Polychloride monoanions from [Cl3]- to [Cl9]- : a Raman spectroscopic and quantum chemical investigation.

Polychloride monoanions stabilized by quaternary ammonium salts are investigated using Raman spectroscopy and state-of-the-art quantum-chemical calculations. A regular V-shaped pentachloride is characterized for the [N(Me)4][Cl5] salt, whereas a hockey-stick-like structure is tentatively assigned for [N(Et)4][Cl2⋅⋅⋅Cl3−]. Increasing the size of the cation to the quaternary ammonium salts [NPr4]+ and [NBu4]+ leads to the formation of the [Cl3]− anion. The latter is found to be a pale yellow liquid at about 40 °C, whereas all the other compounds exist as powders. Further to these observations, the novel [Cl9]− anion is characterized by low-temperature Raman spectroscopy in conjunction with quantum-chemical calculations.