Preparation, structure and analysis of the bonding in the molecular entity (OSO)2Li{[AlF(ORF)3]Li[Al(ORF)4]} (RF = C(CF3)3)

Abstract

The (SO₂)₂Li[AlF(OR_F)₃]Li[Al(OR_F)₄] (1) (R_F = C(CF₃)₃) molecular entity was obtained by thermal decomposition of Li[Al(OR_F)₄] followed by crystallization from liquid SO₂. 1, containing two SO₂ molecules η¹-O coordinated to Li⁺, was structurally characterized by single crystal X-ray diffraction and NMR spectroscopy in SO₂(l). Bonding analyses of 1 (bond valency units, AIM analysis, atomic charges, bond orders) show that 1 can be either considered as a Li(OSO)₂⁺ complex stabilized by the large WCA [AlF(OR_F)₃]⁻Li⁺[Al(OR_F)₄]⁻ or as consisting of 2 SO₂, 2 Li⁺, [AlF(OR_F)₃]⁻, and [Al(OR_F)₄]⁻ joined by electrostatic interactions into the discrete molecular entity 1. The bonding between Li⁺ and SO₂ molecules is shown to be almost completely attributable to monopole–induced dipole electrostatic interactions. Theoretical gas phase lithium ion affinity of SO₂ is determined to be stronger than its silver(I) ion affinity owing largely to the shorter lithium SO₂ contacts in the calculated structures that increase the electrostatic interaction.