Complex of fullerene C60 with partial charge transfer: {(dppf)CpFe(CO)}+(C60)-⋅C6H4Cl2 (δ = 0.54–0.86), where dppf is bis(diphenylphosphino)ferrocene ligand

Inorganic Chemistry Communications. 2026. Vol. 185. Article 116055.

Sobov P. A., Khasanov S., Kuzmin A. V., Faraonov M., Otsuka A., Kitagawa H., Konarev D.

New complex {(dppf)CpFe(CO)}(C60)⋅C6H4Cl2 (1) was obtained when stoichiometric mixture of C60 and CoII(dppf)Cl2 is reduced by two equivalents of (Cs+){CpFe(CO)2−} (dppf: 1,1`-bis(diphenylphosphino)ferrocene). CpFe(CO)2− anion reduces CoII(dppf)Cl2 and CpFe(CO)2 abstracts the dppf ligand from Co(dppf) forming (dppf)CpFeI(CO). Electron transfer from (dppf)CpFeI(CO) to C60 is observed. As a result, the state of {(dppf)CpFe(CO)}δ+(C60)δ−⋅C6H4Cl2 (δ = 0.54–0.86) is intermediate between neutral ((dppf)CpFeI(CO) (S = 1/2) + C60 (S = 0) and ionic ((dppf)CpFeII(CO) (S = 0) + C60•- (S = 1/2)) states. Both paramagnetic (dppf)CpFeI(CO) and C60•− species are manifested in EPR: a broad signal with g1 = 2.0885 and a linewidth (ΔH) of 10.43 mT is from FeI, whereas a narrower signal with g2 = 1.9994 and ΔH = 4.53 mT at room temperature is from C60•−. As a result, the content of both components can be determined from EPR at each temperature. State of the complex is nearly ionic (maximal δ = 0.86) at high temperatures (250–300 K) and decreases to δ = 0.54 at the temperature decrease down to 6 K. The S = 1/2 state of 1 is preserved at such electron transfer to give an effective magnetic moment of 1.82 μB at 300 K. The Weiss temperature of −12 K indicates antiferromagnetic coupling of spins in the loose hexagonal layers of 1 composed of (dppf)CpFe(CO) and C60. Crystal structure and optical properties of 1 were also studied and discussed.

Keywords: фуллерены, Fullerene