Layered Salts with Iron Hexadecachlorophthalocyanine Anions – The Formation of [{FeCl₁₆Pc}₂]^3– Dimers Containing [Fe^ICl₁₆Pc(2–)]^– and Diamagnetic [Fe⁰Cl₁₆Pc(2–)]^2–

Abstract

Iron hexadecachlorophthalocyanine (Cl16Pc) salts with a layered arrangement of phthalocyanine (Pc) macrocycles were obtained by the reduction of FeCl16Pc with sodium fluorenone ketyl in the presence of PPNCl [PPN+: bis(triphenylphosphine)iminium cation] and TBABr (TBA+: tetrabutylammonium cation). (PPN+)[(FeICl16Pc)–]·0.78C6H4Cl2·0.22C6H14 (1) contains π–π stacking columns formed by dimerized (FeICl16Pc)– anions. The side‐by‐side arrangement of neighboring columns results in the formation of a layered iron hexadecachlorophthalocyanine structure. (TBA+)3{[(FeCl16Pc)2]3–} (2) contains hexagonal layers formed by [(FeCl16Pc)2]3– dimers and separated by TBA+ cations. The dimers bear –3 charge and, according to optical and X‐ray diffraction data, consist of a [FeI(Cl16Pc)]– monoanion and a [Fe0(Cl16Pc)]2– dianion. These anions are bonded in the dimer by a Fe–Fe bond of 2.899(4) Å length. It was shown that the negative charge in both anions is localized on the iron atoms to form FeI and Fe0, respectively, and no electron transfer to the hexadecachlorophthalocyanine macrocycles is observed. Magnetic data indicate the presence of only one S = 1/2 spin per [(FeCl16Pc)2]3– dimer. This result is in agreement with the formation of iron(I) and iron(0) hexadecachlorophthalocyanine anions, which have the iron atoms in d7 and diamagnetic d8 electron configuration, respectively. The spins of the iron(I) atoms are arranged in a hexagonal manner and only weakly interact, which results in a Weiss temperature of –1 K because of the long distances between them (>18 Å). Previously studied anionic salts with a columnar arrangement of [FeI(Cl16Pc)]– do not show EPR signals from FeI. In contrast, salt 2 shows an intense EPR signal with main components at g⟂ = 2.249 and g∥ = 1.989, which are characteristic of FeI with d7 electron configuration.

Salt of Ring‐Reduced Iron(II) Octaethyltetrapyrazinoporphyrazine Containing Trimetallic Dianions with Peripherally Coordinated ZnCl2 Units: {FeII(TPyzPzEt8)4–(ZnCl2)2}2–

“…The average Fe–N pyr bond length is 1.921(3) Å. This length is rather close to those observed for neutral iron(II) phthalocyanine and reduced iron(I) phthalocyanine and hexadecachlorophthalocyanines . Therefore, the length of the Fe–N pyr bonds is not so sensitive to charge state of the macrocycle.…”

“…Metal centered reduction observed for iron(II) phthalocyanine and hexadecachlorophthalocyanine modifies the spectra in a different way. Three new bands are manifested in the spectra of the salts with iron(I) phthalocyanine and hexadecachlorophthalocyanine anions at about 800–820, 670–680 and 540–550 nm instead of one band of pristine compounds at 662–686 nm . Bands above 900 nm are not observed in the spectra of these salts.…”

“…Potentially another electronic configuration of {Fe I (Macrocycle ●3– )} 2– is also possible for these dianions but in this case radical trianionic macrocycle ●3– are formed. It is known, for example, that iron(II) phthalocyanine or hexadecachlorophthalocynine show only metal‐centered reduction forming {Fe I (Pc) 2– } – , {Fe I (PcCl 16 ) 2– } – and {Fe 0 (PcCl 16 ) 2– } 2– anions . Therefore, reduction of Fe II TPyzPzEt 8 accompanied by ZnCl 2 coordination to the periphery of the macrocycle differs from that of other iron(II) macrocycles.…”

“…Potentially reduced metal phthalocyanines can also manifest promising conducting and magnetic properties. Metal macrocycles can be reduced successfully by strong reductants such as Na/Hg, potassium graphite (KC 8 ) , , LiCp * , decamethylchromocene,, and sodium fluorenone ketyl . Zinc dust can also be used as suitable reductant especially to obtain reduced compounds of iron(II) phthalocyanine or hexadecachlorophthalocyanine , …”

Tetrabutylammonium Salts of Aluminum(III) and Gallium(III) Phthalocyanine Radical Anions Bonded with Fluoren‐9‐olato− Anions and Indium(III) Phthalocyanine Bromide Radical Anions

“…The transition energy of this NIR absorption band is slightly affected by the central metal atom and shifts from λ =920 (for Cu II ) to 1040 nm (for Sn II ) . The [Fe I (Pc 2− )] − and [Co I (Pc 2− )] − anions with reduced central metals do not show such bands . Reduction of the Pc macrocycle in 1 results in a strong blueshift in the Q and Soret bands of the phthalocyanine, which manifests as a split band at λ =590 and 629 nm in the visible region and a single band at λ =334 nm in the UV region.…”