Lanthanide complexes involving multichelating TTF-based ligands. Issue 4 (1st February 2017)

• Record Type: Journal Article
• Authors: Speed, S.; Feng, M.; Fernandez Garcia, G.; Pointillart, F.; Lefeuvre, B.; Riobé, F.; Golhen, S.; Le Guennic, B.; Totti, F.; Guyot, Y.; Cador, O.; Maury, O.; Ouahab, L.
• Is Part Of: Inorganic chemistry frontiers. Volume 4:Issue 4(2017)
• Page Start: 604
• Page End: 617
• Publication Date: 2017-02-01
• Subjects: Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c6qi00546b
• Languages: English
• ISSNs: 2052-1553

Abstract

Abstract : The TTF-based skeleton could be alkylated with either the di(pyrazol-1-yl)-4-pyridyl (L 1 ) or dimethyl-2, 2′-bipyridine (L 2 ) to design multichelating ligands. The ([Yb2 (hfac)6 (L 1 )]·2(CH2 Cl2 )·C6 H14 (1 ) and [Ln2 (hfac)6 (L 2 )]·CH2 Cl2 (Ln = Yb (2 ) and Dy (3 )) complexes which display either SMM behaviour with the hysteresis loop at 0.5 K or multi-NIR emissions. Abstract : The reaction between the 2-{TTF-fused-1 H -benzimidazol-2-yl}pyridine alkylated with either the di-(pyrazol-1-yl)-4-pyridyl (L 1 ) or dimethyl-2, 2′-bipyridine (L 2 ) moiety and 1 equiv. of Ln(hfac)3 ·2H2 O (Ln III = Dy III and Yb III ) leads to three dinuclear complexes of formula [Yb2 (hfac)6 (L 1 )]·2(CH2 Cl2 )·C6 H14 (1 ) and [Ln2 (hfac)6 (L 2 )]·CH2 Cl2 (Ln III = Yb III (2 ) and Dy III (3 )). The X-ray structures highlight square antiprism ( D 4d symmetry) and spherical tricapped trigonal prism ( D 3h ) for the eight- and nine-coordinated lanthanide ions, respectively. Irradiation of the lowest-energy HOMO → LUMO ILCT absorption band induced a 2 F5/2 → 2 F7/2 Yb-centered emission for1 and2 . Both Yb III ions displayed similar emissions in2 while two distinct emissions, attributed to the two Yb III ions because of their different coordination environments, were observed in1 . Slow magnetic relaxation is detected by dynamic magnetic measurements for3 with a measured relaxation time τ 0 = 3.7(1.3) × 10 −7 s and an energy barrier Δ = 39.6(2) cm −1 . Taking into account the environment of both Dy III ions in3, it was expected that both metallic centers displayed similar dynamic magnetic behavior. The latter was rationalized by ab initio CASSCF/SI-SO calculations.