Journal Article Side-on coordination mode of a pyrazolyl group in the structure of a divalent [Sm{B(3-Mepz)4}2] complex (3-Mepz is 3-methylpyrazol-1-yl)

Arikawa, Yasuhiro  ,  Inada, Kei-ichiro  ,  Onishi, Masayoshi

C72pp.838 - 841 , 2016-11-01 , International Union of Crystallography
ISSN:20532296
Description
The discovery of polypyrazolylborate ligands allowed the development of various chemical fields and these ligands are an alternative to cyclopentadienyl, because both ligands have the same charge and donate the same number of electrons, as well as adopting the same facial geometry. Easy control of the bulkiness of polypyrazolylborate ligands is possible by modification of the substituents in the 3- and 5-positions of the pyrazolyl rings. The title complex, bis[tetrakis(3-methyl-1H-pyrazol-1-yl)borato]samarium(II), [Sm(C16H20BN8)2], was synthesized from the reaction of SmI2 with potassium tetrakis(3-methyl-1H-pyrazol-1-yl)borate, denoted K[B(3-Mepz)4], in tetrahydrofuran. The X-ray structure analysis revealed an unusual side-on coordination mode of a 3-methylpyrazolyl group through an N=N group in the B(3-Mepz)4 ligand. The distortion is defined by the B - N - N - Sm torsion angle [85.5-(4)°]. This is in contrast to the structure of the similar divalent samarium complex [Sm(Tp )2] [Tp is tris(3,5-dimethylpyrazol-1-yl)borate], which displays normal κ3-bonding modes of the Tp ligands.
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http://naosite.lb.nagasaki-u.ac.jp/dspace/bitstream/10069/37367/1/ActaCrystC72_838.pdf

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