Complexes with the general formula [M-II(NCCH3)(6)][TPFB](2) [M = Cr, Fe, Co, Ni, Cu, Zn, (TPFB)(-) = tetrakis-(pentafluorophenyl)borate] were synthesized and characterized both in the solid state and in solution. According to the spectroscopic data, [TPFB] can be considered as a truly noncoordinating anion. The NCCH3 ligands are lost if the samples are kept at room temperature for extended periods of time. Thermolysis leads to the loss of the NCCH3 ligands and decomposition of the anion above 100 degrees C with the formation of MF2. It has to be noted that distortion of the geometries of the Cu-II, Zn-II and Cr-II complexes occurs, as evidenced by infrared spectroscopy. The complexes can be easily prepared and obtained in high yields and are moderately sensitive to air. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).