Formation and structural characterization of a europium(II) mono(scorpionate) complex and a sterically crowded pyraza-bole.

The reaction of EuI(2)(THF)(2) with potassium hydro-tris-(3,5-diiso-propyl-pyrazol-yl)borate (K[HB(3,5- (iPr2)pz)(3)] (= KTp (iPr2), pz = pyrazol-yl) in a molar ratio of 1:1.5 resulted in extensive ligand fragmentation and formation of the europium(II) mono(scorpionate) complex bis-(3,5-diisopropyl-1H-pyrazole)[hydro-tris-(3,5-diiso-propyl-pyrazol-yl)borato]iodido-europium(II), [Eu(C(27)H(46)BN(6))I(C(9)H(16)N(2))(2)] or (Tp (iPr2))(3,5- (iPr2)pzH)(2)Eu(II)I, 1, in high yield (78%). As a typical by-product, small amounts of the sterically crowded pyraza-bole derivative trans-4,8-bis-(3,5-diiso-propyl-pyrazol-1-yl)-1,3,5,7-tetra-iso-propyl-pyraza-bole, C(36)H(62)B(2)H(8) or trans-{(3,5- (iPr2)pz)HB(μ-3,5- (iPr2)pz)}(2), 2, were formed. Both title compounds have been structurally characterized through single-crystal X-ray diffraction. In 1, two isopropyl groups are each disordered over two orientations with occupancy ratios of 0.574†(10):0.426†(10) and 0.719†(16):0.281†(16). In 2, one isopropyl group is similarly disordered, occupancy ratio 0.649†(9):0.351†(9).