Synthesis and structures of tris(pyrazolyl)hydroborato metal complexes as structural model compounds of carbonicanhydrase

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

“…The iodide complex is unique among structurally characterized [(Tp 3R,5R )Ni-X] analogues (Table S1 in Supporting Information). [6,7,9,11,19,[26][27][28][29][30][31][32] The Ni-I bond length of 2.4945(4) Å compares well to distances of 2.479(2) and 2.495(2) Å found in the zinc analogue, [33] and also to a range of 2.48-2.57 Å observed for seven examples of neutral pseudotetrahedral nickel(II) complexes with three distinct classes of tripodal supporting ligation. [34][35][36][37] For two series of isomorphous pseudotetrahedral structures, [(Tp tBu,Me )Fe-X] (X = F, Cl, Br, I) [5] and [(Tp tBu )Zn-X] (X = Cl, Br, I), [38] the observed M-X bond lengths increase in parallel with increasing ionic radius of the halide anion ( Figure S1 in the Supporting Information).…”

“…Moreover, there is some offsetting effect on the scorpionate ligation, which is principally determined by the steric and electronic effects that arise from the pattern of pyrazole substitution. [6,7,11,[26][27][28][29][30][31] Ni-N bond length correlation not shown (r 2 = 0.07). A range of Ni-N-N-B torsion is also obtained, and the Ni-N bond lengths primarily reflect the size of the 3-and 5-pyrazole substituents present on the scorpionate ligand.…”

Ni(II), Co(II) and Mn(II) tris(pyrazolyl)borate complexes with 2,6-di-tert-butyl-4-carboxy-phenol: Formation of coordinated phenoxyl radical

“…2). Guo et al [22] have previously reported an example of such coordination of benzoate in a tris(pyrazolylborate) complex.…”

Efficient mechanochemical synthesis of tris(pyrazolylborate) complexes of manganese(II), cobalt(II) and nickel(II)

“…The most wide-spread method for synthesis of tris(pyrazolylborate) complexes of 3d transition metals consists of addition of ligand solution (as Tl-or K-salt) in THF to the solution of metal salt in water, followed by extraction with CH 2 Cl 2 and isolation of the product by column chromatography [13,14]. Alternative methods of synthesis include long (about 2 h) stirring of ether solution of ligand with water solution of metal salt [15] or slow (up to 12 h) reaction of solid metal salt with solution of Tl-or K-salt of tris(pyrazolylborate) in organic solvent [9]. These schemes normally require from 50 to 200 l of organic solvent per mole of complex, and the yields of products vary from 25% to 80%.…”

“…Tris(pyrazolylborate) usually acts as an unique tridentate, monoanionic, tripodal ligand, leaving at least one coordination site available for another donor group. Such coordination is especially suitable for development of homogeneous catalysts [5][6][7], modeling of metalloenzyme active sites [8,9] and synthesis of polynuclear complexes [7,10], etc. Variation of the substituents on the pyrazole rings of tris(pyrazolylborate) allows versatile control of the steric shielding of the metal center [11], or fine tuning of the electronic influence of ligand on metal [12], which is less accessible for other classes of tripods.…”