Superconducting properties of new heterofullerides synthesized for the first time AnMmHgxC60 (A = K, Rb, Cs; M = Be, Mg, B, Al, Ga, In; n = 1, 2; m = 1, 2; x ≪ 1) were investigated at low temperatures. The low frequency inductive method was used to detect a superconducting transition. All the samples were studied by X-ray diffraction (XRD), solid state nuclear magnetic resonance (NMR), electron spin resonance (ESR), and Raman scattering. It is found that most of the superconducting heterofullerides are potassium heterofullerides. For the fulleride K2GaHgxC60 the critical temperature of the superconducting transition is Tc = 20 K. Indium and boron heterofullerides are not superconductors. The synthesis of heterofullerides via amalgams (Hg–K–Mg, Hg–Rb–Al) gives rise to two different superconducting phases.

The fullerides A(n)M(m)C(60) (A=K, Rb, Cs; M= Be, Mg; B, Al, Ga. In; n=1, 2; m=1, 2) have been synthesized by exchange reactions of alkali metal fullerides with metal chlorides (groups 2 and 13), by method using liquid alloys of metals with mercury (amalgams), and by thermal decomposition of aluminum hydride. The samples are studied by X-ray diffraction, nuclear magnetic resonance, electron paramagnetic resonance, Raman scattering, and differential scanning calorimetry. It was found that the fulleride K2GaC60 is superconductor with transition temperature T-c=22 K that exceeds T-c for K3C60 (19 K). Fullerides with In and B are not supercomductors. The fullerides with composition CsnHgxC60 (n=2;3) are not superconductors and crystallize in orthorhombic lattices.