Charge transfer complexes of metal-free phthalocyanine radical anions with decamethylmetallocenium cations: (Cp*2Co+)(H2Pc˙-)·solvent and (Cp*2Cr+)(H2Pc˙-)·4C6H4Cl2

Dmitri V Konarev; Salavat S Khasanov; Manabu Ishikawa; Akihiro Otsuka; Hideki Yamochi; Gunzi Saito; Rimma N Lyubovskaya

doi:10.1039/c7dt00336f

Charge transfer complexes of metal-free phthalocyanine radical anions with decamethylmetallocenium cations: (Cp₂Co⁺)(H₂Pc˙^-)·solvent and (Cp₂Cr⁺)(H₂Pc˙^-)·4C₆H₄Cl₂

Dalton Trans. 2017 Mar 14;46(11):3492-3499. doi: 10.1039/c7dt00336f.

Authors

Dmitri V Konarev¹, Salavat S Khasanov², Manabu Ishikawa³, Akihiro Otsuka³, Hideki Yamochi³, Gunzi Saito⁴, Rimma N Lyubovskaya¹

Affiliations

¹ Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow Region, 142432 Russia. konarev3@yandex.ru.
² Institute of Solid State Physics RAS, Chernogolovka, Moscow Region, 142432 Russia.
³ Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan and Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
⁴ Faculty of Agriculture, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468- 8502, Japan and Toyota Physical and Chemical Research Institute, 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan.

PMID: 28224152
DOI: 10.1039/c7dt00336f

Abstract

Charge transfer complexes (Cp*₂Co⁺)(H₂Pc˙^-)·0.5C₆H₄Cl₂·0.7C₆H₅CN·0.3C₆H₁₄ (1) and (Cp*₂Cr⁺)(H₂Pc˙^-)·4C₆H₄Cl₂ (2) have been obtained as single crystals. Both complexes contain metal-free phthalocyanine (Pc) radical anions and decamethylmetallocenium cations. Reduction of the Pc macrocycle leads to the appearance of new bands at 1026-1030 nm in the NIR range and blue shifts of both Soret and Q-bands of H₂Pc in the spectra of 1 and 2. The geometry of the Pc macrocycles supports the formation of H₂Pc˙^- by the alternation of shorter and longer C-N(imine) bonds in the macrocycles in 2. Complex 1 contains pairs of H₂Pc˙^- having effective π-π interactions with two sandwiched Cp*₂Co⁺ cations, whereas complex 2 contains stacks composed of alternating Cp*₂Cr⁺ and H₂Pc˙^- ions. The magnetic moment of 1 is 1.64 μ_B at 300 K due to the contribution of the H₂Pc˙^- spins with the S = 1/2 state and diamagnetism of Cp*₂Co⁺. This is supported by the observation of a narrow EPR signal of 1 with g = 2.0032-2.0036 characteristic of H₂Pc˙^-. Strong antiferromagnetic coupling of spins with a Weiss temperature of -23 K is observed between H₂Pc˙^- in 1. This coupling is probably mediated by the Cp*₂Co⁺ cations. The magnetic moment of 2 is 4.18 μ_B at 300 K indicating the contribution of both paramagnetic H₂Pc˙^- (S = 1/2) and Cp*₂Cr⁺ (S = 3/2) species. In spite of the presence of stacks of alternating ions in 2, only weak magnetic coupling is observed with a Weiss temperature of -4 K most probably due to ineffective π-π interactions between Cp*₂Cr⁺ and H₂Pc˙^-. The EPR spectrum of 2 contains an asymmetric signal attributed to Cr^III (g₁ = 3.9059-3.9220) and a narrow Lorentzian signal from H₂Pc˙^- with g₂ = 1.9943-1.9961. In addition to these signals, a broad EPR signal grows in intensity below 80 K with g₄ = 2.1085-2.2438 which can be attributed to both paramagnetic Cp*₂Cr⁺ and H₂Pc˙^- species having exchange interactions.