Dysprosium- and Ytterbium-Based Complexes Involving Tetrathiafulvalene Derivatives Functionalised with 2,2-Bipyridine or 2,6-Di(pyrazol-1-yl)-4-pyridine
Résumé
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 (D3h) or spherical capped square antiprism (C4v) as coordination polyhedra in complexes 1-3. In 4, the YbIII ion adopts an N2O6 eight-coordination with a square antiprism (D4d) coordination sphere. The photophys. properties of the ligands L1 and L3 were studied in both soln. and solid state and rationalised by time-dependent d. functional theory. Complex 2, in which the DyIII ion has the most regular C4v symmetry, behaves as a field-induced single-mol. magnet.