Complexes of transition metal carbonyl clusters with tin(ii) phthalocyanine in neutral and radical anion states: methods of synthesis, structures and properties

Abstract

Coordination of tin(II) phthalocyanine to transition metal carbonyl clusters in neutral {Sn^II(Pc²⁻)}⁰ or radical anion {Sn^II(Pc˙³⁻)}⁻ states is reported. Direct interaction of Co₄(CO)₁₂ with {Sn^II(Pc²⁻)}⁰ yields a crystalline complex {Co₄(CO)₁₁·Sn^II(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 {Sn^II(Pc˙³⁻)}⁻ to yield crystalline {Cryptand[2.2.2](Na⁺)}{Ru₃(CO)₁₁·Sn^II(Pc˙³⁻)}⁻ (2) or {Cryptand[2.2.2](M⁺)}₂{Ru₃(CO)₁₀·[Sn^II(Pc˙³⁻)]₂}²⁻·4C₆H₄Cl₂ (3) (M⁺ is K or Cs). Paramagnetic {Sn^II(Pc˙³⁻)}⁻ species in 2 are packed in π-stacking [{Sn^II(Pc˙³⁻)}⁻]₂ dimers, providing strong antiferromagnetic coupling of spins with exchange interaction J/k_B = −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 {Sn^IVCl₂(Pc²⁻)}⁰ yield a series of complexes with high-spin Cp*₂Cr⁺ counter cations (S = 3/2): (Cp*₂Cr⁺){Ru₃(CO)₁₁·Sn^II(Pc˙³⁻)}⁻·C₆H₄Cl₂ (4), (Cp*₂Cr⁺){Os₃(CO)₁₀Cl·Sn^II(Pc˙³⁻)}⁻·C₆H₄Cl₂ (5) and (Cp*₂Cr⁺){Ir₄(CO)₁₁·Sn^II(Pc˙³⁻)}₂⁻ (6). It is seen that reduced clusters are oxidized by Sn^IV, which is transferred to Sn^II, 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 Os^I center. Rather weak magnetic coupling is observed between paramagnetic Cp*₂Cr⁺ and {Sn^II(Pc˙³⁻)}⁻ species in 4, but this exchange interaction is enhanced in 5 owing to Os₃(CO)₁₀Cl clusters with paramagnetic Os^I (S = 1/2) also being involved in antiferromagnetic coupling of spins. The formation of {Sn^II(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 N_meso–C bond alternation in Pc (for 3–5). On the whole, this work shows that both diamagnetic {Sn^II(Pc²⁻)}⁰ and paramagnetic {Sn^II(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.