Trigonal (-3) symmetry octahedral lanthanide(III) complexes of zwitterionic tripodal ligands: luminescence and magnetism

The Exploration and Analysis of the Magnetic Relaxation Behavior in Three Isostructural Cyano-Bridged 3d–4f Linear Heterotrinuclear Compounds

“…Owing to the coordination ability of the sterically hindered ligands and the difficulty of controlling the coordination orientation, the low-coordinate lanthanide compounds with an axial symmetry are more difficult to obtain. Several reported cases include the nearly linear 2-coordinate (D ∞h ) [21], the equatorially coordinated triangle (C 3 ) [22], the trigonal-pyramidal (pseudo-C 3 ) [23], the five-coordinate [24], and the six-coordinate complexes [9,13,20,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41].…”

“…Relatively lower zero-field energy barriers have been acquired in some six-coordinate Dy-containing examples with a coordination geometry substantially deviated from the ideal octahedron (O h ), such as a trigonal antiprism (U eff = 11 and 14 K) [29], a distorted trigonal prism (U eff = 159 K) [30] and an axially compressed octahedron (for the diluted sample, U eff = 75 K) [31]. Only field-induced energy barriers or even no relaxation parameters could be deduced from the alternating-current (ac) measurements in most of the six-coordinate complexes with more uniform bond lengths [13,[32][33][34][35][36][37][38][39][40][41]. In spite of the above-mentioned six-coordinate dysprosium complexes, as far as we know, an example with a perfect D 4h symmetry has not been found yet [41].…”