Trivalent Rare Earth Complexes of the Unsymmetrical 3-(2′-Thienyl)-5-(trifluoromethyl)pyrazolate Ligand

✍ Scribed by Glen B. Deacon; Peter C. Junk; Aron Urbatsch

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: English
• Weight: 424 KB
• Volume: 2011
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.201100487

✦ Synopsis

Abstract

Trivalent rare earth complexes of the unsymmetrical 3‐(2′‐thienyl)‐5‐(trifluoromethyl)pyrazolate (ttfpz) ligand, namely [RE(ttfpz)~3~(thf)~3~]·__n__solv, where thf = tetrahydrofuran [RE = La, solv = PhMe, n = 0.5 (1); RE = Sm, n = 0 (2); RE = Tb, solv = thf, n = 1 (3)], [RE(ttfpz)~3~(thf)~2~] [RE = Y (4), Ho (5), Lu (6), Sc (7)] and [RE(ttfpz)~3~(dme)~2~]·__n__solv, where dme = 1,2‐dimethoxyethane [RE = La, n = 0 (8a); RE = La, solv = Et~2~O, n = 0.5 (8b); RE = Eu, solv = dme, n = 1 (9)], were prepared, mainly by redox transmetallation/protolysis from the free metal, Hg(C~6~F~5~)~2~ and ttfpzH, and structurally characterised. In the nine‐coordinate, pseudo‐octahedral complexes 1 and 2, η^2^‐pyrazolate and thf ligands are in a facial arrangement, whereas they are arranged meridionally in 3. In the eight‐coordinate complexes 4–7 the arrangement of the η^2^‐pyrazolate and thf ligands can be described as in between pseudo‐trigonal bipyramidal and ‐square pyramidal. Ten‐coordinate complexes 8a, 8b and 9 exhibit η^2^‐bonded pyrazolates and two chelating dme ligands as opposed to the nine‐coordinate 3,5‐diphenylpyrazolate (Ph~2~pz) complexes [RE(Ph~2~pz)~3~(dme)~2~], which possess one unidentate and one chelating dme ligand, suggesting that the ttfpz ligand is less bulky than Ph~2~pz.