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Synthesis and Characterization of Copper(II), Zinc(II), and Potassium Complexes of a Highly Fluorinated Bis(pyrazolyl)borate Ligand

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journal contribution
posted on 17.01.1996, 00:00 by H. V. Rasika Dias, John D. Gorden
Highly fluorinated, dihydridobis(3,5-bis(trifluoromethyl)pyrazolyl)borate ligand, [H2B(3,5-(CF3)2Pz)2]- has been synthesized and characterized as its potassium salt. The copper(II) and zinc(II) complexes, [H2B(3,5-(CF3)2Pz)2]2Cu and [H2B(3,5-(CF3)2Pz)2]2Zn, have been prepared by metathesis of [H2B(3,5-(CF3)2Pz)2]K with Cu(OTf)2 and Zn(OTf)2, respectively. All the new metal adducts have been characterized by X-ray diffraction. The potassium salt is polymeric and shows several K···F interactions. The Cu center of [H2B(3,5-(CF3)2Pz)2]2Cu adopts a square planar geometry, whereas the Zn atom in [H2B(3,5-(CF3)2Pz)2]2Zn displays a tetrahedral coordination. Bis(pyrazolyl)borate ligands in the Zn adduct show a significantly distorted boat conformation. The nature and extent of this distortion is similar to that observed for the methylated analog, [H2B(3,5-(CH3)2Pz)2]2Zn. This ligand allows a comparison of electronic effects of bis(pyrazolyl)borate ligands with similar steric properties. Crystallographic data for [H2B(3,5-(CF3)2Pz)2]K:  triclinic, space group P1̄, with a = 8.385(1) Å, b = 10.097(2) Å, c = 10.317(1) Å, α = 104.193(9)°, β = 104.366(6)°, γ = 91.733(9)°, V = 816.5(3) Å3, and Z = 2. [H2B(3,5-(CF3)2Pz)2]2Cu is monoclinic, space group C2/c with a = 25.632(3) Å, b = 9.197(1) Å, c = 17.342(2) Å, β = 129.292(5)°, V = 3164.0(6) Å3, and Z = 4. [H2B(3,5-(CF3)2Pz)2]2Zn is triclinic, space group P1̄, with a = 9.104(1) Å, b = 9.278(1) Å, c = 18.700(2) Å, α = 83.560(6)°, β = 88.200(10)°, γ = 78.637(9)°, V = 1538.8(3) Å3, and Z = 2. [H2B(3,5-(CH3)2Pz)2]2Zn is monoclinic, space group C2/c with a = 8.445(1) Å, b = 14.514(2) Å, c = 19.983(3) Å, β = 90.831(8)°, V = 2449.1(6) Å3, and Z = 4.

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