Effect of reduction on the molecular structure and optical and magnetic properties of fluorinated copper() phthalocyanines

The reduction of copper( ii ) octafluoro- {Cu II (F 8 Pc)} and hexadecafluorophthalocyanines {Cu II (F 16 Pc)} by NaCpCo(CO) 2 in the presence of cryptand[2.2.2] yields new crystalline {cryptand(Na + )}[Cu II (F 8 Pc)&z.rad; 3− ] − ·2C 6 H 4 Cl 2 ( 1 ) and {cryptand(Na + )} 2 [Cu II (F 16 Pc) 4− ] 2− ·C 6 H 14 ( 2 ) salts. Together with two previously characterized salts of Cu II (F x Pc) ( x = 8 and 16), this allows the study of the molecular structure and optical and magnetic properties of fluorinated copper phthalocyanines in different reduction states (−1 and −2). The blue shift of the Q-band increases together with the negative charge on the macrocycle, and new weak bands of the anions appear at 820-1013 nm. Alternation of the N meso -C bonds manifests itself in reduced macrocycles due to a partial disruption of macrocycle aromaticity. In the case of Cu II (F 8 Pc) this effect is nearly two times stronger for dianions than for monoanions. The alternation of the bonds is less pronounced for perfluorinated Cu II (F 16 Pc) n − ( n = 1, 2) anions most probably due to a partial delocalization of the negative charge on fluoro-substituents. The reduction also noticeably elongates the average C-F bonds in Cu II (F 8 Pc). The first reduction centered on the macrocycle leads to the formation of [Cu II (F 8 Pc)&z.rad; 3− ] − in 1 with two S = 1/2 spins positioned on Cu II and the radical trianion (F 8 Pc)&z.rad; 3− macrocycle. As a result, a broad EPR signal is observed with g = 2.1652 at RT attributable to both paramagnetic species having exchange interactions. The formation of dimerized stacks from [Cu II (F 8 Pc)&z.rad; 3− ] − in 1 results in strong enough magnetic coupling of the (F 8 Pc)&z.rad; 3− spins within the dimers ( J / k B = −21.8 cm −1 ), and weaker intramolecular coupling is observed between Cu II and (F 8 Pc)&z.rad; 3− ( J / k B = −10.8 cm −1 ). Coupling between (F 8 Pc)&z.rad; 3− spins from the neighboring dimers is nearly 1.5 times weaker (−14.6 cm −1 ). Under reduction conditions, a second electron also comes to the macrocycle forming diamagnetic F 16 Pc 4− tetraanions. In this case S = 1/2 spin is preserved on Cu II . Magnetic coupling between these centers is weak due to the long distances between them in the [Cu II (F 8 Pc) 4− ] 2− chains of 2 . Salt 2 shows an EPR signal with a HF splitting characteristic of Cu II with g = 2.1806 ( A = 20.11 mT), and g = 1.9597 at RT. New salts based on reduced fluorinated copper( ii ) phthalocyanines were