Molecular structure, optical and magnetic properties of metal-free phthalocyanine radical anions in crystalline salts (H2Pc˙−)(cryptand[2,2,2][Na+])·1.5C6H4Cl2 and (H2Pc˙−)(TOA+)·C6H4Cl2 (TOA+ is tetraoctylammonium cation)

Abstract

Ionic compounds containing radical anions of metal-free phthalocyanine (H2Pc˙(-)): (H2Pc˙(-))(cryptand[2,2,2][Na(+)])·1.5C6H4Cl2 (1) and (H2Pc˙(-))(TOA(+))·C6H4Cl2 (2) have been obtained as single crystals for the first time. Their crystal structures have been determined, and optical and magnetic properties have been investigated. The H2Pc˙(-) radical anions have a slightly bowl-like shape with four pyrrole nitrogen atoms located below the molecular plane, while four phenylene substituents are located above this plane. Changes in the average length of N-C and C-C bonds in H2Pc˙(-) in comparison with those in neutral H2Pc indicate that negative charge is mainly delocalized over the 24-atom phthalocyanine ring rather than the phenylene substituents. The H2Pc˙(-) formation is accompanied by a shift of up to 10 cm(-1) and disappearance of some intense IR-active bands whereas the band of the N-H stretching mode is shifted by 21-27 cm(-1) to larger wavenumbers. New bands attributed to H2Pc˙(-) appear in the NIR spectra of the salts with maxima at 1033 and 1028 nm for 1 and 2, respectively. The formation of H2Pc˙(-) is accompanied by the splitting of the Soret and Q-bands of H2Pc into several bands and their blue-shift up to 32 nm. Narrow EPR signals with g = 2.0033 and linewidth of 0.16-0.24 mT at room temperature in the spectra of the salts were attributed to the H2Pc˙(-) radical anions. According to SQUID measurements they have S = 1/2 spin states with effective magnetic moments of 1.73 (1) and 1.78 (2) μB at 300 K. Magnetic behavior of 1 and 2 follows the Curie-Weiss law with negative Weiss temperatures of -0.9 and -0.5 K, respectively, indicating weak antiferromagnetic interactions of spins. The EPR signal splits into two lines below 120 and 80 K for 1 and 2, respectively and these lines are noticeably broadened below 25 K.

Layered Salts with Iron Hexadecachlorophthalocyanine Anions – The Formation of [{FeCl16Pc}2]3– Dimers Containing [FeICl16Pc(2–)]– and Diamagnetic [Fe0Cl16Pc(2–)]2–

“…Potentially, upon the formation of the (FeCl 16 Pc) 2– dianions, the second electron can be localized on the iron atoms to form [Fe 0 Cl 16 Pc(2–)] 2– , or it can be transfered to the phthalocyanine macrocycles to form [Fe I Cl 16 Pc(3–)] 2– . The formation of negatively charged phthalocyanine macrocycles in the salts with radical anions of metal‐free phthalocyanine (H 2 Pc · – ) and some metal(II) phthalocyanines is accompanied by the appearance of an intense band in the NIR range9,21 [for example, in the spectrum of (H 2 Pc · – )(TOA + ) · C 6 H 4 Cl 2 (TOA + is the tetraoctylammonium cation) this band is observed at 1024 nm, Figure 5, a]. The spectrum of salt 2 is shown in Figure 5 (b).…”

“… Spectra of the (H 2 Pc · – )(TOA + ) · C 6 H 4 Cl 2 salt (a) with metal‐free phthalocyanine radical anions,9 salt 2 (b), and parent Fe II Cl 16 Pc (c) in KBr pellets. …”

Synthesis, Structures, and Properties of Crystalline Salts with Radical Anions of Metal‐Containing and Metal‐Free Phthalocyanines

“…EPR and SQUID magnetic measurements were performed on polycrystalline samples of 1-11 sealed in 2 mm quarz tubes under 10 À5 Torr. (11) were obtained by the reduction of silver(II) phthalocyanine (25.8 mg, 0.042 mmol) by using excess of sodium fluorenone ketyl (16 mg, 0.0789 mmol) in the presence of TBABr (50 mg, 0.1551 mmol) for two hours at 100 8C until phthalocyanines were completely dissolved and a green solution had formed. The solution was cooled down to room temperature, stirred for two more hours, and filtered into a tube for diffusion.…”

“…[11] We analyzed magnetic properties of 1-11 by SQUID and EPR techniques on polycrystalline samples (Table 4 [25] The highest negative Weiss temperatures of À17 and À57 K were found for 7 and 8. [26,27] The g-factor of these salts drastically increased with decreasing temperature from g = 2.031 near room temperature to g = 2.292 at 20 K (g ?…”

Synthesis of Iron(II) Octachlorotetrapyrazinoporphyrazine, Molecular Structure and Optical Properties of the (X−)2FeTPyzPACl8 Dianions with Two Axial Anionic Ligands (X− = CN−, Cl−)

“…[12] Now the salts with negatively charged cobalt(I), iron(I) and metal free phthalocyanines and porphyrazines have been obtained. [13][14][15][16][17][18][19] However, anionic phthalocyanines with tetra-coordinated metal atoms are not deeply investigated so far because of weak acceptor properties of metal phthalocyanine and as a result high air sensitivity of their anions. Metal-free phthalocyanines are reduced with potential more negative than -0.6 V, whereas zinc(II), copper(II), nickel(II) and manganese(II) phthalocyanines are reduced with potential -0.8 ÷ -0.9 V. [20] To increase the acceptor ability of metal macroheterocycles electron-withdrawing substituents such as Cl, F or CN can be attached to the phthalocyanine macrocycle or the number of nitrogen atoms in the macrocycle should be increased.…”