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

Abstract

Radical anion salts of metal-containing and metal-free phthalocyanines [MPc(3-)](·-), where M = Cu(II), Ni(II), H2, Sn(II), Pb(II), Ti(IV)O, and V(IV)O (1-10) with tetraalkylammonium cations have been obtained as single crystals by phthalocyanine reduction with sodium fluorenone ketyl. Their formation is accompanied by the Pc ligand reduction and affects the molecular structure of metal phthalocyanine radical anions as well as their optical and magnetic properties. Radical anions are characterized by the alternation of short and long C-Nimine bonds in the Pc ligand owing to the disruption of its aromaticity. Salts 1-10 show new bands at 833-1041 nm in the NIR range, whereas the Q- and Soret bands are blue-shifted by 0.13-0.25 eV (38-92 nm) and 0.04-0.07 eV (4-13 nm), respectively. Radical anions with Ni(II), Sn(II), Pb(II), and Ti(IV)O have S = 1/2 spin state, whereas [Cu(II)Pc(3-)](·-) and [V(IV)OPc(3-)](·-) containing paramagnetic Cu(II) and V(IV)O have two S = 1/2 spins per radical anion. Central metal atoms strongly affect EPR spectra of phthalocyanine radical anions. Instead of narrow EPR signals characteristic of metal-free phthalocyanine radical anions [H2Pc(3-)](·-) (linewidth of 0.08-0.24 mT), broad EPR signals are manifested (linewidth of 2-70 mT) with g-factors and linewidths that are strongly temperature-dependent. Salt 11 containing the [Na(I)Pc(2-)](-) anions as well as previously studied [Fe(I)Pc(2-)](-) and [Co(I)Pc(2-)](-) anions that are formed without reduction of the Pc ligand do not show changes in molecular structure or optical and magnetic properties characteristic of [MPc(3-)](·-) in 1-10.

Bis(N‐methylimidazole)‐Substituted Neutral Phthalocyanines {MIII(MeIm)2(Pc)·3–}0 (M = Al, Ga) Containing Radical Trianionic Phthalocyanine Macrocycles

“…The alternation of the C–N(imine) bonds can be attributed to the formation of a 19π‐electron system in the reduced Pc · 3– macrocycle and partial disruption of its aromaticity. Similar changes in the geometry of phthalocyanine macrocycles are observed for all radical anions of metal phthalocyanines with Pc · 3– …”

“…It is seen that both the Soret and Q‐bands are noticeably blueshifted on formation of 1 and 2 (this shift is essentially larger for compound 2 ; Figure b). The appearance of new bands in the NIR range and the blueshift of the Soret and Q‐bands are characteristic of the formation of radical trianionic Pc · 3– macrocycles and are observed in the spectra of radical anion salts with M(Pc) · 3– where M can be H 2 , Ni II , Cu II , Sn II , Pb II , V IV O, Ti IV O, Sn IV Cl 2 , or In III Br …”

“…Unpaired spins appear on the phthalocyanine macrocycles under reduction of metal‐free and metal‐containing phthalocyanines in the presence of organic cations. This provides the formation of anionic phthalocyanines with radical trianionic phthalocyanine macrocycles [M(Pc) · 3– ], where M can be H 2 , Ni II , Cu II , Sn II , Pb II , Ti IV O, V IV O, Sn IV Cl 2 , or In III Br . Several salts were obtained with radical anions and dianions of Mg II Pc, Nb IV OPc, and Zr IV Cl 2 Pc .…”

Valence tautomerism in synthetic models of cytochrome P450

“…One might expect the spin on the thiyl radical to couple with the S = 2 Fe II center. It is possible that either the relaxation of the signal arising from the Fe II center is too fast at RT to be detected in EPR or the coupling between the metal spin and the ligand spin is too weak as has been reported in some transition metal complexes (26)(27)(28). Although density functional theory (DFT) calculation cannot provide optimized geometry of species with higher entropy, a potential energy scan of the Fe-S bond of the aliphatic thiol complex indicates (SI Appendix, Fig.…”

The Salts of Copper Octafluoro- and Hexadecafluorophthalocyanines Containing [CuII(F8Pc)4–]2– Dianions and [CuF16Pc]− Monoanions

“…9), which can be fitted by five components, with g1 . 18 The main spectral feature can be explained as resulting from (1) …”