Self-Associating Behavior of Acetone in Liquid Krypton

S⋯S and S⋯P chalcogen bonding in solution: a cryospectroscopic study of the complexes of 2,2,4,4-tetrafluoro-1,3-dithietane with dimethyl sulfide and trimethylphosphine

Experimental evidence on the formation of S⋯S and P⋯S chalcogen bonded complexes between 2,2,4,4-tetrafluoro-1,3-dithiethane and the Lewis bases dimethyl sulfide and trimethylphosphine is obtained using infrared spectroscopy of solutions in liquid krypton.

Dimers or trimers? A characterization of the halogen bonded complexes of CF3X (X=I or Br) with dimethyl ether and acetone in cryosolutions

Acetone molecules dissolved in liquid krypton are inclined to self-associate into dimers. This behavior affects its use as a prototype Lewis base in studies of weak intermolecular interactions. In this study infrared spectra of mixed solutions of dimethyl ether and CF₃X and of acetone and CF₃X (with X=I or Br) dissolved in liquid argon and liquid krypton are recorded at constant temperature. The dataset for dimethyl ether is used to validate a numerical method based on least-squares fitting of a model including contributions of both monomers and a heterodimer with 1:1 stoichiometry. The resulting monomer and dimer spectra show excellent agreement with previous studies found in literature. The analysis of the dataset for acetone requires an extension of the model with contributions for the acetone homodimer and for (acetone)₂·CF₃X and acetone·(CF₃X)₂ trimers. The results show that many signals for acetone·CF₃I and (acetone)₂·CF₃I are observed, while only a few bands due to acetone·(CF₃I)₂ occur. The use of numerical approaches adjusted to the specificities of a mixture of two compounds allows to reliably resolve overlapping spectra of monomers and heterocomplexes and characterizing heterocomplex features that could not be deduced using earlier methods. To support the assignments made, ab initio calculations predicting geometries, relative stabilities and harmonic vibrational frequencies for the species envisaged are performed.