Heterotrimetallic paramagnetic complex of ring reduced tin(ii) hexadecachlorophthalocyanine

Abstract

Coordination complex (Cp*₂Cr^III)⁺{CpFe^II(CO)₂(Sn^II[PcCl₁₆]⁴⁻)}⁻ (1) has been obtained by the reduction of tin(IV) dichloride hexadecachlorophthalocyanine (PcCl₁₆) by decamethylchromocene (Cp*₂Cr) in the presence of {CpFe^I(CO)₂}₂. The process is accompanied by oxidation of Cr^II and Fe^I centers and the formation of paramagnetic Cr^III and diamagnetic Fe^II species. Two-electron reduction of a macrocycle and the formation of diamagnetic [PcCl₁₆]⁴⁻ as well as a transition of tin(IV) to tin(II) occur. The [PcCl₁₆]⁴⁻ tetraanions are formed in (cryptand(K⁺))₂{Sn^IVCl₂[PcCl₁₆]⁴⁻}²⁻·2C₆H₄Cl₂ (2) obtained by the reduction of Sn^IVPcCl₁₆ by mild reductant – fullerene C₆₀˙⁻ radical anions. Complexes 1 and 2 precipitate as crystals. Sandwich-type assemblies are formed in 1. Two (Cp*₂Cr^III)⁺ cations are sandwiched between two {CpFe^II(CO)₂(Sn^II[PcCl₁₆]⁴⁻)}⁻ planes, whereas layers of the {Sn^IVCl₂[PcCl₁₆]⁴⁻}²⁻ macrocycles are formed in 2. The formation of the [PcCl₁₆]⁴⁻ tetraanions in both 1 and 2 is supported by the data of structural analysis, optical spectroscopy and magnetic measurements. Susceptibility measurements correspond to the contribution of one non-interacting Cr^III spin (S = 3/2) per formula unit. Weak antiferromagnetic coupling is observed between the spins. Only Cr^III atoms contribute to EPR spectra of 1, whereas salt 2 is diamagnetic and EPR silent.