Synthesis and characterization of copper(II), zinc(II), and potassium complexes of a highly fluorinated bis(pyrazolyl)borate ligand

Highly fluorinated, dihydridobis(3,5-bis(trifluoromethyl)pyrazolyl)borate ligand, [H2B(3,5-(CF3)(2)Pz)(2)](-) has been synthesized and characterized as its potassium salt. The copper(II) and zinc(II) complexes, [H2B(3,5-(CF3)(2)Pz)(2)]Cu-2 and [H2B(3,5-(CF3)(2)Pz)(2)]Zn-2, have been prepared by metathesis of [H2B(3,5-(CF3)(2)Pz)(2)]K with Cu(OTf)(2) and Zn(OTf)(2), respectively. Ail 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)(2)Pz)(2)]Cu-2 adopts a square planar geometry, whereas the Zn atom in [H2B(3,5-(CF3)(2)Pz)(2)]Zn-2 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)(2)Pz)(2)]Zn-2. This Ligand allows a comparison of electronic effects of bis(pyrazolyl)borate ligands with similar steric properties. Crystallographic data for [H2B(3,5-(CF3)(2)Pz)(2)]K: triclinic, space group <P(1)over bar>, with a = 8.385(1) Angstrom, b = 10.097(2) Angstrom, c = 10.317(1) Angstrom, alpha = 104.193(9)degrees, beta = 104.366(6)degrees, gamma = 91.733(9)degrees, V = 816.5(3) Angstrom(3), and Z = 2. [H2B(3,5-(CF3)(2)Pz)(2)]Cu-2 is monoclinic, space group C2/c with a = 25.632(3) Angstrom, b = 9.197(1) Angstrom, c = 17.342(2) Angstrom, beta = 129.292(5)degrees, V = 3164.0(6) Angstrom 3, and Z = 4. [H2B(3,5-(CF3)(2)Pz)(2)]Zn-2 is triclinic, space group <P(1)over bar>, with a = 9.104(1) Angstrom, b = 9.278(1) Angstrom, c = 18.700(2) Angstrom, alpha = 83.560(6)degrees, beta = 88.200(10)degrees, gamma = 78.637(9)degrees, V = 1538.8(3) Angstrom(3), and Z = 2. [H2B(3,5-(CH3)(2)Pz)(2)]Zn-2 is monoclinic, space group C2/c with a = 8.445(1) Angstrom, b = 14.514(2) Angstrom, c = 19.983(3) Angstrom, beta = 90.831(8)degrees, V = 2449.1(6) Angstrom 3, and Z = 4.