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 (Cu II F 64 Pc) in o -dichlorobenzene (C 6 H 4 Cl 2 ) by potassium graphite in the presence of cryptand(K + ), abbreviated L + , results in the formation of (L + )[Cu II (F 64 Pc •3- )] - ·2C 6 H 4 Cl 2 ( 1 ), (L + ) 2 [Cu II (F 64 Pc 4- )] 2- ·C 6 H 4 Cl 2 ( 2 ), and (L + ) 2 [Cu II (F 64 Pc 4- )] 2- ( 3 ) 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 meso -C bonds. The complexes are separated by bulky i- C 3 F 7 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 II (F 64 Pc •3- )] - , is a diradical, exhibiting broad electron paramagnetic resonance (EPR) signals, with intermediate parameters between those typical to Cu II and F 64 Pc •3- . The two-electron reduced complexes, [Cu II (F 64 Pc 4- )] 2- , contain a diamagnetic F 64 Pc 4- macrocycle and a single spin, S = 1/2, on Cu II . The bulky perfluoroisopropyl groups are suppressing intermolecular π-π interactions between Pcs in the [Cu II (F 64 Pc n - )] ( n -2)- ( n = 3, 4) anions, 1 - 3 , similar to the case of the nonreduced complex. However, π-π interactions between 1 and o -dichlorobenzene are observed. The d 9 and Pc electrons in 1 are antiferromagnetically coupled, J = -0.56 cm -1 , 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 II (F 8 Pc •3- ) and Cu II (F 16 Pc •3- ), a testimony to the F accretion effect of rendering the Pc macrocycle progressively more electron-deficient. The data for Cu II (F 64 Pc) 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 II (F x Pc), x = 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.