Molecular structures of Pr@C72 and Pr@C72(C6H3Cl2): a combined experimental–theoretical investigation

Abstract

A novel Pr-based monometallofullerene derivative, Pr@C₇₂(C₆H₃Cl₂), was successfully prepared and isolated. Its molecular composition was determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The molecular structure of Pr@C₇₂(C₆H₃Cl₂) was verified as Pr@C₂(10612)-C₇₂(C₆H₃Cl₂) by combined UV-visible-near-infrared absorption spectroscopy and quantum mechanics characterization, as well as a comparison with the structurally characterized analogue La@C₇₂(C₆H₃Cl₂). Furthermore, an additional computation indicated that the nonderivatized Pr@C₇₂ has the lowest-lying structure of Pr@C₂(10612)-C₇₂, followed by Pr@C_2v(11188)-C_72, which lies only 0.62 kcal mol⁻¹ above Pr@C₂(10612)-C₇₂. In addition, the temperature dependence of their thermodynamic distribution was estimated. We also analyzed the charge transfer and orbital interaction between the endohedral Pr atom and the carbon cage as well as the electronic configuration and formal charge state of the encapsulated Pr atom based on the computed quantum mechanics data.