Formation and structural characterization of a europium(II) mono(scorpionate) complex and a sterically crowded pyrazabole

Abstract

The reaction of EuI2(THF)2with potassium hydrotris(3,5-diisopropylpyrazolyl)borate (K[HB(3,5-iPr2pz)3] (= KTpiPr2, pz = pyrazolyl) 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)[hydrotris(3,5-diisopropylpyrazolyl)borato]iodidoeuropium(II), [Eu(C27H46BN6)I(C9H16N2)2] or (TpiPr2)(3,5-iPr2pzH)2EuIII,1, in high yield (78%). As a typical by-product, small amounts of the sterically crowded pyrazabole derivativetrans-4,8-bis(3,5-diisopropylpyrazol-1-yl)-1,3,5,7-tetraisopropylpyrazabole, C36H62B2H8ortrans-{(3,5-iPr2pz)HB(μ-3,5-iPr2pz)}2,2, were formed. Both title compounds have been structurally characterized through single-crystal X-ray diffraction. In1, 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). In2, one isopropyl group is similarly disordered, occupancy ratio 0.649 (9):0.351 (9).