15 research outputs found
Layered Organic Conductors Based on BEDT-TTF and Ho, Dy, Tb Chlorides
Molecular semiconductors with lanthanide ions have been synthesized based on BEDT-TTF and lanthanide chlorides: (BEDT-TTF)2[HoCl2(H2O)6]Cl2(H2O)2 (1, which contains a 4f holmium cation), and (BEDT-TTF)2LnCl4(H2O)n (Ln = Dy, Tb, Ho (2–4), which contain 4f anions of lanthanides). Conductivity and EPR measurements have been carried out along with the SQUID magnetometry, and the crystal structure has been established for 1. The structure of 1 is characterized by an alternation of organic radical cation layers composed of BEDT-TTF chains and inorganic layers consisting of chains of the [HoCl2(H2O)6]+ cations interlinked by chlorine anions and crystallization water molecules. The magnetic susceptibility of 1–3 determined mainly by lanthanide ions follows the Curie–Weiss law with the Weiss temperatures of −3, −3, −2 K for 1–3, respectively, indicating weak antiferromagnetic coupling between paramagnetic lanthanide ions. The signals attributed to the BEDT-TTF+· radical cations only are observed in the EPR spectra of 1–3, which makes it possible to study their magnetic behavior. There are two types of chains in the organic layers of 1: the chains composed of neutral molecules and those formed by BEDT-TTF+· radical cations. As a result, uniform 1D antiferromagnetic coupling of spins is observed in the BEDT-TTF+· chains with estimated exchange interaction J = −10 K. The study of dynamic magnetic properties of 1–3 shows that these compounds are not SMMs
Layered Organic Conductors Based on BEDT-TTF and Ho, Dy, Tb Chlorides
Molecular semiconductors with lanthanide ions have been synthesized based on BEDT-TTF and lanthanide chlorides: (BEDT-TTF)2[HoCl2(H2O)6]Cl2(H2O)2 (1, which contains a 4f holmium cation), and (BEDT-TTF)2LnCl4(H2O)n (Ln = Dy, Tb, Ho (2–4), which contain 4f anions of lanthanides). Conductivity and EPR measurements have been carried out along with the SQUID magnetometry, and the crystal structure has been established for 1. The structure of 1 is characterized by an alternation of organic radical cation layers composed of BEDT-TTF chains and inorganic layers consisting of chains of the [HoCl2(H2O)6]+ cations interlinked by chlorine anions and crystallization water molecules. The magnetic susceptibility of 1–3 determined mainly by lanthanide ions follows the Curie–Weiss law with the Weiss temperatures of −3, −3, −2 K for 1–3, respectively, indicating weak antiferromagnetic coupling between paramagnetic lanthanide ions. The signals attributed to the BEDT-TTF+· radical cations only are observed in the EPR spectra of 1–3, which makes it possible to study their magnetic behavior. There are two types of chains in the organic layers of 1: the chains composed of neutral molecules and those formed by BEDT-TTF+· radical cations. As a result, uniform 1D antiferromagnetic coupling of spins is observed in the BEDT-TTF+· chains with estimated exchange interaction J = −10 K. The study of dynamic magnetic properties of 1–3 shows that these compounds are not SMMs
Coordination Complexes of Transition Metals (M = Mo, Fe, Rh, and Ru) with Tin(II) Phthalocyanine in Neutral, Monoanionic, and Dianionic States
The
ability of tin atoms to form stable Sn–M bonds with transition
metals was used to prepare transition metal complexes with tin(II)
phthalocyanine in neutral, monoanionic, and dianionic states. These
complexes were obtained via the interactions of [Sn<sup>IV</sup>Cl<sub>2</sub>Pc(3−)]<sup>•–</sup> or [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> radical anions with {Cp*Mo(CO)<sub>2</sub>}<sub>2</sub>, {CpFe(CO)<sub>2</sub>}<sub>2</sub>, {CpMo(CO)<sub>3</sub>}<sub>2</sub>, Fe<sub>3</sub>(CO)<sub>12</sub>, {Cp*RhCl<sub>2</sub>}<sub>2</sub>, or Ph<sub>5</sub>CpRu(CO)<sub>2</sub>Cl. The
neutral coordination complexes of Cp*MoBr(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(2−)]·0.5C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>1</b>) and CpFe(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(2−)]·2C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>2</b>) were obtained
from [Sn<sup>IV</sup>Cl<sub>2</sub>Pc(3−)]<sup>•–</sup>. On the other hand, the coordination of transition metals to [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> yielded anionic
coordination complexes preserving the spin on [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>. However, in the case of {cryptand[2,2,2](Na<sup>+</sup>)}{CpFe<sup>II</sup>(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(4−)]}<sup>−</sup>·C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>4</b>), charge transfer from CpFe<sup>I</sup>(CO)<sub>2</sub> to
[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> took place
to form the diamagnetic [Sn<sup>II</sup>Pc(4−)]<sup>2–</sup> dianion and {CpFe<sup>II</sup>(CO)<sub>2</sub>}<sup>+</sup>. The
complexes {cryptand[2,2,2](Na<sup>+</sup>)}{Fe(CO)<sub>4</sub>[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>} (<b>5</b>), {cryptand[2,2,2](Na<sup>+</sup>)}{CpMo(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(2−)Sn<sup>II</sup>Pc(3−)<sup>•–</sup>]} (<b>6</b>), and {cryptand[2,2,2](Na<sup>+</sup>)}{Cp*RhCl<sub>2</sub>[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>}
(<b>7</b>) have magnetic moments of 1.75, 2.41, and 1.75 μ<sub>B</sub>, respectively, owing to the presence of <i>S</i> = 1/2 spins on [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> and CpMo<sup>I</sup>(CO)<sub>2</sub> (for <b>6</b>). In addition,
the strong antiferromagnetic coupling of spins with Weiss temperatures
of −35.5 −28.6 K was realized between the CpMo<sup>I</sup>(CO)<sub>2</sub> and the [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> units in <b>6</b> and the π-stacking {Fe(CO)<sub>4</sub>[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>}<sub>2</sub> dimers of <b>5</b>, respectively. The [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> radical anions substituted the chloride anions
in Ph<sub>5</sub>CpRu(CO)<sub>2</sub>Cl to form the formally neutral
compound {Ph<sub>5</sub>CpRu<sup>II</sup>(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(3−)]} (<b>8</b>) in which the negative charge and
spin are preserved on [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>. The strong antiferromagnetic coupling of spins with a magnetic
exchange interaction <i>J/k</i><sub>B</sub> = −183
K in <b>8</b> is explained by the close packing of [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> in the π-stacked
{Ph<sub>5</sub>CpRu<sup>II</sup>(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>}<sub>2</sub> dimers
Single-Molecule Magnets Based on Heteroleptic Terbium(III) Trisphthalocyaninate in Solvent-Free and Solvent-Containing Forms
Binuclear heteroleptic triple-decker terbium(III) phthalocyaninate (Pc)Tb[(15C5)4Pc]Tb(Pc), where Pc2− is phthalocyaninate dianion and 15C5 is a 15-crown-5 moiety, has been synthesized as a solvent-free powder (1) and a well-defined crystal solvate with o-dichlorobenzene (Pc)Tb[(15C5)4Pc]Tb(Pc)⋅6C6H4Cl2 (2). In the crystal structure of 2, the Tb-N(Pc) distances to the nitrogen atoms in the outer and inner decks are 2.350–2.367(4) and 2.583–2.598(4) Å, respectively, and the Tb–Tb distance is 3.4667(3) Å. The twist angle between the outer and the inner decks is 42.6°. The magnetic properties were studied for both 1 and 2. The χMT magnitude of 23.3 emu⋅K/mol at 300 K indicates a contribution of two TbIII centers with the 7F6 ground state. The χMT product increases with decreasing temperature to reach 38.5 emu⋅K/mol at 2 K. This is indicative of ferromagnetic coupling between TbIII spins in accordance with previous data for triple-decker lanthanide phthalocyaninates of a dipolar nature. Both forms show a single-molecule magnet (SMM) behavior manifesting the in-phase (χ′) and out-of-phase (χ″) AC susceptibility signals in an oscillating field of 3 Oe with estimated effective spin-reversal energy barriers (Ueff) of 222(9) and 93(7) cm−1 for 1 and 2, respectively. The compounds show narrow hysteresis loops in the −1 – +1 kOe range, and the splitting between the zero-field-cooling and field-cooling curves is observed below 6 K. Thus, in spite of similar static magnetic characteristics, each form of the Tb(III) complex shows a different dynamic SMM behavior
Single-Molecule Magnets Based on Heteroleptic Terbium(III) Trisphthalocyaninate in Solvent-Free and Solvent-Containing Forms
Binuclear heteroleptic triple-decker terbium(III) phthalocyaninate (Pc)Tb[(15C5)4Pc]Tb(Pc), where Pc2− is phthalocyaninate dianion and 15C5 is a 15-crown-5 moiety, has been synthesized as a solvent-free powder (1) and a well-defined crystal solvate with o-dichlorobenzene (Pc)Tb[(15C5)4Pc]Tb(Pc)⋅6C6H4Cl2 (2). In the crystal structure of 2, the Tb-N(Pc) distances to the nitrogen atoms in the outer and inner decks are 2.350–2.367(4) and 2.583–2.598(4) Å, respectively, and the Tb–Tb distance is 3.4667(3) Å. The twist angle between the outer and the inner decks is 42.6°. The magnetic properties were studied for both 1 and 2. The χMT magnitude of 23.3 emu⋅K/mol at 300 K indicates a contribution of two TbIII centers with the 7F6 ground state. The χMT product increases with decreasing temperature to reach 38.5 emu⋅K/mol at 2 K. This is indicative of ferromagnetic coupling between TbIII spins in accordance with previous data for triple-decker lanthanide phthalocyaninates of a dipolar nature. Both forms show a single-molecule magnet (SMM) behavior manifesting the in-phase (χ′) and out-of-phase (χ″) AC susceptibility signals in an oscillating field of 3 Oe with estimated effective spin-reversal energy barriers (Ueff) of 222(9) and 93(7) cm−1 for 1 and 2, respectively. The compounds show narrow hysteresis loops in the −1 – +1 kOe range, and the splitting between the zero-field-cooling and field-cooling curves is observed below 6 K. Thus, in spite of similar static magnetic characteristics, each form of the Tb(III) complex shows a different dynamic SMM behavior
Complexes of transition metal carbonyl clusters with tin(ii) phthalocyanine in neutral and radical anion states: methods of synthesis, structures and properties
Coordination of tin(II) phthalocyanine to transition metal carbonyl clusters in neutral {SnII(Pc²⁻)}⁰ or radical anion {SnII(Pc˙³⁻)}⁻ states is reported. Direct interaction of Co₄(CO)₁₂ with {SnII(Pc²⁻)}⁰ yields a crystalline complex {Co₄(CO)₁₁·SnII(Pc²⁻)} (1). There is no charge transfer from the cluster to phthalocyanine in 1, which preserves the diamagnetic Pc²⁻ macrocycle. The Ru₃(CO)₁₂ cluster forms complexes with one or two equivalents of {SnII(Pc˙³⁻)}⁻ to yield crystalline {Cryptand[2.2.2](Na⁺)}{Ru₃(CO)₁₁·SnII(Pc˙³⁻)}⁻ (2) or {Cryptand[2.2.2](M⁺)}2{Ru₃(CO)₁₀·[SnII(Pc˙³⁻)]₂}²⁻·4C₆H₄Cl₂ (3) (M⁺ is K or Cs). Paramagnetic {SnII(Pc˙³⁻)}⁻ species in 2 are packed in π-stacking [{SnII(Pc˙³⁻)}⁻]₂ dimers, providing strong antiferromagnetic coupling of spins with exchange interaction J/kB = −19 K. Reduction of Ru₃(CO)₁₂, Os₃(CO)₁₂ and Ir4(CO)₁₂ clusters by decamethylchromocene (Cp*₂Cr) and subsequent oxidation of the reduced species by {SnIVCl₂(Pc²⁻)}⁰ yield a series of complexes with high-spin Cp*₂Cr⁺ counter cations (S = 3/2): (Cp*₂Cr⁺){Ru₃(CO)₁₁·SnII(Pc˙³⁻)}⁻·C₆H₄Cl₂ (4), (Cp*₂Cr⁺){Os₃(CO)₁₀Cl·SnII(Pc˙³⁻)}⁻·C₆H₄Cl₂ (5) and (Cp*₂Cr⁺){Ir₄(CO)₁₁·SnII(Pc˙³⁻)}₂⁻ (6). It is seen that reduced clusters are oxidized by SnIV, which is transferred to SnII, whereas the Pc²⁻ macrocycle is reduced to Pc˙³⁻. In the case of Os₃(CO)₁₂, oxidation of the metal atom in the cluster is observed to be accompanied by the formation of Os₃(CO)₁₀Cl with one OsI center. Rather weak magnetic coupling is observed between paramagnetic Cp*₂Cr⁺ and {SnII(Pc˙³⁻)}⁻ species in 4, but this exchange interaction is enhanced in 5 owing to Os₃(CO)₁₀Cl clusters with paramagnetic OsI (S = 1/2) also being involved in antiferromagnetic coupling of spins. The formation of {SnII(Pc˙³⁻)}⁻ with radical trianion Pc˙³⁻ macrocycles in 2–5 is supported by the appearance of new absorption bands in the NIR spectra and essential Nmeso–C bond alternation in Pc (for 3–5). On the whole, this work shows that both diamagnetic {SnII(Pc²⁻)}0 and paramagnetic {SnII(Pc˙³⁻)}⁻ ligands substitute carbonyl ligands in the transition metal carbonyl clusters, forming well-soluble paramagnetic solids absorbing light in the visible and NIR ranges
Negatively Charged Iron-Bridged Fullerene Dimer {Fe(CO)<sub>2</sub>‑μ<sub>2</sub>‑η<sup>2</sup>,η<sup>2</sup>‑C<sub>60</sub>}<sub>2</sub><sup>2–</sup>
The interaction of {Cryptand(K+)}(C60•–) with Fe3(CO)12 produced
{Cryptand(K+)}2{Fe(CO)2-μ2-η2,η2-C60}22–·2.5C6H4Cl2 (1) as the first
negatively charged iron-bridged fullerene C60 dimer. The
bridged iron atoms are coordinated to two 6–6 bonds of one
C60 hexagon with short and long C(C60)–Fe
bonds with average lengths of 2.042(3) and 2.088(3) Å. Fullerenes
are close to each other in the dimer with a center-to-center interfullerene
distance of 10.02 Å. Optical spectra support the localization
of negative electron density on the Fe2(CO)4 units, which causes a 50 cm–1 shift of the CO
vibration bands to smaller wavenumbers, and the C60 cages.
Dimers are diamagnetic and electron paramagnetic resonance silent
and have a singlet ground state resulting from the formation of an
Fe–Fe bond in the dimer with a length of 2.978(4) Å. According
to density functional theory calculations, the excited triplet state
is higher than the ground state by 6.5 kcal/mol. Compound 1 shows a broad near-infrared band with a maximum at 970 nm, which
is attributable to the charge transfer from the orbitals localized
mainly on iron atoms to the C60 ligand
Crystalline salts of metal phthalocyanine radical anions [M(Pc˙3−)]˙− (M = CuII, PbII, VIVO, SnIVCl2) with cryptand(Na+) cations: structure, optical and magnetic properties
Radical anion salts of metal phthalocyanines (M = CuII, PbII, VIVO and SnIVCl2) with the {cryptand(Na+)} cations have been obtained and studied.</p