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Photochromic 1,3,3-trimethylindolino-β-naphthopyrylospiran (TMI–NPS) and 1,3,3-trimethylindolinonaphthospirooxazine (TMI–NSO) spiropyrans transform into the open merocyanine (MC) form, which exhibits a red-violet color upon reacting with one equivalent of anhydrous FeIIICl3 or FeIIIBr3 in o-dichlorobenzene. Slow mixing with n-hexane precipitates black crystals of the coordination complexes: (TMI–NPS)·FeIIICl3 (1), (TMI–NPS)·FeIIIBr3·2C6H4Cl2 (2) and (TMI–NSO)·FeX3·0.5C6H4Cl2 (where X = Cl for 3 and Br for 4). The oxygen atoms of the MC form of spiropyrans coordinate to FeIII forming short Fe–O bonds of 1.841(2) for 1, 1.839(2) for 2, and 1.888(2) Å length for 4. Complexes manifest intense absorption bands in the visible range, and the spectra are different for the two spiropyrans. Iron(III) ions have high (S = 5/2) spin states in 1 and 2, and complexes 2–4 manifest broad isotropic EPR signals with g = 2.05–2.11. An asymmetric EPR signal with the main component at g = 3.44 (4.2 K) is observed for 1. According to DFT, strong charge transfer from ligands to electron accepting FeIII ions and large dipole moments are evaluated in the complexes. The intense color of the (TMI–NSO)·FeIIIBr3 complex disappears when it reacts with 5,6,11,12,17,18-hexaazatrinaphthylene (HATNA). This decoloration indicates the formation of a colorless closed form of TMI–NPS and (HATNA)·FeIIIX3. Slow mixing with n-hexane precipitates crystals of (C22H19N2O+)(FeIIIBr4−) (5) salt containing nearly planar C22H19N2O+ cations (1,3,3-trimethyl-2-(naphtho[1,2-d]oxazol-2yl-3H-indol-1-ium cations) obtained as a result of the oxidative rearrangement and deprotonation of TMI–NSO. These cations manifest intense bands at 471 and 497 nm. They are diamagnetic and only an isotropic EPR signal with g = 2.15–2.16 is observed from the FeIIIBr4− anions. The properties of the complexes and possible routes to the formation of 5 are discussed based on DFT calculations. [ABSTRACT FROM AUTHOR]

The oxidation of tetraselenatetracene (TSeT) by tetracyanoquinodimethane in the presence of dysprosium(III) tris(hexafluoroacetylacetonate), DyIII(hfac)3, produces black crystals of {TSeT1.5}●+[DyIII(hfac)4]− (1) salt, which combines conducting and magnetic sublattices. It contains one-dimensional stacks composed of partially oxidized TSeT molecules (formal averaged charge is +2/3). Dimers and monomers can be outlined within these stacks with charge and spin density redistribution. The spin triplet state of the dimers is populated above 128 K with an estimated singlet-triplet energy gap of 542 K, whereas spins localized on the monomers show paramagnetic behavior. A semiconducting behavior is observed for 1 with the activation energy of 91 meV (measured by the four-probe technique for an oriented single crystal). The DyIII ions coordinate four hfac− anions in [DyIII(hfac)4]−, providing D2d symmetry. Slow magnetic relaxation is observed for DyIII under an applied static magnetic field of 1000 Oe, and 1 is a single-ion magnet (SIM) with spin reversal barrier Ueff = 40.2 K and magnetic hysteresis at 2 K. Contributions from DyIII and TSeT●+ paramagnetic species are seen in EPR. The DyIII ion rarely manifests EPR signals, but such signal is observed in 1. It appears due to narrowing below 30 K and has g4 = 6.1871 and g5 = 2.1778 at 5.4 K. [ABSTRACT FROM AUTHOR]