5 research outputs found
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 ironÂ(I) hexadecachlorophthalocyanine
anions have been obtained for the first time as single crystals: (PPN<sup>+</sup>)Â{[FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup>}
(<b>1</b>), (Ph<sub>3</sub>MeP<sup>+</sup>)<sub>2</sub>{[FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup>}Â(Br<sup>–</sup>)·C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>2</b>), and (PPN<sup>+</sup>)<sub>2</sub>[FeÂ(I, II)ÂCl<sub>16</sub>PcÂ(−2)]<sub>3</sub><sup>(2−)</sup>·4C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>3</b>), where PPN<sup>+</sup> is the cation of bisÂ(triphenylphosphoranylidene)Âammonium
and Ph<sub>3</sub>MeP<sup>+</sup> is the triphenylmethylphosphonium
cation. The [FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup> 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 [FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup> in <b>1</b>–<b>3</b> with the overlap integrals
of 4.1–7.6 × 10<sup>–3</sup>. Weak signals attributed
to the [FeÂ(II)ÂCl<sub>16</sub>PcÂ(−3)]<sup>−</sup> 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<sub>B</sub> per formula unit at 300 K. It can originate from the spins
localized on the iron atoms of [FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup>. 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<sub>B</sub> at
6 K. Optical spectra of <b>1</b>–<b>3</b> show
bands ascribed to [FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup> 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 ironÂ(I) hexadecachlorophthalocyanine
anions have been obtained for the first time as single crystals: (PPN<sup>+</sup>)Â{[FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup>}
(<b>1</b>), (Ph<sub>3</sub>MeP<sup>+</sup>)<sub>2</sub>{[FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup>}Â(Br<sup>–</sup>)·C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>2</b>), and (PPN<sup>+</sup>)<sub>2</sub>[FeÂ(I, II)ÂCl<sub>16</sub>PcÂ(−2)]<sub>3</sub><sup>(2−)</sup>·4C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>3</b>), where PPN<sup>+</sup> is the cation of bisÂ(triphenylphosphoranylidene)Âammonium
and Ph<sub>3</sub>MeP<sup>+</sup> is the triphenylmethylphosphonium
cation. The [FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup> 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 [FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup> in <b>1</b>–<b>3</b> with the overlap integrals
of 4.1–7.6 × 10<sup>–3</sup>. Weak signals attributed
to the [FeÂ(II)ÂCl<sub>16</sub>PcÂ(−3)]<sup>−</sup> 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<sub>B</sub> per formula unit at 300 K. It can originate from the spins
localized on the iron atoms of [FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup>. 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<sub>B</sub> at
6 K. Optical spectra of <b>1</b>–<b>3</b> show
bands ascribed to [FeÂ(I)ÂCl<sub>16</sub>PcÂ(−2)]<sup>−</sup> 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<sup>III</sup>(CN)<sub>6</sub>][Mn<sup>II</sup>(dapsc)]}<sub><i>n</i></sub> Coordination Polymers: Origin of Unconventional Single-Chain Magnet Behavior
Two one-dimensional
cyano-bridged coordination polymers, namely,
{[Mn<sup>II</sup>(dapsc)]Â[Mn<sup>III</sup>(CN)<sub>6</sub>]Â[KÂ(H<sub>2</sub>O)<sub>2.75</sub>(MeOH)<sub>0.5</sub>]}<sub><i>n</i></sub>·0.5<i>n</i>(H<sub>2</sub>O) (<b>I</b>) and {[Mn<sup>II</sup>(dapsc)]Â[Mn<sup>III</sup>(CN)<sub>6</sub>]Â[KÂ(H<sub>2</sub>O)<sub>2</sub>(MeOH)<sub>2</sub>]}<sub><i>n</i></sub> (<b>II</b>), based on alternating high-spin
Mn<sup>II</sup>(dapsc) (dapsc = 2,6-diacetylpyridine bisÂ(semicarbazone))
complexes and low-spin orbitally degenerate hexacyanomanganateÂ(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><sub>eff</sub> ≈ 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<sup>III</sup>–CN–Mn<sup>II</sup> spin coupling resulting from a nonmagnetic singlet ground
state of orbitally degenerate complexes [Mn<sup>III</sup>(CN)<sub>6</sub>]<sup>3–</sup>. The prospects of [Mn<sup>III</sup>(CN)<sub>6</sub>]<sup>3–</sup> 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<sup>III</sup>
A diamagnetic complex,
{(<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup>(Cp*Ir<sup>III</sup>)} (<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 [(Bu<sub>4</sub>N<sup>+</sup>)<sub>2</sub>{[Sn<sup>II</sup>(Pc<sup>•3–</sup>)]Â(<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup>Cp*Ir<sup>III</sup>}<sup>•–</sup><sub>2</sub>·0.5Â(H<sub>2</sub>Indigo)·2.5C<sub>6</sub>H<sub>4</sub>C<sub>l2</sub> (<b>2</b>), which has two functional ligands coordinating an Ir<sup>III</sup> center, was obtained. This complex has a magnetic moment
of 1.71 μ<sub>B</sub> at 300 K, in accordance with an <i>S</i> = 1/2 spin state. The spin density is mainly delocalized
over the Pc<sup>•3–</sup> macrocycle and partially on
(<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup>. Due to an effective π–π
interaction, a thermally activated charge transfer from [Sn<sup>II</sup>(Pc<sup>•3–</sup>)]<sup>•–</sup> to (<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup> 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<sup>III</sup> by the
indigo releases H<sup>+</sup> ions, which protonate noncoordinating
indigo molecules to produce leuco <i>cis</i>-indigo (H<sub>2</sub>Indigo). One H<sub>2</sub>indigo links two (<i>cis</i>-indigo-<i>N</i>,<i>N</i>)<sup>2–</sup> 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 [FeÂ{HCÂ(pz)<sub>3</sub>}<sub>2</sub>]Â(TCNQ)<sub>3</sub> demonstrates
conductivity and spin-crossover (SCO) transition associated with FeÂ(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 [FeÂ{HCÂ(pz)<sub>3</sub>}<sub>2</sub>] 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 FeÂ(II) spin subsystems