Molecular Design of Anionic Phthalocyanines with π–π Stacking Columnar Arrangement. Crystal Structures, Optical, and Magnetic Properties of Salts with the Iron(I) Hexadecachlorophthalocyanine Anions

Ionic compounds containing iron­(I) hexadecachlorophthalocyanine anions have been obtained for the first time as single crystals: (PPN⁺)­{[Fe­(I)­Cl₁₆Pc­(−2)]⁻} (<b>1</b>), (Ph₃MeP⁺)₂{[Fe­(I)­Cl₁₆Pc­(−2)]⁻}­(Br^–)·C₆H₄Cl₂ (<b>2</b>), and (PPN⁺)₂[Fe­(I, II)­Cl₁₆Pc­(−2)]₃⁽²⁻⁾·4C₆H₄Cl₂ (<b>3</b>), where PPN⁺ is the cation of bis­(triphenylphosphoranylidene)­ammonium and Ph₃MeP⁺ is the triphenylmethylphosphonium cation. The [Fe­(I)­Cl₁₆Pc­(−2)]⁻ anions form closely packed π–π stacking columns in <b>1</b>–<b>3</b>. Salts <b>1</b> and <b>2</b> with integer −1 charge on iron phthalocyanines have uniform and weakly dimerized columns, respectively. Salt <b>3</b> has two cations per three iron phthalocyanine molecules which are arranged in trimers within the columns. Different shift of phthalocyanines at the same interplanar distances of 3.33–3.38 Å provides essentially shorter Fe···Fe distances in <b>3</b> (3.62–3.84 Å) than those in <b>1</b> and <b>2</b> (5.07–5.45 Å). Calculations show a strong LUMO–LUMO overlapping between [Fe­(I)­Cl₁₆Pc­(−2)]⁻ in <b>1</b>–<b>3</b> with the overlap integrals of 4.1–7.6 × 10^–3. Weak signals attributed to the [Fe­(II)­Cl₁₆Pc­(−3)]⁻ species with the delocalization of electron on the phthalocyanine macrocycles are observed in the EPR spectra of <b>1</b>–<b>3</b>. The content of this admixture is less than 1% in all salts. Nevertheless, static magnetic susceptibility measurements for <b>3</b> detected significant magnetization. The effective magnetic moment is 4.05 μ_B per formula unit at 300 K. It can originate from the spins localized on the iron atoms of [Fe­(I)­Cl₁₆Pc­(−2)]⁻. The Weiss temperature of −53 K in the 60–300 K range indicates a strong antiferromagnetic interaction of spins which results in the decreases of magnetic moment of <b>3</b> with temperature below 220 K down to 2.72 μ_B at 6 K. Optical spectra of <b>1</b>–<b>3</b> show bands ascribed to [Fe­(I)­Cl₁₆Pc­(−2)]⁻ at 339–349, 538–548, 685–691, and 805–821 nm. The bands in the NIR range at 1740–1810 nm were attributed to charge transfer excitations within phthalocyanine columns associated with the unpaired electrons on the iron atoms

Molecular Design of Anionic Phthalocyanines with π–π Stacking Columnar Arrangement. Crystal Structures, Optical, and Magnetic Properties of Salts with the Iron(I) Hexadecachlorophthalocyanine Anions

Ionic compounds containing iron­(I) hexadecachlorophthalocyanine anions have been obtained for the first time as single crystals: (PPN⁺)­{[Fe­(I)­Cl₁₆Pc­(−2)]⁻} (<b>1</b>), (Ph₃MeP⁺)₂{[Fe­(I)­Cl₁₆Pc­(−2)]⁻}­(Br^–)·C₆H₄Cl₂ (<b>2</b>), and (PPN⁺)₂[Fe­(I, II)­Cl₁₆Pc­(−2)]₃⁽²⁻⁾·4C₆H₄Cl₂ (<b>3</b>), where PPN⁺ is the cation of bis­(triphenylphosphoranylidene)­ammonium and Ph₃MeP⁺ is the triphenylmethylphosphonium cation. The [Fe­(I)­Cl₁₆Pc­(−2)]⁻ anions form closely packed π–π stacking columns in <b>1</b>–<b>3</b>. Salts <b>1</b> and <b>2</b> with integer −1 charge on iron phthalocyanines have uniform and weakly dimerized columns, respectively. Salt <b>3</b> has two cations per three iron phthalocyanine molecules which are arranged in trimers within the columns. Different shift of phthalocyanines at the same interplanar distances of 3.33–3.38 Å provides essentially shorter Fe···Fe distances in <b>3</b> (3.62–3.84 Å) than those in <b>1</b> and <b>2</b> (5.07–5.45 Å). Calculations show a strong LUMO–LUMO overlapping between [Fe­(I)­Cl₁₆Pc­(−2)]⁻ in <b>1</b>–<b>3</b> with the overlap integrals of 4.1–7.6 × 10^–3. Weak signals attributed to the [Fe­(II)­Cl₁₆Pc­(−3)]⁻ species with the delocalization of electron on the phthalocyanine macrocycles are observed in the EPR spectra of <b>1</b>–<b>3</b>. The content of this admixture is less than 1% in all salts. Nevertheless, static magnetic susceptibility measurements for <b>3</b> detected significant magnetization. The effective magnetic moment is 4.05 μ_B per formula unit at 300 K. It can originate from the spins localized on the iron atoms of [Fe­(I)­Cl₁₆Pc­(−2)]⁻. The Weiss temperature of −53 K in the 60–300 K range indicates a strong antiferromagnetic interaction of spins which results in the decreases of magnetic moment of <b>3</b> with temperature below 220 K down to 2.72 μ_B at 6 K. Optical spectra of <b>1</b>–<b>3</b> show bands ascribed to [Fe­(I)­Cl₁₆Pc­(−2)]⁻ at 339–349, 538–548, 685–691, and 805–821 nm. The bands in the NIR range at 1740–1810 nm were attributed to charge transfer excitations within phthalocyanine columns associated with the unpaired electrons on the iron atoms

Synthesis, Structure, and Magnetic Properties of 1D {[Mn^III(CN)₆][Mn^II(dapsc)]}_<i>n</i> Coordination Polymers: Origin of Unconventional Single-Chain Magnet Behavior

Two one-dimensional cyano-bridged coordination polymers, namely, {[Mn^II(dapsc)]­[Mn^III(CN)₆]­[K­(H₂O)_2.75(MeOH)_0.5]}_<i>n</i>·0.5<i>n</i>(H₂O) (<b>I</b>) and {[Mn^II(dapsc)]­[Mn^III(CN)₆]­[K­(H₂O)₂(MeOH)₂]}_<i>n</i> (<b>II</b>), based on alternating high-spin Mn^II(dapsc) (dapsc = 2,6-diacetylpyridine bis­(semicarbazone)) complexes and low-spin orbitally degenerate hexacyanomanganate­(III) complexes were synthesized and characterized structurally and magnetically. Static and dynamic magnetic measurements reveal a single-chain magnet (SCM) behavior of <b>I</b> with an energy barrier of <i>U</i>_eff ≈ 40 K. Magnetic properties of <b>I</b> are analyzed in detail in terms of a microscopic theory. It is shown that compound <b>I</b> refers to a peculiar case of SCM that does not fall into the usual Ising and Heisenberg limits due to unconventional character of the Mn^III–CN–Mn^II spin coupling resulting from a nonmagnetic singlet ground state of orbitally degenerate complexes [Mn^III(CN)₆]^3–. The prospects of [Mn^III(CN)₆]^3– complex as magnetically anisotropic molecular building block for engineering molecular magnets are critically analyzed

Interligand Charge Transfer in a Complex of Deprotonated <i>cis</i>-Indigo Dianions and Tin(II) Phthalocyanine Radical Anions with Cp*Ir^III

A diamagnetic complex, {(<i>cis</i>-indigo-<i>N</i>,<i>N</i>)^2–(Cp*Ir^III)} (<b>1</b>), in which deprotonated <i>cis</i>-indigo dianions coordinate an iridium center through two nitrogen atoms was obtained. By employment of the ability of the iridium center in <b>1</b> to coordinate an additional ligand, the complex [(Bu₄N⁺)₂{[Sn^II(Pc^•3–)]­(<i>cis</i>-indigo-<i>N</i>,<i>N</i>)^2–Cp*Ir^III}^•–₂·0.5­(H₂Indigo)·2.5C₆H₄C_l2 (<b>2</b>), which has two functional ligands coordinating an Ir^III center, was obtained. This complex has a magnetic moment of 1.71 μ_B at 300 K, in accordance with an <i>S</i> = 1/2 spin state. The spin density is mainly delocalized over the Pc^•3– macrocycle and partially on (<i>cis</i>-indigo-<i>N</i>,<i>N</i>)^2–. Due to an effective π–π interaction, a thermally activated charge transfer from [Sn^II(Pc^•3–)]^•– to (<i>cis</i>-indigo-<i>N</i>,<i>N</i>)^2– is observed, with an estimated Gibbs energy (−Δ<i>G</i>°) of 9.27 ± 0.18 kJ/mol. The deprotonation of indigo associated with the coordination of Ir^III by the indigo releases H⁺ ions, which protonate noncoordinating indigo molecules to produce leuco <i>cis</i>-indigo (H₂Indigo). One H₂indigo links two (<i>cis</i>-indigo-<i>N</i>,<i>N</i>)^2– dianions in <b>2</b> to produce strong N–H···OC and O–H···OC hydrogen-bonding interactions

The Conducting Spin-Crossover Compound Combining Fe(II) Cation Complex with TCNQ in a Fractional Reduction State

The radical anion salt [Fe­{HC­(pz)₃}₂]­(TCNQ)₃ demonstrates conductivity and spin-crossover (SCO) transition associated with Fe­(II) complex cation subsystem. It was synthesized and structurally characterized at temperatures 100, 300, 400, and 450 K. The compound demonstrates unusual for 7,7,8,8,-tetracyanoquinodimethane (TCNQ)-based salts quasi-two-dimensional conductivity. Pronounced changes of the in-plane direct-current resistivity and intensity of the electron paramagnetic resonance (EPR) signal, originated from TCNQ subsystem, precede the SCO transition at the midpoint <i>T</i>* = 445 K. The boltzmannian growth of the total magnetic response and structural changes in the vicinity of <i>T</i>* uniquely show that half [Fe­{HC­(pz)₃}₂] cations exist in high-spin state. Robust broadening of the EPR signal triggered by the SCO transition is interpreted in terms of cross relaxation between the TCNQ and Fe­(II) spin subsystems