SYNTHESIS, CHARACTERIZATION AND REACTIVITY OF LANTHANIDE(II) POLY(PYRAZOL-1-YL)BORATES (LN=SM, EU AND YB) - FLUORESCENCE STUDIES OF [EUL(2)(THF)(2)] [L=B(PZ)(4), HB(PZ)(3)] - X-RAY CRYSTAL-STRUCTURES OF [EU(B(PZ)(4))(2)(THF)(2)] AND [YB(B(PZ)(4))(3)].C2H5OH

The reaction [LnI(2)(THF)(x)] (Ln = Sm, Eu, Yb) with 2 equiv. of K[B(p z)(4)] (pz = pyrazolyl) in THF resulted in the formation of [Ln{B(pz)( 4)}(2)(THF)(2)] complexes. The molecular structure of [Eu{B(pz)(4)}(2) (THF)(2)] has been determined by single-crystal X-ray diffraction anal ysis. The [Sm{B(pz)(4)}(2)(THF)(2)] and [Yb{B(pz)(4)}(2)(THF)(2)], com plexes are fluxional in solution, as indicated by the equivalence of t he pyrazolyl rings in the H-1 NMR spectra at room temperature. A stati c spectrum could be obtained for the Sm compound at -68 degrees C with a pattern that is in accordance with the geometry found for the Eu co mplex, in the solid state. The complexes [Ln{HB(pz)(3)}(2)(THF)(2)] (L n = Sm, Eu, Yb) have been prepared by the procedure used to synthesize the [Ln{B(pz)(4)}(2)] complexes. The THF molecules can be replaced by 1,2-dimethoxyethane yielding the compounds [Ln{HB(pz)(3)}(2)(DME)] (L n = Sm, Yb). [Sm{B(pz)(4)}(2)(THF)(2)] and [Yb{B(pz)(4)}(2)(THF)(2)] r eact readily with alkyl halides, alcohols or alkynes to yield Ln(III) complexes that disproportionate to the [Ln{B(pz)(4)}(3)] complexes. Th e crystal structure of the compound [Yb{B(pz)(4)}(3)]. C(2)H(5)Oh obta ined in the reaction of [Yb{B(pz)(4)}(2)(THF)(2)] was determined by X- ray diffraction analysis. Fluorescence studies on the Eu compounds are also reported.