Hydrogen-bonded mononuclear nickel(II) benzoate complexes: synthesis and structural studies

Abstract

Tp Ph,Me Ni(Cl)Pz Ph,Me H] (1) has been synthesized by the reaction of hydrotris(3-phenyl-5-methyl-pyrazol-1-yl) borate [Tp Ph,Me ], NiCl 2 Á 6H 2 O and 3-phenyl-5-methyl-pyrazole [Pz Ph,Me H]. The reaction of 1 with variously substituted sodium p-X-benzoates resulted in the formation of complexes of the type [Tp Ph,Me Ni(p-XOBz)Pz Ph,Me H] (X = H for 2, F for 3, Cl for 4, NO 2 for 5, Me for 6, OMe for 7, OH for 8, CHO for 9 and CN for 10). Single crystal X-ray studies suggest that all these complexes have a five-coordinate metal center and the benzoate groups are monodentate in a square pyramidal geometry. The X-ray studies also reveal that the uncoordinated oxygen atom of the benzoate forms intramolecular hydrogenbonds with the NH group of the coordinated pyrazole. The substituents present on the benzoate ring are involved in different types of intermolecular interactions and the complexes exhibit different crystal packing. Complexes 2-10 were tested for superoxide dismutase activity.

Scorpionato Halide Complexes [(TpPh,Me)Ni–X] [X = Cl, Br, I; TpPh,Me = Hydrotris(3‐phenyl‐5‐methyl‐1‐pyrazolyl)borate]: Structures, Spectroscopy, and Pyrazole Adducts

“…We also obtained the pentacoordinate pyrazole adducts [(Tp Ph,Me )Ni(Hpz Ph,Me )(X)] ( Figure 3: X = Cl, [20][21][22][23] I) as side products; the pale green crystals readily contrast with pink or purple [(Tp Ph,Me )Ni-X]. A neutral Hpz Ph,Me ligand is coordinated to nickel through N1, whereas N2 carries a tautomeric proton that exhibits a short contact to the proximal halide.…”

“…A neutral Hpz Ph,Me ligand is coordinated to nickel through N1, whereas N2 carries a tautomeric proton that exhibits a short contact to the proximal halide. Two X-ray structures of pseudo-polymorphic chloride adducts [(Tp Ph,Me )Ni-(Hpz Ph,Me )(Cl)]·C 7 H 8 [22] (UGEYAH.cif) [24,25] and [(Tp Ph,Me )-Ni(Hpz Ph,Me )(Cl)]·H 2 O [23] (DIHLIR.cif) [24,25] were recently reported; [(Tp Ph,Me )Ni(Hpz Ph,Me )(Cl)]·0.5MeCN obtained herein is isomorphous with the latter. Two X-ray structures of pseudo-polymorphic chloride adducts [(Tp Ph,Me )Ni-(Hpz Ph,Me )(Cl)]·C 7 H 8 [22] (UGEYAH.cif) [24,25] and [(Tp Ph,Me )-Ni(Hpz Ph,Me )(Cl)]·H 2 O [23] (DIHLIR.cif) [24,25] were recently reported; [(Tp Ph,Me )Ni(Hpz Ph,Me )(Cl)]·0.5MeCN obtained herein is isomorphous with the latter.…”

“…[52] [(Tp Ph,Me )-Ni(Hpz Ph,Me )(Cl)] is slightly distorted towards a trigonalbipyramidal geometry (τ 5 = 0.54) in the toluene solvate [22] (UGEYAH.cif), [24,25] but towards a square pyramid in the other pseudo-polymorph, τ 5 = 0.45-0.46 [23] (DIHLIR. [52] [(Tp Ph,Me )-Ni(Hpz Ph,Me )(Cl)] is slightly distorted towards a trigonalbipyramidal geometry (τ 5 = 0.54) in the toluene solvate [22] (UGEYAH.cif), [24,25] but towards a square pyramid in the other pseudo-polymorph, τ 5 = 0.45-0.46 [23] (DIHLIR.…”

“…Synthesis and characterization of [(Tp Ph,Me )Ni-Cl] were reported previously; [7,18] in the present work, a disolvated pseudo-polymorph [(Tp Ph,Me )Ni-Cl]· 2CH 2 Cl 2 was obtained, as well as the halide complexes [(Tp Ph,Me )Ni-X] (X = Br, I). [20][21][22][23] [19] We also investigated the pentacoordinate pyrazole adducts [(Tp Ph,Me )Ni(Hpz Ph,Me )(X)] (X = Cl, I); the pentaco-ordinate pyrazole adduct [(Tp Ph,Me )Ni(Hpz Ph,Me )(Cl)] was reported previously, [20][21][22][23] but the iodide analogue reported herein is new.…”

“…The structural and spectroscopic data have been rationalized by DFT calculations. [19] We also investigated the pentacoordinate pyrazole adducts [(Tp Ph,Me )Ni(Hpz Ph,Me )(X)] (X = Cl, I); the pentaco-ordinate pyrazole adduct [(Tp Ph,Me )Ni(Hpz Ph,Me )(Cl)] was reported previously, [20][21][22][23] but the iodide analogue reported herein is new. The analogous series [(Tp Me,Me )Ni-X] (X = Cl, Br, I) was reported previously.…”