Charge controlled changes in the cluster and spin dynamics of Sc3N@C80(CF3)2: the flexible spin density distribution and its impact on ESR spectra

Abstract

Cluster and spin dynamics of a Sc₃N@C₈₀(CF₃)₂ derivative are studied by DFT in different charge states, from −3 to +1. For the neutral Sc₃N@C₈₀(CF₃)₂, static DFT computations of many cluster conformers as well as Born–Oppenheimer molecular dynamics (BOMD) show that addition of two CF₃ groups to Sc₃N@C₈₀ significantly changes dynamics of the Sc₃N cluster: instead of free rotation as in Sc₃N@C₈₀, the cluster in Sc₃N@C₈₀(CF₃)₂ exhibits only hindered motions. Similar cluster dynamics is found in the mono- and trianions of Sc₃N@C₈₀(CF₃)₂, while free rotation of the cluster is found in the cation. In the radical species, motions of the cluster dramatically change spin-density distribution. Spin populations of the metal atoms and the carbon cage are followed along the BOMD trajectories to reveal the details of the spin-flow. ⁴⁵Sc ESR hyperfine coupling constants integrated over BOMD trajectories are found to be substantially different from the results of static DFT computations, which emphasizes that cluster dynamics should be taken into account for reliable predictions of spectroscopic properties.