Coating the fullerene: evaluation of the core–shell interaction nature in a saturated exohedral cuprofullerene†

Abstract

C₆₀ fullerene exhibits a unique structure and properties ideal for forming materials for nanoscale electronic devices. The formation of an exohedral metallofullerene array has been characterized, which reveals a concentric triple core–shell C₆₀@Cu₃₀@Cl₃₆N₁₂ architecture in [C₆₀@Cu₃₀Cl₃₆(Cu(PhCH₂NH₂)₂)₆]⁶⁻ (1), involving saturated coordination over the fullerene surface. The calculated interaction between C₆₀ and the fully coated shell is strong, amounting to −675.4 kcal mol⁻¹, predominantly electrostatic in nature, in contrast to the dispersion-dominated and weaker interaction in the partially coated analogue (−104.5 kcal mol⁻¹). As a result, in 1, thirty Cu–CC interactions exhibit similar coordination characteristics to copper–ethane complexes. The metallic coating induces a symmetry reduction in the C₆₀ cage (from I_h to T_h), giving rise to three distinct ¹³C NMR shifts, and facilitates substantial charge transfer (1.88e⁻) to the fullerene. Notably, a dramatic shift in NICS(0) (−2.08 → −10.9 ppm) reveals a breakdown of the Faraday cage behavior, indicating through-space magnetic shielding effects arising from the outer shell. The fully coated fullerene-based architectures point to tailored modulation of fullerene properties via metal-layer design, advancing prospects for tunable molecular devices.