Sonochemical synthesis and characterization of Ni(C4H6N2)6(PF6)2, Fe(C4H6N2)6(BF4)2, and Ni(C4H6N2)6(BF4)2 in 1-butyl-3-methylimidazole with hexafluorophosphate and tetrafluoroborate

This paper reports on the inorganic sonochemical synthesis of crystalline Ni(C4H6N2)(6)(PF6)(2), Fe(C4H6N2)(6)(BF4)(2), and Ni(C4H6N2)(6)(BF4)(2) in the ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate (BMI)(+)(PF6)(-) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMI)(+)(BF4)(-). The structures of the compounds were determined and refined by using powder X-ray diffraction methods. The salts crystallize in the trigonal P (3) over bar space group. IR, Raman and F-19 NMR spectroscopic studies confirm that the PF6- and BF4- anions are not bonded to the metal cations. Magnetic measurements reveal the paramagnetic nature of the complexes. Mossbauer investigations show that the iron atom in Fe(C4H6N2)(6)(BF4)(2) is in the oxidation +2 state. The broad EPR signals, which reflect the octahedral symmetry of the nickel complexes, were measured for Ni(C4H6N2)(6)(PF6)(2) and Ni(C4H6N2)(6)(BF4)(2). ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).