Bimetallic neutral and anionic complexes of transition metal (Co, Mn) carbonyls with indium(iii) phthalocyanine

Abstract

Heterobimetallic {[Co(CO)₄]⁻[In^III(Pc²⁻)]} (1) and (Cp*₂Cr⁺){[Mn(CO)₅]⁻[In^III(Pc˙³⁻)]}·2C₆H₄Cl₂ (2) complexes based on indium(III) phthalocyanine (Pc) were obtained as crystals. The complexes were synthesized by single (1) and double (2) reduction of indium(III) phthalocyanine chloride in the presence of transition metal carbonyls. Complex 1 contains dianionic Pc²⁻ macrocycles. Thus, the coordinated Co(CO)₄ carbonyl accepts an electron in the one-electron reduction forming a diamagnetic [Co(CO)₄]⁻ anion. Complex 2 contains a heterobimetallic {[Mn(CO)₅]⁻[In^III(Pc˙³⁻)]}⁻ anion and paramagnetic Cp*₂Cr⁺ counter cations. Therefore, in the double reduction, electrons are transferred to Mn(CO)₅ forming a diamagnetic [Mn(CO)₅]⁻ anion and to the Pc²⁻ macrocycle forming a paramagnetic radical Pc˙³⁻ trianion. Such assignments for 1 and 2 are in line with optical spectra, crystal structures and the data of magnetic measurements. The spectrum of 1 in the UV-visible range is similar to that of the starting In^IIIClPc. The formation of 2 is accompanied by an essential blue-shift of the Q-band of Pc as well as by the appearance of an intense NIR band at 1005 nm characteristic of Pc˙³⁻. Compound 1 is EPR silent and diamagnetic, whereas the value of the effective magnetic moment of 2 is 4.24μ_B at 300 K, which corresponds to the contribution of S = 1/2 (Pc˙³⁻) and S = 3/2 (Cp*₂Cr⁺) spins. Both weakly coupled paramagnetic centers (J = −0.41 cm⁻¹) are observed in the EPR spectra.