Rare-Earth Tetracyanidoborate Salts - Structural Features and Properties Including Luminescence of [RE(H2O)(8)][B(CN)(4)](3)center dot nH(2)O and [RE(H2O)(7){kappa N-1-B(CN)(4)}][B(CN)(4)](2) (RE = Y, Tb, Dy, Ho, Er, Tm, Yb, Lu; n = 3)

摘要

New tetracyanidoborate salts with hydrated rare earth-metal cations (RE3+) were synthesized by the reactions of rare-earth-metal oxides or hydroxides with tetracyanidoboronic acid, H[B(CN)(4)]center dot nH(2)O. Two groups of isostructural compounds were obtained with the formulas [RE(H2O)(8)][B(CN)(4)](3)center dot nH(2)O (structure I) and [RE(H2O)(7){(KN)-N-1-B(CN)(4)}][B(CM4](2) (structure II) for RE = Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu and n <= 3. Both structures have discrete eight-coordinate RE3+ complex cations, as [RE(H2O)(8)](3+) in structure I and [RE(H2O)(7){kappa N-1-B(CN)(4)}](2+) in structure II. The heating of the compounds to temperature of ca. 160 degrees C gives anhydrous samples, but elongated heating to temperatures above ca. 200 degrees C leads to the slow decomposition of the tetracyanidoborates. The luminescence properties of a solid sample of the anhydrous Tb salt and a solution of the Dy salt were investigated. Both show intense lines in their excitation and emission spectra that were assigned to electronic transitions within the f and d shells.