Журнал "Макрогетероциклы"

Maxim A. Faraonov,^a@1 Nikita R. Romanenko,^a,b Alexey V. Kuzmin,^c Dmitri V. Konarev,^a@2 Salavat S. Khasanov,^c and Rimma N. Lyubovskaya^a

^aInstitute of Problems of Chemical Physics RAS, 142432 Chernogolovka, Russia

^bMoscow State University, 119991 Moscow, Russia

^cInstitute of Solid State Physics RAS, 142432 Chernogolovka, Russia

^@1Corresponding author E-mail: maksimfaraonov@yandex.ru

^@2Corresponding author E-mail: konarev3@yandex.ru

DOI: 10.6060/mhc190451f

Macroheterocycles 2019 12(2) 202-208

Iron(II) tetra(2,3-quinoxalino)porphyrazine, Fe^IIT(2,3-Q)Pz, was obtained using diaminomaleonitrile and o-phenylenediamine as starting materials. Reduction of Fe^IIT(2,3-Q)Pz by sodium fluorenone ketyl in the presence of cryptand[2.2.2] and N-methylimidazole followed by precipitation of crystals leads to crystalline salt {cryptand[2.2.2](Na⁺)}₂×[(N-MeIm)₂Fe^I{T(2,3-Q)Pz}^·3-]^·2-×3C₆H₄Cl₂×2H₂O (1). Molecular structure and properties of the [(N-MeIm)₂Fe^I{T(2,3-Q)Pz}^·3-]^·2- radical dianions have been studied. Reduction of Fe^IIT(2,3-Q)Pz is accompanied by strong blue shift of Soret band in spectrum of 1 but Q-band has close position to that in the spectrum of neutral macrocycle. There is an alternation of the C-N_meso bonds in the macrocycle in 1, the difference between short and long C-N_meso bonds of 0.017 Ȧ supports the formation of radical trianionic T(2,3-Q)Pz^·3- macrocycle. Coordination of N-methylimidazole molecules to iron (I) atoms with the Fe–N(imidazole) distance of 1.999(7) Ȧ is observed. Both Fe^I atom and radical trianionic {T(2,3-Q)Pz}^3·-macrocyclecontribute to the EPR signal of1, which is well interpreted as the superposition of Lorentzian shapedlines with g₁ = 2.0917, g₂= 2.0679, g₃ = 2.0292, g₄ = 1.9991 and g₅ = 1.9922. The lines with higher g-factor (g₁ and g₂) value can be attributed to low spin (S = 1/2) Fe^I whereas the lines with lower g-factor (g₄ and g₅) values can be attributed to the radical trianionic {T(2,3-Q)Pz}^·3- macrocycle. The line with intermediate g-factor value (g₃) can originate from the contribution of both components. The value of effective magnetic moment at 300 K (2.32 m_B) indicates a contribution of two non-interacting S = 1/2 spins from iron(I) atoms and radical trianionic {T(2,3-Q)Pz}^·3- macrocycle. These spins weakly antiferromagnetically interact with Weiss temperature of –3 K.