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Steric and electronic factor comparisons in hydrotris(3‐phenylpyrazolyl)borate nickel(II) aryloxides
Author(s) -
Green William L.,
Sirianni Eric R.,
Yap Glenn P. A.,
Riordan Charles G.
Publication year - 2016
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229616001789
Subject(s) - nickel , steric effects , tetrahydrofuran , chemistry , boron , intramolecular force , stereochemistry , medicinal chemistry , denticity , metal , solvent , organic chemistry
Hydrotris(pyrazolyl)borate (Tp) ligands, also known as scorpionates, are potent tridentate donors that effectively bind metal ions in a face‐capping array. Hydrotris(3‐phenylpyrazolyl)borate enforces a tetrahedral environment on Ni II to model metalloenzymes. The syntheses and structural characterizations of a number of [hydrotris(3‐phenylpyrazolyl)borato]nickel(II) aryloxides were performed to provide insight into the environment of the model active site; these compounds are chlorido[hydrotris(3‐phenylpyrazolyl‐κ N 2 )borato](3‐phenyl‐1 H ‐pyrazole‐κ N 2 )nickel(II) chloroform monosolvate, [Ni(C 27 H 22 BN 6 )Cl(C 9 H 8 N 2 )]·CHCl 3 , (2), [hydrotris(3‐phenylpyrazolyl‐κ N 2 )borato](phenolato‐κ O )nickel(II), [Ni(C 27 H 22 BN 6 )(C 6 H 5 O)], (3), (2,6‐dimethylphenolato‐κ O )[hydrotris(3‐phenylpyrazolyl‐κ N 2 )borato]nickel(II) [Ni(C 27 H 22 BN 6 )(C 8 H 9 O)], (4), (4‐ tert ‐butylphenolato‐κ O )[hydrotris(3‐phenylpyrazolyl‐κ N 2 )borato]nickel(II), [Ni(C 27 H 22 BN 6 )(C 10 H 13 O)], (5), and [hydrotris(3‐phenylpyrazolyl‐κ N 2 )borato](phenolato‐κ O )(tetrahydrofuran‐κ O )nickel(II) tetrahydrofuran monosolvate, [Ni(C 27 H 22 BN 6 )(C 6 H 5 O)(C 4 H 8 O)]·C 4 H 8 O, (6). Alkyl groups, e.g. tert ‐butyl in (5) and methyl in (4), electronically activate the aryloxide group to intramolecular π–π stacking but can be frustrated by steric encumbrance at the interacting ring faces. The flexibility at the nickel coordination site, afforded by the uncrowded B atom of the Tp Ph ligand, allows tetrahydrofuran coordination in the phenolate compound.