OPTICAL-PROPERTIES AND STRUCTURE OF LN(NCS)(HMPA)(4)-(SCN)(2)-HGCL(SCN)

Praseodymium, neodymium and europium complexes of the formula Ln(NCS)( IImpa)(4)-(SCN)(2)-IIgCl(SCN) were synthesised from non-aqueous soluti ons. The structure of neodymium complexes was determined by X-ray diff raction. The crystals of the title compounds crystallise in the space group Cc, where lanthanide ions are coordinated to seven ligand groups : four of Hmpa molecules and three SCN- ions. The compounds were chara cterised by IR, luminescence, excitation and absorption spectra at 6, 77, and 298 K. Probabilities of electronic transitions for Pr3+ ion we re examined at 6 K and at room temperatures. Vibronic components were observed and analyzed on the basis of IR and Raman data. Asymmetric ar rangement of Ln ions was found from X-ray analysis and its influence o n optical properties of active centre was discussed.