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$\tilde {3}$ space group. IR, Raman and 19F 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. Mössbauer 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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)