Synthesis, X-ray Structures, and Optical and Magnetic Properties of Cu(II) Octafluoro-octakisperfluoro(isopropyl)phthalocyanine: The Effects of Electron Addition and Fluorine Accretion.

The stepwise reduction of copper(II) 1,4,8,11,15,18,22,25-octafluoro-2,3,9,10,16,17,23,24-octakisperfluoro(isopropyl) phthalocyanine (CuFPc) in -dichlorobenzene (CHCl) by potassium graphite in the presence of cryptand(K), abbreviated L, results in the formation of (L)[Cu(FPc)]·2CHCl (), (L)[Cu(FPc)]·CHCl (), and (L)[Cu(FPc)] () complexes. Single-crystal X-ray structures revealed their composition and a monotonic increase with increased phthalocyanine (Pc) negative charges of the magnitude of alternative shortening and elongation of the prior equivalent N-C bonds. The complexes are separated by bulky CF substituents, large cryptand counterions, and solvent molecules. Weak, new bands are generated in the visible and near-infrared (NIR) domains upon reductions. The one-electron reduced complex, [Cu(FPc)], is a diradical, exhibiting broad electron paramagnetic resonance (EPR) signals, with intermediate parameters between those typical to Cu and FPc. The two-electron reduced complexes, [Cu(FPc)], contain a diamagnetic FPc macrocycle and a single spin, = 1/2, on Cu. The bulky perfluoroisopropyl groups are suppressing intermolecular π-π interactions between Pcs in the [Cu(FPc)] ( = 3, 4) anions, -, similar to the case of the nonreduced complex. However, π-π interactions between and -dichlorobenzene are observed. The d and Pc electrons in are antiferromagnetically coupled, = -0.56 cm, as revealed by superconducting quantum interference device (SQUID) magnetometry, but the coupling is at least 1 order of magnitude smaller compared with the coupling observed for Cu(FPc) and Cu(FPc), a testimony to the F accretion effect of rendering the Pc macrocycle progressively more electron-deficient. The data for Cu(FPc) provide structural, spectroscopic, and magnetochemical insights, which establish a trend of the effects of fluorine and charge variations of fluorinated Pcs within the macrocycle series Cu(FPc), = 8, 16, 64. Diamagnetic Pcs might be useful for photodynamic therapy (PDT) and related biomedical applications, while the solvent-processable biradicalic nature of the monoanion salts may constitute the basis for designing robust, air-stable electronic, and magnetically condensed materials.