Structure and paramagnetic properties of tris-pivaloyltrifluoracetonate thulium(III) complexes with 18-crown-6 by X-ray analysis and NMR

Abstract

Synthesis and the crystal structure of a novel complex Tm(III) tris-pivaloyltrifluoracetonate, [Tm2(ptf)6] (I) and Tm(III)-tris-pivaloyltrifluoracetonate-(isopropanol)aqua with 18-crown-6 {[Tm(ptf)3(HOCH(CH3)2)H2O]×(18-crown-6)} (II) are reported. A single crystal X-ray diffraction study revealed that complex I has molecular structure which consists of discrete dimeric [Tm2(ptf)6] molecules. Two thulium atoms are located at the 3.7993(2)Å distance. Complex II has molecular structure with hydrogen bonds between oxygen atoms of water molecule and 18-crown-6. Thermogravimetric data evidence the volatility of compound I. It was found by 1H NMR that complexes I, II, [Tm(H2O)(ptf)3] and [Tm(H2O)(ptf)3]×(18-crown-6) may be used (due to the substantial temperature dependence of the paramagnetic lanthanide-induced shifts {LIS}) as NMR thermometric sensors for controlling the local temperature in organic media. According to our information this is the first example of a detailed study of the essential temperature dependence of the LIS on 1/T for Tm complexes in organic media.