Electrochemically Directed Synthesis of Co 2+ and Ni 2+ Complexes with TCNQF 4 2– (TCNQF 4 = 2,3,5,6‐Tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane)

The electrocrystallization of transition metal coordination polymers MTCNQF 4 containing TCNQF 4 2– dianions and M 2+ cations (TCNQF 4 = 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane, M = Co or Ni) has been achieved in acetonitrile (0.1 M Bu 4 NPF 6 ) at glassy carbon and indium tin oxide electrodes and the reaction pathway monitored by cyclic voltammetry and surface plasmon resonance. TCNQF 4 is sequentially reduced to TCNQF 4 · – and then TCNQF 4 2– . In the presence of M 2+ , the TCNQF 4 2– formation is accompanied by the electrocrystallization of the sparingly soluble MTCNQF 4 on the electrode surface. Cyclic voltammetry studies reveal that two phases of MTCNQF 4 are formed. One is kinetically favoured and rapidly converts to a second thermodynamically stable phase. The formation of MTCNQF 4 is possible because of the relatively high solubility of M(TCNQF 4 ) 2 derivatives. The solubilities of CoTCNQF 4 and NiTCNQF 4 are 8.6 × 10 –6 and 9.2 × 10 –6 M , respectively, in neat acetonitrile and 2.2 × 10 –5 and 2.4 × 10 –5 M , respectively, in an acetonitrile solution containing Bu 4 NPF 6 (0.1 M ). The presence of TCNQF 4 2– dianions rather than TCNQF 4 · – monoanions in the coordination polymers was confirmed by UV/Vis, IR and Raman spectroscopy. Scanning electron microscopy images show that the morphology of the electrocrystallized MTCNQF 4 depends on the applied potential for CoTCNQF 4 , but not for the NiTCNQF 4 complex.