′-ethylenedithiotetrathiafulvene} have been elaborated and four new lanthanide coordination complexes, namely [Dy₂(hfac)₆( L¹)] ·C₆H₁₄ ( 1; hfac^- = 1,1,1,5,5,5-hexafluoroacetylacetonate), [Ln(hfac)₃( L²)] ·CH₂Cl₂ {Ln = Dy ( 2) and Yb ( 3); L² = 4,5-bis[2,6-di(pyrazol-1-yl)-4-pyridylmethylthio]-4′,5′-ethylenedithiotetrathiafulvene} and [Yb(hfac)₃( L³)] ( 4) were isolated as single crystals. The lanthanide ions adopt an N₃O₆ nine-coordination with either a spherical tricapped trigonal prism ( D_{3 h}) or spherical capped square antiprism ( C_{4 v}) as coordination polyhedra in complexes 1- 3. In 4, the Yb^III ion adopts an N₂O₆ eight-coordination with a square antiprism ( D_{4 d}) coordination sphere. The photophysical properties of the ligands L¹ and L³ were studied in both solution and solid state and rationalised by time-dependent density functional theory. Complex 2, in which the Dy^III ion has the most regular C_{4 v} symmetry, behaves as a field-induced single-molecule magnet. [ABSTRACT FROM AUTHOR]