Polymeric polynuclear systems of Pr, Yb and Pr:Cu trichloroacetates; their spectroscopy and magnetism

Abstract

Heteronuclear copper–lanthanide compounds are the subject of the studies for the reason of their unusual structure features, optical, magnetic, catalytic properties and because of their potential application in superconducting ceramics. Synthesis, spectroscopic and magnetic characterisation of polymeric one-dimensional lanthanide (Pr, Yb) trichloroacetates (I, II) and heteronuclear CuPr2(Cl3CCOO)8·6H2O (III) single crystals were undertaken. Structures of I, II are isomorphic with erbium trichloroacetate and that of III with respective neodymium compound. In the structure of III the polymeric chain is built of dimers of two crystallographically independent types of PrO8/9 polyhedra linked by carboxyl bridges. These dimers are separated by square planar coordinated cooper ions bridged to the lanthanide by four carboxyl groups and two water molecules. High resolution spectra down to 4 K were investigated and cooperative effects were analysed. Magnetic susceptibility measurements in the range 300–1.8 K were carried out. Optical and magnetic properties are discussed on the basis of X-ray data. Electron transition probabilities were calculated and cooperative interaction of ion-pairs coupled in polymeric chain was considered. Vibronic components were observed and assigned on the basis of Raman data.