title: High nuclearity complexes of lanthanide involving tetrathiafulvalene ligands: structural, magnetic, and photophysical properties.
abstract: The reaction between the tetrakis(2-pyridyl-N-oxidemethylthio)tetrathiafulvalene ligand (L) and Ln(hfac)(3)·2H(2)O precursors (where hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate anion and Ln = Tb(III) (1), Dy(III) (2), Er(III) (3), and Yb(III) (4) and (4b)) leads to the formation of five tetranuclear complexes of formula [Ln(4)(hfac)(12)(L)(2)](n)·xCHCl(3)·yC(6)H(14) (n = 1, x = 2, y = 0 for (1), (2), and (4), n = 1, x = 4 for (3), and n = 2, x = 2.5, y = 1 for (4b)). Their X-ray structures reveal that the surrounding of each Ln(III) center is filled by two N-oxide groups coming from two different ligands L. These tetranuclear complexes have the highest nuclearity which is reported until now for coordination compounds of lanthanide involving TTF-based ligands. Direct current (dc) measurements highlight the paramagnetic behavior of the compounds with a significant crystal field effect. The temperature dependences of static magnetic measurements for 4 have been fitted. The ground state corresponds to M(J) = ±5/2 while the first excited state (M(J) = ±3/2) was localized at +214 cm(-1) which was well correlated with the luminescence transition. UV-visible absorption properties have been experimentally measured and rationalized by time-dependent density functional theory (TD-DFT) calculations. Upon irradiation at 77 K and room temperature, in the range 24390-20835 cm(-1), both compounds 3 and 4 display a metal-centered luminescence attributed to (4)I(13/2) → (4)I(15/2) (6660 cm(-1)) and (2)F(5/2) → (2)F(7/2) (signal centered around the value of 9966 cm(-1)) transitions, respectively. The observed six transitions could be attributed to the M(J) state splitting due to the existence of two Yb1 and Yb2 ions with slightly different polyhedra in 4.
authors: Organométalliques: Matériaux et Catalyse, UMR 6226 CNRS-UR1 Institut des Sciences Chimiques de Rennes, Université de Rennes 1, 35042, Rennes Cedex, France. fabrice.pointillart@univ-rennes1.fr
authors: Fabrice
authors: F
authors: Pointillart
authors: Boris
authors: B
authors: Le Guennic
authors: Stéphane
authors: S
authors: Golhen
authors: Olivier
authors: O
authors: Cador
authors: Olivier
authors: O
authors: Maury
authors: Lahcène
authors: L
authors: Ouahab
mesh_terms: D006571:Heterocyclic Compounds / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D060526:Magnetic Fields; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D055668:Photochemical Processes
chemical_list: D006571:Heterocyclic Compounds; D028581:Lanthanoid Series Elements; D008024:Ligands; D009942:Organometallic Compounds; C063887:tetrathiafulvalene