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New Yttrium and Europium(+3) Alkoxides Bearing Thiophene Units: Syntheses, Crystal Structure Determinations and Physico‐Chemical Properties
Author(s) -
Veith Michael,
Belot Céline,
Huch Volker
Publication year - 2012
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201101089
Subject(s) - chemistry , toluene , europium , tetrahydrofuran , pyridine , yttrium , trigonal bipyramidal molecular geometry , alkoxide , crystal structure , dibenzoylmethane , thiophene , molecule , pentagonal bipyramidal molecular geometry , crystallography , medicinal chemistry , organic chemistry , oxide , catalysis , ion , solvent
The synthesis, structural characterization, electrochemistry and luminescence properties of a series of new yttrium and europium(+3) alkoxides bearing thiophene moieties are presented. The yttrium compounds were obtained by the reaction between Y[N(SiMe 3 ) 2 ] 3 and the tertiary alcohols HO–C(C 16 H 13 S) ( 2 ), HO–C(C 17 H 15 S) ( 3 ), HO–C(C 14 H 11 S 2 ) ( 4 ) and HO–C(C 16 H 13 S) ( 5 ) in thf or in a mixture of toluene and pyridine. The X‐ray crystal diffraction measurements show a five‐coordinated yttrium atom in distorted trigonal‐bipyramidal geometry. The metal centres are surrounded by threemethoxido ligands in equatorial positions and two tetrahydrofuran [for {Y[OC(C 16 H 13 S)] 3 (thf) 2 } · toluene ( 8 ), {Y[OC(C 17 H 15 S)] 3 (thf) 2 } · toluene ( 10 ) and {Y[OC(C 14 H 11 S 2 )] 3 (thf) 2 } · 1/2 toluene ( 12 )] or two pyridine [for {Y[OC(C 16 H 13 S)] 3 (py) 2 } · toluene ( 9 ) and {Y[OC(C 17 H 15 S)] 3 (py) 2 } · toluene ( 11 )] molecules in axial positions. The compounds Y[OC(C 14 H 11 S 2 )] 3 (py) 2 ( 13 ) and Y[OC(C 16 H 13 S)] 3 (py) 2 ( 14 ) were identified by NMR spectroscopy. In addition, a novel europium(+3) alkoxide {Eu[OC(C 4 H 3 S) 3 ] 3 (thf) 3 } · thf ( 15 ) was synthesized by the reaction between Eu[N(SiMe 3 ) 2 ] 3 and the tertiary alcohol HO–C(C 4 H 3 S) 3 ( 1 ) in thf. The molecular structure of this compound reveals an approximately octahedral coordination sphere around the europium(+3) metal centre with three methoxido ligands and three facially arranged tetrahydrofuran molecules. The cyclic voltammograms of the yttrium alkoxides indicate that the electrochemical properties are essentially dominated by the organic ligands. The electrochemical properties of {Eu[OC(C 4 H 3 S) 3 ] 3 (thf) 3 } · thf ( 15 ) are dominated by the oxidation of the thienyl moieties and in addition a reduction wave due to the reduction of Eu 3+ to Eu 2+ is visible. In comparison to the carbinols, the oxidation peak potentials of the thienyl units for the yttrium and europium(3+) alkoxides are marginally shifted towards higher values. The emission spectra of the carbinols and their derived yttrium compounds display broad bands attributed to the π*→π transitions of the aromatic ligands. Luminescence studies performed on compound 15 reveal the typical f–f transitions of the Eu 3+ ions and suggest that an energy transfer from the ligand to the metal atom operates.