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

Abstract

The reaction of EuI 2 (THF) 2 with potassium hydrotris(3,5-diisopropylpyrazolyl)borate (K[HB(3,5-iPr2 pz) 3 ] (= KTp iPr2, 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(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 pyrazabole derivative trans-4,8-bis(3,5-diisopropylpyrazol-1-yl)-1,3,5,7-tetraisopropylpyrazabole, 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).