Degrees of distortion: synthesis, structure and bonding in approximately icosahedral [Ru@Sn12]4−

Abstract

We report here the synthesis and structural characterisation of the [Ru@Sn₁₂]⁴⁻ anion, a new member of the icosahedral M@E₁₂ family of endohedral Zintl clusters. The cluster is approximately icosahedral, but a significant variance in the Ru–Sn and Sn–Sn bond lengths is a result of back-bonding from the Ru center to the Sn₁₂ cage. We use density functional theory to place the structural chemistry of [Ru@Sn₁₂]⁴⁻ into the wider context of the M@E₁₂ family.