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

Solid State Structure, and Optical and Magnetic Properties, of Free Base Tetra(4-pyridyl)porphyrin {H₂T(4-Py)P}^•– Radical Anions

A crystalline {cryptand[2.2.2.]­(K⁺)}­{H₂T­(4-Py)­P^•–}·C₆H₄Cl₂ (<b>1</b>) salt with tetra­(4-pyridyl)­porphyrin radical anions was obtained, enabling the effect of reduction on a metal-free porphyrin macrocycle to be studied. In contrast to pristine H₂T­(4-Py)­P, the H₂T­(4-Py)­P^•– radical anions have altered C–C­(meso) bonds due to partial loss of aromaticity from the porphyrin macrocycle. Short and long bonds have average lengths of 1.396(3) and 1.426(3) Å, which thus differ by 0.03 Å. Reduction affects the positions of the Soret and Q-bands of porphyrin observed in the spectrum of <b>1</b> at 439 and 512, 583, and 614 nm, and new bands of the radical anion appear at 684, 755, and 900 nm. The H₂T­(4-Py)­P^•– radical anions have a spin state of <i>S</i> = 1/2 and a magnetic moment of 1.64 μ_B at 300 K. Salt <b>1</b> shows a narrow asymmetric EPR signal fitted with two Lorentzian lines, with <i>g</i>_⊥ = 2.0031 and a line width (Δ<i>H</i>) of 0.186 mT, and <i>g</i>_∥ = 2.0019 (Δ<i>H</i> = 0.284 mT) at 295 K, and this signal splits into three components below 39 K. Salt <b>1</b> shows antiferromagnetic spin coupling with a Weiss temperature of −2 K